1 files changed, 54 insertions, 0 deletions
diff --git a/browser/components/shell/ScreenshotChild.jsm b/browser/components/shell/ScreenshotChild.jsm
new file mode 100644
index 0000000000..18e18b2d2d
--- /dev/null
+++ b/browser/components/shell/ScreenshotChild.jsm
@@ -0,0 +1,54 @@
+/* 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 EXPORTED_SYMBOLS = ["ScreenshotChild"];
+
+class ScreenshotChild extends JSWindowActorChild {
+  receiveMessage(message) {
+    if (message.name == "TakeScreenshot") {
+      return this.takeScreenshot(message.data);
+    }
+    return null;
+  }
+
+  async takeScreenshot(params) {
+    if (this.document.readyState != "complete") {
+      await new Promise(resolve =>
+        this.contentWindow.addEventListener("load", resolve, { once: true })
+      );
+    }
+
+    let { fullWidth, fullHeight } = params;
+    let { contentWindow } = this;
+
+    let canvas = contentWindow.document.createElementNS(
+      "http://www.w3.org/1999/xhtml",
+      "html:canvas"
+    );
+    let context = canvas.getContext("2d");
+    let width = contentWindow.innerWidth;
+    let height = contentWindow.innerHeight;
+    if (fullWidth) {
+      width += contentWindow.scrollMaxX - contentWindow.scrollMinX;
+    }
+    if (fullHeight) {
+      height += contentWindow.scrollMaxY - contentWindow.scrollMinY;
+    }
+
+    canvas.width = width;
+    canvas.height = height;
+    context.drawWindow(
+      contentWindow,
+      0,
+      0,
+      width,
+      height,
+      "rgb(255, 255, 255)"
+    );
+
+    return new Promise(resolve => canvas.toBlob(resolve));
+  }
+}