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cosmopolitan/third_party/stb/stb_image_resize.c

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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/macros.h"
#include "libc/math.h"
#include "libc/mem/mem.h"
#include "libc/str/str.h"
#include "third_party/stb/stb_image_resize.h"
asm(".ident\t\"\\n\\n\
stb_image_resize (Public Domain)\\n\
Credit: Jorge L Rodriguez (@VinoBS), Sean Barrett, et al.\\n\
http://nothings.org/stb\"");
#define STBIR_ASSERT(x) assert(x)
#define STBIR_MALLOC(size, c) ((void)(c), malloc(size))
#define STBIR_FREE(ptr, c) ((void)(c), free(ptr))
#define STBIR__UNUSED_PARAM(v)
#define STBIR__NOTUSED(v)
#define STBIR__ARRAY_SIZE(a) ARRAYLEN(a)
#ifndef STBIR_DEFAULT_FILTER_UPSAMPLE
#define STBIR_DEFAULT_FILTER_UPSAMPLE STBIR_FILTER_CATMULLROM
#endif
#ifndef STBIR_DEFAULT_FILTER_DOWNSAMPLE
#define STBIR_DEFAULT_FILTER_DOWNSAMPLE STBIR_FILTER_MITCHELL
#endif
#ifndef STBIR_PROGRESS_REPORT
#define STBIR_PROGRESS_REPORT(float_0_to_1)
#endif
#ifndef STBIR_MAX_CHANNELS
#define STBIR_MAX_CHANNELS 64
#endif
#if STBIR_MAX_CHANNELS > 65536
#error "Too many channels; STBIR_MAX_CHANNELS must be no more than 65536."
// because we store the indices in 16-bit variables
#endif
// This value is added to alpha just before premultiplication to avoid
// zeroing out color values. It is equivalent to 2^-80. If you don't want
// that behavior (it may interfere if you have floating point images with
// very small alpha values) then you can define STBIR_NO_ALPHA_EPSILON to
// disable it.
#ifndef STBIR_ALPHA_EPSILON
#define STBIR_ALPHA_EPSILON \
((float)1 / (1 << 20) / (1 << 20) / (1 << 20) / (1 << 20))
#endif
// must match stbir_datatype
static unsigned char stbir__type_size[] = {
1, // STBIR_TYPE_UINT8
2, // STBIR_TYPE_UINT16
4, // STBIR_TYPE_UINT32
4, // STBIR_TYPE_FLOAT
};
// Kernel function centered at 0
typedef float(stbir__kernel_fn)(float x, float scale);
typedef float(stbir__support_fn)(float scale);
typedef struct {
stbir__kernel_fn* kernel;
stbir__support_fn* support;
} stbir__filter_info;
// When upsampling, the contributors are which source pixels contribute.
// When downsampling, the contributors are which destination pixels are
// contributed to.
typedef struct {
int n0; // First contributing pixel
int n1; // Last contributing pixel
} stbir__contributors;
typedef struct {
const void* input_data;
int input_w;
int input_h;
int input_stride_bytes;
void* output_data;
int output_w;
int output_h;
int output_stride_bytes;
float s0, t0, s1, t1;
float horizontal_shift; // Units: output pixels
float vertical_shift; // Units: output pixels
float horizontal_scale;
float vertical_scale;
int channels;
int alpha_channel;
uint32_t flags;
stbir_datatype type;
stbir_filter horizontal_filter;
stbir_filter vertical_filter;
stbir_edge edge_horizontal;
stbir_edge edge_vertical;
stbir_colorspace colorspace;
stbir__contributors* horizontal_contributors;
float* horizontal_coefficients;
stbir__contributors* vertical_contributors;
float* vertical_coefficients;
int decode_buffer_pixels;
float* decode_buffer;
float* horizontal_buffer;
// cache these because ceil/floor are inexplicably showing up in profile
int horizontal_coefficient_width;
int vertical_coefficient_width;
int horizontal_filter_pixel_width;
int vertical_filter_pixel_width;
int horizontal_filter_pixel_margin;
int vertical_filter_pixel_margin;
int horizontal_num_contributors;
int vertical_num_contributors;
int ring_buffer_length_bytes; // The length of an individual entry in the
// ring buffer. The total number of ring
// buffers is
// stbir__get_filter_pixel_width(filter)
int ring_buffer_num_entries; // Total number of entries in the ring buffer.
int ring_buffer_first_scanline;
int ring_buffer_last_scanline;
int ring_buffer_begin_index; // first_scanline is at this index in the ring
// buffer
float* ring_buffer;
float* encode_buffer; // A temporary buffer to store floats so we don't lose
// precision while we do multiply-adds.
int horizontal_contributors_size;
int horizontal_coefficients_size;
int vertical_contributors_size;
int vertical_coefficients_size;
int decode_buffer_size;
int horizontal_buffer_size;
int ring_buffer_size;
int encode_buffer_size;
} stbir__info;
static const float stbir__max_uint8_as_float = 255.0f;
static const float stbir__max_uint16_as_float = 65535.0f;
static const double stbir__max_uint32_as_float = 4294967295.0;
forceinline int stbir__min(int a, int b) {
return a < b ? a : b;
}
forceinline float stbir__saturate(float x) {
if (x < 0) return 0;
if (x > 1) return 1;
return x;
}
#ifdef STBIR_SATURATE_INT
forceinline uint8_t stbir__saturate8(int x) {
if ((unsigned int)x <= 255) return x;
if (x < 0) return 0;
return 255;
}
forceinline uint16_t stbir__saturate16(int x) {
if ((unsigned int)x <= 65535) return x;
if (x < 0) return 0;
return 65535;
}
#endif
static float stbir__srgb_uchar_to_linear_float[256] = {
0.000000f, 0.000304f, 0.000607f, 0.000911f, 0.001214f, 0.001518f, 0.001821f,
0.002125f, 0.002428f, 0.002732f, 0.003035f, 0.003347f, 0.003677f, 0.004025f,
0.004391f, 0.004777f, 0.005182f, 0.005605f, 0.006049f, 0.006512f, 0.006995f,
0.007499f, 0.008023f, 0.008568f, 0.009134f, 0.009721f, 0.010330f, 0.010960f,
0.011612f, 0.012286f, 0.012983f, 0.013702f, 0.014444f, 0.015209f, 0.015996f,
0.016807f, 0.017642f, 0.018500f, 0.019382f, 0.020289f, 0.021219f, 0.022174f,
0.023153f, 0.024158f, 0.025187f, 0.026241f, 0.027321f, 0.028426f, 0.029557f,
0.030713f, 0.031896f, 0.033105f, 0.034340f, 0.035601f, 0.036889f, 0.038204f,
0.039546f, 0.040915f, 0.042311f, 0.043735f, 0.045186f, 0.046665f, 0.048172f,
0.049707f, 0.051269f, 0.052861f, 0.054480f, 0.056128f, 0.057805f, 0.059511f,
0.061246f, 0.063010f, 0.064803f, 0.066626f, 0.068478f, 0.070360f, 0.072272f,
0.074214f, 0.076185f, 0.078187f, 0.080220f, 0.082283f, 0.084376f, 0.086500f,
0.088656f, 0.090842f, 0.093059f, 0.095307f, 0.097587f, 0.099899f, 0.102242f,
0.104616f, 0.107023f, 0.109462f, 0.111932f, 0.114435f, 0.116971f, 0.119538f,
0.122139f, 0.124772f, 0.127438f, 0.130136f, 0.132868f, 0.135633f, 0.138432f,
0.141263f, 0.144128f, 0.147027f, 0.149960f, 0.152926f, 0.155926f, 0.158961f,
0.162029f, 0.165132f, 0.168269f, 0.171441f, 0.174647f, 0.177888f, 0.181164f,
0.184475f, 0.187821f, 0.191202f, 0.194618f, 0.198069f, 0.201556f, 0.205079f,
0.208637f, 0.212231f, 0.215861f, 0.219526f, 0.223228f, 0.226966f, 0.230740f,
0.234551f, 0.238398f, 0.242281f, 0.246201f, 0.250158f, 0.254152f, 0.258183f,
0.262251f, 0.266356f, 0.270498f, 0.274677f, 0.278894f, 0.283149f, 0.287441f,
0.291771f, 0.296138f, 0.300544f, 0.304987f, 0.309469f, 0.313989f, 0.318547f,
0.323143f, 0.327778f, 0.332452f, 0.337164f, 0.341914f, 0.346704f, 0.351533f,
0.356400f, 0.361307f, 0.366253f, 0.371238f, 0.376262f, 0.381326f, 0.386430f,
0.391573f, 0.396755f, 0.401978f, 0.407240f, 0.412543f, 0.417885f, 0.423268f,
0.428691f, 0.434154f, 0.439657f, 0.445201f, 0.450786f, 0.456411f, 0.462077f,
0.467784f, 0.473532f, 0.479320f, 0.485150f, 0.491021f, 0.496933f, 0.502887f,
0.508881f, 0.514918f, 0.520996f, 0.527115f, 0.533276f, 0.539480f, 0.545725f,
0.552011f, 0.558340f, 0.564712f, 0.571125f, 0.577581f, 0.584078f, 0.590619f,
0.597202f, 0.603827f, 0.610496f, 0.617207f, 0.623960f, 0.630757f, 0.637597f,
0.644480f, 0.651406f, 0.658375f, 0.665387f, 0.672443f, 0.679543f, 0.686685f,
0.693872f, 0.701102f, 0.708376f, 0.715694f, 0.723055f, 0.730461f, 0.737911f,
0.745404f, 0.752942f, 0.760525f, 0.768151f, 0.775822f, 0.783538f, 0.791298f,
0.799103f, 0.806952f, 0.814847f, 0.822786f, 0.830770f, 0.838799f, 0.846873f,
0.854993f, 0.863157f, 0.871367f, 0.879622f, 0.887923f, 0.896269f, 0.904661f,
0.913099f, 0.921582f, 0.930111f, 0.938686f, 0.947307f, 0.955974f, 0.964686f,
0.973445f, 0.982251f, 0.991102f, 1.0f};
static float stbir__srgb_to_linear(float f) {
if (f <= 0.04045f)
return f / 12.92f;
else
return (float)pow((f + 0.055f) / 1.055f, 2.4f);
}
static float stbir__linear_to_srgb(float f) {
if (f <= 0.0031308f)
return f * 12.92f;
else
return 1.055f * (float)pow(f, 1 / 2.4f) - 0.055f;
}
#ifndef STBIR_NON_IEEE_FLOAT
// From https://gist.github.com/rygorous/2203834
typedef union {
uint32_t u;
float f;
} stbir__FP32;
static const uint32_t fp32_to_srgb8_tab4[104] = {
0x0073000d, 0x007a000d, 0x0080000d, 0x0087000d, 0x008d000d, 0x0094000d,
0x009a000d, 0x00a1000d, 0x00a7001a, 0x00b4001a, 0x00c1001a, 0x00ce001a,
0x00da001a, 0x00e7001a, 0x00f4001a, 0x0101001a, 0x010e0033, 0x01280033,
0x01410033, 0x015b0033, 0x01750033, 0x018f0033, 0x01a80033, 0x01c20033,
0x01dc0067, 0x020f0067, 0x02430067, 0x02760067, 0x02aa0067, 0x02dd0067,
0x03110067, 0x03440067, 0x037800ce, 0x03df00ce, 0x044600ce, 0x04ad00ce,
0x051400ce, 0x057b00c5, 0x05dd00bc, 0x063b00b5, 0x06970158, 0x07420142,
0x07e30130, 0x087b0120, 0x090b0112, 0x09940106, 0x0a1700fc, 0x0a9500f2,
0x0b0f01cb, 0x0bf401ae, 0x0ccb0195, 0x0d950180, 0x0e56016e, 0x0f0d015e,
0x0fbc0150, 0x10630143, 0x11070264, 0x1238023e, 0x1357021d, 0x14660201,
0x156601e9, 0x165a01d3, 0x174401c0, 0x182401af, 0x18fe0331, 0x1a9602fe,
0x1c1502d2, 0x1d7e02ad, 0x1ed4028d, 0x201a0270, 0x21520256, 0x227d0240,
0x239f0443, 0x25c003fe, 0x27bf03c4, 0x29a10392, 0x2b6a0367, 0x2d1d0341,
0x2ebe031f, 0x304d0300, 0x31d105b0, 0x34a80555, 0x37520507, 0x39d504c5,
0x3c37048b, 0x3e7c0458, 0x40a8042a, 0x42bd0401, 0x44c20798, 0x488e071e,
0x4c1c06b6, 0x4f76065d, 0x52a50610, 0x55ac05cc, 0x5892058f, 0x5b590559,
0x5e0c0a23, 0x631c0980, 0x67db08f6, 0x6c55087f, 0x70940818, 0x74a007bd,
0x787d076c, 0x7c330723,
};
static uint8_t stbir__linear_to_srgb_uchar(float in) {
static const stbir__FP32 almostone = {0x3f7fffff}; // 1-eps
static const stbir__FP32 minval = {(127 - 13) << 23};
uint32_t tab, bias, scale, t;
stbir__FP32 f;
// Clamp to [2^(-13), 1-eps]; these two values map to 0 and 1, respectively.
