--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/image_load_jpeg.c	Sat Mar 26 22:03:30 2011 +0100
@@ -0,0 +1,310 @@
+
+#include "main.h"
+#include "image-load.h"
+#include "image_load_jpeg.h"
+
+#include <setjmp.h>
+#include <jpeglib.h>
+#include <jerror.h>
+
+typedef struct _ImageLoaderJpeg ImageLoaderJpeg;
+struct _ImageLoaderJpeg {
+	ImageLoaderBackendCbAreaUpdated area_updated_cb;
+	ImageLoaderBackendCbSize size_cb;
+	ImageLoaderBackendCbAreaPrepared area_prepared_cb;
+	
+	gpointer data;
+	
+	GdkPixbuf *pixbuf;
+	guint requested_width;
+	guint requested_height;
+	
+	gboolean abort;
+	
+};
+
+/* error handler data */
+struct error_handler_data {
+	struct jpeg_error_mgr pub;
+	sigjmp_buf setjmp_buffer;
+        GError **error;
+};
+
+/* explode gray image data from jpeg library into rgb components in pixbuf */
+static void
+explode_gray_into_buf (struct jpeg_decompress_struct *cinfo,
+		       guchar **lines) 
+{
+	gint i, j;
+	guint w;
+
+	g_return_if_fail (cinfo != NULL);
+	g_return_if_fail (cinfo->output_components == 1);
+	g_return_if_fail (cinfo->out_color_space == JCS_GRAYSCALE);
+
+	/* Expand grey->colour.  Expand from the end of the
+	 * memory down, so we can use the same buffer.
+	 */
+	w = cinfo->output_width;
+	for (i = cinfo->rec_outbuf_height - 1; i >= 0; i--) {
+		guchar *from, *to;
+		
+		from = lines[i] + w - 1;
+		to = lines[i] + (w - 1) * 3;
+		for (j = w - 1; j >= 0; j--) {
+			to[0] = from[0];
+			to[1] = from[0];
+			to[2] = from[0];
+			to -= 3;
+			from--;
+		}
+	}
+}
+
+
+static void
+convert_cmyk_to_rgb (struct jpeg_decompress_struct *cinfo,
+		     guchar **lines) 
+{
+	gint i, j;
+
+	g_return_if_fail (cinfo != NULL);
+	g_return_if_fail (cinfo->output_components == 4);
+	g_return_if_fail (cinfo->out_color_space == JCS_CMYK);
+
+	for (i = cinfo->rec_outbuf_height - 1; i >= 0; i--) {
+		guchar *p;
+		
+		p = lines[i];
+		for (j = 0; j < cinfo->output_width; j++) {
+			int c, m, y, k;
+			c = p[0];
+			m = p[1];
+			y = p[2];
+			k = p[3];
+			if (cinfo->saw_Adobe_marker) {
+				p[0] = k*c / 255;
+				p[1] = k*m / 255;
+				p[2] = k*y / 255;
+			}
+			else {
+				p[0] = (255 - k)*(255 - c) / 255;
+				p[1] = (255 - k)*(255 - m) / 255;
+				p[2] = (255 - k)*(255 - y) / 255;
+			}
+			p[3] = 255;
+			p += 4;
+		}
+	}
+}
+
+
+static gpointer image_loader_jpeg_new(ImageLoaderBackendCbAreaUpdated area_updated_cb, ImageLoaderBackendCbSize size_cb, ImageLoaderBackendCbAreaPrepared area_prepared_cb, gpointer data)
+{
+        ImageLoaderJpeg *loader = g_new0(ImageLoaderJpeg, 1);
+        
+	loader->area_updated_cb = area_updated_cb;
+	loader->size_cb = size_cb;
+	loader->area_prepared_cb = area_prepared_cb;
+	loader->data = data;
+	return (gpointer) loader;
+}
+
+static void
+fatal_error_handler (j_common_ptr cinfo)
+{
+	struct error_handler_data *errmgr;
+        char buffer[JMSG_LENGTH_MAX];
+        
+	errmgr = (struct error_handler_data *) cinfo->err;
+        
+        /* Create the message */
+        (* cinfo->err->format_message) (cinfo, buffer);
+
+        /* broken check for *error == NULL for robustness against
+         * crappy JPEG library
+         */
+        if (errmgr->error && *errmgr->error == NULL) {
+                g_set_error (errmgr->error,
+                             GDK_PIXBUF_ERROR,
+                             cinfo->err->msg_code == JERR_OUT_OF_MEMORY 
+			     ? GDK_PIXBUF_ERROR_INSUFFICIENT_MEMORY 
+			     : GDK_PIXBUF_ERROR_CORRUPT_IMAGE,
+                             _("Error interpreting JPEG image file (%s)"),
+                             buffer);
+        }
+        
+	siglongjmp (errmgr->setjmp_buffer, 1);
+
+        g_assert_not_reached ();
+}
+
+static void
+output_message_handler (j_common_ptr cinfo)
+{
+  /* This method keeps libjpeg from dumping crap to stderr */
+
+  /* do nothing */
+}
+
+static gboolean image_loader_jpeg_load (gpointer loader, const guchar *buf, gsize count, GError **error)
+{
+	ImageLoaderJpeg *lj = (ImageLoaderJpeg *) loader;
+	struct jpeg_decompress_struct cinfo;
+	guchar *dptr;
+	guint rowstride;
+
+	struct error_handler_data jerr;
+//	stdio_src_ptr src;
+
+	/* setup error handler */
+	cinfo.err = jpeg_std_error (&jerr.pub);
+	jerr.pub.error_exit = fatal_error_handler;
+        jerr.pub.output_message = output_message_handler;
+
+        jerr.error = error;
+
+
+	if (setjmp(jerr.setjmp_buffer)) 
+		{
+		/* If we get here, the JPEG code has signaled an error.
