1 files changed, 144 insertions, 0 deletions
diff --git a/devtools/server/actors/screenshot-content.js b/devtools/server/actors/screenshot-content.js
new file mode 100644
index 0000000000..0e47ae1157
--- /dev/null
+++ b/devtools/server/actors/screenshot-content.js
@@ -0,0 +1,144 @@
+/* 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 { Actor } = require("resource://devtools/shared/protocol.js");
+const {
+  screenshotContentSpec,
+} = require("resource://devtools/shared/specs/screenshot-content.js");
+
+const { LocalizationHelper } = require("resource://devtools/shared/l10n.js");
+const STRINGS_URI = "devtools/shared/locales/screenshot.properties";
+const L10N = new LocalizationHelper(STRINGS_URI);
+loader.lazyRequireGetter(
+  this,
+  ["getCurrentZoom", "getRect"],
+  "resource://devtools/shared/layout/utils.js",
+  true
+);
+
+exports.ScreenshotContentActor = class ScreenshotContentActor extends Actor {
+  constructor(conn, targetActor) {
+    super(conn, screenshotContentSpec);
+    this.targetActor = targetActor;
+  }
+
+  _getRectForNode(node) {
+    const originWindow = this.targetActor.ignoreSubFrames
+      ? node.ownerGlobal
+      : node.ownerGlobal.top;
+    return getRect(originWindow, node, node.ownerGlobal);
+  }
+
+  /**
+   * Retrieve some window-related information that will be passed to the parent process
+   * to actually generate the screenshot.
+   *
+   * @param {Object} args
+   * @param {Boolean} args.fullpage: Should the screenshot be the height of the whole page
+   * @param {String} args.selector: A CSS selector for the element we should take the
+   *                 screenshot of. The function will return true for the `error` property
+   *                 if the screenshot does not match any element.
+   * @param {String} args.nodeActorID: The actorID of the node actor matching the element
+   *                 we should take the screenshot of.
+   * @returns {Object} An object with the following properties:
+   *          - error {Boolean}: Set to true if an issue was encountered that prevents
+   *            taking the screenshot
+   *          - messages {Array<Object{text, level}>}: An array of objects representing
+   *            the messages emitted throught the process and their level.
+   *          - windowDpr {Number}: Value of window.devicePixelRatio
+   *          - windowZoom {Number}: The page current zoom level
+   *          - rect {Object}: Object with left, top, width and height properties
+   *            representing the rect **inside the browser element** that should be rendered.
+   *            For screenshot of the current viewport, we return null, as expected by the
+   *            `drawSnapshot` API.
+   */
+  prepareCapture({ fullpage, selector, nodeActorID }) {
+    const { window } = this.targetActor;
+    // Use the override if set, note that the override is not returned by
+    // devicePixelRatio on privileged code, see bug 1759962.
+    //
+    // FIXME(bug 1760711): Whether zoom is included in devicePixelRatio depends
+    // on whether there's an override, this is a bit suspect.
+    const windowDpr =
+      window.browsingContext.top.overrideDPPX || window.devicePixelRatio;
+    const windowZoom = getCurrentZoom(window);
+    const messages = [];
+
+    // If we're going to take the current view of the page, we don't need to compute a rect,
+    // since it's the default behaviour of drawSnapshot.
+    if (!fullpage && !selector && !nodeActorID) {
+      return {
+        rect: null,
+        messages,
+        windowDpr,
+        windowZoom,
+      };
+    }
+
+    let left;
+    let top;
+    let width;
+    let height;
+
+    if (fullpage) {
+      // We don't want to render the scrollbars
+      const winUtils = window.windowUtils;
+      const scrollbarHeight = {};
+      const scrollbarWidth = {};
+      winUtils.getScrollbarSize(false, scrollbarWidth, scrollbarHeight);
+
+      left = 0;
+      top = 0;
+      width =
+        window.innerWidth +
+        window.scrollMaxX -
+        window.scrollMinX -
+        scrollbarWidth.value;
+      height =
+        window.innerHeight +
+        window.scrollMaxY -
+        window.scrollMinY -
+        scrollbarHeight.value;
+    } else if (selector) {
+      const node = window.document.querySelector(selector);
+
+      if (!node) {
+        messages.push({
+          level: "warn",
+          text: L10N.getFormatStr("screenshotNoSelectorMatchWarning", selector),
+        });
+
+        return {
+          error: true,
+          messages,
+        };
+      }
+
+      ({ left, top, width, height } = this._getRectForNode(node));
+    } else if (nodeActorID) {
+      const nodeActor = this.conn.getActor(nodeActorID);
+      if (!nodeActor) {
+        messages.push({
+          level: "error",
+          text: `Screenshot actor failed to find Node actor for '${nodeActorID}'`,
+        });
+
+        return {
+          error: true,
+          messages,
+        };
+      }
+
+      ({ left, top, width, height } = this._getRectForNode(nodeActor.rawNode));
+    }
+
+    return {
+      windowDpr,
+      windowZoom,
+      rect: { left, top, width, height },
+      messages,
+    };
+  }
+};