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Added support for saving indexed PNG images

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Fixes https://github.com/libsdl-org/SDL/issues/14303
This commit is contained in:
Sam Lantinga
2025-10-23 12:01:30 -07:00
parent 7bff05402a
commit 1fa6475c90
3 changed files with 210 additions and 45 deletions
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56
src/video/SDL_stb.c
View File

@@ -383,6 +383,9 @@ SDL_Surface *SDL_LoadPNG(const char *file)
bool SDL_SavePNG_IO(SDL_Surface *surface, SDL_IOStream *dst, bool closeio)
{
bool retval = false;
Uint8 *plte = NULL;
Uint8 *trns = NULL;
bool free_surface = false;
// Make sure we have somewhere to save
CHECK_PARAM(!SDL_SurfaceValid(surface)) {
@@ -395,17 +398,49 @@ bool SDL_SavePNG_IO(SDL_Surface *surface, SDL_IOStream *dst, bool closeio)
}
#ifdef SDL_HAVE_STB
bool free_surface = false;
if (surface->format != SDL_PIXELFORMAT_RGBA32) {
surface = SDL_ConvertSurface(surface, SDL_PIXELFORMAT_RGBA32);
if (!surface) {
int plte_size = 0;
int trns_size = 0;
if (SDL_ISPIXELFORMAT_INDEXED(surface->format)) {
if (!surface->palette) {
SDL_SetError("Indexed surfaces must have a palette");
goto done;
}
free_surface = true;
if (surface->format != SDL_PIXELFORMAT_INDEX8) {
surface = SDL_ConvertSurface(surface, SDL_PIXELFORMAT_INDEX8);
if (!surface) {
goto done;
}
free_surface = true;
}
plte_size = surface->palette->ncolors * 3;
trns_size = surface->palette->ncolors;
plte = (Uint8 *)SDL_malloc(plte_size);
trns = (Uint8 *)SDL_malloc(trns_size);
if (!plte || !trns) {
goto done;
}
SDL_Color *colors = surface->palette->colors;
for (int i = 0; i < surface->palette->ncolors; ++i) {
plte[i * 3 + 0] = colors[i].r;
plte[i * 3 + 1] = colors[i].g;
plte[i * 3 + 2] = colors[i].b;
trns[i] = colors[i].a;
}
} else {
if (surface->format != SDL_PIXELFORMAT_RGBA32) {
surface = SDL_ConvertSurface(surface, SDL_PIXELFORMAT_RGBA32);
if (!surface) {
goto done;
}
free_surface = true;
}
}
size_t size = 0;
void *png = tdefl_write_image_to_png_file_in_memory(surface->pixels, surface->w, surface->h, SDL_BYTESPERPIXEL(surface->format), surface->pitch, &size);
void *png = tdefl_write_image_to_png_file_in_memory_ex(surface->pixels, surface->w, surface->h, SDL_BYTESPERPIXEL(surface->format), surface->pitch, &size, 6, MZ_FALSE, plte, plte_size, trns, trns_size);
if (png) {
if (SDL_WriteIO(dst, png, size)) {
retval = true;
@@ -415,14 +450,17 @@ bool SDL_SavePNG_IO(SDL_Surface *surface, SDL_IOStream *dst, bool closeio)
SDL_SetError("Failed to convert and save image");
}
if (free_surface) {
SDL_DestroySurface(surface);
}
#else
SDL_SetError("SDL not built with STB image support");
#endif
done:
if (free_surface) {
SDL_DestroySurface(surface);
}
SDL_free(plte);
SDL_free(trns);
if (dst && closeio) {
retval &= SDL_CloseIO(dst);
}

95
src/video/miniz.h
View File

@@ -875,8 +875,10 @@ MINIZ_STATIC size_t tdefl_compress_mem_to_mem(void *pOut_buf, size_t out_buf_len
// Function returns a pointer to the compressed data, or NULL on failure.
