[lasem] svg_filter: import box blur code from librsvg.

[Emmanuel Pacaud <emmanuel src gnome org>]

commit e87f0ff43b77a6ed015ef6b308ac0387d94a8765
Author: Emmanuel Pacaud <emmanuel gnome org>
Date:   Tue Aug 24 18:52:25 2010 +0200

    svg_filter: import box blur code from librsvg.

 src/Makefile.am |    2 +
 src/lsmcairo.c  |  173 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/lsmcairo.h  |   36 +++++++++++
 3 files changed, 211 insertions(+), 0 deletions(-)
---
diff --git a/src/Makefile.am b/src/Makefile.am
index fadac65..589a124 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -29,6 +29,7 @@ liblasem_ LASEM_API_VERSION@_la_SOURCES =				\
 	lsmtraits.c				\
 	lsmproperties.c				\
 	lsmattributes.c				\
+	lsmcairo.c				\
 	lsmdomnode.c				\
 	lsmdomnodelist.c			\
 	lsmdomdocument.c			\
@@ -117,6 +118,7 @@ LASEM_HDRS = \
 	lsmproperties.h				\
 	lsmattributes.h				\
 	lsmdom.h				\
+	lsmcairo.h				\
 	lsmdomnode.h				\
 	lsmdomnodelist.h			\
 	lsmdomdocument.h			\
diff --git a/src/lsmcairo.c b/src/lsmcairo.c
new file mode 100644
index 0000000..d6cb463
--- /dev/null
+++ b/src/lsmcairo.c
@@ -0,0 +1,173 @@
+/*
+ * Copyright © 2004 Caleb Moore
+ * Copyright © 2010 Emmanuel Pacaud
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Authors:
+ *	Caleb Moore <c moore student unsw edu au>
+ * 	Emmanuel Pacaud <emmanuel gnome org>
+ */
+
+#include <lsmcairo.h>
+#include <math.h>
+
+static void
+box_blur (cairo_surface_t *in,
+	  cairo_surface_t *output,
+	  guchar * intermediate,
+	  gint kw, gint kh, gint x1, gint y1, gint x2, gint y2)
+{
+	gint ch;
+	gint x, y;
+	gint rowstride, height, width;
+
+	guchar *in_pixels;
+	guchar *output_pixels;
+
+	gint sum;
+
+	height = cairo_image_surface_get_height (in);
+	width = cairo_image_surface_get_width (in);
+
+	in_pixels = cairo_image_surface_get_data (in);
+	output_pixels = cairo_image_surface_get_data (output);
+
+	rowstride = cairo_image_surface_get_stride (in);
+
+	if (kw > x2 - x1)
+		kw = x2 - x1;
+
+	if (kh > y2 - y1)
+		kh = y2 - y1;
+
+
+	if (kw >= 1) {
+		for (ch = 0; ch < 4; ch++) {
+#if 0
+			switch (ch) {
+				case 0:
+					if (!op.Rused)
+						continue;
+				case 1:
+					if (!op.Gused)
+						continue;
+				case 2:
+					if (!op.Bused)
+						continue;
+				case 3:
+					if (!op.Aused)
+						continue;
+			}
+#endif
+			for (y = y1; y < y2; y++) {
+				sum = 0;
+				for (x = x1; x < x1 + kw; x++) {
+					sum += (intermediate[x % kw] = in_pixels[4 * x + y * rowstride + ch]);
+
+					if (x - kw / 2 >= 0 && x - kw / 2 < x2)
+						output_pixels[4 * (x - kw / 2) + y * rowstride + ch] = sum / kw;
+				}
+				for (x = x1 + kw; x < x2; x++) {
+					sum -= intermediate[x % kw];
+					sum += (intermediate[x % kw] = in_pixels[4 * x + y * rowstride + ch]);
+					output_pixels[4 * (x - kw / 2) + y * rowstride + ch] = sum / kw;
+				}
