From: Mikko Rasa <tdb@tdb.fi>
Date: Thu, 10 Oct 2013 20:49:06 +0000 (+0300)
Subject: Add native libjpeg loader
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgui.git;a=commitdiff_plain;h=0a7b21172f7124439171e3921a12952a060c39fc

Add native libjpeg loader
---

diff --git a/Build b/Build
index b96da4d..7972020 100644
--- a/Build
+++ b/Build
@@ -43,6 +43,18 @@ package "mspgui"
 		require "libpng";
 	};
 
+	feature "libjpeg" "Include libjpeg support for loading JPEG files"
+	{
+		default "yes";
+	};
+	if_feature "libjpeg"
+	{
+		build_info
+		{
+			library "jpeg";
+		};
+	};
+
 	if_arch "darwin"
 	{
 		feature "quartz" "Include Quartz support for loading image files"
@@ -84,6 +96,10 @@ package "mspgui"
 		{
 			source "source/graphics/png";
 		};
+		if_feature "libjpeg"
+		{
+			source "source/graphics/jpeg";
+		};
 		if_feature "devil"
 		{
 			source "source/graphics/devil";
diff --git a/source/graphics/jpeg/jpegloader.cpp b/source/graphics/jpeg/jpegloader.cpp
new file mode 100644
index 0000000..415e79f
--- /dev/null
+++ b/source/graphics/jpeg/jpegloader.cpp
@@ -0,0 +1,150 @@
+#include <stdio.h>
+#include <setjmp.h>
+#include <jpeglib.h>
+#include "jpegloader.h"
+
+using namespace std;
+
+namespace {
+
+struct ErrorManager: jpeg_error_mgr
+{
+	jmp_buf jmp;
+	string message;
+};
+
+void error_exit(j_common_ptr jpeg)
+{
+	ErrorManager *err = reinterpret_cast<ErrorManager *>(jpeg->err);
+	char buf[JMSG_LENGTH_MAX];
+	err->format_message(jpeg, buf);
+	err->message = buf;
+	longjmp(err->jmp, 1);
+}
+
+void emit_message(j_common_ptr, int)
+{
+}
+
+
+struct SourceManager: jpeg_source_mgr
+{
+	Msp::IO::Seekable *io;
+	JOCTET buffer[4096];
+};
+
+void init_source(j_decompress_ptr jpeg)
+{
+	SourceManager *src = reinterpret_cast<SourceManager *>(jpeg->src);
+	src->next_input_byte = src->buffer;
+	src->bytes_in_buffer = 0;
+}
+
+int fill_input_buffer(j_decompress_ptr jpeg)
+{
+	SourceManager *src = reinterpret_cast<SourceManager *>(jpeg->src);
+	src->next_input_byte = src->buffer;
+	src->bytes_in_buffer = src->io->read(reinterpret_cast<char *>(src->buffer), sizeof(src->buffer));
+	return true;
+}
+
+void skip_input_data(j_decompress_ptr jpeg, long count)
+{
+	if(count<=0)
+		return;
+
+	SourceManager *src = reinterpret_cast<SourceManager *>(jpeg->src);
+	if(static_cast<unsigned long>(count)<src->bytes_in_buffer)
+	{
+		src->next_input_byte += count;
+		src->bytes_in_buffer -= count;
+	}
+	else
+	{
+		src->io->seek(count, Msp::IO::S_CUR);
+		src->bytes_in_buffer = 0;
+	}
+}
+
+void term_source(j_decompress_ptr)
+{
+}
+
+} // namespace
+
+
+namespace Msp {
+namespace Graphics {
+
+struct JpegLoader::Private
+{
+	jpeg_decompress_struct jpeg;
+	ErrorManager err_mgr;
+	SourceManager src_mgr;
+};
+
+
+ImageLoader::Register<JpegLoader> JpegLoader::reg;
+
+JpegLoader::JpegLoader(IO::Seekable &io):
+	priv(new Private)
+{
+	priv->jpeg.err = jpeg_std_error(&priv->err_mgr);
+	priv->err_mgr.error_exit = &error_exit;
+	priv->err_mgr.emit_message = &emit_message;
+
+	jpeg_create_decompress(&priv->jpeg);
+
+	priv->jpeg.src = &priv->src_mgr;
+	priv->src_mgr.init_source = &init_source;
+	priv->src_mgr.fill_input_buffer = &fill_input_buffer;
+	priv->src_mgr.skip_input_data = &skip_input_data;
+	priv->src_mgr.resync_to_restart = &jpeg_resync_to_restart;
+	priv->src_mgr.term_source = &term_source;
+	priv->src_mgr.io = &io;
+}
+
+JpegLoader::~JpegLoader()
+{
+	jpeg_destroy_decompress(&priv->jpeg);
+	delete priv;
+}
+
+bool JpegLoader::detect(const string &sig)
+{
+	static const char jpeg_sig[] = "\xFF\xD8\xFF";
+	if(sig.size()<sizeof(jpeg_sig))
+		return false;
+	return !sig.compare(0, 3, jpeg_sig);
+}
+
+void JpegLoader::load(Image::Data &data)
+{
+	if(setjmp(priv->err_mgr.jmp))
+		throw bad_image_data(priv->err_mgr.message);
+
+	jpeg_read_header(&priv->jpeg, true);
+	priv->jpeg.out_color_space = JCS_RGB;
+	jpeg_start_decompress(&priv->jpeg);
+
+	data.width = priv->jpeg.output_width;
+	data.height = priv->jpeg.output_height;
+	data.stride = priv->jpeg.output_width*priv->jpeg.output_components;
+	data.fmt = RGB;
+
+	data.data = new char[data.stride*data.height];
+	JSAMPROW rows[8];
+	while(priv->jpeg.output_scanline<data.height)
+	{
+		unsigned y = data.height-priv->jpeg.output_scanline;
+		unsigned count = min(y, 8U);
+		for(unsigned i=0; i<count; ++i)
+			rows[i] = reinterpret_cast<JSAMPROW>(data.data+(y-i-1)*data.stride);
+		jpeg_read_scanlines(&priv->jpeg, rows, count);
+	}
+
+	jpeg_finish_decompress(&priv->jpeg);
+}
+
+} // namespace Graphics
+} // namespace Msp
diff --git a/source/graphics/jpeg/jpegloader.h b/source/graphics/jpeg/jpegloader.h
new file mode 100644
index 0000000..d45e599
--- /dev/null
+++ b/source/graphics/jpeg/jpegloader.h
@@ -0,0 +1,31 @@
+#ifndef MSP_GRAPHICS_JPEGLOADER_H_
+#define MSP_GRAPHICS_JPEGLOADER_H_
+
+#include <msp/graphics/imageloader.h>
+
+namespace Msp {
+namespace Graphics {
+
+class JpegLoader: public ImageLoader
+{
+private:
+	struct Private;
+
+	Private *priv;
+
+	static Register<JpegLoader> reg;
+
+public:
+	JpegLoader(IO::Seekable &);
+	virtual ~JpegLoader();
+
+	static unsigned get_signature_size() { return 3; }
+	static bool detect(const std::string &);
+
+	virtual void load(Image::Data &);
+};
+
+} // namespace Graphics
+} // namespace Msp
+
+#endif