// *pLen_out will be set to the size of the PNG image file.
// The caller must mz_free() the returned heap block (which will typically be larger than *pLen_out) when it's no longer needed.
MINIZ_STATIC void *tdefl_write_image_to_png_file_in_memory_ex(const void *pImage, int w, int h, int num_chans, int bpl, size_t *pLen_out, mz_uint level, mz_bool flip);
MINIZ_STATIC void *tdefl_write_image_to_png_file_in_memory_ex(const void *pImage, int w, int h, int num_chans, int bpl, size_t *pLen_out, mz_uint level, mz_bool flip, mz_uint8 *plte, int plte_size, mz_uint8 *trns, int trns_size);
#ifndef MINIZ_SDL_NOUNUSED
MINIZ_STATIC void *tdefl_write_image_to_png_file_in_memory(const void *pImage, int w, int h, int num_chans, int bpl, size_t *pLen_out);
#endif
// Output stream interface. The compressor uses this interface to write compressed data. It'll typically be called TDEFL_OUT_BUF_SIZE at a time.
typedef mz_bool (*tdefl_put_buf_func_ptr)(const void* pBuf, int len, void *pUser);
@@ -2911,29 +2913,27 @@ mz_uint tdefl_create_comp_flags_from_zip_params(int level, int window_bits, int
// Simple PNG writer function by Alex Evans, 2011. Released into the public domain: https://gist.github.com/908299, more context at
// http://altdevblogaday.org/2011/04/06/a-smaller-jpg-encoder/.
// This is actually a modification of Alex's original code so PNG files generated by this function pass pngcheck.
MINIZ_STATIC void *tdefl_write_image_to_png_file_in_memory_ex(const void *pImage, int w, int h, int num_chans, int bpl, size_t *pLen_out, mz_uint level, mz_bool flip)
MINIZ_STATIC void *tdefl_write_image_to_png_file_in_memory_ex(const void *pImage, int w, int h, int num_chans, int bpl, size_t *pLen_out, mz_uint level, mz_bool flip, mz_uint8 *plte, int plte_size, mz_uint8 *trns, int trns_size)
{
// Using a local copy of this array here in case MINIZ_NO_ZLIB_APIS was defined.
static const mz_uint s_tdefl_png_num_probes[11] = { 0, 1, 6, 32, 16, 32, 128, 256, 512, 768, 1500 };
tdefl_compressor *pComp = (tdefl_compressor *)MZ_MALLOC(sizeof(tdefl_compressor)); tdefl_output_buffer out_buf; int i, y, z; mz_uint32 c; *pLen_out = 0;
tdefl_compressor *pComp = (tdefl_compressor *)MZ_MALLOC(sizeof(tdefl_compressor)); tdefl_output_buffer out_buf; int i, y, z = 0; mz_uint32 c; *pLen_out = 0; size_t data_start, data_size;
if (!pComp) return NULL;
MZ_CLEAR_OBJ(out_buf); out_buf.m_expandable = MZ_TRUE; out_buf.m_capacity = 57+MZ_MAX(64, (1+bpl)*h); if (NULL == (out_buf.m_pBuf = (mz_uint8*)MZ_MALLOC(out_buf.m_capacity))) { MZ_FREE(pComp); return NULL; }
// write dummy header
for (z = 41; z; --z) tdefl_output_buffer_putter(&z, 1, &out_buf);
// compress image data