+		 * We need to clean up the JPEG object, close the input file, and return.
+		*/
+		jpeg_destroy_decompress(&cinfo);
+		return FALSE;
+		}
+	
+	jpeg_create_decompress(&cinfo);
+
+	jpeg_mem_src(&cinfo, (unsigned char *)buf, count);
+
+
+	jpeg_read_header(&cinfo, TRUE);
+
+	lj->requested_width = cinfo.image_width;
+	lj->requested_height = cinfo.image_height;
+	lj->size_cb(loader, cinfo.image_width, cinfo.image_height, lj->data);
+			
+	cinfo.scale_num = 1;
+	for (cinfo.scale_denom = 2; cinfo.scale_denom <= 8; cinfo.scale_denom *= 2) {
+		jpeg_calc_output_dimensions(&cinfo);
+		if (cinfo.output_width < lj->requested_width || cinfo.output_height < lj->requested_height) {
+			cinfo.scale_denom /= 2;
+			break;
+		}
+	}
+	jpeg_calc_output_dimensions(&cinfo);
+
+	jpeg_start_decompress(&cinfo);
+	
+	lj->pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, 
+				     cinfo.out_color_components == 4 ? TRUE : FALSE, 
+				     8, cinfo.output_width, cinfo.output_height);
+
+	lj->area_prepared_cb(loader, lj->data);
+	rowstride = gdk_pixbuf_get_rowstride(lj->pixbuf);
+	dptr = gdk_pixbuf_get_pixels(lj->pixbuf);
+	      
+	if (!lj->pixbuf) 
+		{
+		jpeg_destroy_decompress (&cinfo);
+		return 0;
+		}
+
+	while (cinfo.output_scanline < cinfo.output_height && !lj->abort) 
+		{
+		guchar *lines[4];
+		guchar **lptr;
+		gint i;
+		guint scanline = cinfo.output_scanline;
+
+		lptr = lines;
+		for (i = 0; i < cinfo.rec_outbuf_height; i++) 
+			{
+			*lptr++ = dptr;
+			dptr += rowstride;
+			}
+
+		jpeg_read_scanlines (&cinfo, lines, cinfo.rec_outbuf_height);
+
+		switch (cinfo.out_color_space) 
+			{
+			    case JCS_GRAYSCALE:
+			      explode_gray_into_buf (&cinfo, lines);
+			      break;
+			    case JCS_RGB:
+			      /* do nothing */
+			      break;
+			    case JCS_CMYK:
+			      convert_cmyk_to_rgb (&cinfo, lines);
+			      break;
+			    default:
+			      break;
+			}
+		lj->area_updated_cb(loader, 0, scanline, cinfo.output_width, cinfo.rec_outbuf_height, lj->data);
+		}
+
+	jpeg_finish_decompress(&cinfo);
+	jpeg_destroy_decompress(&cinfo);
+	return TRUE;
+}
+
+static void image_loader_jpeg_set_size(gpointer loader, int width, int height)
+{
+	ImageLoaderJpeg *lj = (ImageLoaderJpeg *) loader;
+	lj->requested_width = width;
+	lj->requested_height = height;
+}
+
+static GdkPixbuf* image_loader_jpeg_get_pixbuf(gpointer loader)
+{
+	ImageLoaderJpeg *lj = (ImageLoaderJpeg *) loader;
+	return lj->pixbuf;
+}
+
+static gchar* image_loader_jpeg_get_format_name(gpointer loader)
+{
+	return g_strdup("jpeg");
+}
+static gchar** image_loader_jpeg_get_format_mime_types(gpointer loader)
+{
+	static gchar *mime[] = {"image/jpeg", NULL};
+	return g_strdupv(mime);
+}
+
+static gboolean image_loader_jpeg_close(gpointer loader, GError **error)
+{
+	return TRUE;
+}
+
+static void image_loader_jpeg_abort(gpointer loader)
+{
+	ImageLoaderJpeg *lj = (ImageLoaderJpeg *) loader;
+	lj->abort = TRUE;
+}
+
+static void image_loader_jpeg_free(gpointer loader)
+{
+	ImageLoaderJpeg *lj = (ImageLoaderJpeg *) loader;
+	if (lj->pixbuf) g_object_unref(lj->pixbuf);
+	g_free(lj);
+}
+
+
+void image_loader_backend_set_jpeg(ImageLoaderBackend *funcs)
+{
+	funcs->loader_new = image_loader_jpeg_new;
+	funcs->set_size = image_loader_jpeg_set_size;
+	funcs->load = image_loader_jpeg_load;
+	funcs->write = NULL;
+	funcs->get_pixbuf = image_loader_jpeg_get_pixbuf;
+	funcs->close = image_loader_jpeg_close;
+	funcs->abort = image_loader_jpeg_abort;
+	funcs->free = image_loader_jpeg_free;
+	
+	funcs->get_format_name = image_loader_jpeg_get_format_name;
+	funcs->get_format_mime_types = image_loader_jpeg_get_format_mime_types;
+}
+
+
+