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LibGfx: Process colorspace-related chunks in PNGLoader

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This stores the data from all these chunks on PNGLoadingContext
but doesn't do anything with it yet.
This commit is contained in:
Nico Weber 2023-01-27 14:38:08 -05:00 • committed by Andreas Kling
parent 2dc657c77e
commit 53f485c5f0
1 changed files with 115 additions and 0 deletions
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115
Userland/Libraries/LibGfx/PNGLoader.cpp
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@ -27,6 +27,31 @@ struct PNG_IHDR {
static_assert(AssertSize<PNG_IHDR, 13>());
struct ChromaticitiesAndWhitepoint {
NetworkOrdered<u32> white_point_x;
NetworkOrdered<u32> white_point_y;
NetworkOrdered<u32> red_x;
NetworkOrdered<u32> red_y;
NetworkOrdered<u32> green_x;
NetworkOrdered<u32> green_y;
NetworkOrdered<u32> blue_x;
NetworkOrdered<u32> blue_y;
};
static_assert(AssertSize<ChromaticitiesAndWhitepoint, 32>());
struct CodingIndependentCodePoints {
u8 color_primaries;
u8 transfer_function;
u8 matrix_coefficients;
u8 video_full_range_flag;
};
static_assert(AssertSize<CodingIndependentCodePoints, 4>());
struct EmbeddedICCProfile {
StringView profile_name;
ReadonlyBytes compressed_data;
};
struct Scanline {
PNG::FilterType filter;
ReadonlyBytes data {};
@ -67,6 +92,13 @@ enum PngInterlaceMethod {
Adam7 = 1
};
enum RenderingIntent {
Perceptual = 0,
RelativeColorimetric = 1,
Saturation = 2,
AbsoluteColorimetric = 3,
};
struct PNGLoadingContext {
enum State {
NotDecoded = 0,
@ -97,6 +129,12 @@ struct PNGLoadingContext {
Vector<PaletteEntry> palette_data;
Vector<u8> palette_transparency_data;
Optional<ChromaticitiesAndWhitepoint> chromaticities_and_whitepoint;
Optional<CodingIndependentCodePoints> coding_independent_code_points;
Optional<u32> gamma;
Optional<EmbeddedICCProfile> embedded_icc_profile;
Optional<RenderingIntent> sRGB_rendering_intent;
Checked<int> compute_row_size_for_width(int width)
{
Checked<int> row_size = width;
@ -841,6 +879,73 @@ static bool process_tRNS(ReadonlyBytes data, PNGLoadingContext& context)
return true;
}
static bool process_cHRM(ReadonlyBytes data, PNGLoadingContext& context)
{
// https://www.w3.org/TR/png/#11cHRM
if (data.size() != 32)
return false;
context.chromaticities_and_whitepoint = *bit_cast<ChromaticitiesAndWhitepoint* const>(data.data());
return true;
}
static bool process_cICP(ReadonlyBytes data, PNGLoadingContext& context)
{
// https://www.w3.org/TR/png/#cICP-chunk
if (data.size() != 4)
return false;
context.coding_independent_code_points = *bit_cast<CodingIndependentCodePoints* const>(data.data());
return true;
}
static bool process_iCCP(ReadonlyBytes data, PNGLoadingContext& context)
{
// https://www.w3.org/TR/png/#11iCCP
size_t profile_name_length_max = min(80u, data.size());
size_t profile_name_length = strnlen((char const*)data.data(), profile_name_length_max);
if (profile_name_length == 0 || profile_name_length == profile_name_length_max)
return false;
if (data.size() < profile_name_length + 2)
return false;
u8 compression_method = data[profile_name_length + 1];
if (compression_method != 0)
return false;
context.embedded_icc_profile = EmbeddedICCProfile { { data.data(), profile_name_length }, data.slice(profile_name_length + 2) };
return true;
}
static bool process_gAMA(ReadonlyBytes data, PNGLoadingContext& context)
{
// https://www.w3.org/TR/png/#11gAMA
if (data.size() != 4)
return false;
u32 gamma = *bit_cast<NetworkOrdered<u32> const*>(data.data());
if (gamma & 0x8000'0000)
return false;
context.gamma = gamma;
return true;
}
static bool process_sRGB(ReadonlyBytes data, PNGLoadingContext& context)
{
// https://www.w3.org/TR/png/#srgb-standard-colour-space
if (data.size() != 1)
return false;
u8 rendering_intent = data[0];
if (rendering_intent > 3)
return false;
context.sRGB_rendering_intent = (RenderingIntent)rendering_intent;
return true;
}
static bool process_chunk(Streamer& streamer, PNGLoadingContext& context)
{
u32 chunk_size;
@ -872,6 +977,16 @@ static bool process_chunk(Streamer& streamer, PNGLoadingContext& context)
return process_IDAT(chunk_data, context);
if (!strcmp((char const*)chunk_type, "PLTE"))
return process_PLTE(chunk_data, context);
if (!strcmp((char const*)chunk_type, "cHRM"))
return process_cHRM(chunk_data, context);
if (!strcmp((char const*)chunk_type, "cICP"))
return process_cICP(chunk_data, context);
if (!strcmp((char const*)chunk_type, "iCCP"))
return process_iCCP(chunk_data, context);
if (!strcmp((char const*)chunk_type, "gAMA"))
return process_gAMA(chunk_data, context);
if (!strcmp((char const*)chunk_type, "sRGB"))
return process_sRGB(chunk_data, context);
if (!strcmp((char const*)chunk_type, "tRNS"))
return process_tRNS(chunk_data, context);
return true;