tdefl_init(pComp, tdefl_output_buffer_putter, &out_buf, s_tdefl_png_num_probes[MZ_MIN(10, level)] | TDEFL_WRITE_ZLIB_HEADER);
for (y = 0; y < h; ++y) { tdefl_compress_buffer(pComp, &z, 1, TDEFL_NO_FLUSH); tdefl_compress_buffer(pComp, (mz_uint8*)pImage + (flip ? (h - 1 - y) : y) * bpl, bpl, TDEFL_NO_FLUSH); }
if (tdefl_compress_buffer(pComp, NULL, 0, TDEFL_FINISH) != TDEFL_STATUS_DONE) { MZ_FREE(pComp); MZ_FREE(out_buf.m_pBuf); return NULL; }
// write real header
*pLen_out = out_buf.m_size-41;
MZ_CLEAR_OBJ(out_buf); out_buf.m_expandable = MZ_TRUE;
out_buf.m_capacity = 57+MZ_MAX(64, (1+bpl)*h);
if (plte_size > 0)
out_buf.m_capacity += 12+plte_size;
if (trns_size > 0)
out_buf.m_capacity += 12+trns_size;
if (NULL == (out_buf.m_pBuf = (mz_uint8*)MZ_MALLOC(out_buf.m_capacity))) { MZ_FREE(pComp); return NULL; }
// write header
{
static const mz_uint8 chans[] = {0x00, 0x00, 0x04, 0x02, 0x06};
mz_uint8 pnghdr[41]={ 0x89,0x50,0x4e,0x47,0x0d,0x0a,0x1a,0x0a,
mz_uint8 pnghdr[33]={ 0x89,0x50,0x4e,0x47,0x0d,0x0a,0x1a,0x0a,
0x00,0x00,0x00,0x0d,0x49,0x48,0x44,0x52,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x08,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x49,0x44,0x41,0x54};
0x08,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00};
pnghdr[18] = (mz_uint8)(w>>8);
pnghdr[19] = (mz_uint8)(w>>0);
@@ -2941,31 +2941,76 @@ MINIZ_STATIC void *tdefl_write_image_to_png_file_in_memory_ex(const void *pImage
pnghdr[22] = (mz_uint8)(h>>8);
pnghdr[23] = (mz_uint8)(h>>0);
pnghdr[25] = (chans[num_chans]);
pnghdr[33] = (mz_uint8)(*pLen_out>>24);
pnghdr[34] = (mz_uint8)(*pLen_out>>16);
pnghdr[35] = (mz_uint8)(*pLen_out>> 8);
pnghdr[36] = (mz_uint8)(*pLen_out>> 0);
if (num_chans == 1 && plte_size > 0)
pnghdr[25] = 3;
else
pnghdr[25] = (chans[num_chans]);
c = (mz_uint32)mz_crc32(MZ_CRC32_INIT,pnghdr+12,17);
for (i=0; i<4; ++i, c<<=8) ((mz_uint8*)(pnghdr+29))[i] = (mz_uint8)(c>>24);
memcpy(out_buf.m_pBuf, pnghdr, 41);
if (!tdefl_output_buffer_putter(pnghdr, sizeof(pnghdr), &out_buf)) { *pLen_out = 0; MZ_FREE(pComp); MZ_FREE(out_buf.m_pBuf); return NULL; }
}
// write PLTE chunk
if (plte_size > 0)
{
mz_uint8 hdr[8]={0x00,0x00,0x00,0x00,0x50,0x4c,0x54,0x45};
hdr[0] = (mz_uint8)(plte_size>>24);
hdr[1] = (mz_uint8)(plte_size>>16);
hdr[2] = (mz_uint8)(plte_size>> 8);
hdr[3] = (mz_uint8)(plte_size>> 0);
if (!tdefl_output_buffer_putter(hdr, sizeof(hdr), &out_buf)) { *pLen_out = 0; MZ_FREE(pComp); MZ_FREE(out_buf.m_pBuf); return NULL; }
data_start = out_buf.m_size;
if (!tdefl_output_buffer_putter(plte, plte_size, &out_buf)) { *pLen_out = 0; MZ_FREE(pComp); MZ_FREE(out_buf.m_pBuf); return NULL; }
if (!tdefl_output_buffer_putter("\0\0\0\0", 4, &out_buf)) { *pLen_out = 0; MZ_FREE(pComp); MZ_FREE(out_buf.m_pBuf); return NULL; }