// The tests are carefully written so that NaNs map to 0, same as in the
// reference implementation.
if (!(in > minval.f)) // written this way to catch NaNs
in = minval.f;
if (in > almostone.f) in = almostone.f;
// Do the table lookup and unpack bias, scale
f.f = in;
tab = fp32_to_srgb8_tab4[(f.u - minval.u) >> 20];
bias = (tab >> 16) << 9;
scale = tab & 0xffff;
// Grab next-highest mantissa bits and perform linear interpolation
t = (f.u >> 12) & 0xff;
return (unsigned char)((bias + scale * t) >> 16);
}
#else
// sRGB transition values, scaled by 1<<28
static int stbir__srgb_offset_to_linear_scaled[256] = {
0, 40738, 122216, 203693, 285170, 366648, 448125,
529603, 611080, 692557, 774035, 855852, 942009, 1033024,
1128971, 1229926, 1335959, 1447142, 1563542, 1685229, 1812268,
1944725, 2082664, 2226148, 2375238, 2529996, 2690481, 2856753,
3028870, 3206888, 3390865, 3580856, 3776916, 3979100, 4187460,
4402049, 4622919, 4850123, 5083710, 5323731, 5570236, 5823273,
6082892, 6349140, 6622065, 6901714, 7188133, 7481369, 7781466,
8088471, 8402427, 8723380, 9051372, 9386448, 9728650, 10078021,
10434603, 10798439, 11169569, 11548036, 11933879, 12327139, 12727857,
13136073, 13551826, 13975156, 14406100, 14844697, 15290987, 15745007,
16206795, 16676389, 17153826, 17639142, 18132374, 18633560, 19142734,
19659934, 20185196, 20718552, 21260042, 21809696, 22367554, 22933648,
23508010, 24090680, 24681686, 25281066, 25888850, 26505076, 27129772,
27762974, 28404716, 29055026, 29713942, 30381490, 31057708, 31742624,
32436272, 33138682, 33849884, 34569912, 35298800, 36036568, 36783260,
37538896, 38303512, 39077136, 39859796, 40651528, 41452360, 42262316,
43081432, 43909732, 44747252, 45594016, 46450052, 47315392, 48190064,
49074096, 49967516, 50870356, 51782636, 52704392, 53635648, 54576432,
55526772, 56486700, 57456236, 58435408, 59424248, 60422780, 61431036,
62449032, 63476804, 64514376, 65561776, 66619028, 67686160, 68763192,
69850160, 70947088, 72053992, 73170912, 74297864, 75434880, 76581976,
77739184, 78906536, 80084040, 81271736, 82469648, 83677792, 84896192,
86124888, 87363888, 88613232, 89872928, 91143016, 92423512, 93714432,
95015816, 96327688, 97650056, 98982952, 100326408, 101680440, 103045072,
104420320, 105806224, 107202800, 108610064, 110028048, 111456776, 112896264,
114346544, 115807632, 117279552, 118762328, 120255976, 121760536, 123276016,
124802440, 126339832, 127888216, 129447616, 131018048, 132599544, 134192112,
135795792, 137410592, 139036528, 140673648, 142321952, 143981456, 145652208,
147334208, 149027488, 150732064, 152447968, 154175200, 155913792, 157663776,
159425168, 161197984, 162982240, 164777968, 166585184, 168403904, 170234160,
172075968, 173929344, 175794320, 177670896, 179559120, 181458992, 183370528,
185293776, 187228736, 189175424, 191133888, 193104112, 195086128, 197079968,
199085648, 201103184, 203132592, 205173888, 207227120, 209292272, 211369392,
213458480, 215559568, 217672656, 219797792, 221934976, 224084240, 226245600,
228419056, 230604656, 232802400, 235012320, 237234432, 239468736, 241715280,
243974080, 246245120, 248528464, 250824112, 253132064, 255452368, 257785040,
260130080, 262487520, 264857376, 267239664,
};
static uint8_t stbir__linear_to_srgb_uchar(float f) {
int x = (int)(f * (1 << 28)); // has headroom so you don't need to clamp
int v = 0;
int i;
// Refine the guess with a short binary search.
i = v + 128;
if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
i = v + 64;
if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
i = v + 32;
if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
i = v + 16;
if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
i = v + 8;
if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
i = v + 4;
if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
i = v + 2;
if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
i = v + 1;
if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
return (uint8_t)v;
}
#endif
static float stbir__filter_trapezoid(float x, float scale) {
float halfscale = scale / 2;
float t = 0.5f + halfscale;
STBIR_ASSERT(scale <= 1);
x = (float)fabs(x);
if (x >= t)
return 0;
else {
float r = 0.5f - halfscale;
if (x <= r)
return 1;
else
return (t - x) / scale;
}
}
static float stbir__support_trapezoid(float scale) {
STBIR_ASSERT(scale <= 1);
return 0.5f + scale / 2;
}
static float stbir__filter_triangle(float x, float s) {
STBIR__UNUSED_PARAM(s);
x = (float)fabs(x);
if (x <= 1.0f)
return 1 - x;
else
return 0;
}
static float stbir__filter_cubic(float x, float s) {
STBIR__UNUSED_PARAM(s);
x = (float)fabs(x);
if (x < 1.0f)
return (4 + x * x * (3 * x - 6)) / 6;
else if (x < 2.0f)
return (8 + x * (-12 + x * (6 - x))) / 6;
return (0.0f);
}
static float stbir__filter_catmullrom(float x, float s) {
STBIR__UNUSED_PARAM(s);
x = (float)fabs(x);
if (x < 1.0f)
return 1 - x * x * (2.5f - 1.5f * x);
else if (x < 2.0f)
return 2 - x * (4 + x * (0.5f * x - 2.5f));
return (0.0f);
}
static float stbir__filter_mitchell(float x, float s) {
STBIR__UNUSED_PARAM(s);
x = (float)fabs(x);
if (x < 1.0f)
return (16 + x * x * (21 * x - 36)) / 18;
else if (x < 2.0f)
return (32 + x * (-60 + x * (36 - 7 * x))) / 18;
return (0.0f);
}
static float stbir__support_zero(float s) {
STBIR__UNUSED_PARAM(s);
return 0;
}
static float stbir__support_one(float s) {
STBIR__UNUSED_PARAM(s);
return 1;
}
static float stbir__support_two(float s) {
STBIR__UNUSED_PARAM(s);
return 2;
}
static stbir__filter_info stbir__filter_info_table[] = {
{NULL, stbir__support_zero},
{stbir__filter_trapezoid, stbir__support_trapezoid},
{stbir__filter_triangle, stbir__support_one},
{stbir__filter_cubic, stbir__support_two},
{stbir__filter_catmullrom, stbir__support_two},
{stbir__filter_mitchell, stbir__support_two},
};
forceinline int stbir__use_upsampling(float ratio) {
return ratio > 1;
}
forceinline int stbir__use_width_upsampling(stbir__info* stbir_info) {
return stbir__use_upsampling(stbir_info->horizontal_scale);
}
forceinline int stbir__use_height_upsampling(stbir__info* stbir_info) {
return stbir__use_upsampling(stbir_info->vertical_scale);
}
// This is the maximum number of input samples that can affect an output sample
// with the given filter
static int stbir__get_filter_pixel_width(stbir_filter filter, float scale) {
STBIR_ASSERT(filter != 0);
STBIR_ASSERT(filter < STBIR__ARRAY_SIZE(stbir__filter_info_table));
if (stbir__use_upsampling(scale))
return (int)ceil(stbir__filter_info_table[filter].support(1 / scale) * 2);
else
return (int)ceil(stbir__filter_info_table[filter].support(scale) * 2 /
scale);
}
// This is how much to expand buffers to account for filters seeking outside
// the image boundaries.
static int stbir__get_filter_pixel_margin(stbir_filter filter, float scale) {
return stbir__get_filter_pixel_width(filter, scale) / 2;
}
static int stbir__get_coefficient_width(stbir_filter filter, float scale) {
if (stbir__use_upsampling(scale))
return (int)ceil(stbir__filter_info_table[filter].support(1 / scale) * 2);
else
return (int)ceil(stbir__filter_info_table[filter].support(scale) * 2);
}
static int stbir__get_contributors(float scale, stbir_filter filter,
int input_size, int output_size) {
if (stbir__use_upsampling(scale))
return output_size;
else
return (input_size + stbir__get_filter_pixel_margin(filter, scale) * 2);
}
static int stbir__get_total_horizontal_coefficients(stbir__info* info) {
return info->horizontal_num_contributors *
stbir__get_coefficient_width(info->horizontal_filter,
info->horizontal_scale);
}
static int stbir__get_total_vertical_coefficients(stbir__info* info) {
return info->vertical_num_contributors *
stbir__get_coefficient_width(info->vertical_filter,
info->vertical_scale);
}
static stbir__contributors* stbir__get_contributor(
stbir__contributors* contributors, int n) {
return &contributors[n];
}
// For perf reasons this code is duplicated in
// stbir__resample_horizontal_upsample/downsample, if you change it here change
// it there too.
static float* stbir__get_coefficient(float* coefficients, stbir_filter filter,
float scale, int n, int c) {
int width = stbir__get_coefficient_width(filter, scale);
return &coefficients[width * n + c];
}
static int stbir__edge_wrap_slow(stbir_edge edge, int n, int max) {
switch (edge) {
case STBIR_EDGE_ZERO:
return 0; // we'll decode the wrong pixel here, and then overwrite with
// 0s later
case STBIR_EDGE_CLAMP:
if (n < 0) return 0;
if (n >= max) return max - 1;
return n; // NOTREACHED
case STBIR_EDGE_REFLECT: {
if (n < 0) {
if (n < max)
return -n;
else
return max - 1;
}
if (n >= max) {
int max2 = max * 2;
if (n >= max2)
return 0;
else
return max2 - n - 1;
}
return n; // NOTREACHED
}
case STBIR_EDGE_WRAP:
if (n >= 0)
return (n % max);
else {
int m = (-n) % max;
if (m != 0) m = max - m;
return (m);
}
// NOTREACHED
default:
STBIR_ASSERT(!"Unimplemented edge type");
return 0;
}
}
forceinline int stbir__edge_wrap(stbir_edge edge, int n, int max) {
// avoid per-pixel switch
if (n >= 0 && n < max) return n;
return stbir__edge_wrap_slow(edge, n, max);
}
// What input pixels contribute to this output pixel?
