1 files changed, 209 insertions, 0 deletions
diff --git a/browser/modules/ZoomUI.sys.mjs b/browser/modules/ZoomUI.sys.mjs
new file mode 100644
index 0000000000..2e32ba46ec
--- /dev/null
+++ b/browser/modules/ZoomUI.sys.mjs
@@ -0,0 +1,209 @@
+// -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
+/* 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/. */
+
+const gLoadContext = Cu.createLoadContext();
+const gContentPrefs = Cc["@mozilla.org/content-pref/service;1"].getService(
+  Ci.nsIContentPrefService2
+);
+const gZoomPropertyName = "browser.content.full-zoom";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  PanelMultiView: "resource:///modules/PanelMultiView.sys.mjs",
+});
+
+export var ZoomUI = {
+  init(aWindow) {
+    aWindow.addEventListener("EndSwapDocShells", onEndSwapDocShells, true);
+    aWindow.addEventListener("FullZoomChange", onZoomChange);
+    aWindow.addEventListener("TextZoomChange", onZoomChange);
+    aWindow.addEventListener(
+      "unload",
+      () => {
+        aWindow.removeEventListener(
+          "EndSwapDocShells",
+          onEndSwapDocShells,
+          true
+        );
+        aWindow.removeEventListener("FullZoomChange", onZoomChange);
+        aWindow.removeEventListener("TextZoomChange", onZoomChange);
+      },
+      { once: true }
+    );
+  },
+
+  /**
+   * Gets the global browser.content.full-zoom content preference.
+   *
+   * @returns Promise<prefValue>
+   *                  Resolves to the preference value (float) when done.
+   */
+  getGlobalValue() {
+    return new Promise(resolve => {
+      let cachedVal = gContentPrefs.getCachedGlobal(
+        gZoomPropertyName,
+        gLoadContext
+      );
+      if (cachedVal) {
+        // We've got cached information, though it may be we've cached
+        // an undefined value, or the cached info is invalid. To ensure
+        // a valid return, we opt to return the default 1.0 in the
+        // undefined and invalid cases.
+        resolve(parseFloat(cachedVal.value) || 1.0);
+        return;
+      }
+      // Otherwise, nothing is cached, so we must do a full lookup
+      // with  `gContentPrefs.getGlobal()`.
+      let value = 1.0;
+      gContentPrefs.getGlobal(gZoomPropertyName, gLoadContext, {
+        handleResult(pref) {
+          if (pref.value) {
+            value = parseFloat(pref.value);
+          }
+        },
+        handleCompletion(reason) {
+          resolve(value);
+        },
+        handleError(error) {
+          console.error(error);
+        },
+      });
+    });
+  },
+};
+
+function fullZoomLocationChangeObserver(aSubject, aTopic) {
+  // If the tab was the last one in its window and has been dragged to another
+  // window, the original browser's window will be unavailable here. Since that
+  // window is closing, we can just ignore this notification.
+  if (!aSubject.ownerGlobal) {
+    return;
+  }
+  updateZoomUI(aSubject, false);
+}
+Services.obs.addObserver(
+  fullZoomLocationChangeObserver,
+  "browser-fullZoom:location-change"
+);
+
+function onEndSwapDocShells(event) {
+  updateZoomUI(event.originalTarget);
+}
+
+function onZoomChange(event) {
+  let browser;
+  if (event.target.nodeType == event.target.DOCUMENT_NODE) {
+    // In non-e10s, the event is dispatched on the contentDocument
+    // so we need to jump through some hoops to get to the <xul:browser>.
+    let topDoc = event.target.defaultView.top.document;
+    if (!topDoc.documentElement) {
+      // In some events, such as loading synthetic documents, the
+      // documentElement will be null and we won't be able to find
+      // an associated browser.
+      return;
+    }
+    browser = topDoc.ownerGlobal.docShell.chromeEventHandler;
+  } else {
+    browser = event.originalTarget;
+  }
+  updateZoomUI(browser, true);
+}
+
+/**
+ * Updates zoom controls.
