DevTools: Screencast view scaling

Source/devtools/front_end/ScreencastView.js

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 105 matching lines @@
     },
 
     _startCasting: function()
     {
         if (this._timelineActive || this._profilerActive)
             return;
         if (this._isCasting)
             return;
         this._isCasting = true;
 
-        const maxImageDimension = 1024;
+        const maxImageDimension = 2048;
         var dimensions = this._viewportDimensions();
         if (dimensions.width < 0 || dimensions.height < 0) {
             this._isCasting = false;
             return;
         }
-        dimensions.width *= WebInspector.zoomManager.zoomFactor();
-        dimensions.height *= WebInspector.zoomManager.zoomFactor();
+        dimensions.width *= window.devicePixelRatio;
+        dimensions.height *= window.devicePixelRatio;
         this._target.pageAgent().startScreencast("jpeg", 80, Math.min(maxImageDimension, dimensions.width), Math.min(maxImageDimension, dimensions.height));
         this._target.domModel.setHighlighter(this);
     },
 
     _stopCasting: function()
     {
         if (!this._isCasting)
             return;
         this._isCasting = false;
         this._target.pageAgent().stopScreencast();
         this._target.domModel.setHighlighter(null);
     },
 
     /**
      * @param {!WebInspector.Event} event
      */
     _screencastFrame: function(event)
     {
         var metadata = /** type {PageAgent.ScreencastFrameMetadata} */(event.data.metadata);
-
-        if (!metadata.deviceScaleFactor) {
-          console.log(event.data.data);
-          return;
-        }
-
         var base64Data = /** type {string} */(event.data.data);
         this._imageElement.src = "data:image/jpg;base64," + base64Data;
-        this._deviceScaleFactor = metadata.deviceScaleFactor;
         this._pageScaleFactor = metadata.pageScaleFactor;
-        this._viewport = metadata.viewport;
-        if (!this._viewport)
-            return;
-        var offsetTop = metadata.offsetTop || 0;
-        var offsetBottom = metadata.offsetBottom || 0;
+        this._screenOffsetTop = metadata.offsetTop;
+        this._deviceWidth = metadata.deviceWidth;
+        this._deviceHeight = metadata.deviceHeight;
+        this._scrollOffsetX = metadata.scrollOffsetX;
+        this._scrollOffsetY = metadata.scrollOffsetY;
 
-        var screenWidthDIP = this._viewport.width * this._pageScaleFactor;
-        var screenHeightDIP = this._viewport.height * this._pageScaleFactor + offsetTop + offsetBottom;
-        this._screenOffsetTop = offsetTop;
-        this._resizeViewport(screenWidthDIP, screenHeightDIP);
+        var deviceSizeRatio = metadata.deviceHeight / metadata.deviceWidth;
+        var dimensionsCSS = this._viewportDimensions();
 
-        this._imageZoom = this._imageElement.naturalWidth ? this._canvasElement.offsetWidth / this._imageElement.naturalWidth : 1;
+        this._imageZoom = Math.min(dimensionsCSS.width / this._imageElement.naturalWidth, dimensionsCSS.height / (this._imageElement.naturalWidth * deviceSizeRatio));
+        this._viewportElement.classList.remove("hidden");
+        var bordersSize = WebInspector.ScreencastView._bordersSize;
+        //if (this._imageZoom < 1.01 / window.devicePixelRatio)

[dgozman, 2014/06/26 11:34:21]

Dead code.

[vkuzkokov, 2014/06/26 14:15:54]

Forgot to uncomment

+        //    this._imageZoom = 1 / window.devicePixelRatio;
+        this._screenZoom = this._imageElement.naturalWidth * this._imageZoom / metadata.deviceWidth;

[dgozman, 2014/06/26 11:34:21]

Let's call this something like |imageCssToDeviceDipScale|.

