summaryrefslogtreecommitdiffstats
path: root/lib/gui/qoi.h
blob: aea441434c4a83249c504df504d759b2b14b3afc (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
/* SPDX-License-Identifier: MIT */
/* SPDX-FileCopyrightText: 2021 Dominic Szablewski */
/*

QOI - The "Quite OK Image" format for fast, lossless image compression

Dominic Szablewski - https://phoboslab.org


-- LICENSE: The MIT License(MIT)

Copyright(c) 2021 Dominic Szablewski

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files(the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and / or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions :
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.


-- About

QOI encodes and decodes images in a lossless format. Compared to stb_image and
stb_image_write QOI offers 20x-50x faster encoding, 3x-4x faster decoding and
20% better compression.


-- Synopsis

// Define `QOI_IMPLEMENTATION` in *one* C/C++ file before including this
// library to create the implementation.

#define QOI_IMPLEMENTATION
#include "qoi.h"

// Encode and store an RGBA buffer to the file system. The qoi_desc describes
// the input pixel data.
qoi_write("image_new.qoi", rgba_pixels, &(qoi_desc){
	.width = 1920,
	.height = 1080,
	.channels = 4,
	.colorspace = QOI_SRGB
});

// Load and decode a QOI image from the file system into a 32bbp RGBA buffer.
// The qoi_desc struct will be filled with the width, height, number of channels
// and colorspace read from the file header.
qoi_desc desc;
void *rgba_pixels = qoi_read("image.qoi", &desc, 4);



-- Documentation

This library provides the following functions;
- qoi_read    -- read and decode a QOI file
- qoi_decode  -- decode the raw bytes of a QOI image from memory
- qoi_write   -- encode and write a QOI file
- qoi_encode  -- encode an rgba buffer into a QOI image in memory

See the function declaration below for the signature and more information.

If you don't want/need the qoi_read and qoi_write functions, you can define
QOI_NO_STDIO before including this library.

This library uses malloc() and free(). To supply your own malloc implementation
you can define QOI_MALLOC and QOI_FREE before including this library.

This library uses memset() to zero-initialize the index. To supply your own
implementation you can define QOI_ZEROARR before including this library.


-- Data Format

A QOI file has a 14 byte header, followed by any number of data "chunks" and an
8-byte end marker.

struct qoi_header_t {
	char     magic[4];   // magic bytes "qoif"
	uint32_t width;      // image width in pixels (BE)
	uint32_t height;     // image height in pixels (BE)
	uint8_t  channels;   // 3 = RGB, 4 = RGBA
	uint8_t  colorspace; // 0 = sRGB with linear alpha, 1 = all channels linear
};

Images are encoded row by row, left to right, top to bottom. The decoder and
encoder start with {r: 0, g: 0, b: 0, a: 255} as the previous pixel value. An
image is complete when all pixels specified by width * height have been covered.

Pixels are encoded as
 - a run of the previous pixel
 - an index into an array of previously seen pixels
 - a difference to the previous pixel value in r,g,b
 - full r,g,b or r,g,b,a values

The color channels are assumed to not be premultiplied with the alpha channel
("un-premultiplied alpha").

A running array[64] (zero-initialized) of previously seen pixel values is
maintained by the encoder and decoder. Each pixel that is seen by the encoder
and decoder is put into this array at the position formed by a hash function of
the color value. In the encoder, if the pixel value at the index matches the
current pixel, this index position is written to the stream as QOI_OP_INDEX.
The hash function for the index is:

	index_position = (r * 3 + g * 5 + b * 7 + a * 11) % 64

Each chunk starts with a 2- or 8-bit tag, followed by a number of data bits. The
bit length of chunks is divisible by 8 - i.e. all chunks are byte aligned. All
values encoded in these data bits have the most significant bit on the left.

The 8-bit tags have precedence over the 2-bit tags. A decoder must check for the
presence of an 8-bit tag first.

The byte stream's end is marked with 7 0x00 bytes followed a single 0x01 byte.


The possible chunks are:


.- QOI_OP_INDEX ----------.
|         Byte[0]         |
|  7  6  5  4  3  2  1  0 |
|-------+-----------------|
|  0  0 |     index       |
`-------------------------`
2-bit tag b00
6-bit index into the color index array: 0..63

A valid encoder must not issue 2 or more consecutive QOI_OP_INDEX chunks to the
same index. QOI_OP_RUN should be used instead.