static void stbir__calculate_sample_range_upsample(
int n, float out_filter_radius, float scale_ratio, float out_shift,
int* in_first_pixel, int* in_last_pixel, float* in_center_of_out) {
float out_pixel_center = (float)n + 0.5f;
float out_pixel_influence_lowerbound = out_pixel_center - out_filter_radius;
float out_pixel_influence_upperbound = out_pixel_center + out_filter_radius;
float in_pixel_influence_lowerbound =
(out_pixel_influence_lowerbound + out_shift) / scale_ratio;
float in_pixel_influence_upperbound =
(out_pixel_influence_upperbound + out_shift) / scale_ratio;
*in_center_of_out = (out_pixel_center + out_shift) / scale_ratio;
*in_first_pixel = (int)(floor(in_pixel_influence_lowerbound + 0.5));
*in_last_pixel = (int)(floor(in_pixel_influence_upperbound - 0.5));
}
// What output pixels does this input pixel contribute to?
static void stbir__calculate_sample_range_downsample(
int n, float in_pixels_radius, float scale_ratio, float out_shift,
int* out_first_pixel, int* out_last_pixel, float* out_center_of_in) {
float in_pixel_center = (float)n + 0.5f;
float in_pixel_influence_lowerbound = in_pixel_center - in_pixels_radius;
float in_pixel_influence_upperbound = in_pixel_center + in_pixels_radius;
float out_pixel_influence_lowerbound =
in_pixel_influence_lowerbound * scale_ratio - out_shift;
float out_pixel_influence_upperbound =
in_pixel_influence_upperbound * scale_ratio - out_shift;
*out_center_of_in = in_pixel_center * scale_ratio - out_shift;
*out_first_pixel = (int)(floor(out_pixel_influence_lowerbound + 0.5));
*out_last_pixel = (int)(floor(out_pixel_influence_upperbound - 0.5));
}
static void stbir__calculate_coefficients_upsample(
stbir_filter filter, float scale, int in_first_pixel, int in_last_pixel,
float in_center_of_out, stbir__contributors* contributor,
float* coefficient_group) {
int i;
float total_filter = 0;
float filter_scale;
STBIR_ASSERT(
in_last_pixel - in_first_pixel <=
(int)ceil(stbir__filter_info_table[filter].support(1 / scale) *
2)); // Taken directly from stbir__get_coefficient_width()
// which we can't call because we don't know if we're
// horizontal or vertical.
contributor->n0 = in_first_pixel;
contributor->n1 = in_last_pixel;
STBIR_ASSERT(contributor->n1 >= contributor->n0);
for (i = 0; i <= in_last_pixel - in_first_pixel; i++) {
float in_pixel_center = (float)(i + in_first_pixel) + 0.5f;
coefficient_group[i] = stbir__filter_info_table[filter].kernel(
in_center_of_out - in_pixel_center, 1 / scale);
// If the coefficient is zero, skip it. (Don't do the <0 check here, we want
// the influence of those outside pixels.)
if (i == 0 && !coefficient_group[i]) {
contributor->n0 = ++in_first_pixel;
i--;
continue;
}
total_filter += coefficient_group[i];
}
STBIR_ASSERT(stbir__filter_info_table[filter].kernel(
(float)(in_last_pixel + 1) + 0.5f - in_center_of_out,
1 / scale) == 0);
STBIR_ASSERT(total_filter > 0.9);
STBIR_ASSERT(total_filter < 1.1f); // Make sure it's not way off.
// Make sure the sum of all coefficients is 1.
filter_scale = 1 / total_filter;
for (i = 0; i <= in_last_pixel - in_first_pixel; i++)
coefficient_group[i] *= filter_scale;
for (i = in_last_pixel - in_first_pixel; i >= 0; i--) {
if (coefficient_group[i]) break;
// This line has no weight. We can skip it.
contributor->n1 = contributor->n0 + i - 1;
}
}
static void stbir__calculate_coefficients_downsample(
stbir_filter filter, float scale_ratio, int out_first_pixel,
int out_last_pixel, float out_center_of_in,
stbir__contributors* contributor, float* coefficient_group) {
int i;
STBIR_ASSERT(
out_last_pixel - out_first_pixel <=
(int)ceil(stbir__filter_info_table[filter].support(scale_ratio) *
2)); // Taken directly from stbir__get_coefficient_width()
// which we can't call because we don't know if we're
// horizontal or vertical.
contributor->n0 = out_first_pixel;
contributor->n1 = out_last_pixel;
STBIR_ASSERT(contributor->n1 >= contributor->n0);
for (i = 0; i <= out_last_pixel - out_first_pixel; i++) {
float out_pixel_center = (float)(i + out_first_pixel) + 0.5f;
float x = out_pixel_center - out_center_of_in;
coefficient_group[i] =
stbir__filter_info_table[filter].kernel(x, scale_ratio) * scale_ratio;
}
STBIR_ASSERT(stbir__filter_info_table[filter].kernel(
(float)(out_last_pixel + 1) + 0.5f - out_center_of_in,
scale_ratio) == 0);
for (i = out_last_pixel - out_first_pixel; i >= 0; i--) {
if (coefficient_group[i]) break;
// This line has no weight. We can skip it.
contributor->n1 = contributor->n0 + i - 1;
}
}
static void stbir__normalize_downsample_coefficients(
stbir__contributors* contributors, float* coefficients, stbir_filter filter,
float scale_ratio, int input_size, int output_size) {
int num_contributors =
stbir__get_contributors(scale_ratio, filter, input_size, output_size);
int num_coefficients = stbir__get_coefficient_width(filter, scale_ratio);
int i, j;
int skip;
for (i = 0; i < output_size; i++) {
float scale;
float total = 0;
for (j = 0; j < num_contributors; j++) {
if (i >= contributors[j].n0 && i <= contributors[j].n1) {
float coefficient = *stbir__get_coefficient(
coefficients, filter, scale_ratio, j, i - contributors[j].n0);
total += coefficient;
} else if (i < contributors[j].n0)
break;
}
STBIR_ASSERT(total > 0.9f);
STBIR_ASSERT(total < 1.1f);
scale = 1 / total;
for (j = 0; j < num_contributors; j++) {
if (i >= contributors[j].n0 && i <= contributors[j].n1)
*stbir__get_coefficient(coefficients, filter, scale_ratio, j,
i - contributors[j].n0) *= scale;
else if (i < contributors[j].n0)
break;
}
}
// Optimize: Skip zero coefficients and contributions outside of image bounds.
// Do this after normalizing because normalization depends on the n0/n1
// values.
for (j = 0; j < num_contributors; j++) {
int range, max, width;
skip = 0;
while (*stbir__get_coefficient(coefficients, filter, scale_ratio, j,
skip) == 0)
skip++;
contributors[j].n0 += skip;
while (contributors[j].n0 < 0) {
contributors[j].n0++;
skip++;
}
range = contributors[j].n1 - contributors[j].n0 + 1;
max = stbir__min(num_coefficients, range);
width = stbir__get_coefficient_width(filter, scale_ratio);
for (i = 0; i < max; i++) {
if (i + skip >= width) break;
*stbir__get_coefficient(coefficients, filter, scale_ratio, j, i) =
*stbir__get_coefficient(coefficients, filter, scale_ratio, j,
i + skip);
}
continue;
}
// Using min to avoid writing into invalid pixels.
for (i = 0; i < num_contributors; i++)
contributors[i].n1 = stbir__min(contributors[i].n1, output_size - 1);
}
// Each scan line uses the same kernel values so we should calculate the kernel
// values once and then we can use them for every scan line.
static void stbir__calculate_filters(stbir__contributors* contributors,
float* coefficients, stbir_filter filter,
float scale_ratio, float shift,
int input_size, int output_size) {
int n;
int total_contributors =
stbir__get_contributors(scale_ratio, filter, input_size, output_size);
if (stbir__use_upsampling(scale_ratio)) {
float out_pixels_radius =
stbir__filter_info_table[filter].support(1 / scale_ratio) * scale_ratio;
// Looping through out pixels
for (n = 0; n < total_contributors; n++) {
float in_center_of_out; // Center of the current out pixel in the in
// pixel space
int in_first_pixel, in_last_pixel;
stbir__calculate_sample_range_upsample(n, out_pixels_radius, scale_ratio,
shift, &in_first_pixel,
&in_last_pixel, &in_center_of_out);
stbir__calculate_coefficients_upsample(
filter, scale_ratio, in_first_pixel, in_last_pixel, in_center_of_out,
stbir__get_contributor(contributors, n),
stbir__get_coefficient(coefficients, filter, scale_ratio, n, 0));
}
} else {
float in_pixels_radius =
stbir__filter_info_table[filter].support(scale_ratio) / scale_ratio;
// Looping through in pixels
for (n = 0; n < total_contributors; n++) {
float out_center_of_in; // Center of the current out pixel in the in
// pixel space
int out_first_pixel, out_last_pixel;
int n_adjusted = n - stbir__get_filter_pixel_margin(filter, scale_ratio);
stbir__calculate_sample_range_downsample(
n_adjusted, in_pixels_radius, scale_ratio, shift, &out_first_pixel,
&out_last_pixel, &out_center_of_in);
stbir__calculate_coefficients_downsample(
filter, scale_ratio, out_first_pixel, out_last_pixel,
out_center_of_in, stbir__get_contributor(contributors, n),
stbir__get_coefficient(coefficients, filter, scale_ratio, n, 0));
}
stbir__normalize_downsample_coefficients(contributors, coefficients, filter,
scale_ratio, input_size,
output_size);
}
}
static float* stbir__get_decode_buffer(stbir__info* stbir_info) {
// The 0 index of the decode buffer starts after the margin. This makes
// it okay to use negative indexes on the decode buffer.