c = (mz_uint32)mz_crc32(MZ_CRC32_INIT,out_buf.m_pBuf+data_start-4, plte_size+4);
for (i=0; i<4; ++i, c<<=8) (out_buf.m_pBuf+out_buf.m_size-4)[i] = (mz_uint8)(c >> 24);
}
// write tRNS chunk
if (trns_size > 0)
{
mz_uint8 hdr[8]={0x00,0x00,0x00,0x00,0x74,0x52,0x4E,0x53};
hdr[0] = (mz_uint8)(trns_size>>24);
hdr[1] = (mz_uint8)(trns_size>>16);
hdr[2] = (mz_uint8)(trns_size>> 8);
hdr[3] = (mz_uint8)(trns_size>> 0);
if (!tdefl_output_buffer_putter(hdr, sizeof(hdr), &out_buf)) { *pLen_out = 0; MZ_FREE(pComp); MZ_FREE(out_buf.m_pBuf); return NULL; }
data_start = out_buf.m_size;
if (!tdefl_output_buffer_putter(trns, trns_size, &out_buf)) { *pLen_out = 0; MZ_FREE(pComp); MZ_FREE(out_buf.m_pBuf); return NULL; }
if (!tdefl_output_buffer_putter("\0\0\0\0", 4, &out_buf)) { *pLen_out = 0; MZ_FREE(pComp); MZ_FREE(out_buf.m_pBuf); return NULL; }
c = (mz_uint32)mz_crc32(MZ_CRC32_INIT,out_buf.m_pBuf+data_start-4, trns_size+4);
for (i=0; i<4; ++i, c<<=8) (out_buf.m_pBuf+out_buf.m_size-4)[i] = (mz_uint8)(c >> 24);
}
// write IDAT chunk
if (!tdefl_output_buffer_putter("\0\0\0\0\x49\x44\x41\x54", 8, &out_buf)) { *pLen_out = 0; MZ_FREE(pComp); MZ_FREE(out_buf.m_pBuf); return NULL; }
data_start = out_buf.m_size;
// compress image data
tdefl_init(pComp, tdefl_output_buffer_putter, &out_buf, s_tdefl_png_num_probes[MZ_MIN(10, level)] | TDEFL_WRITE_ZLIB_HEADER);
for (y = 0; y < h; ++y) { tdefl_compress_buffer(pComp, &z, 1, TDEFL_NO_FLUSH); tdefl_compress_buffer(pComp, (mz_uint8*)pImage + (flip ? (h - 1 - y) : y) * bpl, bpl, TDEFL_NO_FLUSH); }
if (tdefl_compress_buffer(pComp, NULL, 0, TDEFL_FINISH) != TDEFL_STATUS_DONE) { MZ_FREE(pComp); MZ_FREE(out_buf.m_pBuf); return NULL; }
// write IDAT size
data_size = out_buf.m_size-data_start;
(out_buf.m_pBuf+data_start-8)[0] = (mz_uint8)(data_size>>24);
(out_buf.m_pBuf+data_start-8)[1] = (mz_uint8)(data_size>>16);
(out_buf.m_pBuf+data_start-8)[2] = (mz_uint8)(data_size>> 8);
(out_buf.m_pBuf+data_start-8)[3] = (mz_uint8)(data_size>> 0);
// write footer (IDAT CRC-32, followed by IEND chunk)
if (!tdefl_output_buffer_putter("\0\0\0\0\0\0\0\0\x49\x45\x4e\x44\xae\x42\x60\x82", 16, &out_buf)) { *pLen_out = 0; MZ_FREE(pComp); MZ_FREE(out_buf.m_pBuf); return NULL; }
c = (mz_uint32)mz_crc32(MZ_CRC32_INIT,out_buf.m_pBuf+41-4, *pLen_out+4);
c = (mz_uint32)mz_crc32(MZ_CRC32_INIT,out_buf.m_pBuf+data_start-4, data_size+4);
for (i=0; i<4; ++i, c<<=8) (out_buf.m_pBuf+out_buf.m_size-16)[i] = (mz_uint8)(c >> 24);
// compute final size of file, grab compressed data buffer and return
*pLen_out += 57;
*pLen_out = out_buf.m_size;
MZ_FREE(pComp);
return out_buf.m_pBuf;
}
#ifndef MINIZ_SDL_NOUNUSED
