Optimized CanvasGraphics_executeOperatorList 66% faster

src/display/canvas.js

@@ -394,6 +394,8 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
   // Defines the time the executeOperatorList is going to be executing
   // before it stops and shedules a continue of execution.
   var EXECUTION_TIME = 15;
+  // Defines the number of steps before checking the execution time
+  var EXECUTION_STEPS = 10;
 
   function CanvasGraphics(canvasCtx, commonObjs, objs, imageLayer) {
     this.ctx = canvasCtx;
@@ -726,18 +728,21 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
       var argsArrayLen = argsArray.length;
 
       // Sometimes the OperatorList to execute is empty.
-      if (argsArrayLen == i) {
+      if (argsArrayLen === i) {
         return i;
       }
 
-      var endTime = Date.now() + EXECUTION_TIME;
+      var chunkOperations = (argsArrayLen - i > EXECUTION_STEPS &&
+                             typeof continueCallback === 'function');
+      var endTime = chunkOperations ? Date.now() + EXECUTION_TIME : 0;
+      var steps = 0;
 
       var commonObjs = this.commonObjs;
       var objs = this.objs;
       var fnId;
 
       while (true) {
-        if (stepper && i === stepper.nextBreakPoint) {
+        if (stepper !== undefined && i === stepper.nextBreakPoint) {
           stepper.breakIt(i, continueCallback);
           return i;
         }
@@ -750,16 +755,13 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
           var deps = argsArray[i];
           for (var n = 0, nn = deps.length; n < nn; n++) {
             var depObjId = deps[n];
-            var common = depObjId.substring(0, 2) == 'g_';
+            var common = depObjId[0] === 'g' && depObjId[1] === '_';
+            var objsPool = common ? commonObjs : objs;
 
             // If the promise isn't resolved yet, add the continueCallback
             // to the promise and bail out.
-            if (!common && !objs.isResolved(depObjId)) {
+            if (!objsPool.isResolved(depObjId)) {
-              objs.get(depObjId, continueCallback);
+              objsPool.get(depObjId, continueCallback);
-              return i;
-            }
-            if (common && !commonObjs.isResolved(depObjId)) {
-              commonObjs.get(depObjId, continueCallback);
               return i;
             }
           }
@@ -768,15 +770,18 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
         i++;
 
         // If the entire operatorList was executed, stop as were done.
-        if (i == argsArrayLen) {
+        if (i === argsArrayLen) {
           return i;
         }
 
         // If the execution took longer then a certain amount of time and
         // `continueCallback` is specified, interrupt the execution.
-        if (continueCallback && Date.now() > endTime) {
+        if (chunkOperations && ++steps > EXECUTION_STEPS) {
-          continueCallback();
+          if (Date.now() > endTime) {
-          return i;
+            continueCallback();
+            return i;
+          }
+          steps = 0;
         }
 
         // If the operatorList isn't executed completely yet OR the execution