+        this._viewportElement.style.width = metadata.deviceWidth * this._screenZoom + bordersSize + "px";
+        this._viewportElement.style.height = metadata.deviceHeight* this._screenZoom + bordersSize + "px";
+
         this.highlightDOMNode(this._highlightNode, this._highlightConfig);
     },
 
     _isGlassPaneActive: function()
     {
         return !this._glassPaneElement.classList.contains("hidden");
     },
 
     /**
      * @param {!WebInspector.Event} event
@@ skipping 42 matching lines @@
             this._glassPaneElement.classList.remove("hidden");
         } else if (this._profilerActive) {
             this._glassPaneElement.textContent = WebInspector.UIString("CPU profiler is active");
             this._glassPaneElement.classList.remove("hidden");
         } else {
             this._glassPaneElement.classList.add("hidden");
         }
     },
 
     /**
-     * @param {number} screenWidthDIP
-     * @param {number} screenHeightDIP
-     */
-    _resizeViewport: function(screenWidthDIP, screenHeightDIP)
-    {
-        var dimensions = this._viewportDimensions();
-        this._screenZoom = Math.min(dimensions.width / screenWidthDIP, dimensions.height / screenHeightDIP);
-
-        var bordersSize = WebInspector.ScreencastView._bordersSize;
-        this._viewportElement.classList.remove("hidden");
-        this._viewportElement.style.width = screenWidthDIP * this._screenZoom + bordersSize + "px";
-        this._viewportElement.style.height = screenHeightDIP * this._screenZoom + bordersSize + "px";
-    },
-
-    /**
      * @param {?Event} event
      */
     _handleMouseEvent: function(event)
     {
         if (this._isGlassPaneActive()) {
           event.consume();
           return;
         }
 
-        if (!this._viewport)
+        if (!this._pageScaleFactor)
             return;
 
         if (!this._inspectModeConfig || event.type === "mousewheel") {
             this._simulateTouchGestureForMouseEvent(event);
             event.preventDefault();
             if (event.type === "mousedown")
                 this._canvasElement.focus();
             return;
         }
 
         var position = this._convertIntoScreenSpace(event);
-        this._target.domModel.nodeForLocation(position.x / this._pageScaleFactor, position.y / this._pageScaleFactor, callback.bind(this));
+        this._target.domModel.nodeForLocation(position.x / this._pageScaleFactor + this._scrollOffsetX, position.y / this._pageScaleFactor + this._scrollOffsetY, callback.bind(this));
 
         /**
          * @param {?WebInspector.DOMNode} node
          * @this {WebInspector.ScreencastView}
          */
         function callback(node)
         {
             if (!node)
                 return;
             if (event.type === "mousemove")
@@ skipping 203 matching lines @@
         default:
         }
     },
 
     /**
      * @param {?Event} event
      * @return {!{x: number, y: number}}
      */
     _zoomIntoScreenSpace: function(event)
     {
-        var zoom = this._canvasElement.offsetWidth / this._viewport.width / this._pageScaleFactor;
+        var zoom = this._canvasElement.offsetWidth / this._deviceWidth;
         var position  = {};
         position.x = Math.round(event.offsetX / zoom);
         position.y = Math.round(event.offsetY / zoom);
         return position;
     },
 
     /**
      * @param {?Event} event
      * @return {!{x: number, y: number}}
      */
@@ skipping 53 matching lines @@
 
         this._node = node;
         node.boxModel(callback.bind(this));
 
         /**
          * @param {?DOMAgent.BoxModel} model
          * @this {WebInspector.ScreencastView}
          */
         function callback(model)
         {
-            if (!model) {
+            if (!model || !this._pageScaleFactor) {
                 this._repaint();
                 return;
             }
             this._model = this._scaleModel(model);
             this._config = config;
             this._repaint();
         }
     },
 