return &stbir_info->decode_buffer[stbir_info->horizontal_filter_pixel_margin *
stbir_info->channels];
}
#define STBIR__DECODE(type, colorspace) \
((type) * (STBIR_MAX_COLORSPACES) + (colorspace))
static optimizespeed void stbir__decode_scanline(stbir__info* stbir_info,
int n) {
int c;
int channels = stbir_info->channels;
int alpha_channel = stbir_info->alpha_channel;
int type = stbir_info->type;
int colorspace = stbir_info->colorspace;
int input_w = stbir_info->input_w;
size_t input_stride_bytes = stbir_info->input_stride_bytes;
float* decode_buffer = stbir__get_decode_buffer(stbir_info);
stbir_edge edge_horizontal = stbir_info->edge_horizontal;
stbir_edge edge_vertical = stbir_info->edge_vertical;
size_t in_buffer_row_offset =
stbir__edge_wrap(edge_vertical, n, stbir_info->input_h) *
input_stride_bytes;
const void* input_data = (char*)stbir_info->input_data + in_buffer_row_offset;
int max_x = input_w + stbir_info->horizontal_filter_pixel_margin;
int decode = STBIR__DECODE(type, colorspace);
int x = -stbir_info->horizontal_filter_pixel_margin;
// special handling for STBIR_EDGE_ZERO because it needs to return an item
// that doesn't appear in the input, and we want to avoid paying overhead on
// every pixel if not STBIR_EDGE_ZERO
if (edge_vertical == STBIR_EDGE_ZERO && (n < 0 || n >= stbir_info->input_h)) {
for (; x < max_x; x++)
for (c = 0; c < channels; c++) decode_buffer[x * channels + c] = 0;
return;
}
switch (decode) {
case STBIR__DECODE(STBIR_TYPE_UINT8, STBIR_COLORSPACE_LINEAR):
for (; x < max_x; x++) {
int decode_pixel_index = x * channels;
int input_pixel_index =
stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
for (c = 0; c < channels; c++)
decode_buffer[decode_pixel_index + c] =
((float)((
const unsigned char*)input_data)[input_pixel_index + c]) /
stbir__max_uint8_as_float;
}
break;
case STBIR__DECODE(STBIR_TYPE_UINT8, STBIR_COLORSPACE_SRGB):
for (; x < max_x; x++) {
int decode_pixel_index = x * channels;
int input_pixel_index =
stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
for (c = 0; c < channels; c++)
decode_buffer[decode_pixel_index + c] =
stbir__srgb_uchar_to_linear_float[(
(const unsigned char*)input_data)[input_pixel_index + c]];
if (!(stbir_info->flags & STBIR_FLAG_ALPHA_USES_COLORSPACE))
decode_buffer[decode_pixel_index + alpha_channel] =
((float)((const unsigned char*)
input_data)[input_pixel_index + alpha_channel]) /
stbir__max_uint8_as_float;
}
break;
case STBIR__DECODE(STBIR_TYPE_UINT16, STBIR_COLORSPACE_LINEAR):
for (; x < max_x; x++) {
int decode_pixel_index = x * channels;
int input_pixel_index =
stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
for (c = 0; c < channels; c++)
decode_buffer[decode_pixel_index + c] =
((float)((
const unsigned short*)input_data)[input_pixel_index + c]) /
stbir__max_uint16_as_float;
}
break;
case STBIR__DECODE(STBIR_TYPE_UINT16, STBIR_COLORSPACE_SRGB):
for (; x < max_x; x++) {
int decode_pixel_index = x * channels;
int input_pixel_index =
stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
for (c = 0; c < channels; c++)
decode_buffer[decode_pixel_index + c] = stbir__srgb_to_linear(
((float)((
const unsigned short*)input_data)[input_pixel_index + c]) /
stbir__max_uint16_as_float);
if (!(stbir_info->flags & STBIR_FLAG_ALPHA_USES_COLORSPACE))
decode_buffer[decode_pixel_index + alpha_channel] =
((float)((const unsigned short*)
input_data)[input_pixel_index + alpha_channel]) /
stbir__max_uint16_as_float;
}
break;
case STBIR__DECODE(STBIR_TYPE_UINT32, STBIR_COLORSPACE_LINEAR):
for (; x < max_x; x++) {
int decode_pixel_index = x * channels;
int input_pixel_index =
stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
for (c = 0; c < channels; c++)
decode_buffer[decode_pixel_index + c] =
(float)(((double)((const unsigned int*)
input_data)[input_pixel_index + c]) /
stbir__max_uint32_as_float);
}
break;
case STBIR__DECODE(STBIR_TYPE_UINT32, STBIR_COLORSPACE_SRGB):
for (; x < max_x; x++) {
int decode_pixel_index = x * channels;
int input_pixel_index =
stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
for (c = 0; c < channels; c++)
decode_buffer[decode_pixel_index + c] = stbir__srgb_to_linear(
(float)(((double)((const unsigned int*)
input_data)[input_pixel_index + c]) /
stbir__max_uint32_as_float));
if (!(stbir_info->flags & STBIR_FLAG_ALPHA_USES_COLORSPACE))
decode_buffer[decode_pixel_index + alpha_channel] =
(float)(((double)((
const unsigned int*)input_data)[input_pixel_index +
alpha_channel]) /
stbir__max_uint32_as_float);
}
break;
case STBIR__DECODE(STBIR_TYPE_FLOAT, STBIR_COLORSPACE_LINEAR):
for (; x < max_x; x++) {
int decode_pixel_index = x * channels;
int input_pixel_index =
stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
for (c = 0; c < channels; c++)
decode_buffer[decode_pixel_index + c] =
((const float*)input_data)[input_pixel_index + c];
}
break;
case STBIR__DECODE(STBIR_TYPE_FLOAT, STBIR_COLORSPACE_SRGB):
for (; x < max_x; x++) {
int decode_pixel_index = x * channels;
int input_pixel_index =
stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
for (c = 0; c < channels; c++)
decode_buffer[decode_pixel_index + c] = stbir__srgb_to_linear(
((const float*)input_data)[input_pixel_index + c]);
if (!(stbir_info->flags & STBIR_FLAG_ALPHA_USES_COLORSPACE))
decode_buffer[decode_pixel_index + alpha_channel] =
((const float*)input_data)[input_pixel_index + alpha_channel];
}
break;
default:
STBIR_ASSERT(!"Unknown type/colorspace/channels combination.");
break;
}
if (!(stbir_info->flags & STBIR_FLAG_ALPHA_PREMULTIPLIED)) {
for (x = -stbir_info->horizontal_filter_pixel_margin; x < max_x; x++) {
int decode_pixel_index = x * channels;
// If the alpha value is 0 it will clobber the color values. Make sure
// it's not.
float alpha = decode_buffer[decode_pixel_index + alpha_channel];
#ifndef STBIR_NO_ALPHA_EPSILON
if (stbir_info->type != STBIR_TYPE_FLOAT) {
alpha += STBIR_ALPHA_EPSILON;
decode_buffer[decode_pixel_index + alpha_channel] = alpha;
}
#endif
for (c = 0; c < channels; c++) {
if (c == alpha_channel) continue;
decode_buffer[decode_pixel_index + c] *= alpha;
}
}
}
if (edge_horizontal == STBIR_EDGE_ZERO) {
for (x = -stbir_info->horizontal_filter_pixel_margin; x < 0; x++) {
for (c = 0; c < channels; c++) decode_buffer[x * channels + c] = 0;
}
for (x = input_w; x < max_x; x++) {
for (c = 0; c < channels; c++) decode_buffer[x * channels + c] = 0;
}
}
}
static float* stbir__get_ring_buffer_entry(float* ring_buffer, int index,
int ring_buffer_length) {
return &ring_buffer[index * ring_buffer_length];
}
static float* stbir__add_empty_ring_buffer_entry(stbir__info* stbir_info,
int n) {
int ring_buffer_index;
float* ring_buffer;
stbir_info->ring_buffer_last_scanline = n;
if (stbir_info->ring_buffer_begin_index < 0) {
ring_buffer_index = stbir_info->ring_buffer_begin_index = 0;
stbir_info->ring_buffer_first_scanline = n;
} else {
ring_buffer_index = (stbir_info->ring_buffer_begin_index +
(stbir_info->ring_buffer_last_scanline -
stbir_info->ring_buffer_first_scanline)) %
stbir_info->ring_buffer_num_entries;
STBIR_ASSERT(ring_buffer_index != stbir_info->ring_buffer_begin_index);
}
ring_buffer = stbir__get_ring_buffer_entry(
stbir_info->ring_buffer, ring_buffer_index,
stbir_info->ring_buffer_length_bytes / sizeof(float));
memset(ring_buffer, 0, stbir_info->ring_buffer_length_bytes);
return ring_buffer;
}
static void stbir__resample_horizontal_upsample(stbir__info* stbir_info,
float* output_buffer) {
int x, k;
int output_w = stbir_info->output_w;
int channels = stbir_info->channels;
float* decode_buffer = stbir__get_decode_buffer(stbir_info);
stbir__contributors* horizontal_contributors =
stbir_info->horizontal_contributors;
float* horizontal_coefficients = stbir_info->horizontal_coefficients;
int coefficient_width = stbir_info->horizontal_coefficient_width;
for (x = 0; x < output_w; x++) {
int n0 = horizontal_contributors[x].n0;
int n1 = horizontal_contributors[x].n1;
int out_pixel_index = x * channels;
int coefficient_group = coefficient_width * x;
int coefficient_counter = 0;
STBIR_ASSERT(n1 >= n0);
STBIR_ASSERT(n0 >= -stbir_info->horizontal_filter_pixel_margin);
STBIR_ASSERT(n1 >= -stbir_info->horizontal_filter_pixel_margin);
STBIR_ASSERT(n0 < stbir_info->input_w +
stbir_info->horizontal_filter_pixel_margin);
STBIR_ASSERT(n1 < stbir_info->input_w +
stbir_info->horizontal_filter_pixel_margin);
switch (channels) {
case 1:
for (k = n0; k <= n1; k++) {
int in_pixel_index = k * 1;
float coefficient = horizontal_coefficients[coefficient_group +
coefficient_counter++];
STBIR_ASSERT(coefficient != 0);
output_buffer[out_pixel_index + 0] +=
decode_buffer[in_pixel_index + 0] * coefficient;
}
break;
case 2:
for (k = n0; k <= n1; k++) {
int in_pixel_index = k * 2;
float coefficient = horizontal_coefficients[coefficient_group +
coefficient_counter++];
STBIR_ASSERT(coefficient != 0);
output_buffer[out_pixel_index + 0] +=
decode_buffer[in_pixel_index + 0] * coefficient;
output_buffer[out_pixel_index + 1] +=
decode_buffer[in_pixel_index + 1] * coefficient;
}
break;
case 3:
for (k = n0; k <= n1; k++) {
int in_pixel_index = k * 3;
float coefficient = horizontal_coefficients[coefficient_group +
coefficient_counter++];
STBIR_ASSERT(coefficient != 0);
output_buffer[out_pixel_index + 0] +=
decode_buffer[in_pixel_index + 0] * coefficient;
output_buffer[out_pixel_index + 1] +=
decode_buffer[in_pixel_index + 1] * coefficient;
output_buffer[out_pixel_index + 2] +=
decode_buffer[in_pixel_index + 2] * coefficient;
}
break;
case 4:
for (k = n0; k <= n1; k++) {
int in_pixel_index = k * 4;
float coefficient = horizontal_coefficients[coefficient_group +
coefficient_counter++];
STBIR_ASSERT(coefficient != 0);
output_buffer[out_pixel_index + 0] +=
decode_buffer[in_pixel_index + 0] * coefficient;
output_buffer[out_pixel_index + 1] +=
decode_buffer[in_pixel_index + 1] * coefficient;
output_buffer[out_pixel_index + 2] +=
decode_buffer[in_pixel_index + 2] * coefficient;
output_buffer[out_pixel_index + 3] +=
decode_buffer[in_pixel_index + 3] * coefficient;
}
break;
default:
for (k = n0; k <= n1; k++) {
int in_pixel_index = k * channels;
float coefficient = horizontal_coefficients[coefficient_group +
coefficient_counter++];
int c;
STBIR_ASSERT(coefficient != 0);
for (c = 0; c < channels; c++)
output_buffer[out_pixel_index + c] +=
decode_buffer[in_pixel_index + c] * coefficient;
}
break;
}
}
}
static void stbir__resample_horizontal_downsample(stbir__info* stbir_info,
float* output_buffer) {
int x, k;
int input_w = stbir_info->input_w;
int channels = stbir_info->channels;
float* decode_buffer = stbir__get_decode_buffer(stbir_info);
stbir__contributors* horizontal_contributors =
stbir_info->horizontal_contributors;
float* horizontal_coefficients = stbir_info->horizontal_coefficients;
int coefficient_width = stbir_info->horizontal_coefficient_width;
int filter_pixel_margin = stbir_info->horizontal_filter_pixel_margin;
int max_x = input_w + filter_pixel_margin * 2;
STBIR_ASSERT(!stbir__use_width_upsampling(stbir_info));
switch (channels) {
case 1:
for (x = 0; x < max_x; x++) {
int n0 = horizontal_contributors[x].n0;
int n1 = horizontal_contributors[x].n1;
int in_x = x - filter_pixel_margin;
int in_pixel_index = in_x * 1;
int max_n = n1;
int coefficient_group = coefficient_width * x;
for (k = n0; k <= max_n; k++) {
int out_pixel_index = k * 1;
float coefficient =
horizontal_coefficients[coefficient_group + k - n0];
STBIR_ASSERT(coefficient != 0);
output_buffer[out_pixel_index + 0] +=
decode_buffer[in_pixel_index + 0] * coefficient;
}
}
break;
case 2:
for (x = 0; x < max_x; x++) {
int n0 = horizontal_contributors[x].n0;
int n1 = horizontal_contributors[x].n1;
int in_x = x - filter_pixel_margin;
int in_pixel_index = in_x * 2;
int max_n = n1;
int coefficient_group = coefficient_width * x;
for (k = n0; k <= max_n; k++) {
int out_pixel_index = k * 2;
float coefficient =
horizontal_coefficients[coefficient_group + k - n0];
STBIR_ASSERT(coefficient != 0);
output_buffer[out_pixel_index + 0] +=
decode_buffer[in_pixel_index + 0] * coefficient;
output_buffer[out_pixel_index + 1] +=
decode_buffer[in_pixel_index + 1] * coefficient;
}
}
break;
case 3:
for (x = 0; x < max_x; x++) {
int n0 = horizontal_contributors[x].n0;
int n1 = horizontal_contributors[x].n1;
int in_x = x - filter_pixel_margin;
int in_pixel_index = in_x * 3;
int max_n = n1;
int coefficient_group = coefficient_width * x;
for (k = n0; k <= max_n; k++) {
int out_pixel_index = k * 3;
float coefficient =
horizontal_coefficients[coefficient_group + k - n0];
STBIR_ASSERT(coefficient != 0);
output_buffer[out_pixel_index + 0] +=
decode_buffer[in_pixel_index + 0] * coefficient;
output_buffer[out_pixel_index + 1] +=
decode_buffer[in_pixel_index + 1] * coefficient;
output_buffer[out_pixel_index + 2] +=
decode_buffer[in_pixel_index + 2] * coefficient;
}
}
break;
case 4:
for (x = 0; x < max_x; x++) {
int n0 = horizontal_contributors[x].n0;
int n1 = horizontal_contributors[x].n1;
int in_x = x - filter_pixel_margin;
int in_pixel_index = in_x * 4;
int max_n = n1;
int coefficient_group = coefficient_width * x;
for (k = n0; k <= max_n; k++) {
int out_pixel_index = k * 4;
float coefficient =
horizontal_coefficients[coefficient_group + k - n0];
STBIR_ASSERT(coefficient != 0);
output_buffer[out_pixel_index + 0] +=
decode_buffer[in_pixel_index + 0] * coefficient;
output_buffer[out_pixel_index + 1] +=
decode_buffer[in_pixel_index + 1] * coefficient;
output_buffer[out_pixel_index + 2] +=
decode_buffer[in_pixel_index + 2] * coefficient;
output_buffer[out_pixel_index + 3] +=
decode_buffer[in_pixel_index + 3] * coefficient;
}
}
break;
default:
for (x = 0; x < max_x; x++) {
int n0 = horizontal_contributors[x].n0;
int n1 = horizontal_contributors[x].n1;
int in_x = x - filter_pixel_margin;
int in_pixel_index = in_x * channels;
int max_n = n1;
int coefficient_group = coefficient_width * x;
for (k = n0; k <= max_n; k++) {
int c;
int out_pixel_index = k * channels;
float coefficient =
horizontal_coefficients[coefficient_group + k - n0];
STBIR_ASSERT(coefficient != 0);
for (c = 0; c < channels; c++)
output_buffer[out_pixel_index + c] +=
decode_buffer[in_pixel_index + c] * coefficient;
}
}
break;
}
}
static void stbir__decode_and_resample_upsample(stbir__info* stbir_info,
int n) {
// Decode the nth scanline from the source image into the decode buffer.
