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PNGLoader: Support for color type 2 (RGB triplets) and multiple IDAT chunks.

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This commit is contained in:
Andreas Kling 2019-03-21 05:24:42 +01:00
parent 42755e98cf
commit 65348e7dc1
4 changed files with 83 additions and 54 deletions
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Base/res/wallpapers/sunset-retro.png Normal file
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Width:  |  Height:  |  Size: 876 KiB

131
SharedGraphics/PNGLoader.cpp
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@ -33,8 +33,14 @@ struct PNGLoadingContext {
byte compression_method { 0 };
byte filter_method { 0 };
byte interlace_method { 0 };
byte bytes_per_pixel { 0 };
bool has_seen_zlib_header { false };
bool has_alpha() const { return color_type & 4; }
Vector<Scanline> scanlines;
RetainPtr<GraphicsBitmap> bitmap;
byte* decompression_buffer { nullptr };
int decompression_buffer_size { 0 };
Vector<byte> compressed_data;
};
class Streamer {
@ -158,6 +164,30 @@ static RetainPtr<GraphicsBitmap> load_png_impl(const byte* data, int data_size)
}
}
unsigned long srclen = context.compressed_data.size() - 6;
unsigned long destlen = context.decompression_buffer_size;
int ret = puff(context.decompression_buffer, &destlen, context.compressed_data.data() + 2, &srclen);
if (ret < 0)
return nullptr;
context.compressed_data.clear();
{
Streamer streamer(context.decompression_buffer, context.decompression_buffer_size);
for (int y = 0; y < context.height; ++y) {
byte filter;
if (!streamer.read(filter))
return nullptr;
context.scanlines.append({ filter, ByteBuffer::create_uninitialized(context.width * context.bytes_per_pixel) });
auto& scanline_buffer = context.scanlines.last().data;
if (!streamer.read_bytes(scanline_buffer.pointer(), scanline_buffer.size()))
return nullptr;
}
munmap(context.decompression_buffer, context.decompression_buffer_size);
context.decompression_buffer = nullptr;
context.decompression_buffer_size = 0;
}
context.bitmap = GraphicsBitmap::create(GraphicsBitmap::Format::RGBA32, { context.width, context.height });
union [[gnu::packed]] Pixel {
@ -171,11 +201,28 @@ static RetainPtr<GraphicsBitmap> load_png_impl(const byte* data, int data_size)
};
static_assert(sizeof(Pixel) == 4);
printf("unfiltering %d scanlines\n", context.height);
for (int y = 0; y < context.height; ++y) {
auto filter = context.scanlines[y].filter;
printf("[%d] filter=%u\n", y, context.scanlines[y].filter);
memcpy(context.bitmap->scanline(y), context.scanlines[y].data.pointer(), context.scanlines[y].data.size());
switch (context.color_type) {
case 2: {
struct [[gnu::packed]] Triplet { byte r; byte g; byte b; };
auto* triplets = (Triplet*)context.scanlines[y].data.pointer();
for (int i = 0; i < context.width; ++i) {
auto& pixel = (Pixel&)context.bitmap->scanline(y)[i];
pixel.r = triplets[i].r;
pixel.g = triplets[i].g;
pixel.b = triplets[i].b;
pixel.a = 0xff;
}
break;
}
case 6:
memcpy(context.bitmap->scanline(y), context.scanlines[y].data.pointer(), context.scanlines[y].data.size());
break;
default:
ASSERT_NOT_REACHED();
break;
}
if (filter == 0)
continue;
for (int i = 0; i < context.width; ++i) {
@ -192,28 +239,26 @@ static RetainPtr<GraphicsBitmap> load_png_impl(const byte* data, int data_size)
x.r += a.r;
x.g += a.g;
x.b += a.b;
x.a += a.a;
}
if (filter == 2) {
if (context.has_alpha())
x.a += a.a;
} else if (filter == 2) {
x.r += b.r;
x.g += b.g;
x.b += b.b;
x.a += b.a;
}
if (filter == 3) {
if (context.has_alpha())
x.a += b.a;
} if (filter == 3) {
