1/*
2 Simple DirectMedia Layer
3 Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org>
4
5 This software is provided 'as-is', without any express or implied
6 warranty. In no event will the authors be held liable for any damages
7 arising from the use of this software.
8
9 Permission is granted to anyone to use this software for any purpose,
10 including commercial applications, and to alter it and redistribute it
11 freely, subject to the following restrictions:
12
13 1. The origin of this software must not be misrepresented; you must not
14 claim that you wrote the original software. If you use this software
15 in a product, an acknowledgment in the product documentation would be
16 appreciated but is not required.
17 2. Altered source versions must be plainly marked as such, and must not be
18 misrepresented as being the original software.
19 3. This notice may not be removed or altered from any source distribution.
20*/
21#include "SDL_internal.h"
22
23#include "SDL_stb_c.h"
24
25
26// We currently only support JPEG, but we could add other image formats if we wanted
27#ifdef SDL_HAVE_STB
28#define malloc SDL_malloc
29#define realloc SDL_realloc
30#define free SDL_free
31#undef memcpy
32#define memcpy SDL_memcpy
33#undef memset
34#define memset SDL_memset
35#undef strcmp
36#define strcmp SDL_strcmp
37#undef strncmp
38#define strncmp SDL_strncmp
39#define strtol SDL_strtol
40
41#define abs SDL_abs
42#define pow SDL_pow
43#define ldexp SDL_scalbn
44
45#define STB_IMAGE_STATIC
46#define STBI_NO_THREAD_LOCALS
47#define STBI_FAILURE_USERMSG
48#if defined(SDL_NEON_INTRINSICS)
49#define STBI_NEON
50#endif
51#define STBI_ONLY_JPEG
52#define STBI_NO_GIF
53#define STBI_NO_PNG
54#define STBI_NO_HDR
55#define STBI_NO_LINEAR
56#define STBI_NO_ZLIB
57#define STBI_NO_STDIO
58#define STBI_ASSERT SDL_assert
59#define STB_IMAGE_IMPLEMENTATION
60#include "stb_image.h"
61
62#undef memset
63#endif
64
65#ifdef SDL_HAVE_STB
66static bool SDL_ConvertPixels_MJPG_to_NV12(int width, int height, const void *src, int src_pitch, void *dst, int dst_pitch)
67{
68 int w = 0, h = 0, format = 0;
69 stbi__context s;
70 stbi__start_mem(&s, src, src_pitch);
71
72 stbi__result_info ri;
73 SDL_zero(ri);
74 ri.bits_per_channel = 8;
75 ri.channel_order = STBI_ORDER_RGB;
76 ri.num_channels = 0;
77
78 stbi__nv12 nv12;
79 nv12.w = width;
80 nv12.h = height;
81 nv12.pitch = dst_pitch;
82 nv12.y = (stbi_uc *)dst;
83 nv12.uv = nv12.y + (nv12.h * nv12.pitch);
84
85 void *pixels = stbi__jpeg_load(&s, &w, &h, &format, 4, &nv12, &ri);
86 if (!pixels) {
87 return false;
88 }
89 return true;
90}
91#endif // SDL_HAVE_STB
92
93bool SDL_ConvertPixels_STB(int width, int height,
94 SDL_PixelFormat src_format, SDL_Colorspace src_colorspace, SDL_PropertiesID src_properties, const void *src, int src_pitch,
95 SDL_PixelFormat dst_format, SDL_Colorspace dst_colorspace, SDL_PropertiesID dst_properties, void *dst, int dst_pitch)
96{
97#ifdef SDL_HAVE_STB
98 if (src_format == SDL_PIXELFORMAT_MJPG && dst_format == SDL_PIXELFORMAT_NV12) {
99 return SDL_ConvertPixels_MJPG_to_NV12(width, height, src, src_pitch, dst, dst_pitch);
100 }
101
102 bool result;
103 int w = 0, h = 0, format = 0;
104 int len = (src_format == SDL_PIXELFORMAT_MJPG) ? src_pitch : (height * src_pitch);
105 void *pixels = stbi_load_from_memory(src, len, &w, &h, &format, 4);
106 if (!pixels) {
107 return false;
108 }
109
110 if (w == width && h == height) {
111 result = SDL_ConvertPixelsAndColorspace(w, h, SDL_PIXELFORMAT_RGBA32, SDL_COLORSPACE_SRGB, 0, pixels, width * 4, dst_format, dst_colorspace, dst_properties, dst, dst_pitch);
112 } else {
113 result = SDL_SetError("Expected image size %dx%d, actual size %dx%d", width, height, w, h);
114 }
115 stbi_image_free(pixels);
116
117 return result;
118#else
119 return SDL_SetError("SDL not built with STB image support");
120#endif
121}
122