stbir__decode_scanline(stbir_info, n);
// Now resample it into the ring buffer.
if (stbir__use_width_upsampling(stbir_info))
stbir__resample_horizontal_upsample(
stbir_info, stbir__add_empty_ring_buffer_entry(stbir_info, n));
else
stbir__resample_horizontal_downsample(
stbir_info, stbir__add_empty_ring_buffer_entry(stbir_info, n));
// Now it's sitting in the ring buffer ready to be used as source for the
// vertical sampling.
}
static void stbir__decode_and_resample_downsample(stbir__info* stbir_info,
int n) {
// Decode the nth scanline from the source image into the decode buffer.
stbir__decode_scanline(stbir_info, n);
memset(stbir_info->horizontal_buffer, 0,
stbir_info->output_w * stbir_info->channels * sizeof(float));
// Now resample it into the horizontal buffer.
if (stbir__use_width_upsampling(stbir_info))
stbir__resample_horizontal_upsample(stbir_info,
stbir_info->horizontal_buffer);
else
stbir__resample_horizontal_downsample(stbir_info,
stbir_info->horizontal_buffer);
// Now it's sitting in the horizontal buffer ready to be distributed into the
// ring buffers.
}
// Get the specified scan line from the ring buffer.
static float* stbir__get_ring_buffer_scanline(
int get_scanline, float* ring_buffer, int begin_index, int first_scanline,
int ring_buffer_num_entries, int ring_buffer_length) {
int ring_buffer_index =
(begin_index + (get_scanline - first_scanline)) % ring_buffer_num_entries;
return stbir__get_ring_buffer_entry(ring_buffer, ring_buffer_index,
ring_buffer_length);
}
static void stbir__encode_scanline(stbir__info* stbir_info, int num_pixels,
void* output_buffer, float* encode_buffer,
int channels, int alpha_channel,
int decode) {
int x;
int n;
int num_nonalpha;
uint16_t nonalpha[STBIR_MAX_CHANNELS];
if (!(stbir_info->flags & STBIR_FLAG_ALPHA_PREMULTIPLIED)) {
for (x = 0; x < num_pixels; ++x) {
int pixel_index = x * channels;
float alpha = encode_buffer[pixel_index + alpha_channel];
float reciprocal_alpha = alpha ? 1.0f / alpha : 0;
// unrolling this produced a 1% slowdown upscaling a large RGBA
// linear-space image on my machine - stb
for (n = 0; n < channels; n++)
if (n != alpha_channel)
encode_buffer[pixel_index + n] *= reciprocal_alpha;
// We added in a small epsilon to prevent the color channel from being
// deleted with zero alpha. Because we only add it for integer types, it
// will automatically be discarded on integer conversion, so we don't need
// to subtract it back out (which would be problematic for numeric
// precision reasons).
}
}
// build a table of all channels that need colorspace correction, so
// we don't perform colorspace correction on channels that don't need it.
for (x = 0, num_nonalpha = 0; x < channels; ++x) {
if (x != alpha_channel ||
(stbir_info->flags & STBIR_FLAG_ALPHA_USES_COLORSPACE)) {
nonalpha[num_nonalpha++] = (uint16_t)x;
}
}
#define STBIR__ROUND_INT(f) ((int)((f) + 0.5))
#define STBIR__ROUND_UINT(f) ((uint32_t)((f) + 0.5))
#ifdef STBIR__SATURATE_INT
#define STBIR__ENCODE_LINEAR8(f) \
stbir__saturate8(STBIR__ROUND_INT((f)*stbir__max_uint8_as_float))
#define STBIR__ENCODE_LINEAR16(f) \
stbir__saturate16(STBIR__ROUND_INT((f)*stbir__max_uint16_as_float))
#else
#define STBIR__ENCODE_LINEAR8(f) \
(unsigned char)STBIR__ROUND_INT(stbir__saturate(f) * \
stbir__max_uint8_as_float)
#define STBIR__ENCODE_LINEAR16(f) \
(unsigned short)STBIR__ROUND_INT(stbir__saturate(f) * \
stbir__max_uint16_as_float)
#endif
switch (decode) {
case STBIR__DECODE(STBIR_TYPE_UINT8, STBIR_COLORSPACE_LINEAR):
for (x = 0; x < num_pixels; ++x) {
int pixel_index = x * channels;
for (n = 0; n < channels; n++) {
int index = pixel_index + n;
((unsigned char*)output_buffer)[index] =
STBIR__ENCODE_LINEAR8(encode_buffer[index]);
}
}
break;
case STBIR__DECODE(STBIR_TYPE_UINT8, STBIR_COLORSPACE_SRGB):
for (x = 0; x < num_pixels; ++x) {
int pixel_index = x * channels;
for (n = 0; n < num_nonalpha; n++) {
int index = pixel_index + nonalpha[n];
((unsigned char*)output_buffer)[index] =
stbir__linear_to_srgb_uchar(encode_buffer[index]);
}
if (!(stbir_info->flags & STBIR_FLAG_ALPHA_USES_COLORSPACE))
((unsigned char*)output_buffer)[pixel_index + alpha_channel] =
STBIR__ENCODE_LINEAR8(encode_buffer[pixel_index + alpha_channel]);
}
break;
case STBIR__DECODE(STBIR_TYPE_UINT16, STBIR_COLORSPACE_LINEAR):
for (x = 0; x < num_pixels; ++x) {
int pixel_index = x * channels;
for (n = 0; n < channels; n++) {
int index = pixel_index + n;
((unsigned short*)output_buffer)[index] =
STBIR__ENCODE_LINEAR16(encode_buffer[index]);
}
}
break;
case STBIR__DECODE(STBIR_TYPE_UINT16, STBIR_COLORSPACE_SRGB):
for (x = 0; x < num_pixels; ++x) {
int pixel_index = x * channels;
for (n = 0; n < num_nonalpha; n++) {
int index = pixel_index + nonalpha[n];
((unsigned short*)output_buffer)[index] =
(unsigned short)STBIR__ROUND_INT(
stbir__linear_to_srgb(stbir__saturate(encode_buffer[index])) *
stbir__max_uint16_as_float);
}
if (!(stbir_info->flags & STBIR_FLAG_ALPHA_USES_COLORSPACE))
((unsigned short*)output_buffer)[pixel_index + alpha_channel] =
STBIR__ENCODE_LINEAR16(
encode_buffer[pixel_index + alpha_channel]);
}
break;
case STBIR__DECODE(STBIR_TYPE_UINT32, STBIR_COLORSPACE_LINEAR):
for (x = 0; x < num_pixels; ++x) {
int pixel_index = x * channels;
for (n = 0; n < channels; n++) {
int index = pixel_index + n;
((unsigned int*)output_buffer)[index] =
(unsigned int)STBIR__ROUND_UINT(
((double)stbir__saturate(encode_buffer[index])) *
stbir__max_uint32_as_float);
}
}
break;
case STBIR__DECODE(STBIR_TYPE_UINT32, STBIR_COLORSPACE_SRGB):
for (x = 0; x < num_pixels; ++x) {
int pixel_index = x * channels;
for (n = 0; n < num_nonalpha; n++) {
int index = pixel_index + nonalpha[n];
((unsigned int*)output_buffer)[index] =
(unsigned int)STBIR__ROUND_UINT(
((double)stbir__linear_to_srgb(
stbir__saturate(encode_buffer[index]))) *
stbir__max_uint32_as_float);
}
if (!(stbir_info->flags & STBIR_FLAG_ALPHA_USES_COLORSPACE))
((unsigned int*)output_buffer)[pixel_index + alpha_channel] =
(unsigned int)STBIR__ROUND_INT(
((double)stbir__saturate(
encode_buffer[pixel_index + alpha_channel])) *
stbir__max_uint32_as_float);
}
break;
case STBIR__DECODE(STBIR_TYPE_FLOAT, STBIR_COLORSPACE_LINEAR):
for (x = 0; x < num_pixels; ++x) {
int pixel_index = x * channels;
for (n = 0; n < channels; n++) {
int index = pixel_index + n;
((float*)output_buffer)[index] = encode_buffer[index];
}
}
break;
case STBIR__DECODE(STBIR_TYPE_FLOAT, STBIR_COLORSPACE_SRGB):
for (x = 0; x < num_pixels; ++x) {
int pixel_index = x * channels;
for (n = 0; n < num_nonalpha; n++) {
int index = pixel_index + nonalpha[n];
((float*)output_buffer)[index] =
stbir__linear_to_srgb(encode_buffer[index]);
}
if (!(stbir_info->flags & STBIR_FLAG_ALPHA_USES_COLORSPACE))
((float*)output_buffer)[pixel_index + alpha_channel] =
encode_buffer[pixel_index + alpha_channel];
}
break;
default:
STBIR_ASSERT(!"Unknown type/colorspace/channels combination.");
break;
}
}
static void stbir__resample_vertical_upsample(stbir__info* stbir_info, int n) {
int x, k;
int output_w = stbir_info->output_w;
stbir__contributors* vertical_contributors =
stbir_info->vertical_contributors;
float* vertical_coefficients = stbir_info->vertical_coefficients;
int channels = stbir_info->channels;
int alpha_channel = stbir_info->alpha_channel;
int type = stbir_info->type;
int colorspace = stbir_info->colorspace;
int ring_buffer_entries = stbir_info->ring_buffer_num_entries;
void* output_data = stbir_info->output_data;
float* encode_buffer = stbir_info->encode_buffer;
int decode = STBIR__DECODE(type, colorspace);
int coefficient_width = stbir_info->vertical_coefficient_width;
int coefficient_counter;
int contributor = n;
float* ring_buffer = stbir_info->ring_buffer;
int ring_buffer_begin_index = stbir_info->ring_buffer_begin_index;
int ring_buffer_first_scanline = stbir_info->ring_buffer_first_scanline;
int ring_buffer_length = stbir_info->ring_buffer_length_bytes / sizeof(float);
int n0, n1, output_row_start;
int coefficient_group = coefficient_width * contributor;
n0 = vertical_contributors[contributor].n0;
n1 = vertical_contributors[contributor].n1;
output_row_start = n * stbir_info->output_stride_bytes;
STBIR_ASSERT(stbir__use_height_upsampling(stbir_info));
memset(encode_buffer, 0, output_w * sizeof(float) * channels);
// I tried reblocking this for better cache usage of encode_buffer
// (using x_outer, k, x_inner), but it lost speed. -- stb
coefficient_counter = 0;
switch (channels) {
case 1:
for (k = n0; k <= n1; k++) {
int coefficient_index = coefficient_counter++;
float* ring_buffer_entry = stbir__get_ring_buffer_scanline(
k, ring_buffer, ring_buffer_begin_index, ring_buffer_first_scanline,
ring_buffer_entries, ring_buffer_length);
float coefficient =
vertical_coefficients[coefficient_group + coefficient_index];
for (x = 0; x < output_w; ++x) {
int in_pixel_index = x * 1;
encode_buffer[in_pixel_index + 0] +=
ring_buffer_entry[in_pixel_index + 0] * coefficient;
