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Code Issues Projects Releases Packages Wiki Activity Actions 10

LibGfx: Support loading GIF local color maps if present :^)

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This commit is contained in:
Andreas Kling 2020-08-20 19:41:52 +02:00
parent 28e34ffe38
commit 7903cfa5e4
Notes: sideshowbarker 2024-07-19 03:23:46 +09:00
1 changed files with 18 additions and 3 deletions
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21
Libraries/LibGfx/GIFLoader.cpp
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@ -278,7 +278,9 @@ static bool decode_frames_up_to_index(GIFLoadingContext& context, size_t frame_i
const int clear_code = decoder.add_control_code();
const int end_of_information_code = decoder.add_control_code();
auto background_rgb = context.logical_screen.color_map[context.background_color_index];
auto& color_map = image.use_global_color_map ? context.logical_screen.color_map : image.color_map;
auto background_rgb = color_map[context.background_color_index];
Color background_color = Color(background_rgb.r, background_rgb.g, background_rgb.b);
image.bitmap = Bitmap::create_purgeable(BitmapFormat::RGBA32, { context.logical_screen.width, context.logical_screen.height });
@ -315,7 +317,7 @@ static bool decode_frames_up_to_index(GIFLoadingContext& context, size_t frame_i
auto colors = decoder.get_output();
for (const auto& color : colors) {
auto rgb = context.logical_screen.color_map[color];
auto rgb = color_map[color];
int x = pixel_index % image.width + image.x;
int y = pixel_index / image.width + image.y;
@ -410,7 +412,7 @@ static bool load_gif_frame_descriptors(GIFLoadingContext& context)
for (;;) {
u8 sentinel = 0;
stream >> sentinel;
printf("Sentinel: %02x\n", sentinel);
printf("Sentinel: %02x at offset %x\n", sentinel, (unsigned)stream.offset());
if (sentinel == 0x21) {
u8 extension_type = 0;
@ -493,6 +495,19 @@ static bool load_gif_frame_descriptors(GIFLoadingContext& context)
stream >> packed_fields;
if (stream.handle_read_failure())
return false;
image.use_global_color_map = !(packed_fields & 0x80);
if (!image.use_global_color_map) {
size_t local_color_table_size = pow(2, (packed_fields & 7) + 1);
for (size_t i = 0; i < local_color_table_size; ++i) {
stream >> image.color_map[i].r;
stream >> image.color_map[i].g;
stream >> image.color_map[i].b;
}
}
printf("Image descriptor: %d,%d %dx%d, %02x\n", image.x, image.y, image.width, image.height, packed_fields);
stream >> image.lzw_min_code_size;