x.r = x.r + ((a.r + b.r) / 2);
x.g = x.g + ((a.g + b.g) / 2);
x.b = x.b + ((a.b + b.b) / 2);
x.a = x.a + ((a.a + b.a) / 2);
}
if (filter == 4) {
if (context.has_alpha())
x.a = x.a + ((a.a + b.a) / 2);
} if (filter == 4) {
x.r += paeth_predictor(a.r, b.r, c.r);
x.g += paeth_predictor(a.g, b.g, c.g);
x.b += paeth_predictor(a.b, b.b, c.b);
x.a += paeth_predictor(a.a, b.a, c.a);
if (context.has_alpha())
x.a += paeth_predictor(a.a, b.a, c.a);
}
}
}
@ -233,46 +278,30 @@ static bool process_IHDR(const ByteBuffer& data, PNGLoadingContext& context)
context.compression_method = ihdr.compression_method;
context.filter_method = ihdr.filter_method;
context.interlace_method = ihdr.interlace_method;
switch (context.color_type) {
case 2:
context.bytes_per_pixel = 3;
break;
case 6:
context.bytes_per_pixel = 4;
break;
default:
ASSERT_NOT_REACHED();
}
printf("PNG: %dx%d (%d bpp)\n", context.width, context.height, context.bit_depth);
printf(" Color type: %b\n", context.color_type);
printf(" Interlace type: %b\n", context.interlace_method);
context.decompression_buffer_size = (context.width * context.height * context.bytes_per_pixel + context.height);
context.decompression_buffer = (byte*)mmap(nullptr, context.decompression_buffer_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
return true;
}
static bool process_IDAT(const ByteBuffer& data, PNGLoadingContext& context)
{
for (int i = 0; i < data.size(); ++i) {
printf("%c", data[i]);
}
printf("\n");
printf("first byte into puff: %c (%b)\n", data[0], data[0]);
struct [[gnu::packed]] ZlibHeader {
byte compression_method : 4;
byte compression_info : 4;
byte flags;
};
static_assert(sizeof(ZlibHeader) == 2);
auto& zhdr = *(ZlibHeader*)data.pointer();
printf("compression_method: %u\n", zhdr.compression_method);
printf("compression_info: %u\n", zhdr.compression_info);
printf("flags: %b\n", zhdr.flags);
unsigned long destlen = (context.width * context.height * sizeof(RGBA32)) + context.height;
unsigned long srclen = data.size() - 2;
auto decompression_buffer = ByteBuffer::create_uninitialized(destlen + context.height);
int ret = puff(decompression_buffer.pointer(), &destlen, data.pointer() + 2, &srclen);
if (ret != 0)
return false;
Streamer streamer(decompression_buffer.pointer(), decompression_buffer.size());
for (int y = 0; y < context.height; ++y) {
byte filter;
if (!streamer.read(filter))
return false;
context.scanlines.append({ filter, ByteBuffer::create_uninitialized(context.width * sizeof(RGBA32)) });
auto& scanline_buffer = context.scanlines.last().data;
if (!streamer.read_bytes(scanline_buffer.pointer(), scanline_buffer.size()))
return false;
}
context.compressed_data.append(data.pointer(), data.size());
return true;
}

2
SharedGraphics/Size.h
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@ -48,7 +48,7 @@ public:
operator WSAPI_Size() const;
String to_string() const { return String::format("[%d,%d]", m_width, m_height); }
String to_string() const { return String::format("[%dx%d]", m_width, m_height); }
private:
int m_width { 0 };

4
Userland/qs.cpp
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@ -15,7 +15,7 @@ int main(int argc, char** argv)
}
#endif
const char* path = "/res/icons/folder32.png";
const char* path = "/res/wallpapers/sunset-retro.png";
if (argc > 1)
path = argv[1];
@ -26,7 +26,7 @@ int main(int argc, char** argv)
}
auto* window = new GWindow;
window->set_title(String::format("qs: %s", path));
window->set_title(String::format("QuickShow: %s %s", path, bitmap->size().to_string().characters()));
window->set_rect(200, 200, bitmap->width(), bitmap->height());
auto* widget = new GWidget;