}
}
break;
case 2:
for (k = n0; k <= n1; k++) {
int coefficient_index = coefficient_counter++;
float* ring_buffer_entry = stbir__get_ring_buffer_scanline(
k, ring_buffer, ring_buffer_begin_index, ring_buffer_first_scanline,
ring_buffer_entries, ring_buffer_length);
float coefficient =
vertical_coefficients[coefficient_group + coefficient_index];
for (x = 0; x < output_w; ++x) {
int in_pixel_index = x * 2;
encode_buffer[in_pixel_index + 0] +=
ring_buffer_entry[in_pixel_index + 0] * coefficient;
encode_buffer[in_pixel_index + 1] +=
ring_buffer_entry[in_pixel_index + 1] * coefficient;
}
}
break;
case 3:
for (k = n0; k <= n1; k++) {
int coefficient_index = coefficient_counter++;
float* ring_buffer_entry = stbir__get_ring_buffer_scanline(
k, ring_buffer, ring_buffer_begin_index, ring_buffer_first_scanline,
ring_buffer_entries, ring_buffer_length);
float coefficient =
vertical_coefficients[coefficient_group + coefficient_index];
for (x = 0; x < output_w; ++x) {
int in_pixel_index = x * 3;
encode_buffer[in_pixel_index + 0] +=
ring_buffer_entry[in_pixel_index + 0] * coefficient;
encode_buffer[in_pixel_index + 1] +=
ring_buffer_entry[in_pixel_index + 1] * coefficient;
encode_buffer[in_pixel_index + 2] +=
ring_buffer_entry[in_pixel_index + 2] * coefficient;
}
}
break;
case 4:
for (k = n0; k <= n1; k++) {
int coefficient_index = coefficient_counter++;
float* ring_buffer_entry = stbir__get_ring_buffer_scanline(
k, ring_buffer, ring_buffer_begin_index, ring_buffer_first_scanline,
ring_buffer_entries, ring_buffer_length);
float coefficient =
vertical_coefficients[coefficient_group + coefficient_index];
for (x = 0; x < output_w; ++x) {
int in_pixel_index = x * 4;
encode_buffer[in_pixel_index + 0] +=
ring_buffer_entry[in_pixel_index + 0] * coefficient;
encode_buffer[in_pixel_index + 1] +=
ring_buffer_entry[in_pixel_index + 1] * coefficient;
encode_buffer[in_pixel_index + 2] +=
ring_buffer_entry[in_pixel_index + 2] * coefficient;
encode_buffer[in_pixel_index + 3] +=
ring_buffer_entry[in_pixel_index + 3] * coefficient;
}
}
break;
default:
for (k = n0; k <= n1; k++) {
int coefficient_index = coefficient_counter++;
float* ring_buffer_entry = stbir__get_ring_buffer_scanline(
k, ring_buffer, ring_buffer_begin_index, ring_buffer_first_scanline,
ring_buffer_entries, ring_buffer_length);
float coefficient =
vertical_coefficients[coefficient_group + coefficient_index];
for (x = 0; x < output_w; ++x) {
int in_pixel_index = x * channels;
int c;
for (c = 0; c < channels; c++)
encode_buffer[in_pixel_index + c] +=
ring_buffer_entry[in_pixel_index + c] * coefficient;
}
}
break;
}
stbir__encode_scanline(stbir_info, output_w,
(char*)output_data + output_row_start, encode_buffer,
channels, alpha_channel, decode);
}
static void stbir__resample_vertical_downsample(stbir__info* stbir_info,
int n) {
int x, k;
int output_w = stbir_info->output_w;
stbir__contributors* vertical_contributors =
stbir_info->vertical_contributors;
float* vertical_coefficients = stbir_info->vertical_coefficients;
int channels = stbir_info->channels;
int ring_buffer_entries = stbir_info->ring_buffer_num_entries;
float* horizontal_buffer = stbir_info->horizontal_buffer;
int coefficient_width = stbir_info->vertical_coefficient_width;
int contributor = n + stbir_info->vertical_filter_pixel_margin;
float* ring_buffer = stbir_info->ring_buffer;
int ring_buffer_begin_index = stbir_info->ring_buffer_begin_index;
int ring_buffer_first_scanline = stbir_info->ring_buffer_first_scanline;
int ring_buffer_length = stbir_info->ring_buffer_length_bytes / sizeof(float);
int n0, n1;
n0 = vertical_contributors[contributor].n0;
n1 = vertical_contributors[contributor].n1;
STBIR_ASSERT(!stbir__use_height_upsampling(stbir_info));
for (k = n0; k <= n1; k++) {
int coefficient_index = k - n0;
int coefficient_group = coefficient_width * contributor;
float coefficient =
vertical_coefficients[coefficient_group + coefficient_index];
float* ring_buffer_entry = stbir__get_ring_buffer_scanline(
k, ring_buffer, ring_buffer_begin_index, ring_buffer_first_scanline,
ring_buffer_entries, ring_buffer_length);
switch (channels) {
case 1:
for (x = 0; x < output_w; x++) {
int in_pixel_index = x * 1;
ring_buffer_entry[in_pixel_index + 0] +=
horizontal_buffer[in_pixel_index + 0] * coefficient;
}
break;
case 2:
for (x = 0; x < output_w; x++) {
int in_pixel_index = x * 2;
ring_buffer_entry[in_pixel_index + 0] +=
horizontal_buffer[in_pixel_index + 0] * coefficient;
ring_buffer_entry[in_pixel_index + 1] +=
horizontal_buffer[in_pixel_index + 1] * coefficient;
}
break;
case 3:
for (x = 0; x < output_w; x++) {
int in_pixel_index = x * 3;
ring_buffer_entry[in_pixel_index + 0] +=
horizontal_buffer[in_pixel_index + 0] * coefficient;
ring_buffer_entry[in_pixel_index + 1] +=
horizontal_buffer[in_pixel_index + 1] * coefficient;
ring_buffer_entry[in_pixel_index + 2] +=
horizontal_buffer[in_pixel_index + 2] * coefficient;
}
break;
case 4:
for (x = 0; x < output_w; x++) {
int in_pixel_index = x * 4;
ring_buffer_entry[in_pixel_index + 0] +=
horizontal_buffer[in_pixel_index + 0] * coefficient;
ring_buffer_entry[in_pixel_index + 1] +=
horizontal_buffer[in_pixel_index + 1] * coefficient;
ring_buffer_entry[in_pixel_index + 2] +=
horizontal_buffer[in_pixel_index + 2] * coefficient;
ring_buffer_entry[in_pixel_index + 3] +=
horizontal_buffer[in_pixel_index + 3] * coefficient;
}
break;
default:
for (x = 0; x < output_w; x++) {
int in_pixel_index = x * channels;
int c;
for (c = 0; c < channels; c++)
ring_buffer_entry[in_pixel_index + c] +=
horizontal_buffer[in_pixel_index + c] * coefficient;
}
break;
}
}
}
static void stbir__buffer_loop_upsample(stbir__info* stbir_info) {
int y;
float scale_ratio = stbir_info->vertical_scale;
float out_scanlines_radius =
stbir__filter_info_table[stbir_info->vertical_filter].support(
1 / scale_ratio) *
scale_ratio;
STBIR_ASSERT(stbir__use_height_upsampling(stbir_info));
for (y = 0; y < stbir_info->output_h; y++) {
float in_center_of_out =
0; // Center of the current out scanline in the in scanline space
int in_first_scanline = 0, in_last_scanline = 0;
stbir__calculate_sample_range_upsample(
y, out_scanlines_radius, scale_ratio, stbir_info->vertical_shift,
&in_first_scanline, &in_last_scanline, &in_center_of_out);
STBIR_ASSERT(in_last_scanline - in_first_scanline + 1 <=
stbir_info->ring_buffer_num_entries);
if (stbir_info->ring_buffer_begin_index >= 0) {
// Get rid of whatever we don't need anymore.
while (in_first_scanline > stbir_info->ring_buffer_first_scanline) {
if (stbir_info->ring_buffer_first_scanline ==
stbir_info->ring_buffer_last_scanline) {
// We just popped the last scanline off the ring buffer.
// Reset it to the empty state.
stbir_info->ring_buffer_begin_index = -1;
stbir_info->ring_buffer_first_scanline = 0;
stbir_info->ring_buffer_last_scanline = 0;
break;
} else {
stbir_info->ring_buffer_first_scanline++;
stbir_info->ring_buffer_begin_index =
(stbir_info->ring_buffer_begin_index + 1) %
stbir_info->ring_buffer_num_entries;
}
}
}
// Load in new ones.
if (stbir_info->ring_buffer_begin_index < 0)
stbir__decode_and_resample_upsample(stbir_info, in_first_scanline);
while (in_last_scanline > stbir_info->ring_buffer_last_scanline)
stbir__decode_and_resample_upsample(
stbir_info, stbir_info->ring_buffer_last_scanline + 1);
// Now all buffers should be ready to write a row of vertical sampling.
stbir__resample_vertical_upsample(stbir_info, y);
STBIR_PROGRESS_REPORT((float)y / stbir_info->output_h);
}
}
static void stbir__empty_ring_buffer(stbir__info* stbir_info,
int first_necessary_scanline) {
int output_stride_bytes = stbir_info->output_stride_bytes;
int channels = stbir_info->channels;
int alpha_channel = stbir_info->alpha_channel;
int type = stbir_info->type;
int colorspace = stbir_info->colorspace;
int output_w = stbir_info->output_w;
void* output_data = stbir_info->output_data;
int decode = STBIR__DECODE(type, colorspace);
float* ring_buffer = stbir_info->ring_buffer;
int ring_buffer_length = stbir_info->ring_buffer_length_bytes / sizeof(float);
if (stbir_info->ring_buffer_begin_index >= 0) {
// Get rid of whatever we don't need anymore.
while (first_necessary_scanline > stbir_info->ring_buffer_first_scanline) {
if (stbir_info->ring_buffer_first_scanline >= 0 &&
stbir_info->ring_buffer_first_scanline < stbir_info->output_h) {
int output_row_start =
stbir_info->ring_buffer_first_scanline * output_stride_bytes;
float* ring_buffer_entry = stbir__get_ring_buffer_entry(
ring_buffer, stbir_info->ring_buffer_begin_index,
ring_buffer_length);
stbir__encode_scanline(
stbir_info, output_w, (char*)output_data + output_row_start,
ring_buffer_entry, channels, alpha_channel, decode);
STBIR_PROGRESS_REPORT((float)stbir_info->ring_buffer_first_scanline /
stbir_info->output_h);
}
if (stbir_info->ring_buffer_first_scanline ==
stbir_info->ring_buffer_last_scanline) {
// We just popped the last scanline off the ring buffer.
