feat(patch): support requestAnimationFrame time loops

justindujardin · vicb · commit 3d6dc0850b20 · 2015-08-27T10:22:05.000-07:00
- Add custom patching function for repeating callback functions to
support requestAnimationFrame wrapping.
- Bind requestAnimationFrame callback functions to the current zone
unless it is the root zone.
- DRY up requestAnimationFrame spec file (to remove duplication across
browsers)
- Add test that verifies that when registering frame callbacks from
within a frame callback, the zone in which they execute remains
constant.
- Add test to verify the wrapper is tolerant of invalid arguments.
- Add note to readme about behavior of raf
diff --git a/README.md b/README.md
@@ -232,6 +232,14 @@ For instance `clearTimeout` and `removeEventListener`.
 These hooks allow you to change the behavior of `window.setTimeout`, `window.setInterval`, etc.
 While in this zone, calls to `window.setTimeout` will redirect to `zone.setTimeout`.
 
+### `zone.requestAnimationFrame`, `zone.webkitRequestAnimationFrame`, `zone.mozRequestAnimationFrame`
+
+These hooks allow you to change the behavior of `window.requestAnimationFrame()`, 
+`window.webkitRequestAnimationFrame`, and `window.mozRequestAnimationFrame`.
+
+By default the callback is executed in the zone where those methods have been called to avoid 
+growing the stack size on each recursive call.
+
 ### `zone.addEventListener`
 
 This hook allows you to intercept calls to `EventTarget.addEventListener`.
diff --git a/lib/patch/browser.js b/lib/patch/browser.js
@@ -17,7 +17,7 @@ function apply() {
     'immediate'
   ]);
 
-  fnPatch.patchSetFunction(global, [
+  fnPatch.patchRequestAnimationFrame(global, [
     'requestAnimationFrame',
     'mozRequestAnimationFrame',
     'webkitRequestAnimationFrame'
diff --git a/lib/patch/functions.js b/lib/patch/functions.js
@@ -48,6 +48,33 @@ function patchSetClearFunction(obj, fnNames) {
   });
 };
 
+
+/**
+ * requestAnimationFrame is typically recursively called from within the callback function
+ * that it executes.  To handle this case, only fork a zone if this is executed
+ * within the root zone.
+ */
+function patchRequestAnimationFrame(obj, fnNames) {
+  fnNames.forEach(function (name) {
+    var delegate = obj[name];
+    if (delegate) {
+      global.zone[name] = function (fn) {
+        var callZone = global.zone.isRootZone() ? global.zone.fork() : global.zone;
+        if (fn) {
+          arguments[0] = function () {
+            return callZone.run(fn, arguments);
+          };
+        }
+        return delegate.apply(obj, arguments);
+      };
+
+      obj[name] = function () {
+        return global.zone[name].apply(this, arguments);
+      };
+    }
+  });
+};
+
 function patchSetFunction(obj, fnNames) {
   fnNames.forEach(function (name) {
     var delegate = obj[name];
@@ -86,5 +113,6 @@ function patchFunction(obj, fnNames) {
 module.exports = {
   patchSetClearFunction: patchSetClearFunction,
   patchSetFunction: patchSetFunction,
+  patchRequestAnimationFrame: patchRequestAnimationFrame,
   patchFunction: patchFunction
 };
diff --git a/test/patch/requestAnimationFrame.spec.js b/test/patch/requestAnimationFrame.spec.js
@@ -3,63 +3,41 @@
 describe('requestAnimationFrame', function () {
   var testZone = zone.fork();
 
-  describe('requestAnimationFrame', function () {
-    it('should run the passed callback in a zone', function (done) {
-      testZone.run(function() {
-        if (typeof requestAnimationFrame === 'undefined') {
-          console.log('WARNING: skipping requestAnimationFrame test (missing this API)');
-          return done();
-        }
+  var functions = [
+    'requestAnimationFrame',
+    'webkitRequestAnimationFrame',
+    'mozRequestAnimationFrame'
+  ];
 
-        // Some browsers (especially Safari) do not fire requestAnimationFrame
-        // if they are offscreen. We can disable this test for those browsers and
-        // assume the patch works if setTimeout works, since they are mechanically
-        // the same
-        requestAnimationFrame(function () {
-          expect(zone).toBeDirectChildOf(testZone);
-          done();
-        });
-      });
-    });
-  });
+  functions.forEach(function (fnName) {
+    describe(fnName, ifEnvSupports(fnName, function () {
+      var rAF = window[fnName];
 
-  describe('mozRequestAnimationFrame', function () {
-    it('should run the passed callback in a zone', function (done) {
-      testZone.run(function() {
-        if (typeof mozRequestAnimationFrame === 'undefined') {
-          console.log('WARNING: skipping mozRequestAnimationFrame test (missing this API)');
-          return done();
-        }
-
-        // Some browsers (especially Safari) do not fire mozRequestAnimationFrame
-        // if they are offscreen. We can disable this test for those browsers and
-        // assume the patch works if setTimeout works, since they are mechanically
-        // the same
-        mozRequestAnimationFrame(function () {
-          expect(zone).toBeDirectChildOf(testZone);
+      it('should be tolerant of invalid arguments', function (done) {
+        testZone.run(function () {
+          // rAF throws an error on invalid arguments, so expect that.
+          expect(function () {
+            rAF(null);
+          }).toThrow();
           done();
         });
       });
-    });
-  });
 
-  describe('webkitRequestAnimationFrame', function () {
-    it('should run the passed callback in a zone', function (done) {
-      testZone.run(function() {
-        if (typeof webkitRequestAnimationFrame === 'undefined') {
-          console.log('WARNING: skipping webkitRequestAnimationFrame test (missing this API)');
-          return done();
-        }
+      it('should bind to same zone when called recursively', function (done) {
+        testZone.run(function () {
+          var frames = 0;
 
-        // Some browsers (especially Safari) do not fire webkitRequestAnimationFrame
-        // if they are offscreen. We can disable this test for those browsers and
-        // assume the patch works if setTimeout works, since they are mechanically
-        // the same
-        webkitRequestAnimationFrame(function () {
-          expect(zone).toBeDirectChildOf(testZone);
-          done();
+          function frameCallback() {
+            expect(zone === testZone).toBe(true);
+            if (frames++ > 15) {
+              return done();
+            }
+            rAF(frameCallback);
+          }
+
+          rAF(frameCallback);
         });
       });
-    });
+    }));
   });
 });