.- QOI_OP_DIFF -----------.
|         Byte[0]         |
|  7  6  5  4  3  2  1  0 |
|-------+-----+-----+-----|
|  0  1 |  dr |  dg |  db |
`-------------------------`
2-bit tag b01
2-bit   red channel difference from the previous pixel between -2..1
2-bit green channel difference from the previous pixel between -2..1
2-bit  blue channel difference from the previous pixel between -2..1

The difference to the current channel values are using a wraparound operation,
so "1 - 2" will result in 255, while "255 + 1" will result in 0.

Values are stored as unsigned integers with a bias of 2. E.g. -2 is stored as
0 (b00). 1 is stored as 3 (b11).

The alpha value remains unchanged from the previous pixel.


.- QOI_OP_LUMA -------------------------------------.
|         Byte[0]         |         Byte[1]         |
|  7  6  5  4  3  2  1  0 |  7  6  5  4  3  2  1  0 |
|-------+-----------------+-------------+-----------|
|  1  0 |  green diff     |   dr - dg   |  db - dg  |
`---------------------------------------------------`
2-bit tag b10
6-bit green channel difference from the previous pixel -32..31
4-bit   red channel difference minus green channel difference -8..7
4-bit  blue channel difference minus green channel difference -8..7

The green channel is used to indicate the general direction of change and is
encoded in 6 bits. The red and blue channels (dr and db) base their diffs off
of the green channel difference and are encoded in 4 bits. I.e.:
	dr_dg = (cur_px.r - prev_px.r) - (cur_px.g - prev_px.g)
	db_dg = (cur_px.b - prev_px.b) - (cur_px.g - prev_px.g)

The difference to the current channel values are using a wraparound operation,
so "10 - 13" will result in 253, while "250 + 7" will result in 1.

Values are stored as unsigned integers with a bias of 32 for the green channel
and a bias of 8 for the red and blue channel.

The alpha value remains unchanged from the previous pixel.


.- QOI_OP_RUN ------------.
|         Byte[0]         |
|  7  6  5  4  3  2  1  0 |
|-------+-----------------|
|  1  1 |       run       |
`-------------------------`
2-bit tag b11
6-bit run-length repeating the previous pixel: 1..62

The run-length is stored with a bias of -1. Note that the run-lengths 63 and 64
(b111110 and b111111) are illegal as they are occupied by the QOI_OP_RGB and
QOI_OP_RGBA tags.


.- QOI_OP_RGB ------------------------------------------.
|         Byte[0]         | Byte[1] | Byte[2] | Byte[3] |
|  7  6  5  4  3  2  1  0 | 7 .. 0  | 7 .. 0  | 7 .. 0  |
|-------------------------+---------+---------+---------|
|  1  1  1  1  1  1  1  0 |   red   |  green  |  blue   |
`-------------------------------------------------------`
8-bit tag b11111110
8-bit   red channel value
8-bit green channel value
8-bit  blue channel value

The alpha value remains unchanged from the previous pixel.


.- QOI_OP_RGBA ---------------------------------------------------.
|         Byte[0]         | Byte[1] | Byte[2] | Byte[3] | Byte[4] |
|  7  6  5  4  3  2  1  0 | 7 .. 0  | 7 .. 0  | 7 .. 0  | 7 .. 0  |
|-------------------------+---------+---------+---------+---------|
|  1  1  1  1  1  1  1  1 |   red   |  green  |  blue   |  alpha  |
`-----------------------------------------------------------------`
8-bit tag b11111111
8-bit   red channel value
8-bit green channel value
8-bit  blue channel value
8-bit alpha channel value

*/


/* -----------------------------------------------------------------------------
Header - Public functions */

#ifndef QOI_H
#define QOI_H

#ifdef __cplusplus
extern "C" {
#endif

/* A pointer to a qoi_desc struct has to be supplied to all of qoi's functions.
It describes either the input format (for qoi_write and qoi_encode), or is
filled with the description read from the file header (for qoi_read and
qoi_decode).

The colorspace in this qoi_desc is an enum where
	0 = sRGB, i.e. gamma scaled RGB channels and a linear alpha channel
	1 = all channels are linear
You may use the constants QOI_SRGB or QOI_LINEAR. The colorspace is purely
informative. It will be saved to the file header, but does not affect
how chunks are en-/decoded. */

#define QOI_SRGB   0
#define QOI_LINEAR 1

typedef struct {
	unsigned int width;
	unsigned int height;
	unsigned char channels;
	unsigned char colorspace;
} qoi_desc;

#ifndef QOI_NO_STDIO

/* Encode raw RGB or RGBA pixels into a QOI image and write it to the file
system. The qoi_desc struct must be filled with the image width, height,
number of channels (3 = RGB, 4 = RGBA) and the colorspace.

