Bug 1025023 - Prevent redrawing the canvas graph on window resize if the graph dimensions haven't changed, r=pbrosset

--HG--
rename : browser/devtools/shared/test/browser_graphs-10.js => browser/devtools/shared/test/browser_graphs-10a.js
rename : browser/devtools/shared/test/browser_graphs-10.js => browser/devtools/shared/test/browser_graphs-10b.js

browser/devtools/shared/test/browser.ini

@@ -21,7 +21,8 @@ support-files =
 [browser_graphs-07.js]
 [browser_graphs-08.js]
 [browser_graphs-09.js]
-[browser_graphs-10.js]
+[browser_graphs-10a.js]
+[browser_graphs-10b.js]
 [browser_graphs-11.js]
 [browser_graphs-12.js]
 [browser_graphs-13.js]

browser/devtools/shared/test/browser_graphs-10a.js

@@ -1,7 +1,7 @@
 /* Any copyright is dedicated to the Public Domain.
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
-// Tests that line graphs properly handle resizing.
+// Tests that graphs properly handle resizing.
 
 const TEST_DATA = [{ delta: 112, value: 48 }, { delta: 213, value: 59 }, { delta: 313, value: 60 }, { delta: 413, value: 59 }, { delta: 530, value: 59 }, { delta: 646, value: 58 }, { delta: 747, value: 60 }, { delta: 863, value: 48 }, { delta: 980, value: 37 }, { delta: 1097, value: 30 }, { delta: 1213, value: 29 }, { delta: 1330, value: 23 }, { delta: 1430, value: 10 }, { delta: 1534, value: 17 }, { delta: 1645, value: 20 }, { delta: 1746, value: 22 }, { delta: 1846, value: 39 }, { delta: 1963, value: 26 }, { delta: 2080, value: 27 }, { delta: 2197, value: 35 }, { delta: 2312, value: 47 }, { delta: 2412, value: 53 }, { delta: 2514, value: 60 }, { delta: 2630, value: 37 }, { delta: 2730, value: 36 }, { delta: 2830, value: 37 }, { delta: 2946, value: 36 }, { delta: 3046, value: 40 }, { delta: 3163, value: 47 }, { delta: 3280, value: 41 }, { delta: 3380, value: 35 }, { delta: 3480, value: 27 }, { delta: 3580, value: 39 }, { delta: 3680, value: 42 }, { delta: 3780, value: 49 }, { delta: 3880, value: 55 }, { delta: 3980, value: 60 }, { delta: 4080, value: 60 }, { delta: 4180, value: 60 }];
 let {LineGraphWidget} = Cu.import("resource:///modules/devtools/Graphs.jsm", {});

browser/devtools/shared/test/browser_graphs-10b.js

@@ -0,0 +1,51 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Tests that graphs aren't refreshed when the owner window resizes but
+// the graph dimensions stay the same.
+
+const TEST_DATA = [{ delta: 112, value: 48 }, { delta: 213, value: 59 }, { delta: 313, value: 60 }, { delta: 413, value: 59 }, { delta: 530, value: 59 }, { delta: 646, value: 58 }, { delta: 747, value: 60 }, { delta: 863, value: 48 }, { delta: 980, value: 37 }, { delta: 1097, value: 30 }, { delta: 1213, value: 29 }, { delta: 1330, value: 23 }, { delta: 1430, value: 10 }, { delta: 1534, value: 17 }, { delta: 1645, value: 20 }, { delta: 1746, value: 22 }, { delta: 1846, value: 39 }, { delta: 1963, value: 26 }, { delta: 2080, value: 27 }, { delta: 2197, value: 35 }, { delta: 2312, value: 47 }, { delta: 2412, value: 53 }, { delta: 2514, value: 60 }, { delta: 2630, value: 37 }, { delta: 2730, value: 36 }, { delta: 2830, value: 37 }, { delta: 2946, value: 36 }, { delta: 3046, value: 40 }, { delta: 3163, value: 47 }, { delta: 3280, value: 41 }, { delta: 3380, value: 35 }, { delta: 3480, value: 27 }, { delta: 3580, value: 39 }, { delta: 3680, value: 42 }, { delta: 3780, value: 49 }, { delta: 3880, value: 55 }, { delta: 3980, value: 60 }, { delta: 4080, value: 60 }, { delta: 4180, value: 60 }];
+let {LineGraphWidget} = Cu.import("resource:///modules/devtools/Graphs.jsm", {});
+let {DOMHelpers} = Cu.import("resource:///modules/devtools/DOMHelpers.jsm", {});
+let {Promise} = devtools.require("resource://gre/modules/Promise.jsm");
+let {Hosts} = devtools.require("devtools/framework/toolbox-hosts");
+
+let test = Task.async(function*() {
+  yield promiseTab("about:blank");
+  yield performTest();
+  gBrowser.removeCurrentTab();
+  finish();
+});
+
+function* performTest() {
+  let [host, win, doc] = yield createHost("window");
+  doc.body.setAttribute("style", "position: fixed; width: 100%; height: 100%; margin: 0;");
+
+  let graph = new LineGraphWidget(doc.body, "fps");
+  graph.fixedWidth = 200;
+  graph.fixedHeight = 100;
+  yield graph.once("ready");
+
+  let refreshCount = 0;
+  let refreshCancelledCount = 0;
+  graph.on("refresh", () => refreshCount++);
+  graph.on("refresh-cancelled", () => refreshCancelledCount++);
+
+  yield testGraph(host, graph);
+
+  is(refreshCount, 0, "The graph shouldn't have been refreshed at all.");
+  is(refreshCancelledCount, 2, "The graph should've had 2 refresh attempts.");
+
+  graph.destroy();
+  host.destroy();
+}
+
+function* testGraph(host, graph) {
+  graph.setData(TEST_DATA);
+
+  host._window.resizeBy(-100, -100);
+  yield graph.once("refresh-cancelled");
+
+  host._window.resizeBy(100, 100);
+  yield graph.once("refresh-cancelled");
+}

browser/devtools/shared/widgets/Graphs.jsm

@@ -502,8 +502,18 @@ AbstractCanvasGraph.prototype = {
    */
   refresh: function() {
     let bounds = this._parent.getBoundingClientRect();
-    bounds.width = this.fixedWidth || bounds.width;
-    bounds.height = this.fixedHeight || bounds.height;
+    let newWidth = this.fixedWidth || bounds.width;
+    let newHeight = this.fixedHeight || bounds.height;
+
+    // Prevent redrawing everything if the graph's width & height won't change.
+    if (this._width == newWidth * this._pixelRatio &&
+        this._height == newHeight * this._pixelRatio) {
+      this.emit("refresh-cancelled");
+      return;
+    }
+
+    bounds.width = newWidth;
+    bounds.height = newHeight;
     this._iframe.setAttribute("width", bounds.width);
     this._iframe.setAttribute("height", bounds.height);
     this._width = this._canvas.width = bounds.width * this._pixelRatio;