Split image loading into headers and pixels

[libs/gui.git] / source / graphics / png / pngloader.cpp

diff --git a/source/graphics/png/pngloader.cpp b/source/graphics/png/pngloader.cpp
index ede91b0c37be3615ae7ca9e714d93c0d3aa10d67..190d3cf297488e10977884080c5ad847b8645099 100644 (file)
--- a/source/graphics/png/pngloader.cpp
+++ b/source/graphics/png/pngloader.cpp
@@ -29,6 +29,7 @@ struct PngLoader::Private
        std::string message;
        png_struct *png;
        png_info *info;
+       int interlace;
 };
 
 
@@ -54,17 +55,19 @@ bool PngLoader::detect(const std::string &sig)
        return !png_sig_cmp(reinterpret_cast<png_byte *>(const_cast<char*>(sig.data())), 0, sig.size());
 }
 
-void PngLoader::load(Image::Data &data)
+void PngLoader::load_headers_(Image::Data &data)
 {
        if(setjmp(png_jmpbuf(priv->png)))
+       {
                throw bad_image_data(priv->message);
+       }
 
        png_read_info(priv->png, priv->info);
        png_uint_32 width;
        png_uint_32 height;
        int depth;
        int color;
-       png_get_IHDR(priv->png, priv->info, &width, &height, &depth, &color, 0, 0, 0);
+       png_get_IHDR(priv->png, priv->info, &width, &height, &depth, &color, &priv->interlace, 0, 0);
        unsigned nchans = png_get_channels(priv->png, priv->info);
 
        if(depth!=8)
@@ -83,10 +86,39 @@ void PngLoader::load(Image::Data &data)
        case PNG_COLOR_TYPE_RGB_ALPHA:  data.fmt = RGBA; break;
        default: throw unsupported_image_format("unknown color type");
        }
+}
+
+void PngLoader::load_pixels_(Image::Data &data)
+{
+       png_byte **rows = 0;
 
-       data.data = new char[data.stride*data.height];
-       for(unsigned y=0; y<data.height; ++y)
-               png_read_row(priv->png, reinterpret_cast<png_byte *>(data.data+data.stride*(data.height-1-y)), 0);
+       if(setjmp(png_jmpbuf(priv->png)))
+       {
+               delete[] rows;
+               throw bad_image_data(priv->message);
+       }
+
+       data.pixels = new char[data.stride*data.height];
+
+       if(priv->interlace==PNG_INTERLACE_ADAM7)
+       {
+               // ADAM7 requires all rows to be loaded at once
+               unsigned n_passes = png_set_interlace_handling(priv->png);
+               rows = new png_byte *[data.height];
+               for(unsigned y=0; y<data.height; ++y)
+                       rows[y] = reinterpret_cast<png_byte *>(data.pixels+data.stride*(data.height-1-y));
+
+               for(unsigned i=0; i<n_passes; ++i)
+                       png_read_rows(priv->png, rows, 0, data.height);
+
+               delete[] rows;
+               rows = 0;
+       }
+       else
+       {
+               for(unsigned y=0; y<data.height; ++y)
+                       png_read_row(priv->png, reinterpret_cast<png_byte *>(data.pixels+data.stride*(data.height-1-y)), 0);
+       }
 
        png_read_end(priv->png, 0);
 }