The function returns 0 on failure (invalid parameters, or fopen or malloc
failed) or the number of bytes written on success. */

int qoi_write(const char *filename, const void *data, const qoi_desc *desc);


/* Read and decode a QOI image from the file system. If channels is 0, the
number of channels from the file header is used. If channels is 3 or 4 the
output format will be forced into this number of channels.

The function either returns NULL on failure (invalid data, or malloc or fopen
failed) or a pointer to the decoded pixels. On success, the qoi_desc struct
will be filled with the description from the file header.

The returned pixel data should be free()d after use. */

void *qoi_read(const char *filename, qoi_desc *desc, int channels);

#endif /* QOI_NO_STDIO */


/* Encode raw RGB or RGBA pixels into a QOI image in memory.

The function either returns NULL on failure (invalid parameters or malloc
failed) or a pointer to the encoded data on success. On success the out_len
is set to the size in bytes of the encoded data.

The returned qoi data should be free()d after use. */

void *qoi_encode(const void *data, const qoi_desc *desc, int *out_len);


/* Decode a QOI image from memory.

The function either returns NULL on failure (invalid parameters or malloc
failed) or a pointer to the decoded pixels. On success, the qoi_desc struct
is filled with the description from the file header.

The returned pixel data should be free()d after use. */

void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels);


#ifdef __cplusplus
}
#endif
#endif /* QOI_H */


/* -----------------------------------------------------------------------------
Implementation */

#ifdef QOI_IMPLEMENTATION
#include <stdlib.h>
#include <string.h>

#ifndef QOI_MALLOC
	#define QOI_MALLOC(sz) malloc(sz)
	#define QOI_FREE(p)    free(p)
#endif
#ifndef QOI_ZEROARR
	#define QOI_ZEROARR(a) memset((a),0,sizeof(a))
#endif

#define QOI_OP_INDEX  0x00 /* 00xxxxxx */
#define QOI_OP_DIFF   0x40 /* 01xxxxxx */
#define QOI_OP_LUMA   0x80 /* 10xxxxxx */
#define QOI_OP_RUN    0xc0 /* 11xxxxxx */
#define QOI_OP_RGB    0xfe /* 11111110 */
#define QOI_OP_RGBA   0xff /* 11111111 */

#define QOI_MASK_2    0xc0 /* 11000000 */

#define QOI_COLOR_HASH(C) (C.rgba.r*3 + C.rgba.g*5 + C.rgba.b*7 + C.rgba.a*11)
#define QOI_MAGIC \
	(((unsigned int)'q') << 24 | ((unsigned int)'o') << 16 | \
	 ((unsigned int)'i') <<  8 | ((unsigned int)'f'))
#define QOI_HEADER_SIZE 14

/* 2GB is the max file size that this implementation can safely handle. We guard
against anything larger than that, assuming the worst case with 5 bytes per
pixel, rounded down to a nice clean value. 400 million pixels ought to be
enough for anybody. */
#define QOI_PIXELS_MAX ((unsigned int)400000000)

typedef union {
	struct { unsigned char r, g, b, a; } rgba;
	unsigned int v;
} qoi_rgba_t;

static const unsigned char qoi_padding[8] = {0,0,0,0,0,0,0,1};

static void qoi_write_32(unsigned char *bytes, int *p, unsigned int v) {
	bytes[(*p)++] = (0xff000000 & v) >> 24;
	bytes[(*p)++] = (0x00ff0000 & v) >> 16;
	bytes[(*p)++] = (0x0000ff00 & v) >> 8;
	bytes[(*p)++] = (0x000000ff & v);
}

static unsigned int qoi_read_32(const unsigned char *bytes, int *p) {
	unsigned int a = bytes[(*p)++];
	unsigned int b = bytes[(*p)++];
	unsigned int c = bytes[(*p)++];
	unsigned int d = bytes[(*p)++];
	return a << 24 | b << 16 | c << 8 | d;
}