// Reset it to the empty state.
stbir_info->ring_buffer_begin_index = -1;
stbir_info->ring_buffer_first_scanline = 0;
stbir_info->ring_buffer_last_scanline = 0;
break;
} else {
stbir_info->ring_buffer_first_scanline++;
stbir_info->ring_buffer_begin_index =
(stbir_info->ring_buffer_begin_index + 1) %
stbir_info->ring_buffer_num_entries;
}
}
}
}
static void stbir__buffer_loop_downsample(stbir__info* stbir_info) {
int y;
float scale_ratio = stbir_info->vertical_scale;
int output_h = stbir_info->output_h;
float in_pixels_radius =
stbir__filter_info_table[stbir_info->vertical_filter].support(
scale_ratio) /
scale_ratio;
int pixel_margin = stbir_info->vertical_filter_pixel_margin;
int max_y = stbir_info->input_h + pixel_margin;
STBIR_ASSERT(!stbir__use_height_upsampling(stbir_info));
for (y = -pixel_margin; y < max_y; y++) {
float out_center_of_in; // Center of the current out scanline in the in
// scanline space
int out_first_scanline, out_last_scanline;
stbir__calculate_sample_range_downsample(
y, in_pixels_radius, scale_ratio, stbir_info->vertical_shift,
&out_first_scanline, &out_last_scanline, &out_center_of_in);
STBIR_ASSERT(out_last_scanline - out_first_scanline + 1 <=
stbir_info->ring_buffer_num_entries);
if (out_last_scanline < 0 || out_first_scanline >= output_h) continue;
stbir__empty_ring_buffer(stbir_info, out_first_scanline);
stbir__decode_and_resample_downsample(stbir_info, y);
// Load in new ones.
if (stbir_info->ring_buffer_begin_index < 0)
stbir__add_empty_ring_buffer_entry(stbir_info, out_first_scanline);
while (out_last_scanline > stbir_info->ring_buffer_last_scanline)
stbir__add_empty_ring_buffer_entry(
stbir_info, stbir_info->ring_buffer_last_scanline + 1);
// Now the horizontal buffer is ready to write to all ring buffer rows.
stbir__resample_vertical_downsample(stbir_info, y);
}
stbir__empty_ring_buffer(stbir_info, stbir_info->output_h);
}
static void stbir__setup(stbir__info* info, int input_w, int input_h,
int output_w, int output_h, int channels) {
info->input_w = input_w;
info->input_h = input_h;
info->output_w = output_w;
info->output_h = output_h;
info->channels = channels;
}
static void stbir__calculate_transform(stbir__info* info, float s0, float t0,
float s1, float t1, float* transform) {
info->s0 = s0;
info->t0 = t0;
info->s1 = s1;
info->t1 = t1;
if (transform) {
info->horizontal_scale = transform[0];
info->vertical_scale = transform[1];
info->horizontal_shift = transform[2];
info->vertical_shift = transform[3];
} else {
info->horizontal_scale =
((float)info->output_w / info->input_w) / (s1 - s0);
info->vertical_scale = ((float)info->output_h / info->input_h) / (t1 - t0);
info->horizontal_shift = s0 * info->output_w / (s1 - s0);
info->vertical_shift = t0 * info->output_h / (t1 - t0);
}
}
static void stbir__choose_filter(stbir__info* info, stbir_filter h_filter,
stbir_filter v_filter) {
if (h_filter == 0)
h_filter = stbir__use_upsampling(info->horizontal_scale)
? STBIR_DEFAULT_FILTER_UPSAMPLE
: STBIR_DEFAULT_FILTER_DOWNSAMPLE;
if (v_filter == 0)
v_filter = stbir__use_upsampling(info->vertical_scale)
? STBIR_DEFAULT_FILTER_UPSAMPLE
: STBIR_DEFAULT_FILTER_DOWNSAMPLE;
info->horizontal_filter = h_filter;
info->vertical_filter = v_filter;
}
static uint32_t stbir__calculate_memory(stbir__info* info) {
int pixel_margin = stbir__get_filter_pixel_margin(info->horizontal_filter,
info->horizontal_scale);
int filter_height = stbir__get_filter_pixel_width(info->vertical_filter,
info->vertical_scale);
info->horizontal_num_contributors =
stbir__get_contributors(info->horizontal_scale, info->horizontal_filter,
info->input_w, info->output_w);
info->vertical_num_contributors =
stbir__get_contributors(info->vertical_scale, info->vertical_filter,
info->input_h, info->output_h);
// One extra entry because floating point precision problems sometimes cause
// an extra to be necessary.
info->ring_buffer_num_entries = filter_height + 1;
info->horizontal_contributors_size =
info->horizontal_num_contributors * sizeof(stbir__contributors);
info->horizontal_coefficients_size =
stbir__get_total_horizontal_coefficients(info) * sizeof(float);
info->vertical_contributors_size =
info->vertical_num_contributors * sizeof(stbir__contributors);
info->vertical_coefficients_size =
stbir__get_total_vertical_coefficients(info) * sizeof(float);
info->decode_buffer_size =
(info->input_w + pixel_margin * 2) * info->channels * sizeof(float);
info->horizontal_buffer_size =
info->output_w * info->channels * sizeof(float);
info->ring_buffer_size = info->output_w * info->channels *
info->ring_buffer_num_entries * sizeof(float);
info->encode_buffer_size = info->output_w * info->channels * sizeof(float);
STBIR_ASSERT(info->horizontal_filter != 0);
STBIR_ASSERT(info->horizontal_filter <
STBIR__ARRAY_SIZE(
stbir__filter_info_table)); // this now happens too late
STBIR_ASSERT(info->vertical_filter != 0);
STBIR_ASSERT(info->vertical_filter <
STBIR__ARRAY_SIZE(
stbir__filter_info_table)); // this now happens too late
if (stbir__use_height_upsampling(info))
// The horizontal buffer is for when we're downsampling the height and we
// can't output the result of sampling the decode buffer directly into the
// ring buffers.
info->horizontal_buffer_size = 0;
else
// The encode buffer is to retain precision in the height upsampling method
// and isn't used when height downsampling.
info->encode_buffer_size = 0;
return info->horizontal_contributors_size +
info->horizontal_coefficients_size + info->vertical_contributors_size +
info->vertical_coefficients_size + info->decode_buffer_size +
info->horizontal_buffer_size + info->ring_buffer_size +
info->encode_buffer_size;
}
static int stbir__resize_allocated(
stbir__info* info, const void* input_data, int input_stride_in_bytes,
void* output_data, int output_stride_in_bytes, int alpha_channel,
uint32_t flags, stbir_datatype type, stbir_edge edge_horizontal,
stbir_edge edge_vertical, stbir_colorspace colorspace, void* tempmem,
size_t tempmem_size_in_bytes) {
size_t memory_required = stbir__calculate_memory(info);
int width_stride_input =
input_stride_in_bytes
? input_stride_in_bytes
: info->channels * info->input_w * stbir__type_size[type];
int width_stride_output =
output_stride_in_bytes
? output_stride_in_bytes
: info->channels * info->output_w * stbir__type_size[type];
#ifdef STBIR_DEBUG_OVERWRITE_TEST
#define OVERWRITE_ARRAY_SIZE 8
unsigned char overwrite_output_before_pre[OVERWRITE_ARRAY_SIZE];
unsigned char overwrite_tempmem_before_pre[OVERWRITE_ARRAY_SIZE];
unsigned char overwrite_output_after_pre[OVERWRITE_ARRAY_SIZE];
unsigned char overwrite_tempmem_after_pre[OVERWRITE_ARRAY_SIZE];
size_t begin_forbidden =
width_stride_output * (info->output_h - 1) +
info->output_w * info->channels * stbir__type_size[type];
memcpy(overwrite_output_before_pre,
&((unsigned char*)output_data)[-OVERWRITE_ARRAY_SIZE],
OVERWRITE_ARRAY_SIZE);
memcpy(overwrite_output_after_pre,
&((unsigned char*)output_data)[begin_forbidden], OVERWRITE_ARRAY_SIZE);
memcpy(overwrite_tempmem_before_pre,
&((unsigned char*)tempmem)[-OVERWRITE_ARRAY_SIZE],
OVERWRITE_ARRAY_SIZE);
memcpy(overwrite_tempmem_after_pre,
&((unsigned char*)tempmem)[tempmem_size_in_bytes],
OVERWRITE_ARRAY_SIZE);
#endif
STBIR_ASSERT(info->channels >= 0);
STBIR_ASSERT(info->channels <= STBIR_MAX_CHANNELS);
if (info->channels < 0 || info->channels > STBIR_MAX_CHANNELS) return 0;
STBIR_ASSERT(info->horizontal_filter <
STBIR__ARRAY_SIZE(stbir__filter_info_table));
STBIR_ASSERT(info->vertical_filter <
STBIR__ARRAY_SIZE(stbir__filter_info_table));
if (info->horizontal_filter >= STBIR__ARRAY_SIZE(stbir__filter_info_table))
return 0;
if (info->vertical_filter >= STBIR__ARRAY_SIZE(stbir__filter_info_table))
return 0;
if (alpha_channel < 0)
flags |= STBIR_FLAG_ALPHA_USES_COLORSPACE | STBIR_FLAG_ALPHA_PREMULTIPLIED;
if (!(flags & STBIR_FLAG_ALPHA_USES_COLORSPACE) ||
!(flags & STBIR_FLAG_ALPHA_PREMULTIPLIED)) {
STBIR_ASSERT(alpha_channel >= 0 && alpha_channel < info->channels);
}
if (alpha_channel >= info->channels) return 0;
STBIR_ASSERT(tempmem);
if (!tempmem) return 0;
STBIR_ASSERT(tempmem_size_in_bytes >= memory_required);
if (tempmem_size_in_bytes < memory_required) return 0;
memset(tempmem, 0, tempmem_size_in_bytes);
info->input_data = input_data;
info->input_stride_bytes = width_stride_input;
info->output_data = output_data;
info->output_stride_bytes = width_stride_output;
info->alpha_channel = alpha_channel;
info->flags = flags;
info->type = type;
info->edge_horizontal = edge_horizontal;
info->edge_vertical = edge_vertical;
info->colorspace = colorspace;
info->horizontal_coefficient_width = stbir__get_coefficient_width(
info->horizontal_filter, info->horizontal_scale);
info->vertical_coefficient_width =
stbir__get_coefficient_width(info->vertical_filter, info->vertical_scale);
info->horizontal_filter_pixel_width = stbir__get_filter_pixel_width(
info->horizontal_filter, info->horizontal_scale);
info->vertical_filter_pixel_width = stbir__get_filter_pixel_width(
info->vertical_filter, info->vertical_scale);
info->horizontal_filter_pixel_margin = stbir__get_filter_pixel_margin(
info->horizontal_filter, info->horizontal_scale);
info->vertical_filter_pixel_margin = stbir__get_filter_pixel_margin(
info->vertical_filter, info->vertical_scale);
info->ring_buffer_length_bytes =
info->output_w * info->channels * sizeof(float);
info->decode_buffer_pixels =
info->input_w + info->horizontal_filter_pixel_margin * 2;
#define STBIR__NEXT_MEMPTR(current, newtype) \
(newtype*)(((unsigned char*)current) + current##_size)
info->horizontal_contributors = (stbir__contributors*)tempmem;
info->horizontal_coefficients =
STBIR__NEXT_MEMPTR(info->horizontal_contributors, float);
info->vertical_contributors =
STBIR__NEXT_MEMPTR(info->horizontal_coefficients, stbir__contributors);
info->vertical_coefficients =
