[broadway] Send diffs as bilevel rgba instead of true diff

The true diff only works if the destination keeps perfect 32bit
canvas data, which is not always true. So, instead we send only
changed pixels, masking the others to 0 via alpha 0.

gdk/broadway/broadway-demo.c

@@ -5,14 +5,15 @@
 #include "broadway.h"
 #include <math.h>
 #include <unistd.h>
+#include <stdint.h>
 #include <cairo.h>
 
 static void
 diff_surfaces (cairo_surface_t *surface,
 	       cairo_surface_t *old_surface)
 {
-  unsigned char *data, *old_data;
+  uint8_t *data, *old_data;
-  unsigned char *line, *old_line;
+  uint32_t *line, *old_line;
   int w, h, stride, old_stride;
   int x, y;
 
@@ -27,16 +28,17 @@ diff_surfaces (cairo_surface_t *surface,
 
   for (y = 0; y < h; y++)
     {
-      line = data;
+      line = (uint32_t *)data;
-      old_line = old_data;
+      old_line = (uint32_t *)old_data;
 
       for (x = 0; x < w; x++)
 	{
-	  int j;
+	  if (*line & 0xffffff == *old_line & 0xffffff)
-	  for (j = 0; j < 4; j++)
+	    *old_line = 0;
-	    old_line[j] = line[j] - old_line[j];
+	  else
-	  line += 4;
+	    *old_line = *line | 0xff000000;
-	  old_line += 4;
+	  line ++;
+	  old_line ++;
 	}
 
       data += stride;
@@ -181,7 +183,7 @@ demo2 (BroadwayClient *client)
 	{
 	  diff_surfaces (surface,
 			 old_surface);
-	  broadway_client_put_delta_rgb (client, 0, 0, 0, 800, 600, 800*4,
+	  broadway_client_put_rgba (client, 0, 0, 0, 800, 600, 800*4,
 				    cairo_image_surface_get_data(old_surface));
 	}
       broadway_client_move_surface (client, 0, 100 + i, 100 + i);

gdk/broadway/broadway.c

@@ -834,12 +834,12 @@ broadway_client_put_rgb (BroadwayClient *client,  int id, int x, int y,
 }
 
 static void
-rgb_autocrop (unsigned char *data,
+rgba_autocrop (unsigned char *data,
 	       int byte_stride,
 	       int *x_arg, int *y_arg,
 	       int *w_arg, int *h_arg)
 {
-  unsigned char *line;
+  uint32_t *line;
   int w, h;
   int x, y, xx, yy;
   boolean non_zero;
@@ -851,16 +851,16 @@ rgb_autocrop (unsigned char *data,
 
   while (h > 0)
     {
-      line = data + y * byte_stride + x * 4;
+      line = (uint32_t *)(data + y * byte_stride + x * 4);
 
       non_zero = FALSE;
       for (xx = 0; xx < w; xx++)
 	{
-	  if (line[1] != 0 || line[2] != 0 || line[3] != 0) {
+	  if (*line != 0) {
 	    non_zero = TRUE;
 	    break;
 	  }
-	  line += 4;
+	  line++;
 	}
 
       if (non_zero)
@@ -872,16 +872,16 @@ rgb_autocrop (unsigned char *data,
 
   while (h > 0)
     {
-      line = data + (y + h - 1) * byte_stride + x * 4;
+      line = (uint32_t *)(data + (y + h - 1) * byte_stride + x * 4);
 
       non_zero = FALSE;
       for (xx = 0; xx < w; xx++)
 	{
-	  if (line[1] != 0 || line[2] != 0 || line[3] != 0) {
+	  if (*line != 0) {
 	    non_zero = TRUE;
 	    break;
 	  }
-	  line += 4;
+	  line++;
 	}
 
       if (non_zero)
@@ -891,16 +891,16 @@ rgb_autocrop (unsigned char *data,
 
   while (w > 0)
     {
-      line = data + y * byte_stride + x * 4;
+      line = (uint32_t *)(data + y * byte_stride + x * 4);
 
