1 files changed, 91 insertions, 0 deletions
diff --git a/devtools/shared/fronts/canvas.js b/devtools/shared/fronts/canvas.js
new file mode 100644
index 000000000..f3a1a6075
--- /dev/null
+++ b/devtools/shared/fronts/canvas.js
@@ -0,0 +1,91 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+"use strict";
+
+const {
+  frameSnapshotSpec,
+  canvasSpec,
+  CANVAS_CONTEXTS,
+  ANIMATION_GENERATORS,
+  LOOP_GENERATORS,
+  DRAW_CALLS,
+  INTERESTING_CALLS,
+} = require("devtools/shared/specs/canvas");
+const protocol = require("devtools/shared/protocol");
+const promise = require("promise");
+
+/**
+ * The corresponding Front object for the FrameSnapshotActor.
+ */
+const FrameSnapshotFront = protocol.FrontClassWithSpec(frameSnapshotSpec, {
+  initialize: function (client, form) {
+    protocol.Front.prototype.initialize.call(this, client, form);
+    this._animationFrameEndScreenshot = null;
+    this._cachedScreenshots = new WeakMap();
+  },
+
+  /**
+   * This implementation caches the animation frame end screenshot to optimize
+   * frontend requests to `generateScreenshotFor`.
+   */
+  getOverview: protocol.custom(function () {
+    return this._getOverview().then(data => {
+      this._animationFrameEndScreenshot = data.screenshot;
+      return data;
+    });
+  }, {
+    impl: "_getOverview"
+  }),
+
+  /**
+   * This implementation saves a roundtrip to the backend if the screenshot
+   * was already generated and retrieved once.
+   */
+  generateScreenshotFor: protocol.custom(function (functionCall) {
+    if (CanvasFront.ANIMATION_GENERATORS.has(functionCall.name) ||
+        CanvasFront.LOOP_GENERATORS.has(functionCall.name)) {
+      return promise.resolve(this._animationFrameEndScreenshot);
+    }
+    let cachedScreenshot = this._cachedScreenshots.get(functionCall);
+    if (cachedScreenshot) {
+      return cachedScreenshot;
+    }
+    let screenshot = this._generateScreenshotFor(functionCall);
+    this._cachedScreenshots.set(functionCall, screenshot);
+    return screenshot;
+  }, {
+    impl: "_generateScreenshotFor"
+  })
+});
+
+exports.FrameSnapshotFront = FrameSnapshotFront;
+
+/**
+ * The corresponding Front object for the CanvasActor.
+ */
+const CanvasFront = protocol.FrontClassWithSpec(canvasSpec, {
+  initialize: function (client, { canvasActor }) {
+    protocol.Front.prototype.initialize.call(this, client, { actor: canvasActor });
+    this.manage(this);
+  }
+});
+
+/**
+ * Constants.
+ */
+CanvasFront.CANVAS_CONTEXTS = new Set(CANVAS_CONTEXTS);
+CanvasFront.ANIMATION_GENERATORS = new Set(ANIMATION_GENERATORS);
+CanvasFront.LOOP_GENERATORS = new Set(LOOP_GENERATORS);
+CanvasFront.DRAW_CALLS = new Set(DRAW_CALLS);
+CanvasFront.INTERESTING_CALLS = new Set(INTERESTING_CALLS);
+CanvasFront.THUMBNAIL_SIZE = 50;
+CanvasFront.WEBGL_SCREENSHOT_MAX_HEIGHT = 256;
+CanvasFront.INVALID_SNAPSHOT_IMAGE = {
+  index: -1,
+  width: 0,
+  height: 0,
+  pixels: []
+};
+
+exports.CanvasFront = CanvasFront;