MINIZ_STATIC void *tdefl_write_image_to_png_file_in_memory(const void *pImage, int w, int h, int num_chans, int bpl, size_t *pLen_out)
{
// Level 6 corresponds to TDEFL_DEFAULT_MAX_PROBES or MZ_DEFAULT_LEVEL (but we can't depend on MZ_DEFAULT_LEVEL being available in case the zlib API's where #defined out)
return tdefl_write_image_to_png_file_in_memory_ex(pImage, w, h, num_chans, bpl, pLen_out, 6, MZ_FALSE);
return tdefl_write_image_to_png_file_in_memory_ex(pImage, w, h, num_chans, bpl, pLen_out, 6, MZ_FALSE, NULL, 0, NULL, 0);
}
#endif
#ifdef _MSC_VER
#pragma warning (pop)

104
test/testautomation_surface.c
View File

@@ -3,14 +3,6 @@
* Adapted/rewritten for test lib by Andreas Schiffler
*/
/* Suppress C4996 VS compiler warnings for unlink() */
#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_DEPRECATE)
#define _CRT_SECURE_NO_DEPRECATE
#endif
#if defined(_MSC_VER) && !defined(_CRT_NONSTDC_NO_DEPRECATE)
#define _CRT_NONSTDC_NO_DEPRECATE
#endif
#include <stdio.h>
#ifndef _MSC_VER
#include <unistd.h>
@@ -337,6 +329,13 @@ static int SDLCALL surface_testSaveLoad(void *arg)
const char *sampleFilename = "testSaveLoad.tmp";
SDL_Surface *face;
SDL_Surface *rface;
SDL_Palette *palette;
SDL_Color colors[] = {
{ 255, 0, 0, SDL_ALPHA_OPAQUE }, /* Red */
{ 0, 255, 0, SDL_ALPHA_OPAQUE } /* Green */
};
SDL_IOStream *stream;
Uint8 r, g, b, a;
/* Create sample surface */
face = SDLTest_ImageFace();
@@ -346,7 +345,7 @@ static int SDLCALL surface_testSaveLoad(void *arg)
}
/* Delete test file; ignore errors */
unlink(sampleFilename);
SDL_RemovePath(sampleFilename);
/* Save a BMP surface */
ret = SDL_SaveBMP(face, sampleFilename);
@@ -366,7 +365,7 @@ static int SDLCALL surface_testSaveLoad(void *arg)
}
/* Delete test file; ignore errors */
unlink(sampleFilename);
SDL_RemovePath(sampleFilename);
/* Save a PNG surface */
ret = SDL_SavePNG(face, sampleFilename);
@@ -386,12 +385,95 @@ static int SDLCALL surface_testSaveLoad(void *arg)
}
/* Delete test file; ignore errors */
unlink(sampleFilename);
SDL_RemovePath(sampleFilename);
/* Clean up */
SDL_DestroySurface(face);
face = NULL;
/* Create an 8-bit image */
face = SDL_CreateSurface(1, 1, SDL_PIXELFORMAT_INDEX8);
SDLTest_AssertCheck(face != NULL, "Verify 8-bit surface is not NULL");
if (face == NULL) {
return TEST_ABORTED;
}
palette = SDL_CreatePalette(2);
SDLTest_AssertCheck(palette != NULL, "Verify palette is not NULL");
if (palette == NULL) {
return TEST_ABORTED;
}
SDL_SetPaletteColors(palette, colors, 0, SDL_arraysize(colors));
SDL_SetSurfacePalette(face, palette);
SDL_DestroyPalette(palette);
/* Set a green pixel */
*(Uint8 *)face->pixels = 1;
/* Save and reload as a BMP */
stream = SDL_IOFromDynamicMem();
SDLTest_AssertCheck(stream != NULL, "Verify iostream is not NULL");