+				for (x = x2; x < x2 + kw; x++) {
+					sum -= intermediate[x % kw];
+
+					if (x - kw / 2 >= 0 && x - kw / 2 < x2)
+						output_pixels[4 * (x - kw / 2) + y * rowstride + ch] = sum / kw;
+				}
+			}
+		}
+		in_pixels = output_pixels;
+	}
+
+	if (kh >= 1) {
+		for (ch = 0; ch < 4; ch++) {
+#if 0
+			switch (ch) {
+				case 0:
+					if (!op.Rused)
+						continue;
+				case 1:
+					if (!op.Gused)
+						continue;
+				case 2:
+					if (!op.Bused)
+						continue;
+				case 3:
+					if (!op.Aused)
+						continue;
+			}
+#endif
+			for (x = x1; x < x2; x++) {
+				sum = 0;
+
+				for (y = y1; y < y1 + kh; y++) {
+					sum += (intermediate[y % kh] = in_pixels[4 * x + y * rowstride + ch]);
+
+					if (y - kh / 2 >= 0 && y - kh / 2 < y2)
+						output_pixels[4 * x + (y - kh / 2) * rowstride + ch] = sum / kh;
+				}
+				for (; y < y2; y++) {
+					sum -= intermediate[y % kh];
+					sum += (intermediate[y % kh] = in_pixels[4 * x + y * rowstride + ch]);
+					output_pixels[4 * x + (y - kh / 2) * rowstride + ch] = sum / kh;
+				}
+				for (; y < y2 + kh; y++) {
+					sum -= intermediate[y % kh];
+
+					if (y - kh / 2 >= 0 && y - kh / 2 < y2)
+						output_pixels[4 * x + (y - kh / 2) * rowstride + ch] = sum / kh;
+				}
+			}
+		}
+	}
+}
+
+void
+lsm_cairo_fast_blur (cairo_surface_t * in, cairo_surface_t * output,
+		     double sx, double sy, double x1, double y1, double x2, double y2)
+{
+	gint kx, ky;
+	guchar *intermediate;
+
+	g_return_if_fail (in != NULL);
+	g_return_if_fail (output != NULL);
+
+	g_return_if_fail (cairo_surface_get_type (in) == CAIRO_SURFACE_TYPE_IMAGE);
+	g_return_if_fail (cairo_surface_get_type (output) == CAIRO_SURFACE_TYPE_IMAGE);
+
+	g_return_if_fail (cairo_image_surface_get_format (in) == CAIRO_FORMAT_ARGB32);
+	g_return_if_fail (cairo_image_surface_get_format (output) == CAIRO_FORMAT_ARGB32);
+
+	kx = floor (sx * 3 * sqrt (2 * M_PI) / 4 + 0.5);
+	ky = floor (sy * 3 * sqrt (2 * M_PI) / 4 + 0.5);
+
+	if (kx < 1 && ky < 1)
+		return;
+
+	intermediate = g_new (guchar, MAX (kx, ky));
+
+	box_blur (in, output, intermediate, kx, ky, x1, y1, x2, y2);
+	box_blur (output, output, intermediate, kx, ky, x1, y1, x2, y2);
+	box_blur (output, output, intermediate, kx, ky, x1, y1, x2, y2);
+
+	g_free (intermediate);
+}
+
diff --git a/src/lsmcairo.h b/src/lsmcairo.h
new file mode 100644
index 0000000..da66dd4
--- /dev/null
+++ b/src/lsmcairo.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright © 2010 Emmanuel Pacaud
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Author:
+ * 	Emmanuel Pacaud <emmanuel gnome org>
+ */
+
+#ifndef LSM_CAIRO_H
+#define LSM_CAIRO_H
+
+#include <lsm.h>
+#include <cairo.h>
+
+G_BEGIN_DECLS
+
+void 	lsm_cairo_fast_blur 		(cairo_surface_t * in, cairo_surface_t * output,
+					 double sx, double sy, double x1, double y1, double x2, double y2);
+
+G_END_DECLS
+
+#endif