     /**
      * @param {!DOMAgent.BoxModel} model
      * @return {!DOMAgent.BoxModel}
      */
     _scaleModel: function(model)
     {
-        var scale = this._canvasElement.offsetWidth / this._viewport.width;
+        var scale = this._canvasElement.offsetWidth * this._pageScaleFactor / this._deviceWidth;
 
         /**
          * @param {!DOMAgent.Quad} quad
          * @this {WebInspector.ScreencastView}
          */
         function scaleQuad(quad)
         {
             for (var i = 0; i < quad.length; i += 2) {
-                quad[i] = (quad[i] - this._viewport.x) * scale;
-                quad[i + 1] = (quad[i + 1] - this._viewport.y) * scale + this._screenOffsetTop * this._screenZoom;
+                quad[i] = (quad[i] - this._scrollOffsetX) * scale;
+                quad[i + 1] = (quad[i + 1] - this._scrollOffsetY) * scale + this._screenOffsetTop * this._screenZoom;
             }
         }
 
         scaleQuad.call(this, model.content);
         scaleQuad.call(this, model.padding);
         scaleQuad.call(this, model.border);
         scaleQuad.call(this, model.margin);
         return model;
     },
 
@@ skipping 38 matching lines @@
             }
             if (hasContent)
                 this._drawOutlinedQuad(model.content, config.contentColor);
             this._context.restore();
 
             this._drawElementTitle();
 
             this._context.globalCompositeOperation = "destination-over";
         }
 
-        this._context.drawImage(this._imageElement, 0, this._screenOffsetTop * this._screenZoom, this._imageElement.naturalWidth * this._imageZoom, this._imageElement.naturalHeight * this._imageZoom);
+        this._context.scale(1 / window.devicePixelRatio, 1 / window.devicePixelRatio);
+        this._context.drawImage(this._imageElement, 0,
+                                this._screenOffsetTop * this._screenZoom * window.devicePixelRatio,
+                                this._imageElement.naturalWidth * this._imageZoom * window.devicePixelRatio,

[dgozman, 2014/06/26 11:34:21]

Why scale context and then multiply everything by the same devicePixelRatio?

[vkuzkokov, 2014/06/26 14:15:54]

No reason

+                                this._imageElement.naturalHeight * this._imageZoom * window.devicePixelRatio);
+        this._context.restore();
 
-        this._context.restore();
     },
 
 
     /**
      * @param {!DOMAgent.Quad} quad1
      * @param {!DOMAgent.Quad} quad2
      * @return {boolean}
      */
     _quadsAreEqual: function(quad1, quad2)
     {
@@ skipping 141 matching lines @@
         this._titleElement.style.left = (boxX + 3) + "px";
     },
 
     /**
      * @return {!{width: number, height: number}}
      */
     _viewportDimensions: function()
     {
         const gutterSize = 30;
         const bordersSize = WebInspector.ScreencastView._bordersSize;
-        return { width: this.element.offsetWidth - bordersSize - gutterSize,
-                 height: this.element.offsetHeight - bordersSize - gutterSize - WebInspector.ScreencastView._navBarHeight};
+        var width = Math.floor(this.element.offsetWidth - bordersSize - gutterSize);
+        var height = Math.floor(this.element.offsetHeight - bordersSize - gutterSize - WebInspector.ScreencastView._navBarHeight);

[dgozman, 2014/06/26 11:34:21]

Ensure that canvas has exactly integer width/height properties.

+        return { width: width, height: height };
     },
 
     /**
      * @param {boolean} enabled
      * @param {boolean} inspectUAShadowDOM
      * @param {!DOMAgent.HighlightConfig} config
      * @param {function(?Protocol.Error)=} callback
      */
     setInspectModeEnabled: function(enabled, inspectUAShadowDOM, config, callback)
     {
@@ skipping 182 matching lines @@
           return;
         this._maxDisplayedProgress = progress;
         this._displayProgress(progress);
     },
 
     _displayProgress: function(progress)
     {
         this._element.style.width = (100 * progress) + "%";
     }
 };