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LibGfx: Move PNG header and paeth_predictor function to a shared header

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This commit is contained in:
Karol Kosek 2022-07-10 00:14:19 +02:00 committed by Andreas Kling
parent ebc20f7ac3
commit 98a90d79de
3 changed files with 28 additions and 27 deletions
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35
Userland/Libraries/LibGfx/PNGLoader.cpp
View file

@ -20,8 +20,6 @@
namespace Gfx {
static constexpr Array<u8, 8> png_header = { 0x89, 'P', 'N', 'G', 13, 10, 26, 10 };
struct PNG_IHDR {
NetworkOrdered<u32> width;
NetworkOrdered<u32> height;
@ -166,19 +164,6 @@ private:
static bool process_chunk(Streamer&, PNGLoadingContext& context);
ALWAYS_INLINE static u8 paeth_predictor(int a, int b, int c)
{
int p = a + b - c;
int pa = abs(p - a);
int pb = abs(p - b);
int pc = abs(p - c);
if (pa <= pb && pa <= pc)
return a;
if (pb <= pc)
return b;
return c;
}
union [[gnu::packed]] Pixel {
ARGB32 rgba { 0 };
u8 v[4];
@ -264,11 +249,11 @@ ALWAYS_INLINE static void unfilter_impl(Gfx::Bitmap& bitmap, int y, void const*
a = pixels[i - 1];
c = pixels_y_minus_1[i - 1];
}
x.v[0] += paeth_predictor(a.v[0], b.v[0], c.v[0]);
x.v[1] += paeth_predictor(a.v[1], b.v[1], c.v[1]);
x.v[2] += paeth_predictor(a.v[2], b.v[2], c.v[2]);
x.v[0] += PNG::paeth_predictor(a.v[0], b.v[0], c.v[0]);
x.v[1] += PNG::paeth_predictor(a.v[1], b.v[1], c.v[1]);
x.v[2] += PNG::paeth_predictor(a.v[2], b.v[2], c.v[2]);
if constexpr (has_alpha)
x.v[3] += paeth_predictor(a.v[3], b.v[3], c.v[3]);
x.v[3] += PNG::paeth_predictor(a.v[3], b.v[3], c.v[3]);
}
}
}
@ -513,13 +498,13 @@ static bool decode_png_header(PNGLoadingContext& context)
if (context.state >= PNGLoadingContext::HeaderDecoded)
return true;
if (!context.data || context.data_size < sizeof(png_header)) {
if (!context.data || context.data_size < sizeof(PNG::header)) {
dbgln_if(PNG_DEBUG, "Missing PNG header");
context.state = PNGLoadingContext::State::Error;
return false;
}
if (memcmp(context.data, png_header.span().data(), sizeof(png_header)) != 0) {
if (memcmp(context.data, PNG::header.span().data(), sizeof(PNG::header)) != 0) {
dbgln_if(PNG_DEBUG, "Invalid PNG header");
context.state = PNGLoadingContext::State::Error;
return false;
@ -539,8 +524,8 @@ static bool decode_png_size(PNGLoadingContext& context)
return false;
}
u8 const* data_ptr = context.data + sizeof(png_header);
size_t data_remaining = context.data_size - sizeof(png_header);
u8 const* data_ptr = context.data + sizeof(PNG::header);
size_t data_remaining = context.data_size - sizeof(PNG::header);
Streamer streamer(data_ptr, data_remaining);
while (!streamer.at_end()) {
@ -567,8 +552,8 @@ static bool decode_png_chunks(PNGLoadingContext& context)
return false;
}
u8 const* data_ptr = context.data + sizeof(png_header);
int data_remaining = context.data_size - sizeof(png_header);
u8 const* data_ptr = context.data + sizeof(PNG::header);
int data_remaining = context.data_size - sizeof(PNG::header);
context.compressed_data.ensure_capacity(context.data_size);

17
Userland/Libraries/LibGfx/PNGShared.h
View file

@ -8,6 +8,9 @@
namespace Gfx::PNG {
// https://www.w3.org/TR/PNG/#5PNG-file-signature
static constexpr Array<u8, 8> header = { 0x89, 'P', 'N', 'G', 13, 10, 26, 10 };
// https://www.w3.org/TR/PNG/#6Colour-values
enum class ColorType : u8 {
Greyscale = 0,
@ -26,4 +29,18 @@ enum class FilterType : u8 {
Paeth,
};
// https://www.w3.org/TR/PNG/#9Filter-type-4-Paeth
ALWAYS_INLINE u8 paeth_predictor(u8 a, u8 b, u8 c)
{
int p = a + b - c;
int pa = abs(p - a);
int pb = abs(p - b);
int pc = abs(p - c);
if (pa <= pb && pa <= pc)
return a;
if (pb <= pc)
return b;
return c;
}
};

3
Userland/Libraries/LibGfx/PNGWriter.cpp
View file

@ -112,8 +112,7 @@ void PNGWriter::add_chunk(PNGChunk& png_chunk)
void PNGWriter::add_png_header()
{
const u8 png_header[8] = { 0x89, 'P', 'N', 'G', 13, 10, 26, 10 };
m_data.append(png_header, sizeof(png_header));
m_data.append(PNG::header.data(), PNG::header.size());
}
void PNGWriter::add_IHDR_chunk(u32 width, u32 height, u8 bit_depth, PNG::ColorType color_type, u8 compression_method, u8 filter_method, u8 interlace_method)