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LibGfx: Prefer the largest image in the file when loading an ICO

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Since the current image handling APIs don't provide a way to handle a
file which can contain multiple images, we just pick the largest one.
This gives the best chance of a good looking result.
This commit is contained in:
Paul Roukema 2020-06-16 23:24:01 -04:00 • committed by Andreas Kling
parent b1e3f728a1
commit 82a75bcf5f
1 changed files with 29 additions and 9 deletions
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38
Libraries/LibGfx/ICOLoader.cpp
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@ -113,6 +113,7 @@ struct ICOLoadingContext {
const u8* data { nullptr }; const u8* data { nullptr };
size_t data_size { 0 }; size_t data_size { 0 };
Vector<ImageDescriptor> images; Vector<ImageDescriptor> images;
size_t largest_index;
}; };
RefPtr<Gfx::Bitmap> load_ico(const StringView& path) RefPtr<Gfx::Bitmap> load_ico(const StringView& path)
@ -164,6 +165,21 @@ static Optional<ImageDescriptor> decode_ico_direntry(BufferStream& stream)
return { desc }; return { desc };
} }
static size_t find_largest_image(const ICOLoadingContext& context)
{
size_t max_area = 0;
size_t index = 0;
size_t largest_index = 0;
for(const auto& desc : context.images) {
if (desc.width * desc.height > max_area) {
max_area = desc.width * desc.height;
largest_index = index;
}
++index;
}
return largest_index;
}
static bool load_ico_directory(ICOLoadingContext& context) static bool load_ico_directory(ICOLoadingContext& context)
{ {
auto buffer = ByteBuffer::wrap(context.data, context.data_size); auto buffer = ByteBuffer::wrap(context.data, context.data_size);
@ -197,6 +213,7 @@ static bool load_ico_directory(ICOLoadingContext& context)
#endif #endif
context.images.append(desc); context.images.append(desc);
} }
context.largest_index = find_largest_image(context);
context.state = ICOLoadingContext::State::DirectoryDecoded; context.state = ICOLoadingContext::State::DirectoryDecoded;
return true; return true;
} }
@ -292,7 +309,7 @@ static bool load_ico_bmp(ICOLoadingContext& context, ImageDescriptor& desc)
return true; return true;
} }
static bool load_ico_bitmap(ICOLoadingContext& context, size_t index) static bool load_ico_bitmap(ICOLoadingContext& context, Optional<size_t> index)
{ {
if (context.state < ICOLoadingContext::State::DirectoryDecoded) { if (context.state < ICOLoadingContext::State::DirectoryDecoded) {
if (!load_ico_directory(context)) { if (!load_ico_directory(context)) {
@ -301,18 +318,21 @@ static bool load_ico_bitmap(ICOLoadingContext& context, size_t index)
} }
context.state = ICOLoadingContext::State::DirectoryDecoded; context.state = ICOLoadingContext::State::DirectoryDecoded;
} }
if (index >= context.images.size()) { size_t real_index = context.largest_index;
if (index.has_value())
real_index = index.value();
if (real_index >= context.images.size()) {
return false; return false;
} }
ImageDescriptor& desc = context.images[index]; ImageDescriptor& desc = context.images[real_index];
PNGImageDecoderPlugin png_decoder(context.data + desc.offset, desc.size); PNGImageDecoderPlugin png_decoder(context.data + desc.offset, desc.size);
if (png_decoder.sniff()) { if (png_decoder.sniff()) {
desc.bitmap = png_decoder.bitmap(); desc.bitmap = png_decoder.bitmap();
if (!desc.bitmap) { if (!desc.bitmap) {
#ifdef ICO_DEBUG #ifdef ICO_DEBUG
printf("load_ico_bitmap: failed to load PNG encoded image index: %lu\n", index); printf("load_ico_bitmap: failed to load PNG encoded image index: %lu\n", real_index);
#endif #endif
return false; return false;
} }
@ -320,7 +340,7 @@ static bool load_ico_bitmap(ICOLoadingContext& context, size_t index)
} else { } else {
if (!load_ico_bmp(context, desc)) { if (!load_ico_bmp(context, desc)) {
#ifdef ICO_DEBUG #ifdef ICO_DEBUG
printf("load_ico_bitmap: failed to load BMP encoded image index: %lu\n", index); printf("load_ico_bitmap: failed to load BMP encoded image index: %lu\n", real_index);
#endif #endif
return false; return false;
} }
@ -351,7 +371,7 @@ IntSize ICOImageDecoderPlugin::size()
m_context->state = ICOLoadingContext::State::DirectoryDecoded; m_context->state = ICOLoadingContext::State::DirectoryDecoded;
} }
return { m_context->images[0].width, m_context->images[0].height }; return { m_context->images[m_context->largest_index].width, m_context->images[m_context->largest_index].height };
} }
RefPtr<Gfx::Bitmap> ICOImageDecoderPlugin::bitmap() RefPtr<Gfx::Bitmap> ICOImageDecoderPlugin::bitmap()
@ -361,7 +381,7 @@ RefPtr<Gfx::Bitmap> ICOImageDecoderPlugin::bitmap()
if (m_context->state < ICOLoadingContext::State::BitmapDecoded) { if (m_context->state < ICOLoadingContext::State::BitmapDecoded) {
// NOTE: This forces the chunk decoding to happen. // NOTE: This forces the chunk decoding to happen.
bool success = load_ico_bitmap(*m_context, 0); bool success = load_ico_bitmap(*m_context, {});
if (!success) { if (!success) {
m_context->state = ICOLoadingContext::State::Error; m_context->state = ICOLoadingContext::State::Error;
return nullptr; return nullptr;
@ -369,8 +389,8 @@ RefPtr<Gfx::Bitmap> ICOImageDecoderPlugin::bitmap()
m_context->state = ICOLoadingContext::State::BitmapDecoded; m_context->state = ICOLoadingContext::State::BitmapDecoded;
} }
ASSERT(m_context->images[0].bitmap); ASSERT(m_context->images[m_context->largest_index].bitmap);
return m_context->images[0].bitmap; return m_context->images[m_context->largest_index].bitmap;
} }
void ICOImageDecoderPlugin::set_volatile() void ICOImageDecoderPlugin::set_volatile()