Demos (master): egl/openvg: Add a demo for blend modes.

[Chia-I Wu]

Module: Demos
Branch: master
Commit: 49fe311a20dd96c06cada73e6f5b72864234a266
URL:    http://cgit.freedesktop.org/mesa/demos/commit/?id=49fe311a20dd96c06cada73e6f5b72864234a266

Author: Chia-I Wu <olvaffe at gmail.com>
Date:   Tue Nov 30 14:03:19 2010 +0800

egl/openvg: Add a demo for blend modes.

---

 src/egl/openvg/trivial/Makefile.am |    2 +
 src/egl/openvg/trivial/blend.c     |  150 ++++++++++++++++++++++++++++++++++++
 2 files changed, 152 insertions(+), 0 deletions(-)

diff --git a/src/egl/openvg/trivial/Makefile.am b/src/egl/openvg/trivial/Makefile.am
index 34122ae..870b49f 100644
--- a/src/egl/openvg/trivial/Makefile.am
+++ b/src/egl/openvg/trivial/Makefile.am
@@ -46,6 +46,7 @@ libcommon_la_SOURCES = \
 noinst_PROGRAMS = \
 	arc \
 	cap \
+	blend \
 	clear \
 	color_transform \
 	coord \
@@ -74,6 +75,7 @@ noinst_PROGRAMS = \
 #	vguarc
 
 arc_LDADD = libcommon.la
+blend_LDADD = libcommon.la
 cap_LDADD = libcommon.la
 clear_LDADD = libcommon.la
 color_transform_LDADD = libcommon.la
diff --git a/src/egl/openvg/trivial/blend.c b/src/egl/openvg/trivial/blend.c
new file mode 100644
index 0000000..fe8af87
--- /dev/null
+++ b/src/egl/openvg/trivial/blend.c
@@ -0,0 +1,150 @@
+#include "eglcommon.h"
+
+#include <VG/openvg.h>
+
+#include <math.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+VGPath rect;
+
+static void
+init(void)
+{
+   VGPaint paint;
+
+   VGubyte cmd[] = {
+      VG_MOVE_TO_ABS,
+      VG_LINE_TO_ABS,
+      VG_LINE_TO_ABS,
+      VG_LINE_TO_ABS,
+      VG_CLOSE_PATH
+   };
+   VGfloat val[] = {
+      0.0f, 0.0f,
+      1.0f, 0.0f,
+      1.0f, 1.0f,
+      0.0f, 1.0f
+   };
+
+   rect = vgCreatePath(VG_PATH_FORMAT_STANDARD,
+                       VG_PATH_DATATYPE_F, 1.0f, 0.0f, 0, 0,
+                       VG_PATH_CAPABILITY_ALL);
+   vgAppendPathData(rect, sizeof(cmd), cmd, val);
+
+   paint = vgCreatePaint();
+   /* alpha = 0.8 */
+   vgSetColor(paint, 0xff0000cc);
+   vgSetPaint(paint, VG_FILL_PATH);
+
+   vgSeti(VG_MASKING, VG_TRUE);
+}
+
+/* new window size or exposure */
+static void
+reshape(int w, int h)
+{
+   VGfloat coverage[4] = { 0.0f, 0.0f, 0.0f, 0.4f };
+   VGImage img;
+
+   img = vgCreateImage(VG_A_8, w, h / 2, VG_IMAGE_QUALITY_NONANTIALIASED);
+   vgSetfv(VG_CLEAR_COLOR, 4, coverage);
+   vgClearImage(img, 0, 0, w, h / 2);
+
+   vgMask(img, VG_SET_MASK, 0, (h + 1) / 2, w, h / 2);
+}
+
+static void
+rectangle(VGint x, VGint y, VGint width, VGint height)
+{
+   vgLoadIdentity();
+   vgTranslate(x, y);
+   vgScale(width, height);
+   vgDrawPath(rect, VG_FILL_PATH);
+}
+
+static void
+test_blend(VGint x, VGint y, VGint width, VGint height)
+{
+   /* src is red with alpha 0.8 */
+   /* dst is green with alpha 0.3 */
+
+   /* 0.8 * red */
+   vgSeti(VG_BLEND_MODE, VG_BLEND_SRC);
+   rectangle(x, y, width, height);
+   x += width + 5;
+
+   /* 0.8 * red + 0.06 * green */
+   vgSeti(VG_BLEND_MODE, VG_BLEND_SRC_OVER);
+   rectangle(x, y, width, height);
+   x += width + 5;
+
+   /* 0.56 * red + 0.3 * green */
+   vgSeti(VG_BLEND_MODE, VG_BLEND_DST_OVER);
+   rectangle(x, y, width, height);
+   x += width + 5;
+
+   /* 0.24 * red */
+   vgSeti(VG_BLEND_MODE, VG_BLEND_SRC_IN);
+   rectangle(x, y, width, height);
+   x += width + 5;
+
+   /* 0.24 * green */
+   vgSeti(VG_BLEND_MODE, VG_BLEND_DST_IN);
+   rectangle(x, y, width, height);
+   x += width + 5;
+
+   /* (...) * 0.8 * red + 0.06 * green */
+   vgSeti(VG_BLEND_MODE, VG_BLEND_MULTIPLY);
+   rectangle(x, y, width, height);
+   x += width + 5;
+
+   /* 0.8 * red + (white - 0.8 * red) * 0.3 * green */
+   vgSeti(VG_BLEND_MODE, VG_BLEND_SCREEN);
+   rectangle(x, y, width, height);
+   x += width + 5;
+
+   /* min(SRC_OVER, DST_OVER) */
+   vgSeti(VG_BLEND_MODE, VG_BLEND_DARKEN);
+   rectangle(x, y, width, height);
+   x += width + 5;
+
+   /* max(SRC_OVER, DST_OVER) */
+   vgSeti(VG_BLEND_MODE, VG_BLEND_LIGHTEN);
+   rectangle(x, y, width, height);
+   x += width + 5;
+}
+
+static void
+draw(void)
+{
+   const VGfloat white[4] = { 1.0f, 1.0f, 1.0f, 1.0f };
+   const VGfloat green[4] = { 0.0f, 1.0f, 0.0f, 0.3f };
+   VGint x, y;
+
+   vgSetfv(VG_CLEAR_COLOR, 4, white);
+   vgClear(0, 0, window_width(), window_height());
+
+   vgSetfv(VG_CLEAR_COLOR, 4, green);
+
+   x = y = 5;
+   vgClear(x, y, window_width(), 20);
+   test_blend(x, y, 20, 20);
+
+   y += window_height() / 2;
+   vgClear(x, y, window_width(), 20);
+   /*
+    * This will have more green because
+    *
+    *   result = blended * coverage + dst * (1 - coverage)
+    */
+   test_blend(x, y, 20, 20);
+}
+
+
+int main(int argc, char **argv)
+{
+   set_window_size(300, 300);
+   return run(argc, argv, init, reshape,
+              draw, 0);
+}