rebaseline_server: get "image size" working again

gm/rebaseline_server/static/diff_viewer.js

-var MAX_SWAP_IMG_SIZE = 200;
-var MAGNIFIER_WIDTH = 100;
-var MAGNIFIER_HEIGHT = 100;
-var MAGNIFIER_HALF_WIDTH = MAGNIFIER_WIDTH * 0.5;
-var MAGNIFIER_HALF_HEIGHT = MAGNIFIER_HEIGHT * 0.5;
-var MAGNIFIER_SCALE_FACTOR = 2.0;
+// What portion of the image width will be taken up by the magnifier.
+var MAGNIFIER_WIDTH_FACTOR = 0.66;

[epoger, 2014/02/05 20:51:14]

Moved the old constants into ImageController; they are now set based on
imageWidth.

 
 angular.module('diff_viewer', []).directive('imgCompare', function() {
   // Custom directive for comparing (3-way) images
   return {
       restrict: 'E', // The directive can be used as an element name
       replace: true, // The directive replaces itself with the template
       template: '<canvas/>',
       scope: true,
       link: function(scope, elm, attrs, ctrl) {
           var image = new Image();
           var canvas = elm[0];
           var ctx = canvas.getContext('2d');
           var magnifyContent = false;
 
-          // When the type attribute changes, load the image and then render
+          // When the type attribute changes, set magnifyContent appropriately.
           attrs.$observe('type', function(value) {
-              switch(value) {
+              switch(attrs.type) {
                 case "differingPixelsInWhite":
                     magnifyContent = true;
                     break;
                 case "differencePerPixel":
                     break;
                 case "baseline":
                     magnifyContent = true;
                     break;
                 case "test":
                     magnifyContent = true;
                     break;
                 default:
                     console.log("Unknown type attribute on <img-compare>: " + value);
                     return;
               }
+          });
 
+          // Reset ImageController's scale and render the image;
+          // we need to do this whenever attrs.src or attrs.width changes.
+          scope.setScaleAndRender = function() {
+              // compute the scaled image width/height for image and canvas
+              scope.setImgScale(image.width, attrs.width);

[epoger, 2014/02/05 20:51:14]

We don't require that images are scaled down by a factor of 2 anymore.  Instead,
the scale is computed such that the image fits exactly within the desired canvas
width.

+
+              // Set canvas to correct size
+              canvas.width = image.width / scope.imgScaleDivisor;
+              canvas.height = image.height / scope.imgScaleDivisor;
+
+              scope.renderImage();
+          };
+          attrs.$observe('src', function(value) {

[epoger, 2014/02/05 20:51:14]

New behavor:
- Only load the images when src= changes on the img-compare element.
- Only set imgScale when EITHER src= or width= changes.
- Only set magnifyContent when type= changes.

This allows the user to change imageSize anytime, and the redraws are correct
and fast.

               image.src = attrs.src;
-              image.onload = function() {
-                  // compute the scaled image width/height for image and canvas
-                  var divisor = 1;
-                  // Make it so the maximum size of an image is MAX_SWAP_IMG_SIZE,
-                  // and the images are scaled down in halves.
-                  while ((image.width / divisor) > MAX_SWAP_IMG_SIZE) {
-                      divisor *= 2;
-                  }
-
-                  scope.setImgScaleFactor(1 / divisor);
-
-                  // Set canvas to correct size
-                  canvas.width = image.width * scope.imgScaleFactor;
-                  canvas.height = image.height * scope.imgScaleFactor;
-
-                  scope.renderImage();
-              }
+              image.onload = scope.setScaleAndRender;
           });
+          attrs.$observe('width', scope.setScaleAndRender);
 
           // When the magnify attribute changes, render the magnified rect at
           // the default zoom level.
           scope.$watch('magnifyCenter', function(magCenter) {
               if (!magnifyContent) {
                   return;
               }
 
               scope.renderImage();
 
               if (!magCenter) {
                   return;
               }
 
-              var magX = magCenter.x - MAGNIFIER_HALF_WIDTH;
-              var magY = magCenter.y - MAGNIFIER_HALF_HEIGHT;
+              var magX = magCenter.x - scope.magnifierHalfWidth;
+              var magY = magCenter.y - scope.magnifierHalfHeight;
 