void *qoi_encode(const void *data, const qoi_desc *desc, int *out_len) {
	int i, max_size, p, run;
	int px_len, px_end, px_pos, channels;
	unsigned char *bytes;
	const unsigned char *pixels;
	qoi_rgba_t index[64];
	qoi_rgba_t px, px_prev;

	if (
		data == NULL || out_len == NULL || desc == NULL ||
		desc->width == 0 || desc->height == 0 ||
		desc->channels < 3 || desc->channels > 4 ||
		desc->colorspace > 1 ||
		desc->height >= QOI_PIXELS_MAX / desc->width
	) {
		return NULL;
	}

	max_size =
		desc->width * desc->height * (desc->channels + 1) +
		QOI_HEADER_SIZE + sizeof(qoi_padding);

	p = 0;
	bytes = (unsigned char *) QOI_MALLOC(max_size);
	if (!bytes) {
		return NULL;
	}

	qoi_write_32(bytes, &p, QOI_MAGIC);
	qoi_write_32(bytes, &p, desc->width);
	qoi_write_32(bytes, &p, desc->height);
	bytes[p++] = desc->channels;
	bytes[p++] = desc->colorspace;


	pixels = (const unsigned char *)data;

	QOI_ZEROARR(index);

	run = 0;
	px_prev.rgba.r = 0;
	px_prev.rgba.g = 0;
	px_prev.rgba.b = 0;
	px_prev.rgba.a = 255;
	px = px_prev;

	px_len = desc->width * desc->height * desc->channels;
	px_end = px_len - desc->channels;
	channels = desc->channels;

	for (px_pos = 0; px_pos < px_len; px_pos += channels) {
		if (channels == 4) {
			px = *(qoi_rgba_t *)(pixels + px_pos);
		}
		else {
			px.rgba.r = pixels[px_pos + 0];
			px.rgba.g = pixels[px_pos + 1];
			px.rgba.b = pixels[px_pos + 2];
		}

		if (px.v == px_prev.v) {
			run++;
			if (run == 62 || px_pos == px_end) {
				bytes[p++] = QOI_OP_RUN | (run - 1);
				run = 0;
			}
		}
		else {
			int index_pos;

			if (run > 0) {
				bytes[p++] = QOI_OP_RUN | (run - 1);
				run = 0;
			}

			index_pos = QOI_COLOR_HASH(px) % 64;

			if (index[index_pos].v == px.v) {
				bytes[p++] = QOI_OP_INDEX | index_pos;
			}
			else {
				index[index_pos] = px;

				if (px.rgba.a == px_prev.rgba.a) {
					signed char vr = px.rgba.r - px_prev.rgba.r;
					signed char vg = px.rgba.g - px_prev.rgba.g;
					signed char vb = px.rgba.b - px_prev.rgba.b;

					signed char vg_r = vr - vg;
					signed char vg_b = vb - vg;

					if (
						vr > -3 && vr < 2 &&
						vg > -3 && vg < 2 &&
						vb > -3 && vb < 2
					) {
						bytes[p++] = QOI_OP_DIFF | (vr + 2) << 4 | (vg + 2) << 2 | (vb + 2);
					}
					else if (
						vg_r >  -9 && vg_r <  8 &&
						vg   > -33 && vg   < 32 &&
						vg_b >  -9 && vg_b <  8
					) {
						bytes[p++] = QOI_OP_LUMA     | (vg   + 32);
						bytes[p++] = (vg_r + 8) << 4 | (vg_b +  8);
					}
					else {
						bytes[p++] = QOI_OP_RGB;
						bytes[p++] = px.rgba.r;
						bytes[p++] = px.rgba.g;
						bytes[p++] = px.rgba.b;
					}
				}
				else {
					bytes[p++] = QOI_OP_RGBA;
					bytes[p++] = px.rgba.r;
					bytes[p++] = px.rgba.g;
					bytes[p++] = px.rgba.b;
					bytes[p++] = px.rgba.a;
				}
			}
		}
		px_prev = px;
	}

	for (i = 0; i < (int)sizeof(qoi_padding); i++) {
		bytes[p++] = qoi_padding[i];
	}

