Add alpha blending

2 files changed, 100 insertions, 1 deletions

diff --git a/client.html b/client.html
index 8ec0337..7211bbe 100644
--- a/client.html
+++ b/client.html
@@ -17,6 +17,13 @@ var base64_val = [
    41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,255,255,255,255,255
 ]
 
+function base64_8(str, index) {
+  var v =
+    (base64_val[str.charCodeAt(index)]) +
+    (base64_val[str.charCodeAt(index+1)] << 6);
+  return v;
+}
+
 function base64_16(str, index) {
   var v =
     (base64_val[str.charCodeAt(index)]) +
@@ -156,6 +163,54 @@ function handleLoad(event)
 
         break;
 
+      /* blend from surface */
+      case 'e':
+	source_id = base64_16(cmd, i);
+	i = i + 3;
+        sx = base64_16(cmd, i);
+        i = i + 3;
+        sy = base64_16(cmd, i);
+        i = i + 3;
+        w = base64_16(cmd, i);
+        i = i + 3;
+        h = base64_16(cmd, i);
+        i = i + 3;
+        dx = base64_16(cmd, i);
+        i = i + 3;
+        dy = base64_16(cmd, i);
+        i = i + 3;
+	current_context.globalCompositeOperation = "source-over"
+        current_context.drawImage(surfaces[source_id], sx, sy, w, h, dx, dy, w, h);
+	current_context.globalCompositeOperation = "copy"
+
+        break;
+
+      /* blend from surface w/ overall alpha */
+      case 'E':
+	source_id = base64_16(cmd, i);
+	i = i + 3;
+        sx = base64_16(cmd, i);
+        i = i + 3;
+        sy = base64_16(cmd, i);
+        i = i + 3;
+        w = base64_16(cmd, i);
+        i = i + 3;
+        h = base64_16(cmd, i);
+        i = i + 3;
+        dx = base64_16(cmd, i);
+        i = i + 3;
+        dy = base64_16(cmd, i);
+        i = i + 3;
+        alpha = base64_8(cmd, i);
+        i = i + 2;
+	current_context.globalAlpha = alpha / 255.0;
+	current_context.globalCompositeOperation = "source-over"
+        current_context.drawImage(surfaces[source_id], sx, sy, w, h, dx, dy, w, h);
+	current_context.globalAlpha = 1.0;
+	current_context.globalCompositeOperation = "copy"
+
+        break;
+
       /* fill rect */
       case 'r':
         x = base64_16(cmd, i);
diff --git a/daemon.c b/daemon.c
index b4e57fa..1b03212 100644
--- a/daemon.c
+++ b/daemon.c
@@ -17,6 +17,13 @@ static const char base64_alphabet[] =
 	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 
 static void
+base64_uint8 (guint8 v, char *c)
+{
+  c[0] = base64_alphabet[(v >> 0) & 0x3f];
+  c[1] = base64_alphabet[(v >> 6) & 0x3];
+}
+
+static void
 base64_uint16 (guint32 v, char *c)
 {
   c[0] = base64_alphabet[(v >> 0) & 0x3f];
@@ -101,6 +108,43 @@ send_copyrect (GOutputStream *out,  int sx, int sy, int w, int h, int dx, int dy
 }
 
 static void
+send_blend (GOutputStream *out, int source_surface, int sx, int sy, int w, int h, int dx, int dy)
+{
+  char buf[22];
+
+  buf[0] = 'e';
+  base64_uint16(source_surface, &buf[1]);
+  base64_uint16(sx, &buf[4]);
+  base64_uint16(sy, &buf[7]);
+  base64_uint16(w, &buf[10]);
+  base64_uint16(h, &buf[13]);
+  base64_uint16(dx, &buf[16]);
+  base64_uint16(dy, &buf[19]);
+
+  g_output_stream_write_all (out, buf, 22,
+			     NULL, NULL, NULL);
+}
+
+static void
+send_blend_alpha (GOutputStream *out, int source_surface, int sx, int sy, int w, int h, int dx, int dy, guint8 overall_alpha)
+{
+  char buf[24];
+
+  buf[0] = 'E';
+  base64_uint16(source_surface, &buf[1]);
+  base64_uint16(sx, &buf[4]);
+  base64_uint16(sy, &buf[7]);
+  base64_uint16(w, &buf[10]);
+  base64_uint16(h, &buf[13]);
+  base64_uint16(dx, &buf[16]);
+  base64_uint16(dy, &buf[19]);
+  base64_uint8(dy, &buf[22]);
+
+  g_output_stream_write_all (out, buf, 24,
+			     NULL, NULL, NULL);
+}
+
+static void
 send_blit (GOutputStream *out, int source_surface, int sx, int sy, int w, int h, int dx, int dy)
 {
   char buf[22];
@@ -411,7 +455,7 @@ send_draw_ops (GOutputStream *out)
 
       send_copyrect (cout, 15, 15, 800, 40, 20, 15);
 
-      send_blit (cout, 1, 0, 0, 50, 50, 200, 200);
+      send_blend_alpha (cout, 1, 0, 0, 50, 50, 200 + i * 20, 200 - i * 30, 70);
 
       send_image_rgb (cout, 30, 30,
 		      2, 2, 2, pixel);