Bug 1885106 - Implement LayoutUtils.rectToTopLevelWidgetRect. r=layout-reviewers,emilio

Differential Revision: https://phabricator.services.mozilla.com/D211131

dom/base/nsDOMWindowUtils.cpp

@@ -1856,8 +1856,8 @@ nsDOMWindowUtils::TransformRectLayoutToVisual(float aX, float aY, float aWidth,
   return NS_OK;
 }
 
-Result<mozilla::ScreenRect, nsresult> nsDOMWindowUtils::ConvertToScreenRect(
-    float aX, float aY, float aWidth, float aHeight) {
+Result<mozilla::LayoutDeviceRect, nsresult> nsDOMWindowUtils::ConvertTo(
+    float aX, float aY, float aWidth, float aHeight, CoordsType aCoordsType) {
   nsCOMPtr<nsPIDOMWindowOuter> window = do_QueryReferent(mWindow);
   if (!window) {
     return Err(NS_ERROR_NOT_AVAILABLE);
@@ -1894,25 +1894,28 @@ Result<mozilla::ScreenRect, nsresult> nsDOMWindowUtils::ConvertToScreenRect(
   LayoutDeviceRect devPixelsRect = LayoutDeviceRect::FromAppUnits(
       appUnitsRect, presContext->AppUnitsPerDevPixel());
   devPixelsRect =
-      widget->WidgetToTopLevelWidgetTransform().TransformBounds(devPixelsRect) +
-      widget->TopLevelWidgetToScreenOffset();
+      widget->WidgetToTopLevelWidgetTransform().TransformBounds(devPixelsRect);
 
-  return ViewAs<ScreenPixel>(
-      devPixelsRect, PixelCastJustification::ScreenIsParentLayerForRoot);
+  switch (aCoordsType) {
+    case CoordsType::Screen:
+      devPixelsRect += widget->TopLevelWidgetToScreenOffset();
+      break;
+    case CoordsType::TopLevelWidget:
+      // There's nothing to do.
+      break;
+  }
+  return devPixelsRect;
 }
 
 NS_IMETHODIMP
 nsDOMWindowUtils::ToScreenRectInCSSUnits(float aX, float aY, float aWidth,
                                          float aHeight, DOMRect** aResult) {
-  ScreenRect rect;
-  MOZ_TRY_VAR(rect, ConvertToScreenRect(aX, aY, aWidth, aHeight));
+  LayoutDeviceRect devRect;
+  MOZ_TRY_VAR(devRect, ConvertTo(aX, aY, aWidth, aHeight, CoordsType::Screen));
 
   nsPresContext* presContext = GetPresContext();
   MOZ_ASSERT(presContext);
 
-  const auto devRect = ViewAs<LayoutDevicePixel>(
-      rect, PixelCastJustification::ScreenIsParentLayerForRoot);
-
   // We want to return the screen rect in CSS units of the browser chrome.
   //
   // TODO(emilio): It'd be cleaner to convert callers to use plain toScreenRect,
@@ -1931,8 +1934,25 @@ nsDOMWindowUtils::ToScreenRectInCSSUnits(float aX, float aY, float aWidth,
 NS_IMETHODIMP
 nsDOMWindowUtils::ToScreenRect(float aX, float aY, float aWidth, float aHeight,
                                DOMRect** aResult) {
-  ScreenRect rect;
-  MOZ_TRY_VAR(rect, ConvertToScreenRect(aX, aY, aWidth, aHeight));
+  LayoutDeviceRect devPixelsRect;
+  MOZ_TRY_VAR(devPixelsRect,
+              ConvertTo(aX, aY, aWidth, aHeight, CoordsType::Screen));
+
+  ScreenRect rect = ViewAs<ScreenPixel>(
+      devPixelsRect, PixelCastJustification::ScreenIsParentLayerForRoot);
+
+  RefPtr<DOMRect> outRect = new DOMRect(mWindow);
+  outRect->SetRect(rect.x, rect.y, rect.width, rect.height);
+  outRect.forget(aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDOMWindowUtils::ToTopLevelWidgetRect(float aX, float aY, float aWidth,
+                                       float aHeight, DOMRect** aResult) {
+  LayoutDeviceRect rect;
+  MOZ_TRY_VAR(rect,
+              ConvertTo(aX, aY, aWidth, aHeight, CoordsType::TopLevelWidget));
 