       non_zero = FALSE;
       for (yy = 0; yy < h; yy++)
 	{
-	  if (line[1] != 0 || line[2] != 0 || line[3] != 0) {
+	  if (*line != 0) {
 	    non_zero = TRUE;
 	    break;
 	  }
-	  line += byte_stride;
+	  line += byte_stride / 4;
 	}
 
       if (non_zero)
@@ -912,16 +912,16 @@ rgb_autocrop (unsigned char *data,
 
   while (w > 0)
     {
-      line = data + y * byte_stride + (x + w - 1) * 4;
+      line = (uint32_t *)(data + y * byte_stride + (x + w - 1) * 4);
 
       non_zero = FALSE;
       for (yy = 0; yy < h; yy++)
 	{
-	  if (line[1] != 0 || line[2] != 0 || line[3] != 0) {
+	  if (*line != 0) {
 	    non_zero = TRUE;
 	    break;
 	  }
-	  line += byte_stride;
+	  line += byte_stride / 4;
 	}
 
       if (non_zero)
@@ -935,43 +935,6 @@ rgb_autocrop (unsigned char *data,
     *h_arg = h;
 }
 
-void
-broadway_client_put_delta_rgb (BroadwayClient *client,  int id, int dest_x, int dest_y,
-			       int w, int h, int byte_stride, void *data)
-{
-  char buf[16];
-  size_t len;
-  char *url;
-  int src_x, src_y;
-
-  src_x = 0;
-  src_y = 0;
-
-  rgb_autocrop (data,
-		byte_stride,
-		&src_x, &src_y, &w, &h);
-
-  if (w == 0 || h == 0)
-    return;
-
-  data = (uint8_t *)data + src_x * 4 + src_y * byte_stride;
-
-  buf[0] = 'D';
-  base64_uint16(id, &buf[1]);
-  base64_uint16(dest_x + src_x, &buf[4]);
-  base64_uint16(dest_y + src_y, &buf[7]);
-
-  url = to_png_rgb (w, h, byte_stride, (uint32_t*)data);
-  len = strlen (url);
-  base64_uint32(len, &buf[10]);
-
-  broadway_client_write (client, buf, 16);
-
-  broadway_client_write (client, url, len);
-
-  free (url);
-}
-
 void
 broadway_client_put_rgba (BroadwayClient *client,  int id, int x, int y,
 			  int w, int h, int byte_stride, void *data)
@@ -979,11 +942,26 @@ broadway_client_put_rgba (BroadwayClient *client,  int id, int x, int y,
   char buf[16];
   size_t len;
   char *url;
+  int crop_x, crop_y;
+
+  crop_x = 0;
+  crop_y = 0;
+
+  printf ("pre crop: %dx%d\n", w, h);
+  rgba_autocrop (data,
+		 byte_stride,
+		 &crop_x, &crop_y, &w, &h);
+  printf ("post crop: %dx%d %d,%d\n", w, h, crop_x, crop_y);
+
+  if (w == 0 || h == 0)
+    return;
+
+  data = (uint8_t *)data + crop_x * 4 + crop_y * byte_stride;
 
   buf[0] = 'i';
   base64_uint16(id, &buf[1]);
-  base64_uint16(x, &buf[4]);
+  base64_uint16(x + crop_x, &buf[4]);
-  base64_uint16(y, &buf[7]);
+  base64_uint16(y + crop_y, &buf[7]);
 
   url = to_png_rgba (w, h, byte_stride, (uint32_t*)data);
   len = strlen (url);

gdk/broadway/broadway.h

@@ -39,14 +39,6 @@ void            broadway_client_put_rgba        (BroadwayClient *client,
 						 int             h,
 						 int             byte_stride,
 						 void           *data);
-void            broadway_client_put_delta_rgb   (BroadwayClient *client,
-						 int             id,
-						 int             dest_x,
-						 int             dest_y,
-						 int             w,
-						 int             h,
-						 int             byte_stride,
-						 void           *data);
 void            broadway_client_copy_rectangles (BroadwayClient *client,
 						 int             id,
 						 BroadwayRect   *rects,

gdk/broadway/broadway.js

@@ -68,31 +68,6 @@ var surfaces = {};
 var outstanding_commands = new Array();
 var input_socket = null;
 