-              var magMaxX = canvas.width - MAGNIFIER_WIDTH;
-              var magMaxY = canvas.height - MAGNIFIER_HEIGHT;
+              var magMaxX = canvas.width - scope.magnifierWidth;
+              var magMaxY = canvas.height - scope.magnifierHeight;
 
               var magRect = { x: Math.max(0, Math.min(magX, magMaxX)),
                               y: Math.max(0, Math.min(magY, magMaxY)),
-                              width: MAGNIFIER_WIDTH,
-                              height: MAGNIFIER_HEIGHT
+                              width: scope.magnifierWidth,
+                              height: scope.magnifierHeight
                             };
 
-              var imgRect = { x: (magCenter.x / scope.imgScaleFactor) - MAGNIFIER_HALF_WIDTH,
-                              y: (magCenter.y  / scope.imgScaleFactor) - MAGNIFIER_HALF_HEIGHT,
-                              width: MAGNIFIER_WIDTH,
-                              height: MAGNIFIER_HEIGHT
+              var imgRect = { x: (magCenter.x * scope.imgScaleDivisor) - scope.magnifierHalfWidth,
+                              y: (magCenter.y * scope.imgScaleDivisor) - scope.magnifierHalfHeight,
+                              width: scope.magnifierWidth,
+                              height: scope.magnifierHeight
                             };
 
               // draw the magnified image
               ctx.clearRect(magRect.x, magRect.y, magRect.width, magRect.height);
               ctx.drawImage(image, imgRect.x, imgRect.y, imgRect.width, imgRect.height,
                             magRect.x, magRect.y, magRect.width, magRect.height);
 
               // draw the outline rect
               ctx.beginPath();
               ctx.rect(magRect.x, magRect.y, magRect.width, magRect.height);
               ctx.lineWidth = 2;
               ctx.strokeStyle = 'red';
               ctx.stroke();
 
           });
 
           // render the image to the canvas. This is often done every frame prior
           // to any special effects (i.e. magnification).
           scope.renderImage = function() {
             ctx.clearRect(0, 0, canvas.width, canvas.height);
             ctx.drawImage(image, 0, 0, canvas.width, canvas.height);
           };
 
           // compute a rect (x,y,width,height) that represents the bounding box for
           // the magnification effect
           scope.computeMagnifierOutline = function(event) {
-            var scaledWidth = MAGNIFIER_WIDTH * scope.imgScaleFactor;
-            var scaledHeight = MAGNIFIER_HEIGHT * scope.imgScaleFactor;
+            var scaledWidth = scope.magnifierWidth / scope.imgScaleDivisor;
+            var scaledHeight = scope.magnifierHeight / scope.imgScaleDivisor;
             return {
               x: event.offsetX - (scaledWidth * 0.5),
               y: event.offsetY  - (scaledHeight * 0.5),
               width: scaledWidth,
               height: scaledHeight
             };
           };
 
           // event handler for mouse events that triggers the magnification
           // effect across the 4 images being compared.
@@ skipping 26 matching lines @@
               scope.renderImage();
               // update scope on baseline / test that will cause them to render
               scope.setMagnifierState(false);
               scope.setMagnifyCenter(undefined);
           };
       }
   };
 });
 
 function ImageController($scope, $http, $location, $timeout, $parse) {
-  $scope.imgScaleFactor = 1.0;
+  $scope.imgScaleDivisor = 1.0;
   $scope.magnifierOn = false;
   $scope.magnifyCenter = undefined;
 
-  $scope.setImgScaleFactor = function(scaleFactor) {
-    $scope.imgScaleFactor = scaleFactor;
+  $scope.setImgScale = function(srcImageWidth, displayWidth) {
+    $scope.imgScaleDivisor = srcImageWidth / displayWidth;
+    $scope.magnifierWidth = displayWidth * MAGNIFIER_WIDTH_FACTOR;
+    $scope.magnifierHeight = $scope.magnifierWidth;
+    $scope.magnifierHalfWidth = $scope.magnifierWidth / 2;
+    $scope.magnifierHalfHeight = $scope.magnifierHeight / 2;
   }
 
   $scope.setMagnifierState = function(magnifierOn) {
     $scope.magnifierOn = magnifierOn;
   }
 
   $scope.setMagnifyCenter = function(magnifyCenter) {
-      $scope.magnifyCenter = magnifyCenter;
+    $scope.magnifyCenter = magnifyCenter;
   }
 }
-