Limit the size of canvases to 5MP (iOS restriction)

src/display/api.js

@@ -140,6 +140,14 @@ PDFJS.useOnlyCssZoom = (PDFJS.useOnlyCssZoom === undefined ?
 PDFJS.verbosity = (PDFJS.verbosity === undefined ?
                    PDFJS.VERBOSITY_LEVELS.warnings : PDFJS.verbosity);
 
+/**
+ * The maximum supported canvas size in total pixels e.g. width * height. 
+ * The default value is 4096 * 4096. Use -1 for no limit.
+ * @var {number}
+ */
+PDFJS.maxCanvasPixels = (PDFJS.maxCanvasPixels === undefined ?
+                         16777216 : PDFJS.maxCanvasPixels);
+
 /**
  * Document initialization / loading parameters object.
  *

web/compatibility.js

@@ -507,3 +507,12 @@ if (typeof PDFJS === 'undefined') {
       window.setTimeout(callback, 20);
     });
 })();
+
+(function checkCanvasSizeLimitation() {
+  var isIOS = /(iPad|iPhone|iPod)/g.test(navigator.userAgent);
+  var isAndroid = /Android/g.test(navigator.userAgent);
+  if (isIOS || isAndroid) {
+    // 5MP
+    PDFJS.maxCanvasPixels = 5242880;
+  }
+})();

web/page_view.js

@@ -29,6 +29,7 @@ var PageView = function pageView(container, id, scale,
   this.scale = scale || 1.0;
   this.viewport = defaultViewport;
   this.pdfPageRotate = defaultViewport.rotation;
+  this.hasRestrictedScaling = false;
 
   this.renderingState = RenderingStates.INITIAL;
   this.resume = null;
@@ -125,8 +126,23 @@ var PageView = function pageView(container, id, scale,
       rotation: totalRotation
     });
 
-    if (PDFJS.useOnlyCssZoom && this.canvas) {
+    var isScalingRestricted = false;
-      this.cssTransform(this.canvas);
+    if (this.canvas && PDFJS.maxCanvasPixels > 0) {
+      var ctx = this.canvas.getContext('2d');
+      var outputScale = getOutputScale(ctx);
+      var pixelsInViewport = this.viewport.width * this.viewport.height;
+      var maxScale = Math.sqrt(PDFJS.maxCanvasPixels / pixelsInViewport);
+      if (((Math.floor(this.viewport.width) * outputScale.sx) | 0) *
+          ((Math.floor(this.viewport.height) * outputScale.sy) | 0) >
+          PDFJS.maxCanvasPixels) {
+        isScalingRestricted = true;
+      }
+    }
+
+    if (this.canvas &&
+        (PDFJS.useOnlyCssZoom ||
+          (this.hasRestrictedScaling && isScalingRestricted))) {
+      this.cssTransform(this.canvas, true);
       return;
     } else if (this.canvas && !this.zoomLayer) {
       this.zoomLayer = this.canvas.parentNode;
@@ -138,7 +154,7 @@ var PageView = function pageView(container, id, scale,
     this.reset(true);
   };
 
-  this.cssTransform = function pageCssTransform(canvas) {
+  this.cssTransform = function pageCssTransform(canvas, redrawAnnotations) {
     // Scale canvas, canvas wrapper, and page container.
     var width = this.viewport.width;
     var height = this.viewport.height;
@@ -201,7 +217,7 @@ var PageView = function pageView(container, id, scale,
       CustomStyle.setProp('transformOrigin', textLayerDiv, '0% 0%');
     }
 
-    if (PDFJS.useOnlyCssZoom && this.annotationLayer) {
+    if (redrawAnnotations && this.annotationLayer) {
       setupAnnotations(div, this.pdfPage, this.viewport);
     }
   };
@@ -507,6 +523,19 @@ var PageView = function pageView(container, id, scale,
       outputScale.scaled = true;
     }
 
+    if (PDFJS.maxCanvasPixels > 0) {
+      var pixelsInViewport = viewport.width * viewport.height;
+      var maxScale = Math.sqrt(PDFJS.maxCanvasPixels / pixelsInViewport);
+      if (outputScale.sx > maxScale || outputScale.sy > maxScale) {
+        outputScale.sx = maxScale;
+        outputScale.sy = maxScale;
+        outputScale.scaled = true;
+        this.hasRestrictedScaling = true;
+      } else {
+        this.hasRestrictedScaling = false;
+      }
+    }
+
     canvas.width = (Math.floor(viewport.width) * outputScale.sx) | 0;
     canvas.height = (Math.floor(viewport.height) * outputScale.sy) | 0;
     canvas.style.width = Math.floor(viewport.width) + 'px';

web/viewer.js

@@ -34,7 +34,7 @@ var SCROLLBAR_PADDING = 40;
 var VERTICAL_PADDING = 5;
 var MAX_AUTO_SCALE = 1.25;
 var MIN_SCALE = 0.25;
-var MAX_SCALE = 4.0;
+var MAX_SCALE = 10.0;
 var VIEW_HISTORY_MEMORY = 20;
 var SCALE_SELECT_CONTAINER_PADDING = 8;
 var SCALE_SELECT_PADDING = 22;