diff options
| -rw-r--r-- | Userland/Libraries/LibGfx/WebPLoader.cpp | 28 |
1 files changed, 25 insertions, 3 deletions
diff --git a/Userland/Libraries/LibGfx/WebPLoader.cpp b/Userland/Libraries/LibGfx/WebPLoader.cpp index 7c9f7793ea..80d7f710eb 100644 --- a/Userland/Libraries/LibGfx/WebPLoader.cpp +++ b/Userland/Libraries/LibGfx/WebPLoader.cpp @@ -204,11 +204,33 @@ static ErrorOr<void> decode_webp_simple_lossy(WebPLoadingContext& context, Chunk } // 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_simple_lossless(WebPLoadingContext& context, Chunk const& vp8l_chunk) { - // FIXME - (void)context; - (void)vp8l_chunk; + VERIFY(vp8l_chunk.type == FourCC("VP8L")); + + // https://developers.google.com/speed/webp/docs/webp_lossless_bitstream_specification#3_riff_header + if (vp8l_chunk.data.size() < 5) + return context.error("WebPImageDecoderPlugin: VP8L chunk too small"); + + u8 const* data = vp8l_chunk.data.data(); + u8 signature = data[0]; + if (signature != 0x2f) + return context.error("WebPImageDecoderPlugin: VP8L chunk invalid signature"); + + // 14 bits width-1, 14 bits height-1, 1 bit alpha hint, 3 bit version_number. + u16 width = (data[1] | ((data[2] & 0x3f) << 8)) + 1; + u16 height = ((data[2] >> 6) | (data[3] << 2) | ((data[4] & 0xf) << 12)) + 1; + bool is_alpha_used = (data[4] & 0x10) != 0; + u8 version_number = (data[4] & 0xe0) >> 5; + + dbgln_if(WEBP_DEBUG, "width {}, height {}, is_alpha_used {}, version_number {}", + width, height, is_alpha_used, version_number); + + // "The version_number is a 3 bit code that must be set to 0. Any other value should be treated as an error. [AMENDED]" + if (version_number != 0) + return context.error("WebPImageDecoderPlugin: VP8L chunk invalid version_number"); + return {}; } |