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LibGfx: Move webp image decoding function up a bit

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Pure code move, no changes (except that this allows removing the
explicit prototype for this function, so it removes that).
This commit is contained in:
Nico Weber 2023-04-04 09:34:16 -04:00 committed by Linus Groh
parent f21af311c2
commit 4bd7090bc5
Notes: sideshowbarker 2024-07-17 00:59:43 +09:00 
Author: https://github.com/nico
Commit: https://github.com/SerenityOS/serenity/commit/4bd7090bc5
Pull-request: https://github.com/SerenityOS/serenity/pull/18192
1 changed files with 65 additions and 68 deletions
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133
Userland/Libraries/LibGfx/ImageFormats/WebPLoader.cpp
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@ -443,74 +443,6 @@ static ErrorOr<PrefixCodeGroup> decode_webp_chunk_VP8L_prefix_code_group(WebPLoa
return group;
}
static ErrorOr<NonnullRefPtr<Bitmap>> decode_webp_chunk_VP8L_image(WebPLoadingContext&, VP8LHeader const& vp8l_header, LittleEndianInputBitStream&);
// https://developers.google.com/speed/webp/docs/riff_container#simple_file_format_lossless
// https://developers.google.com/speed/webp/docs/webp_lossless_bitstream_specification#7_overall_structure_of_the_format
static ErrorOr<void> decode_webp_chunk_VP8L(WebPLoadingContext& context, Chunk const& vp8l_chunk)
{
VERIFY(context.first_chunk->type == FourCC("VP8L") || context.first_chunk->type == FourCC("VP8X"));
VERIFY(vp8l_chunk.type == FourCC("VP8L"));
auto vp8l_header = TRY(decode_webp_chunk_VP8L_header(context, vp8l_chunk));
// Check that size in VP8X chunk matches dimensions in VP8L chunk if both are present.
if (context.first_chunk->type == FourCC("VP8X")) {
if (vp8l_header.width != context.vp8x_header.width)
return context.error("WebPImageDecoderPlugin: VP8X and VP8L chunks store different widths");
if (vp8l_header.height != context.vp8x_header.height)
return context.error("WebPImageDecoderPlugin: VP8X and VP8L chunks store different heights");
if (vp8l_header.is_alpha_used != context.vp8x_header.has_alpha)
return context.error("WebPImageDecoderPlugin: VP8X and VP8L chunks store different alpha");
}
FixedMemoryStream memory_stream { vp8l_chunk.data.slice(5) };
LittleEndianInputBitStream bit_stream { MaybeOwned<Stream>(memory_stream) };
// image-stream = optional-transform spatially-coded-image
// https://developers.google.com/speed/webp/docs/webp_lossless_bitstream_specification#4_transformations
// https://developers.google.com/speed/webp/docs/webp_lossless_bitstream_specification#72_structure_of_transforms
// optional-transform = (%b1 transform optional-transform) / %b0
while (TRY(bit_stream.read_bits(1))) {
// transform = predictor-tx / color-tx / subtract-green-tx
// transform =/ color-indexing-tx
enum TransformType {
// predictor-tx = %b00 predictor-image
PREDICTOR_TRANSFORM = 0,
// color-tx = %b01 color-image
COLOR_TRANSFORM = 1,
// subtract-green-tx = %b10
SUBTRACT_GREEN_TRANSFORM = 2,
// color-indexing-tx = %b11 color-indexing-image
COLOR_INDEXING_TRANSFORM = 3,
};
TransformType transform_type = static_cast<TransformType>(TRY(bit_stream.read_bits(2)));
dbgln_if(WEBP_DEBUG, "transform type {}", (int)transform_type);
switch (transform_type) {
case PREDICTOR_TRANSFORM:
return context.error("WebPImageDecoderPlugin: VP8L PREDICTOR_TRANSFORM handling not yet implemented");
case COLOR_TRANSFORM:
return context.error("WebPImageDecoderPlugin: VP8L COLOR_TRANSFORM handling not yet implemented");
case SUBTRACT_GREEN_TRANSFORM:
return context.error("WebPImageDecoderPlugin: VP8L SUBTRACT_GREEN_TRANSFORM handling not yet implemented");
