//
// PImageNativeLoaderJpeg.cc for pekwm
// Copyright (C) 2005 Claes Nasten <pekdon{@}pekdon{.}net>
//
// This program is licensed under the GNU GPL.
// See the LICENSE file for more information.
//

#include "../config.h"

#ifdef HAVE_IMAGE_JPEG

#include "PImageNativeLoaderJpeg.hh"

#include <iostream>

extern "C" {
#include <jpeglib.h>
}

using std::string;
using std::cerr;
using std::endl;

//! @brief PImageNativeLoaderJpeg constructor.
PImageNativeLoaderJpeg::PImageNativeLoaderJpeg(void)
	: PImageNativeLoader("JPG")
{
}

//! @brief PImageNativeLoaderJpeg destructor.
PImageNativeLoaderJpeg::~PImageNativeLoaderJpeg(void)
{
}

//! @brief Loads file into data.
//! @param file File to load data from.
//! @param width Set to the width of image.
//! @param height Set to the height of image.
//! @param alpha Set to wheter image has alpha channel.
//! @return Pointer to data on success, else NULL.
uchar*
PImageNativeLoaderJpeg::load(const std::string &file, uint &width,
														 uint &height, bool &alpha)
{
	FILE *fp;

	fp= fopen(file.c_str(), "rb");
	if (!fp) {
		cerr << " *** WARNING: unable to open " << file << " for reading!" << endl;
		return NULL;
	}

	struct jpeg_decompress_struct cinfo;
	struct jpeg_error_mgr jerr;

	cinfo.err = jpeg_std_error(&jerr);
	jpeg_create_decompress(&cinfo);

	jpeg_stdio_src(&cinfo, fp);

	// Read jpeg header.
	jpeg_read_header(&cinfo, TRUE);

	// Make sure we get data in 24bit RGB.
	if (cinfo.out_color_space != JCS_RGB)
		cinfo.out_color_space = JCS_RGB;

	jpeg_start_decompress(&cinfo);

	uint channels;
	uint rowbytes;

	width = cinfo.output_width;
	height = cinfo.output_height;
	channels = cinfo.output_components;
	rowbytes = width * channels;

	// Allocate image data.
	uchar *data = new uchar[width * height * channels];

	// Read image.
	JSAMPROW row;
	for (uint i = 0; i < height; ++i) {
		row = data + i * rowbytes;
		jpeg_read_scanlines(&cinfo, &row, 1);
	}

	// Clean up.
	jpeg_finish_decompress(&cinfo);
	jpeg_destroy_decompress(&cinfo);

	fclose(fp);

	alpha = false; // Jpeg doesn't support alpha.

	return data;
}

#endif // HAVE_IMAGE_JPEG