-function apply_delta(id, img, x, y)
-{
-  var tmp_surface = document.createElement("canvas");
-  var w = img.width;
-  var h = img.height;
-  tmp_surface.width = w;
-  tmp_surface.height = h;
-
-  tmp_context = tmp_surface.getContext("2d");
-  tmp_context.drawImage(img, 0, 0);
-
-  var data = surfaces[id].getImageData(x, y, w, h);
-  var d = data.data
-  var delta = tmp_context.getImageData(0, 0, w, h).data;
-  var imax = w * h * 4;
-  for (var i = 0; i < imax; i += 4) {
-    d[i  ] = (d[i  ] + delta[i  ]) & 0xff;
-    d[i+1] = (d[i+1] + delta[i+1]) & 0xff;
-    d[i+2] = (d[i+2] + delta[i+2]) & 0xff;
-    d[i+3] = 255;
-  }
-  surfaces[id].putImageData(data, x, y);
-  delete tmp_surface
-}
-
 function initContext(canvas, x, y, id)
 {
   canvas.surface_id = id;
@@ -101,7 +76,7 @@ function initContext(canvas, x, y, id)
   canvas.style["left"] = y + "px"
   canvas.style["display"] = "none"
   context = canvas.getContext("2d")
-  context.globalCompositeOperation = "copy"
+  context.globalCompositeOperation = "src-over"
   context.fillRect(0, 0, canvas.width, canvas.height);
   document.body.appendChild(canvas)
 
@@ -194,30 +169,6 @@ function handleCommands(cmd_obj)
 
         break;
 
-      /* put delta image data surface */
-      case 'D':
-        var id = base64_16(cmd, i);
-        i = i + 3;
-        var x = base64_16(cmd, i);
-        i = i + 3;
-        var y = base64_16(cmd, i);
-        i = i + 3;
-        var size = base64_32(cmd, i);
-        i = i + 6;
-	var url = cmd.slice(i, i + size);
-	i = i + size;
-        var img = new Image();
-	img.src = url
-	if (img.complete) {
-	  apply_delta(id, img, x, y);
-	} else {
-	  cmd_obj.pos = i;
-          img.onload = function() { apply_delta(id, img, x, y); handleOutstanding(); }
-	  return false
-	}
-
-        break;
-
       /* copy rects */
       case 'b':
         var id = base64_16(cmd, i);

gdk/broadway/gdkwindow-broadway.c

@@ -87,7 +87,7 @@ diff_surfaces (cairo_surface_t *surface,
 	       cairo_surface_t *old_surface)
 {
   guint8 *data, *old_data;
-  guint8 *line, *old_line;
+  guint32 *line, *old_line;
   int w, h, stride, old_stride;
   int x, y;
 
@@ -102,16 +102,17 @@ diff_surfaces (cairo_surface_t *surface,
 
   for (y = 0; y < h; y++)
     {
-      line = data;
+      line = (guint32 *)data;
-      old_line = old_data;
+      old_line = (guint32 *)old_data;
 
       for (x = 0; x < w; x++)
 	{
-	  int j;
+	  if ((*line & 0xffffff) == (*old_line & 0xffffff))
-	  for (j = 0; j < 4; j++)
+	    *old_line = 0;
-	    old_line[j] = line[j] - old_line[j];
+	  else
-	  line += 4;
+	    *old_line = *line | 0xff000000;
-	  old_line += 4;
+	  line ++;
+	  old_line ++;
 	}
 
       data += stride;
@@ -127,11 +128,14 @@ window_data_send (BroadwayClient *client, GdkWindowImplBroadway *impl)
   GdkDrawableImplBroadway *drawable_impl = GDK_DRAWABLE_IMPL_BROADWAY (impl);
   cairo_t *cr;
 
+  if (drawable_impl->surface == NULL)
+    return;
+
   if (impl->last_synced)
     {
       diff_surfaces (drawable_impl->surface,
 		     drawable_impl->last_surface);
-      broadway_client_put_delta_rgb (client, impl->id, 0, 0,
+      broadway_client_put_rgba (client, impl->id, 0, 0,
 				cairo_image_surface_get_width (drawable_impl->last_surface),
 				cairo_image_surface_get_height (drawable_impl->last_surface),
 				cairo_image_surface_get_stride (drawable_impl->last_surface),