From 054fca09f0bbd64fdbd6406a0643de938a9cd4fb Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 7 Feb 2021 18:13:51 +0200
Subject: [PATCH] Split image loading into headers and pixels

---
 source/graphics/bmploader.cpp           | 12 +++++++++---
 source/graphics/bmploader.h             |  4 +++-
 source/graphics/devil/devilloader.cpp   | 12 ++++++++++--
 source/graphics/devil/devilloader.h     |  3 ++-
 source/graphics/image.cpp               | 10 +++++++++-
 source/graphics/image.h                 |  1 +
 source/graphics/imageloader.cpp         | 13 ++++++++++++-
 source/graphics/imageloader.h           |  5 ++++-
 source/graphics/jpeg/jpegloader.cpp     |  5 ++++-
 source/graphics/jpeg/jpegloader.h       |  3 ++-
 source/graphics/png/pngloader.cpp       | 22 +++++++++++++++-------
 source/graphics/png/pngloader.h         |  3 ++-
 source/graphics/quartz/quartzloader.cpp | 23 +++++++++++++----------
 source/graphics/quartz/quartzloader.h   |  3 ++-
 14 files changed, 88 insertions(+), 31 deletions(-)

diff --git a/source/graphics/bmploader.cpp b/source/graphics/bmploader.cpp
index 39629f7..d88e2aa 100644
--- a/source/graphics/bmploader.cpp
+++ b/source/graphics/bmploader.cpp
@@ -29,7 +29,8 @@ namespace Graphics {
 
 BmpLoader::BmpLoader(IO::Base &i, unsigned sb):
 	io(i),
-	sig_bytes(sb)
+	sig_bytes(sb),
+	invert_row_order(false)
 {
 	// Image data location is stored at offset 10 and can't be skipped
 	if(sig_bytes>10)
@@ -44,7 +45,7 @@ bool BmpLoader::detect(const std::string &sig)
 	return !sig.compare(0, sizeof(bmp_sig), bmp_sig, sizeof(bmp_sig));
 }
 
-void BmpLoader::load_(Image::Data &data)
+void BmpLoader::load_headers_(Image::Data &data)
 {
 	char bm_header[14];
 	read_full(io, bm_header+sig_bytes, sizeof(bm_header)-sig_bytes);
@@ -92,8 +93,13 @@ void BmpLoader::load_(Image::Data &data)
 		skip -= size;
 	}
 
+	invert_row_order = (height<0);
+}
+
+void BmpLoader::load_pixels_(Image::Data &data)
+{
 	data.pixels = new char[data.stride*data.height];
-	if(height<0)
+	if(invert_row_order)
 	{
 		for(unsigned y=0; y<data.height; ++y)
 			read_full(io, data.pixels+(data.height-1-y)*data.stride, data.stride);
diff --git a/source/graphics/bmploader.h b/source/graphics/bmploader.h
index 9ae8f4e..60be2dc 100644
--- a/source/graphics/bmploader.h
+++ b/source/graphics/bmploader.h
@@ -11,6 +11,7 @@ class BmpLoader: public ImageLoader
 private:
 	IO::Base &io;
 	unsigned sig_bytes;
+	bool invert_row_order;
 
 public:
 	BmpLoader(IO::Base &, unsigned = 0);
@@ -18,7 +19,8 @@ public:
 	static unsigned get_signature_size() { return 2; }
 	static bool detect(const std::string &);
 
-	virtual void load_(Image::Data &);
+	virtual void load_headers_(Image::Data &);
+	virtual void load_pixels_(Image::Data &);
 };
 
 } // namespace Graphics
diff --git a/source/graphics/devil/devilloader.cpp b/source/graphics/devil/devilloader.cpp
index 423b108..a669308 100644
--- a/source/graphics/devil/devilloader.cpp
+++ b/source/graphics/devil/devilloader.cpp
@@ -101,7 +101,7 @@ bool DevilLoader::detect(const string &sig)
 	return type!=IL_TYPE_UNKNOWN;
 }
 
-void DevilLoader::load_(Image::Data &data)
+void DevilLoader::load_headers_(Image::Data &data)
 {
 	ilSetRead(0, 0, eof, get, read, seek, tell);
 	ilBindImage(id);
@@ -125,13 +125,21 @@ void DevilLoader::load_(Image::Data &data)
 	data.width = ilGetInteger(IL_IMAGE_WIDTH);
 	data.height = ilGetInteger(IL_IMAGE_HEIGHT);
 	data.stride = data.width*ilGetInteger(IL_IMAGE_BYTES_PER_PIXEL);
+
+	ilBindImage(0);
+	ilResetRead();
+}
+
+void DevilLoader::load_pixels_(Image::Data &data)
+{
+	ilBindImage(id);
+
 	unsigned data_size = data.stride*data.height;
 	data.pixels = new char[data_size];
 	ILubyte *il_data = ilGetData();
 	copy(il_data, il_data+data_size, data.pixels);
 
 	ilBindImage(0);
-	ilResetRead();
 }
 
 } // namespace Graphics
diff --git a/source/graphics/devil/devilloader.h b/source/graphics/devil/devilloader.h
index 3cba0d5..01c26b1 100644
--- a/source/graphics/devil/devilloader.h
+++ b/source/graphics/devil/devilloader.h
@@ -19,7 +19,8 @@ public:
 	static unsigned get_signature_size() { return 128; }
 	static bool detect(const std::string &);
 