+ *
+ * @param {object} aBrowser The browser that the zoomed content resides in.
+ * @param {boolean} aAnimate Should be True for all cases unless the zoom
+ *   change is related to tab switching. Optional
+ */
+async function updateZoomUI(aBrowser, aAnimate = false) {
+  let win = aBrowser.ownerGlobal;
+  if (!win.gBrowser || win.gBrowser.selectedBrowser != aBrowser) {
+    return;
+  }
+
+  let appMenuZoomReset = lazy.PanelMultiView.getViewNode(
+    win.document,
+    "appMenu-zoomReset-button2"
+  );
+
+  // Exit early if UI elements aren't present.
+  if (!appMenuZoomReset) {
+    return;
+  }
+
+  let customizableZoomControls = win.document.getElementById("zoom-controls");
+  let customizableZoomReset = win.document.getElementById("zoom-reset-button");
+  let urlbarZoomButton = win.document.getElementById("urlbar-zoom-button");
+  let zoomFactor = Math.round(win.ZoomManager.zoom * 100);
+
+  let defaultZoom = Math.round((await ZoomUI.getGlobalValue()) * 100);
+
+  if (!win.gBrowser || win.gBrowser.selectedBrowser != aBrowser) {
+    // Because the CPS call is async, at this point the selected browser
+    // may have changed. We should re-check whether the browser for which we've
+    // been notified is still the selected browser and bail out if not.
+    // If the selected browser changed (again), we will have been called again
+    // with the "right" browser, and that'll update the zoom level.
+    return;
+  }
+
+  // Hide urlbar zoom button if zoom is at the default zoom level,
+  // if we're viewing an about:blank page with an empty/null
+  // principal, if the PDF viewer is currently open,
+  // or if the customizable control is in the toolbar.
+
+  urlbarZoomButton.hidden =
+    defaultZoom == zoomFactor ||
+    (aBrowser.currentURI.spec == "about:blank" &&
+      (!aBrowser.contentPrincipal ||
+        aBrowser.contentPrincipal.isNullPrincipal)) ||
+    (aBrowser.contentPrincipal &&
+      aBrowser.contentPrincipal.spec == "resource://pdf.js/web/viewer.html") ||
+    (customizableZoomControls &&
+      customizableZoomControls.getAttribute("cui-areatype") == "toolbar");
+
+  let label = win.gNavigatorBundle.getFormattedString("zoom-button.label", [
+    zoomFactor,
+  ]);
+  if (appMenuZoomReset) {
+    appMenuZoomReset.setAttribute("label", label);
+  }
+  if (customizableZoomReset) {
+    customizableZoomReset.setAttribute("label", label);
+  }
+  if (!urlbarZoomButton.hidden) {
+    if (aAnimate && !win.gReduceMotion) {
+      urlbarZoomButton.setAttribute("animate", "true");
+    } else {
+      urlbarZoomButton.removeAttribute("animate");
+    }
+    urlbarZoomButton.setAttribute("label", label);
+  }
+
+  win.FullZoom.updateCommands();
+}
+
+import { CustomizableUI } from "resource:///modules/CustomizableUI.sys.mjs";
+
+let customizationListener = {};
+customizationListener.onWidgetAdded =
+  customizationListener.onWidgetRemoved =
+  customizationListener.onWidgetMoved =
+    function (aWidgetId) {
+      if (aWidgetId == "zoom-controls") {
+        for (let window of CustomizableUI.windows) {
+          updateZoomUI(window.gBrowser.selectedBrowser);
+        }
+      }
+    };
+customizationListener.onWidgetReset = customizationListener.onWidgetUndoMove =
+  function (aWidgetNode) {
+    if (aWidgetNode.id == "zoom-controls") {
+      updateZoomUI(aWidgetNode.ownerGlobal.gBrowser.selectedBrowser);
+    }
+  };
+CustomizableUI.addListener(customizationListener);