From 69aaca13ae0949acf12056e390cbd1009a8487b2 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 13 Jul 2015 12:54:06 +0300
Subject: [PATCH] Handle interlaced PNG images

---
 source/graphics/png/pngloader.cpp | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/source/graphics/png/pngloader.cpp b/source/graphics/png/pngloader.cpp
index ede91b0..c2691bd 100644
--- a/source/graphics/png/pngloader.cpp
+++ b/source/graphics/png/pngloader.cpp
@@ -56,15 +56,21 @@ bool PngLoader::detect(const std::string &sig)
 
 void PngLoader::load(Image::Data &data)
 {
+	png_byte **rows = 0;
+
 	if(setjmp(png_jmpbuf(priv->png)))
+	{
+		delete[] rows;
 		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);
+	int interlace;
+	png_get_IHDR(priv->png, priv->info, &width, &height, &depth, &color, &interlace, 0, 0);
 	unsigned nchans = png_get_channels(priv->png, priv->info);
 
 	if(depth!=8)
@@ -85,8 +91,26 @@ void PngLoader::load(Image::Data &data)
 	}
 
 	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(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.data+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.data+data.stride*(data.height-1-y)), 0);
+	}
 
 	png_read_end(priv->png, 0);
 }
-- 
2.43.0