Change GTK plotting to use cairo surfaces throughout

svn path=/trunk/netsurf/; revision=13354

1 files changed, 124 insertions, 0 deletions

diff --git a/gtk/gdk.c b/gtk/gdk.c
new file mode 100644
index 000000000..22569285d
--- /dev/null
+++ b/gtk/gdk.c
@@ -0,0 +1,124 @@
+/*
+ * Copyright 2011 Vincent Sanders <vince@netsurf-browser.org>
+ *
+ * This file is part of NetSurf, http://www.netsurf-browser.org/
+ *
+ * NetSurf is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * NetSurf is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <string.h>
+
+#include "utils/log.h"
+
+#include "gtk/gdk.h"
+
+static void
+convert_alpha(guchar  *dest_data,
+               int      dest_stride,
+               guchar  *src_data,
+               int      src_stride,
+               int      width,
+               int      height)
+{
+	int x, y;
+
+	for (y = 0; y < height; y++) {
+		guint32 *src = (guint32 *) src_data;
+
+		for (x = 0; x < width; x++) {
+			guint alpha = src[x] >> 24;
+
+			if (alpha == 0)	{
+				dest_data[x * 4 + 0] = 0;
+				dest_data[x * 4 + 1] = 0;
+				dest_data[x * 4 + 2] = 0;
+			} else {
+				dest_data[x * 4 + 0] = (((src[x] & 0xff0000) >> 16) * 255 + alpha / 2) / alpha;
+				dest_data[x * 4 + 1] = (((src[x] & 0x00ff00) >>  8) * 255 + alpha / 2) / alpha;
+				dest_data[x * 4 + 2] = (((src[x] & 0x0000ff) >>  0) * 255 + alpha / 2) / alpha;
+			}
+			dest_data[x * 4 + 3] = alpha;
+		}
+
+		src_data += src_stride;
+		dest_data += dest_stride;
+	}
+}
+
+
+GdkPixbuf *
+nsgdk_pixbuf_get_from_surface(cairo_surface_t *surface, int scwidth, int scheight)
+{
+	int width, height; /* source width and height */
+	cairo_surface_t *scsurface; /* scaled surface */
+	cairo_t *cr; /* cairo context for scaled surface */
+	GdkPixbuf *pixbuf; /* The result pixel buffer */
+
+	/* create pixmap */
+	pixbuf = gdk_pixbuf_new(GDK_COLORSPACE_RGB, true, 8, scwidth, scheight);
+	if (pixbuf == NULL) {
+		return NULL;
+	}
+
+	memset(gdk_pixbuf_get_pixels(pixbuf),
+	       0xff, 
+	       gdk_pixbuf_get_rowstride(pixbuf) * scheight);
+
+	/* scale cairo surface into new surface the target size */
+	cairo_surface_flush(surface); /* ensure source surface is ready */
+
+	/* get source surface dimensions */
+	width = cairo_image_surface_get_width(surface);
+	height = cairo_image_surface_get_height(surface);
+
+	/* scaled surface always has an alpha chanel for ease */
+	scsurface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, scwidth, scheight);
+	if (cairo_surface_status(scsurface) != CAIRO_STATUS_SUCCESS) {
+		cairo_surface_destroy(scsurface);
+		g_object_unref(pixbuf);
+		LOG(("Surface creation failed"));
+		return NULL;
+	}
+
+	cr = cairo_create(scsurface);
+
+	/* Scale *before* setting the source surface */
+	cairo_scale(cr, (double)scwidth / width, (double)scheight / height);
+	cairo_set_source_surface(cr, surface, 0, 0);
+
+	/* To avoid getting the edge pixels blended with 0
+	 * alpha, which would occur with the default
+	 * EXTEND_NONE. Use EXTEND_PAD for 1.2 or newer
+	 */
+	cairo_pattern_set_extend(cairo_get_source(cr), CAIRO_EXTEND_REFLECT); 
+
+	/* Replace the destination with the source instead of overlaying */
+	cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
+
+	/* Do the actual drawing */
+	cairo_paint(cr);
+   
+	cairo_destroy(cr);
+
+	/* copy data from surface into pixmap */
+	convert_alpha(gdk_pixbuf_get_pixels(pixbuf),
+		      gdk_pixbuf_get_rowstride(pixbuf),
+		      cairo_image_surface_get_data(scsurface),
+		      cairo_image_surface_get_stride(scsurface),
+		      scwidth, scheight);
+
+	cairo_surface_destroy(scsurface);
+
+	return pixbuf;
+}
+