	*out_len = p;
	return bytes;
}

void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels) {
	const unsigned char *bytes;
	unsigned int header_magic;
	unsigned char *pixels;
	qoi_rgba_t index[64];
	qoi_rgba_t px;
	int px_len, chunks_len, px_pos;
	int p = 0, run = 0;

	if (
		data == NULL || desc == NULL ||
		(channels != 0 && channels != 3 && channels != 4) ||
		size < QOI_HEADER_SIZE + (int)sizeof(qoi_padding)
	) {
		return NULL;
	}

	bytes = (const unsigned char *)data;

	header_magic = qoi_read_32(bytes, &p);
	desc->width = qoi_read_32(bytes, &p);
	desc->height = qoi_read_32(bytes, &p);
	desc->channels = bytes[p++];
	desc->colorspace = bytes[p++];

	if (
		desc->width == 0 || desc->height == 0 ||
		desc->channels < 3 || desc->channels > 4 ||
		desc->colorspace > 1 ||
		header_magic != QOI_MAGIC ||
		desc->height >= QOI_PIXELS_MAX / desc->width
	) {
		return NULL;
	}

	if (channels == 0) {
		channels = desc->channels;
	}

	px_len = desc->width * desc->height * channels;
	pixels = (unsigned char *) QOI_MALLOC(px_len);
	if (!pixels) {
		return NULL;
	}

	QOI_ZEROARR(index);
	px.rgba.r = 0;
	px.rgba.g = 0;
	px.rgba.b = 0;
	px.rgba.a = 255;

	chunks_len = size - (int)sizeof(qoi_padding);
	for (px_pos = 0; px_pos < px_len; px_pos += channels) {
		if (run > 0) {
			run--;
		}
		else if (p < chunks_len) {
			int b1 = bytes[p++];

			if (b1 == QOI_OP_RGB) {
				px.rgba.r = bytes[p++];
				px.rgba.g = bytes[p++];
				px.rgba.b = bytes[p++];
			}
			else if (b1 == QOI_OP_RGBA) {
				px.rgba.r = bytes[p++];
				px.rgba.g = bytes[p++];
				px.rgba.b = bytes[p++];
				px.rgba.a = bytes[p++];
			}
			else if ((b1 & QOI_MASK_2) == QOI_OP_INDEX) {
				px = index[b1];
			}
			else if ((b1 & QOI_MASK_2) == QOI_OP_DIFF) {
				px.rgba.r += ((b1 >> 4) & 0x03) - 2;
				px.rgba.g += ((b1 >> 2) & 0x03) - 2;
				px.rgba.b += ( b1       & 0x03) - 2;
			}
			else if ((b1 & QOI_MASK_2) == QOI_OP_LUMA) {
				int b2 = bytes[p++];
				int vg = (b1 & 0x3f) - 32;
				px.rgba.r += vg - 8 + ((b2 >> 4) & 0x0f);
				px.rgba.g += vg;
				px.rgba.b += vg - 8 +  (b2       & 0x0f);
			}
			else if ((b1 & QOI_MASK_2) == QOI_OP_RUN) {
				run = (b1 & 0x3f);
			}

			index[QOI_COLOR_HASH(px) % 64] = px;
		}

		if (channels == 4) {
			*(qoi_rgba_t*)(pixels + px_pos) = px;
		}
		else {
			pixels[px_pos + 0] = px.rgba.r;
			pixels[px_pos + 1] = px.rgba.g;
			pixels[px_pos + 2] = px.rgba.b;
		}
	}

	return pixels;
}

#ifndef QOI_NO_STDIO
#include <stdio.h>

int qoi_write(const char *filename, const void *data, const qoi_desc *desc) {
	FILE *f = fopen(filename, "wb");
	int size;
	void *encoded;

	if (!f) {
		return 0;
	}

	encoded = qoi_encode(data, desc, &size);
	if (!encoded) {
		fclose(f);
		return 0;
	}

	fwrite(encoded, 1, size, f);
	fclose(f);

	QOI_FREE(encoded);
	return size;
}

void *qoi_read(const char *filename, qoi_desc *desc, int channels) {
	FILE *f = fopen(filename, "rb");
	int size, bytes_read;
	void *pixels, *data;

	if (!f) {
		return NULL;
	}

	fseek(f, 0, SEEK_END);
	size = ftell(f);
	if (size <= 0) {
		fclose(f);
		return NULL;
	}
	fseek(f, 0, SEEK_SET);

	data = QOI_MALLOC(size);
	if (!data) {
		fclose(f);
		return NULL;
	}

	bytes_read = fread(data, 1, size, f);
	fclose(f);

	pixels = qoi_decode(data, bytes_read, desc, channels);
	QOI_FREE(data);
	return pixels;
}

#endif /* QOI_NO_STDIO */
#endif /* QOI_IMPLEMENTATION */