STBIR__NEXT_MEMPTR(info->vertical_contributors, float);
info->decode_buffer = STBIR__NEXT_MEMPTR(info->vertical_coefficients, float);
if (stbir__use_height_upsampling(info)) {
info->horizontal_buffer = NULL;
info->ring_buffer = STBIR__NEXT_MEMPTR(info->decode_buffer, float);
info->encode_buffer = STBIR__NEXT_MEMPTR(info->ring_buffer, float);
STBIR_ASSERT(
(size_t)STBIR__NEXT_MEMPTR(info->encode_buffer, unsigned char) ==
(size_t)tempmem + tempmem_size_in_bytes);
} else {
info->horizontal_buffer = STBIR__NEXT_MEMPTR(info->decode_buffer, float);
info->ring_buffer = STBIR__NEXT_MEMPTR(info->horizontal_buffer, float);
info->encode_buffer = NULL;
STBIR_ASSERT((size_t)STBIR__NEXT_MEMPTR(info->ring_buffer, unsigned char) ==
(size_t)tempmem + tempmem_size_in_bytes);
}
#undef STBIR__NEXT_MEMPTR
// This signals that the ring buffer is empty
info->ring_buffer_begin_index = -1;
stbir__calculate_filters(
info->horizontal_contributors, info->horizontal_coefficients,
info->horizontal_filter, info->horizontal_scale, info->horizontal_shift,
info->input_w, info->output_w);
stbir__calculate_filters(info->vertical_contributors,
info->vertical_coefficients, info->vertical_filter,
info->vertical_scale, info->vertical_shift,
info->input_h, info->output_h);
STBIR_PROGRESS_REPORT(0);
if (stbir__use_height_upsampling(info))
stbir__buffer_loop_upsample(info);
else
stbir__buffer_loop_downsample(info);
STBIR_PROGRESS_REPORT(1);
#ifdef STBIR_DEBUG_OVERWRITE_TEST
STBIR_ASSERT(memcmp(overwrite_output_before_pre,
&((unsigned char*)output_data)[-OVERWRITE_ARRAY_SIZE],
OVERWRITE_ARRAY_SIZE) == 0);
STBIR_ASSERT(memcmp(overwrite_output_after_pre,
&((unsigned char*)output_data)[begin_forbidden],
OVERWRITE_ARRAY_SIZE) == 0);
STBIR_ASSERT(memcmp(overwrite_tempmem_before_pre,
&((unsigned char*)tempmem)[-OVERWRITE_ARRAY_SIZE],
OVERWRITE_ARRAY_SIZE) == 0);
STBIR_ASSERT(memcmp(overwrite_tempmem_after_pre,
&((unsigned char*)tempmem)[tempmem_size_in_bytes],
OVERWRITE_ARRAY_SIZE) == 0);
#endif
return 1;
}
static int stbir__resize_arbitrary(
void* alloc_context, const void* input_data, int input_w, int input_h,
int input_stride_in_bytes, void* output_data, int output_w, int output_h,
int output_stride_in_bytes, float s0, float t0, float s1, float t1,
float* transform, int channels, int alpha_channel, uint32_t flags,
stbir_datatype type, stbir_filter h_filter, stbir_filter v_filter,
stbir_edge edge_horizontal, stbir_edge edge_vertical,
stbir_colorspace colorspace) {
stbir__info info;
int result;
size_t memory_required;
void* extra_memory;
stbir__setup(&info, input_w, input_h, output_w, output_h, channels);
stbir__calculate_transform(&info, s0, t0, s1, t1, transform);
stbir__choose_filter(&info, h_filter, v_filter);
memory_required = stbir__calculate_memory(&info);
extra_memory = STBIR_MALLOC(memory_required, alloc_context);
if (!extra_memory) return 0;
result = stbir__resize_allocated(
&info, input_data, input_stride_in_bytes, output_data,
output_stride_in_bytes, alpha_channel, flags, type, edge_horizontal,
edge_vertical, colorspace, extra_memory, memory_required);
STBIR_FREE(extra_memory, alloc_context);
return result;
}
int stbir_resize_uint8(const unsigned char* input_pixels, int input_w,
int input_h, int input_stride_in_bytes,
unsigned char* output_pixels, int output_w, int output_h,
int output_stride_in_bytes, int num_channels) {
return stbir__resize_arbitrary(
NULL, input_pixels, input_w, input_h, input_stride_in_bytes,
output_pixels, output_w, output_h, output_stride_in_bytes, 0, 0, 1, 1,
NULL, num_channels, -1, 0, STBIR_TYPE_UINT8, STBIR_FILTER_DEFAULT,
STBIR_FILTER_DEFAULT, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP,
STBIR_COLORSPACE_LINEAR);
}
int stbir_resize_float(const float* input_pixels, int input_w, int input_h,
int input_stride_in_bytes, float* output_pixels,
int output_w, int output_h, int output_stride_in_bytes,
int num_channels) {
return stbir__resize_arbitrary(
NULL, input_pixels, input_w, input_h, input_stride_in_bytes,
output_pixels, output_w, output_h, output_stride_in_bytes, 0, 0, 1, 1,
NULL, num_channels, -1, 0, STBIR_TYPE_FLOAT, STBIR_FILTER_DEFAULT,
STBIR_FILTER_DEFAULT, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP,
STBIR_COLORSPACE_LINEAR);
}
int stbir_resize_uint8_srgb(const unsigned char* input_pixels, int input_w,
int input_h, int input_stride_in_bytes,
unsigned char* output_pixels, int output_w,
int output_h, int output_stride_in_bytes,
int num_channels, int alpha_channel, int flags) {
return stbir__resize_arbitrary(
NULL, input_pixels, input_w, input_h, input_stride_in_bytes,
output_pixels, output_w, output_h, output_stride_in_bytes, 0, 0, 1, 1,
NULL, num_channels, alpha_channel, flags, STBIR_TYPE_UINT8,
STBIR_FILTER_DEFAULT, STBIR_FILTER_DEFAULT, STBIR_EDGE_CLAMP,
STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB);
}
int stbir_resize_uint8_srgb_edgemode(const unsigned char* input_pixels,
int input_w, int input_h,
int input_stride_in_bytes,
unsigned char* output_pixels, int output_w,
int output_h, int output_stride_in_bytes,
int num_channels, int alpha_channel,
int flags, stbir_edge edge_wrap_mode) {
return stbir__resize_arbitrary(
NULL, input_pixels, input_w, input_h, input_stride_in_bytes,
output_pixels, output_w, output_h, output_stride_in_bytes, 0, 0, 1, 1,
NULL, num_channels, alpha_channel, flags, STBIR_TYPE_UINT8,
STBIR_FILTER_DEFAULT, STBIR_FILTER_DEFAULT, edge_wrap_mode,
edge_wrap_mode, STBIR_COLORSPACE_SRGB);
}
int stbir_resize_uint8_generic(const unsigned char* input_pixels, int input_w,
int input_h, int input_stride_in_bytes,
unsigned char* output_pixels, int output_w,
int output_h, int output_stride_in_bytes,
int num_channels, int alpha_channel, int flags,
stbir_edge edge_wrap_mode, stbir_filter filter,
stbir_colorspace space, void* alloc_context) {
return stbir__resize_arbitrary(
alloc_context, input_pixels, input_w, input_h, input_stride_in_bytes,
output_pixels, output_w, output_h, output_stride_in_bytes, 0, 0, 1, 1,
NULL, num_channels, alpha_channel, flags, STBIR_TYPE_UINT8, filter,
filter, edge_wrap_mode, edge_wrap_mode, space);
}
int stbir_resize_uint16_generic(const uint16_t* input_pixels, int input_w,
int input_h, int input_stride_in_bytes,
uint16_t* output_pixels, int output_w,
int output_h, int output_stride_in_bytes,
int num_channels, int alpha_channel, int flags,
stbir_edge edge_wrap_mode, stbir_filter filter,
stbir_colorspace space, void* alloc_context) {
return stbir__resize_arbitrary(
alloc_context, input_pixels, input_w, input_h, input_stride_in_bytes,
output_pixels, output_w, output_h, output_stride_in_bytes, 0, 0, 1, 1,
NULL, num_channels, alpha_channel, flags, STBIR_TYPE_UINT16, filter,
filter, edge_wrap_mode, edge_wrap_mode, space);
}
int stbir_resize_float_generic(const float* input_pixels, int input_w,
int input_h, int input_stride_in_bytes,
float* output_pixels, int output_w, int output_h,
int output_stride_in_bytes, int num_channels,
int alpha_channel, int flags,
stbir_edge edge_wrap_mode, stbir_filter filter,
stbir_colorspace space, void* alloc_context) {
return stbir__resize_arbitrary(
alloc_context, input_pixels, input_w, input_h, input_stride_in_bytes,
output_pixels, output_w, output_h, output_stride_in_bytes, 0, 0, 1, 1,
NULL, num_channels, alpha_channel, flags, STBIR_TYPE_FLOAT, filter,
filter, edge_wrap_mode, edge_wrap_mode, space);
}
int stbir_resize(const void* input_pixels, int input_w, int input_h,
int input_stride_in_bytes, void* output_pixels, int output_w,
int output_h, int output_stride_in_bytes,
stbir_datatype datatype, int num_channels, int alpha_channel,
int flags, stbir_edge edge_mode_horizontal,
stbir_edge edge_mode_vertical, stbir_filter filter_horizontal,
stbir_filter filter_vertical, stbir_colorspace space,
void* alloc_context) {
return stbir__resize_arbitrary(
alloc_context, input_pixels, input_w, input_h, input_stride_in_bytes,
output_pixels, output_w, output_h, output_stride_in_bytes, 0, 0, 1, 1,
NULL, num_channels, alpha_channel, flags, datatype, filter_horizontal,
filter_vertical, edge_mode_horizontal, edge_mode_vertical, space);
}
int stbir_resize_subpixel(
const void* input_pixels, int input_w, int input_h,
int input_stride_in_bytes, void* output_pixels, int output_w, int output_h,
int output_stride_in_bytes, stbir_datatype datatype, int num_channels,
int alpha_channel, int flags, stbir_edge edge_mode_horizontal,
stbir_edge edge_mode_vertical, stbir_filter filter_horizontal,
stbir_filter filter_vertical, stbir_colorspace space, void* alloc_context,
float x_scale, float y_scale, float x_offset, float y_offset) {
float transform[4];
transform[0] = x_scale;
transform[1] = y_scale;
transform[2] = x_offset;
transform[3] = y_offset;
return stbir__resize_arbitrary(
alloc_context, input_pixels, input_w, input_h, input_stride_in_bytes,
output_pixels, output_w, output_h, output_stride_in_bytes, 0, 0, 1, 1,
transform, num_channels, alpha_channel, flags, datatype,
filter_horizontal, filter_vertical, edge_mode_horizontal,
edge_mode_vertical, space);
}
int stbir_resize_region(
const void* input_pixels, int input_w, int input_h,
int input_stride_in_bytes, void* output_pixels, int output_w, int output_h,
int output_stride_in_bytes, stbir_datatype datatype, int num_channels,
int alpha_channel, int flags, stbir_edge edge_mode_horizontal,
stbir_edge edge_mode_vertical, stbir_filter filter_horizontal,
stbir_filter filter_vertical, stbir_colorspace space, void* alloc_context,
float s0, float t0, float s1, float t1) {
return stbir__resize_arbitrary(
alloc_context, input_pixels, input_w, input_h, input_stride_in_bytes,
output_pixels, output_w, output_h, output_stride_in_bytes, s0, t0, s1, t1,
NULL, num_channels, alpha_channel, flags, datatype, filter_horizontal,
filter_vertical, edge_mode_horizontal, edge_mode_vertical, space);
}
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