case COLOR_INDEXING_TRANSFORM:
return context.error("WebPImageDecoderPlugin: VP8L COLOR_INDEXING_TRANSFORM handling not yet implemented");
}
}
context.bitmap = TRY(decode_webp_chunk_VP8L_image(context, vp8l_header, bit_stream));
return {};
}
static ErrorOr<NonnullRefPtr<Bitmap>> decode_webp_chunk_VP8L_image(WebPLoadingContext& context, VP8LHeader const& vp8l_header, LittleEndianInputBitStream& bit_stream)
{
// https://developers.google.com/speed/webp/docs/webp_lossless_bitstream_specification#623_decoding_entropy-coded_image_data
@ -680,6 +612,71 @@ static ErrorOr<NonnullRefPtr<Bitmap>> decode_webp_chunk_VP8L_image(WebPLoadingCo
return bitmap;
}
// https://developers.google.com/speed/webp/docs/riff_container#simple_file_format_lossless
// https://developers.google.com/speed/webp/docs/webp_lossless_bitstream_specification#7_overall_structure_of_the_format
static ErrorOr<void> decode_webp_chunk_VP8L(WebPLoadingContext& context, Chunk const& vp8l_chunk)
{
VERIFY(context.first_chunk->type == FourCC("VP8L") || context.first_chunk->type == FourCC("VP8X"));
VERIFY(vp8l_chunk.type == FourCC("VP8L"));
auto vp8l_header = TRY(decode_webp_chunk_VP8L_header(context, vp8l_chunk));
// Check that size in VP8X chunk matches dimensions in VP8L chunk if both are present.
if (context.first_chunk->type == FourCC("VP8X")) {
if (vp8l_header.width != context.vp8x_header.width)
return context.error("WebPImageDecoderPlugin: VP8X and VP8L chunks store different widths");
if (vp8l_header.height != context.vp8x_header.height)
return context.error("WebPImageDecoderPlugin: VP8X and VP8L chunks store different heights");
if (vp8l_header.is_alpha_used != context.vp8x_header.has_alpha)
return context.error("WebPImageDecoderPlugin: VP8X and VP8L chunks store different alpha");
}
FixedMemoryStream memory_stream { vp8l_chunk.data.slice(5) };
LittleEndianInputBitStream bit_stream { MaybeOwned<Stream>(memory_stream) };
// image-stream = optional-transform spatially-coded-image
// https://developers.google.com/speed/webp/docs/webp_lossless_bitstream_specification#4_transformations
// https://developers.google.com/speed/webp/docs/webp_lossless_bitstream_specification#72_structure_of_transforms
// optional-transform = (%b1 transform optional-transform) / %b0
while (TRY(bit_stream.read_bits(1))) {
// transform = predictor-tx / color-tx / subtract-green-tx
// transform =/ color-indexing-tx
enum TransformType {
// predictor-tx = %b00 predictor-image
PREDICTOR_TRANSFORM = 0,
// color-tx = %b01 color-image
COLOR_TRANSFORM = 1,
// subtract-green-tx = %b10
SUBTRACT_GREEN_TRANSFORM = 2,
// color-indexing-tx = %b11 color-indexing-image
COLOR_INDEXING_TRANSFORM = 3,
};
TransformType transform_type = static_cast<TransformType>(TRY(bit_stream.read_bits(2)));
dbgln_if(WEBP_DEBUG, "transform type {}", (int)transform_type);
switch (transform_type) {
case PREDICTOR_TRANSFORM:
return context.error("WebPImageDecoderPlugin: VP8L PREDICTOR_TRANSFORM handling not yet implemented");
case COLOR_TRANSFORM:
return context.error("WebPImageDecoderPlugin: VP8L COLOR_TRANSFORM handling not yet implemented");
case SUBTRACT_GREEN_TRANSFORM:
return context.error("WebPImageDecoderPlugin: VP8L SUBTRACT_GREEN_TRANSFORM handling not yet implemented");
case COLOR_INDEXING_TRANSFORM:
return context.error("WebPImageDecoderPlugin: VP8L COLOR_INDEXING_TRANSFORM handling not yet implemented");
}
}
context.bitmap = TRY(decode_webp_chunk_VP8L_image(context, vp8l_header, bit_stream));
return {};
}
static ErrorOr<VP8XHeader> decode_webp_chunk_VP8X(WebPLoadingContext& context, Chunk const& vp8x_chunk)
{
VERIFY(vp8x_chunk.type == FourCC("VP8X"));