-	virtual void load_(Image::Data &);
+	virtual void load_headers_(Image::Data &);
+	virtual void load_pixels_(Image::Data &);
 };
 
 } // namespace Graphics
diff --git a/source/graphics/image.cpp b/source/graphics/image.cpp
index 50e85df..fcfd222 100644
--- a/source/graphics/image.cpp
+++ b/source/graphics/image.cpp
@@ -67,9 +67,17 @@ void Image::load_io(IO::Seekable &io)
 
 void Image::load(ImageLoader &loader)
 {
-	data = Data();
+	if(loader.get_state()==ImageLoader::INITIAL)
+		data = Data();
 	loader.load(data);
 }
 
+void Image::load_headers(ImageLoader &loader)
+{
+	if(loader.get_state()==ImageLoader::INITIAL)
+		data = Data();
+	loader.load_headers(data);
+}
+
 } // namespace Graphics
 } // namespace Msp
diff --git a/source/graphics/image.h b/source/graphics/image.h
index 86cfa45..7b5236e 100644
--- a/source/graphics/image.h
+++ b/source/graphics/image.h
@@ -35,6 +35,7 @@ public:
 	void load_file(const std::string &);
 	void load_io(IO::Seekable &);
 	void load(ImageLoader &);
+	void load_headers(ImageLoader &);
 
 	PixelFormat get_format() const { return data.fmt; }
 	unsigned get_width() const { return data.width; }
diff --git a/source/graphics/imageloader.cpp b/source/graphics/imageloader.cpp
index 2c6ce21..fa6fcf8 100644
--- a/source/graphics/imageloader.cpp
+++ b/source/graphics/imageloader.cpp
@@ -89,10 +89,21 @@ void ImageLoader::load(Image::Data &data)
 	if(state>=FINISHED)
 		throw logic_error("already loaded");
 
-	load_(data);
+	if(state<HEADERS_LOADED)
+		load_headers_(data);
+	load_pixels_(data);
 	state = FINISHED;
 }
 
+void ImageLoader::load_headers(Image::Data &data)
+{
+	if(state>=HEADERS_LOADED)
+		throw logic_error("headers already loaded");
+
+	load_headers_(data);
+	state = HEADERS_LOADED;
+}
+
 ImageLoader::Registry &ImageLoader::get_registry()
 {
 	static Registry registry;
diff --git a/source/graphics/imageloader.h b/source/graphics/imageloader.h
index cb3f54a..1ad6cc8 100644
--- a/source/graphics/imageloader.h
+++ b/source/graphics/imageloader.h
@@ -27,6 +27,7 @@ public:
 	enum State
 	{
 		INITIAL,
+		HEADERS_LOADED,
 		FINISHED
 	};
 
@@ -74,8 +75,10 @@ public:
 	static ImageLoader *open_io(IO::Seekable &);
 
 	virtual void load(Image::Data &);
+	virtual void load_headers(Image::Data &);
 protected:
-	virtual void load_(Image::Data &) = 0;
+	virtual void load_headers_(Image::Data &) = 0;
+	virtual void load_pixels_(Image::Data &) = 0;
 
 public:
 	State get_state() const { return state; }
diff --git a/source/graphics/jpeg/jpegloader.cpp b/source/graphics/jpeg/jpegloader.cpp
index f61f651..4dd9440 100644
--- a/source/graphics/jpeg/jpegloader.cpp
+++ b/source/graphics/jpeg/jpegloader.cpp
@@ -119,7 +119,7 @@ bool JpegLoader::detect(const string &sig)
 	return !sig.compare(0, sizeof(jpeg_sig), jpeg_sig, sizeof(jpeg_sig));
 }
 
-void JpegLoader::load_(Image::Data &data)
+void JpegLoader::load_headers_(Image::Data &data)
 {
 	if(setjmp(priv->err_mgr.jmp))
 		throw bad_image_data(priv->err_mgr.message);
@@ -132,7 +132,10 @@ void JpegLoader::load_(Image::Data &data)
 	data.height = priv->jpeg.output_height;
 	data.stride = priv->jpeg.output_width*priv->jpeg.output_components;
 	data.fmt = RGB;
+}
 
