Improving the decoder pipeline.

remoting/webapp/client_session.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @fileoverview
  * Class handling creation and teardown of a remoting client session.
  *
  * The ClientSession class controls lifetime of the client plugin
  * object and provides the plugin with the functionality it needs to
@@ skipping 424 matching lines @@
  * @return {void} Nothing.
  */
 remoting.ClientSession.prototype.updateDimensions = function() {
   if (this.plugin.desktopWidth == 0 ||
       this.plugin.desktopHeight == 0) {
     return;
   }
 
   var windowWidth = window.innerWidth;
   var windowHeight = window.innerHeight;
+
+  // Estimate browser scale factor in order to be able to translate logical
+  // pixels on the page into physical pixels on the screen. Scale factor can
+  // be roughly estimated as a ratio between outerWidth and innerWidth of
+  // the document view. The result is not precise because outerWidth can
+  // include pixels allocated for toolbars, window borders and such.
+  var windowOuterWidth = window.outerWidth;
+
+  // TODO(alexeypa): remove this hack once proper zooming API is available.
+  // See issue #30583 for details.
+  // Now pick the exact scale factor from the list of known zoom levels.
+  var zoom_levels = [ 0.25, 1.0/3, 0.5, 2.0/3, 0.75, 0.9, 1.0, 1.1, 1.25, 1.5,
+      1.75, 2, 2.5, 3.0, 4.0 ];
+  var min_delta = Number.MAX_VALUE;
   var scale = 1.0;
+  for (var i in zoom_levels) {
+    var delta = Math.abs(windowOuterWidth - windowWidth * zoom_levels[i]);

[Jamie, 2012/02/16 18:45:22]

I'm don't think that taking an absolute value is right. Given a choice of
decoration widths of 16px or -15px, the former is far more likely, but this code
will pick the latter. It seems we should reject zoom levels that suggest a
negative window border, or am I missing something?

[alexeypa (please no reviews), 2012/02/16 23:58:17]

I added a comment explaining why it is needed. I was surprised too. :-)

+    if (delta < min_delta) {
+      min_delta = delta;
+      scale = 1.0 / zoom_levels[i];
+    }
+  }
 
   if (this.getScaleToFit()) {
-    var scaleFitWidth = 1.0 * windowWidth / this.plugin.desktopWidth;
-    var scaleFitHeight = 1.0 * windowHeight / this.plugin.desktopHeight;
-    scale = Math.min(1.0, scaleFitHeight, scaleFitWidth);
+    var scaledWidth = 1.0 * windowWidth / (scale * this.plugin.desktopWidth);
+    var scaledHeight = 1.0 * windowHeight / (scale * this.plugin.desktopHeight);
+    scale = Math.min(1.0, scaledHeight, scaledWidth) * scale;
   }
 
   var width = this.plugin.desktopWidth * scale;
   var height = this.plugin.desktopHeight * scale;
 
   // Resize the plugin if necessary.
-  this.plugin.element().width = width;
-  this.plugin.element().height = height;
+  this.plugin.element().width = Math.ceil(this.plugin.desktopWidth * scale);
+  this.plugin.element().height = Math.ceil(this.plugin.desktopHeight * scale);
 
   // Position the container.
   // TODO(wez): We should take into account scrollbars when positioning.
   var parentNode = this.plugin.element().parentNode;
 
   if (width < windowWidth) {
     parentNode.style.left = (windowWidth - width) / 2 + 'px';
   } else {
     parentNode.style.left = '0';
   }
@@ skipping 21 matching lines @@
 };
 
 /**
  * Logs statistics.
  *
  * @param {remoting.ClientSession.PerfStats} stats
  */
 remoting.ClientSession.prototype.logStatistics = function(stats) {
   this.logToServer.logStatistics(stats, this.mode);
 };