if (stream == NULL) {
return TEST_ABORTED;
}
ret = SDL_SaveBMP_IO(face, stream, false);
SDLTest_AssertPass("Call to SDL_SaveBMP()");
SDLTest_AssertCheck(ret == true, "Verify result from SDL_SaveBMP, expected: true, got: %i", ret);
SDL_SeekIO(stream, 0, SDL_IO_SEEK_SET);
rface = SDL_LoadBMP_IO(stream, false);
SDLTest_AssertPass("Call to SDL_LoadBMP()");
SDLTest_AssertCheck(rface != NULL, "Verify result from SDL_LoadBMP is not NULL");
if (rface != NULL) {
SDLTest_AssertCheck(face->w == rface->w, "Verify width of loaded surface, expected: %i, got: %i", face->w, rface->w);
SDLTest_AssertCheck(face->h == rface->h, "Verify height of loaded surface, expected: %i, got: %i", face->h, rface->h);
SDLTest_AssertCheck(rface->format == SDL_PIXELFORMAT_INDEX8, "Verify format of loaded surface, expected: %s, got: %s", SDL_GetPixelFormatName(face->format), SDL_GetPixelFormatName(rface->format));
SDL_ReadSurfacePixel(rface, 0, 0, &r, &g, &b, &a);
SDLTest_AssertCheck(r == colors[1].r &&
g == colors[1].g &&
b == colors[1].b &&
a == colors[1].a,
"Verify color of loaded surface, expected: %d,%d,%d,%d, got: %d,%d,%d,%d",
r, g, b, a,
colors[1].r, colors[1].g, colors[1].b, colors[1].a);
SDL_DestroySurface(rface);
rface = NULL;
}
SDL_CloseIO(stream);
stream = NULL;
/* Save and reload as a PNG */
stream = SDL_IOFromDynamicMem();
SDLTest_AssertCheck(stream != NULL, "Verify iostream is not NULL");
if (stream == NULL) {
return TEST_ABORTED;
}
ret = SDL_SavePNG_IO(face, stream, false);
SDLTest_AssertPass("Call to SDL_SavePNG()");
SDLTest_AssertCheck(ret == true, "Verify result from SDL_SavePNG, expected: true, got: %i", ret);
SDL_SeekIO(stream, 0, SDL_IO_SEEK_SET);
rface = SDL_LoadPNG_IO(stream, false);
SDLTest_AssertPass("Call to SDL_LoadPNG()");
SDLTest_AssertCheck(rface != NULL, "Verify result from SDL_LoadPNG is not NULL");
if (rface != NULL) {
SDLTest_AssertCheck(face->w == rface->w, "Verify width of loaded surface, expected: %i, got: %i", face->w, rface->w);
SDLTest_AssertCheck(face->h == rface->h, "Verify height of loaded surface, expected: %i, got: %i", face->h, rface->h);
SDLTest_AssertCheck(rface->format == SDL_PIXELFORMAT_INDEX8, "Verify format of loaded surface, expected: %s, got: %s", SDL_GetPixelFormatName(face->format), SDL_GetPixelFormatName(rface->format));
SDL_ReadSurfacePixel(rface, 0, 0, &r, &g, &b, &a);
SDLTest_AssertCheck(r == colors[1].r &&
g == colors[1].g &&
b == colors[1].b &&
a == colors[1].a,
"Verify color of loaded surface, expected: %d,%d,%d,%d, got: %d,%d,%d,%d",
r, g, b, a,
colors[1].r, colors[1].g, colors[1].b, colors[1].a);
SDL_DestroySurface(rface);
rface = NULL;
}
SDL_CloseIO(stream);
stream = NULL;
SDL_DestroySurface(face);
return TEST_COMPLETED;
}