+void JpegLoader::load_pixels_(Image::Data &data)
+{
 	data.pixels = new char[data.stride*data.height];
 	JSAMPROW rows[8];
 	while(priv->jpeg.output_scanline<data.height)
diff --git a/source/graphics/jpeg/jpegloader.h b/source/graphics/jpeg/jpegloader.h
index bf902d6..a18d37e 100644
--- a/source/graphics/jpeg/jpegloader.h
+++ b/source/graphics/jpeg/jpegloader.h
@@ -20,7 +20,8 @@ public:
 	static unsigned get_signature_size() { return 3; }
 	static bool detect(const std::string &);
 
-	virtual void load_(Image::Data &);
+	virtual void load_headers_(Image::Data &);
+	virtual void load_pixels_(Image::Data &);
 };
 
 } // namespace Graphics
diff --git a/source/graphics/png/pngloader.cpp b/source/graphics/png/pngloader.cpp
index 16ad36b..190d3cf 100644
--- 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;
 };
 
 
@@ -54,13 +55,10 @@ 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)
 {
-	png_byte **rows = 0;
-
 	if(setjmp(png_jmpbuf(priv->png)))
 	{
-		delete[] rows;
 		throw bad_image_data(priv->message);
 	}
 
@@ -69,8 +67,7 @@ void PngLoader::load_(Image::Data &data)
 	png_uint_32 height;
 	int depth;
 	int color;
-	int interlace;
-	png_get_IHDR(priv->png, priv->info, &width, &height, &depth, &color, &interlace, 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)
@@ -89,10 +86,21 @@ 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;
+
+	if(setjmp(png_jmpbuf(priv->png)))
+	{
+		delete[] rows;
+		throw bad_image_data(priv->message);
+	}
 
 	data.pixels = new char[data.stride*data.height];
 
-	if(interlace==PNG_INTERLACE_ADAM7)
+	if(priv->interlace==PNG_INTERLACE_ADAM7)
 	{
 		// ADAM7 requires all rows to be loaded at once
 		unsigned n_passes = png_set_interlace_handling(priv->png);
diff --git a/source/graphics/png/pngloader.h b/source/graphics/png/pngloader.h
index 21c1c72..7c9390f 100644
--- a/source/graphics/png/pngloader.h
+++ b/source/graphics/png/pngloader.h
@@ -20,7 +20,8 @@ public:
 	static unsigned get_signature_size() { return 8; }
 	static bool detect(const std::string &);
 
-	virtual void load_(Image::Data &);
+	virtual void load_headers_(Image::Data &);
+	virtual void load_pixels_(Image::Data &);
 };
 
 } // namespace Graphics
diff --git a/source/graphics/quartz/quartzloader.cpp b/source/graphics/quartz/quartzloader.cpp
index 472e066..e025b66 100644
--- a/source/graphics/quartz/quartzloader.cpp
+++ b/source/graphics/quartz/quartzloader.cpp
@@ -109,16 +109,6 @@ void QuartzLoader::load_(Image::Data &data)
 		}
 		else
 			throw unsupported_image_format("unknown colorspace");
-
-		CGDataProviderRef dp = CGImageGetDataProvider(image);
-		CFDataRef image_data = CGDataProviderCopyData(dp);
-		data.pixels = new char[data.height*data.stride];
-		unsigned offset = (alpha==kCGImageAlphaNoneSkipFirst);
-		CFRange range = CFRangeMake(offset, CFDataGetLength(image_data)-offset);
-		CFDataGetBytes(image_data, range, reinterpret_cast<UInt8 *>(data.pixels));
-		CFRelease(image_data);
-
-		CFRelease(image);
 	}
 	catch(...)
 	{
@@ -127,5 +117,18 @@ void QuartzLoader::load_(Image::Data &data)
 	}
 }
 
+void QuartzLoader::load_(Image::Data &data)
+{
+	CGDataProviderRef dp = CGImageGetDataProvider(image);
+	CFDataRef image_data = CGDataProviderCopyData(dp);
+	data.pixels = new char[data.height*data.stride];
+	unsigned offset = (alpha==kCGImageAlphaNoneSkipFirst);
+	CFRange range = CFRangeMake(offset, CFDataGetLength(image_data)-offset);
+	CFDataGetBytes(image_data, range, reinterpret_cast<UInt8 *>(data.pixels));
+	CFRelease(image_data);
+
+	CFRelease(image);
+}
+
 } // namespace Graphics
 } // namespace Msp
diff --git a/source/graphics/quartz/quartzloader.h b/source/graphics/quartz/quartzloader.h
index cf4a447..3e856a9 100644
--- a/source/graphics/quartz/quartzloader.h
+++ b/source/graphics/quartz/quartzloader.h
@@ -22,7 +22,8 @@ public:
 	static unsigned get_signature_size() { return 12; }
 	static bool detect(const std::string &);
 
-	virtual void load_(Image::Data &);
+	virtual void load_headers_(Image::Data &);
+	virtual void load_pixels_(Image::Data &);
 };
 
 } // namespace Graphics
-- 
2.43.0