TeamHepta/SDL
1
0
Fork 0
mirror of https://github.com/libsdl-org/SDL.git synced 2026-05-01 22:02:08 +02:00
Code Issues Packages Projects Releases Wiki Activity

Support indexed surfaces without palettes (thanks @sulix!)

Browse Source 
Currently, all SDL_Surfaces with an indexed pixel format have an
associated SDL_Palette. This palette either consists of entirely the
colour black, or -- in the special case of 1-bit surfaces, black and
white.

When an indexed surface is blitted to another indexed surface, a 'map'
is generated from the source surface's palette to the destination
surfaces palette, in order to preserve the look of the image if the
palettes differ.

However, in most cases, applications will want to blit the raw index
values, rather than translate to make the colours as similar as
possible. For instance, the destination surface's palette may have been
modified to fade the screen out.

This change allows an indexed surface to have no associated palette. If
either the source or destination surface of a blit do not have a
palette, then the raw indices are copied (assuming both have an indexed
format).

This mimics better what happens with most other APIs (such as
DirectDraw), where most users do not set a palette on any surface but
the screen, whose palette is implicitly used for the whole application.
This commit is contained in:
Sam Lantinga
2024-07-11 00:40:27 -07:00
parent 83d4251540
commit 875c4f0a4c
5 changed files with 65 additions and 45 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
src/video/SDL_bmp.c
View File

@@ -203,7 +203,6 @@ SDL_Surface *SDL_LoadBMP_IO(SDL_IOStream *src, SDL_bool closeio)
Uint32 Gmask = 0;
Uint32 Bmask = 0;
Uint32 Amask = 0;
SDL_Palette *palette;
Uint8 *bits;
Uint8 *top, *end;
SDL_bool topDown;
@@ -439,8 +438,10 @@ SDL_Surface *SDL_LoadBMP_IO(SDL_IOStream *src, SDL_bool closeio)
}
/* Load the palette, if any */
palette = SDL_GetSurfacePalette(surface);
if (palette) {
if (SDL_ISPIXELFORMAT_INDEXED(surface->format)) {
int max_colors = (1 << SDL_BITSPERPIXEL(surface->format));
SDL_Palette *palette;
if (SDL_SeekIO(src, fp_offset + 14 + biSize, SDL_IO_SEEK_SET) < 0) {
SDL_SetError("Error seeking in datastream");
goto done;
@@ -455,14 +456,19 @@ SDL_Surface *SDL_LoadBMP_IO(SDL_IOStream *src, SDL_bool closeio)
biClrUsed = 1 << biBitCount;
}
if (biClrUsed > (Uint32)palette->ncolors) {
if (biClrUsed > (Uint32)max_colors) {
biClrUsed = 1 << biBitCount; /* try forcing it? */
if (biClrUsed > (Uint32)palette->ncolors) {
if (biClrUsed > (Uint32)max_colors) {
SDL_SetError("Unsupported or incorrect biClrUsed field");
goto done;
}
}
palette = SDL_CreatePalette(biClrUsed);
if (!palette) {
goto done;
}
if (biSize == 12) {
for (i = 0; i < (int)biClrUsed; ++i) {
if (!SDL_ReadU8(src, &palette->colors[i].b) ||
@@ -488,7 +494,9 @@ SDL_Surface *SDL_LoadBMP_IO(SDL_IOStream *src, SDL_bool closeio)
palette->colors[i].a = SDL_ALPHA_OPAQUE;
}
}
palette->ncolors = biClrUsed;
SDL_SetSurfacePalette(surface, palette);
SDL_DestroyPalette(palette);
}
/* Read the surface pixels. Note that the bmp image is upside down */
@@ -515,7 +523,7 @@ SDL_Surface *SDL_LoadBMP_IO(SDL_IOStream *src, SDL_bool closeio)
if (SDL_ReadIO(src, bits, surface->pitch) != (size_t)surface->pitch) {
goto done;
}
if (biBitCount == 8 && palette && biClrUsed < (1u << biBitCount)) {
if (biBitCount == 8 && surface->internal->palette && biClrUsed < (1u << biBitCount)) {
for (i = 0; i < surface->w; ++i) {
if (bits[i] >= biClrUsed) {
SDL_SetError("A BMP image contains a pixel with a color out of the palette");

20
src/video/SDL_pixels.c
View File

@@ -1022,8 +1022,7 @@ SDL_Palette *SDL_CreatePalette(int ncolors)
if (!palette) {
return NULL;
}
palette->colors =
(SDL_Color *)SDL_malloc(ncolors * sizeof(*palette->colors));
palette->colors = (SDL_Color *)SDL_malloc(ncolors * sizeof(*palette->colors));
if (!palette->colors) {
SDL_free(palette);
return NULL;
@@ -1386,6 +1385,11 @@ static Uint8 *Map1toN(const SDL_Palette *pal, Uint8 Rmod, Uint8 Gmod, Uint8 Bmod
return NULL;
}
/* An all-zero map for surfaces without a palette. */
if (!pal) {
return map;
}
/* We memory copy to the pixel map so the endianness is preserved */
for (i = 0; i < pal->ncolors; ++i) {
Uint8 R = (Uint8)((pal->colors[i].r * Rmod) / 255);
@@ -1405,6 +1409,11 @@ static Uint8 *MapNto1(const SDL_PixelFormatDetails *src, const SDL_Palette *pal,
SDL_Palette dithered;
SDL_Color colors[256];
if (!pal) {
*identical = 1;
return NULL;
}
dithered.ncolors = 256;
SDL_DitherColors(colors, 8);
dithered.colors = colors;
@@ -1467,8 +1476,11 @@ int SDL_MapSurface(SDL_Surface *src, SDL_Surface *dst)
if (SDL_ISPIXELFORMAT_INDEXED(srcfmt->format)) {
if (SDL_ISPIXELFORMAT_INDEXED(dstfmt->format)) {
/* Palette --> Palette */
map->info.table =
Map1to1(srcpal, dstpal, &map->identity);
if (srcpal && dstpal) {
map->info.table = Map1to1(srcpal, dstpal, &map->identity);
} else {
map->identity = 1;
}
if (!map->identity) {
if (!map->info.table) {
return -1;

19
src/video/SDL_surface.c
View File

@@ -158,25 +158,6 @@ static SDL_Surface *SDL_InitializeSurface(SDL_InternalSurface *mem, int width, i
surface->internal->map.info.b = 0xFF;
surface->internal->map.info.a = 0xFF;
if (SDL_ISPIXELFORMAT_INDEXED(surface->format)) {
SDL_Palette *palette = SDL_CreatePalette((1 << SDL_BITSPERPIXEL(surface->format)));
if (!palette) {
SDL_DestroySurface(surface);
return NULL;
}
if (palette->ncolors == 2) {
/* Create a black and white bitmap palette */
palette->colors[0].r = 0xFF;
palette->colors[0].g = 0xFF;
palette->colors[0].b = 0xFF;
palette->colors[1].r = 0x00;
palette->colors[1].g = 0x00;
palette->colors[1].b = 0x00;
}
SDL_SetSurfacePalette(surface, palette);
SDL_DestroyPalette(palette);
}
if (colorspace != SDL_COLORSPACE_UNKNOWN &&
colorspace != SDL_GetDefaultColorspaceForFormat(format)) {
SDL_SetSurfaceColorspace(surface, colorspace);