   RefPtr<DOMRect> outRect = new DOMRect(mWindow);
   outRect->SetRect(rect.x, rect.y, rect.width, rect.height);

dom/base/nsDOMWindowUtils.h

@@ -110,8 +110,12 @@ class nsDOMWindowUtils final : public nsIDOMWindowUtils,
                                    bool aFromChrome);
 
  private:
-  mozilla::Result<mozilla::ScreenRect, nsresult> ConvertToScreenRect(
-      float aX, float aY, float aWidth, float aHeight);
+  enum class CoordsType {
+    Screen,
+    TopLevelWidget,
+  };
+  mozilla::Result<mozilla::LayoutDeviceRect, nsresult> ConvertTo(
+      float aX, float aY, float aWidth, float aHeight, CoordsType);
 };
 
 #endif

dom/interfaces/base/nsIDOMWindowUtils.idl

@@ -1088,6 +1088,13 @@ interface nsIDOMWindowUtils : nsISupports {
   DOMRect toScreenRect(in float aX, in float aY,
                        in float aWidth, in float aHeight);
 
+  /**
+   * Transform a rectangle given in coordinates relative to the top level widget
+   * coordinates of this document (i.e. browser.xhml).
+   */
+  DOMRect toTopLevelWidgetRect(in float aX, in float aY,
+                          in float aWidth, in float aHeight);
+
   /**
    * Transform a rectangle given in coordinates relative to the top level
    * parent process widget to the local widget. This window should be in a

toolkit/modules/LayoutUtils.sys.mjs

@@ -25,6 +25,20 @@ export var LayoutUtils = {
     return win.ownerGlobal.windowUtils.toScreenRect(x, y, width, height);
   },
 
+  /**
+   * Convert rect into the top level widget coordinates in LayoutDevicePixel
+   * units.
+   */
+  rectToTopLevelWidgetRect(win, rect) {
+    const { x, y, width, height } = this._rectToClientRect(win, rect);
+    return win.ownerGlobal.windowUtils.toTopLevelWidgetRect(
+      x,
+      y,
+      width,
+      height
+    );
+  },
+
   _rectToClientRect(win, rect) {
     // We need to compensate the position for ancestor iframes in the same
     // process that might shift things over. Those might have different CSS

toolkit/modules/tests/browser/browser.toml

@@ -41,6 +41,8 @@ skip-if = ["verify && debug && (os == 'mac' || os == 'linux')"]
 
 ["browser_InlineSpellChecker.js"]
 
+["browser_LayoutUtils.js"]
+
 ["browser_Troubleshoot.js"]
 
 ["browser_web_channel.js"]

toolkit/modules/tests/browser/browser_LayoutUtils.js

@@ -0,0 +1,58 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+add_task(async function test_rectToBrowserRect() {
+  const tab = await BrowserTestUtils.openNewForegroundTab(
+    gBrowser,
+    "data:text/html;charset=utf-8,test"
+  );
+
+  SpecialPowers.addTaskImport(
+    "LayoutUtils",
+    "resource://gre/modules/LayoutUtils.sys.mjs"
+  );
+
+  // Convert (12, 34) in a content document coordinates into this browser window
+  // coordinates.
+  const positionInBrowser = await SpecialPowers.spawn(
+    tab.linkedBrowser,
+    [],
+    () => {
+      /* global LayoutUtils */
+      return LayoutUtils.rectToTopLevelWidgetRect(content.window, {
+        left: 12,
+        top: 34,
+        width: 0,
+        height: 0,
+      });
+    }
+  );
+
+  // Dispatch a mousedown event on the browser window coordinates position to
+  // see whether it's fired on the correct position in the content document.
+  const mouseDownPromise = BrowserTestUtils.waitForContentEvent(
+    tab.linkedBrowser,
+    "mousedown",
+    false,
+    event => {
+      dump(`mousedown on (${event.clientX}, ${event.clientY})`);
+      return event.clientX == 12 && event.clientY == 34;
+    }
+  );
+
+  // A workaround for bug 1743857.
+  await SpecialPowers.spawn(tab.linkedBrowser, [], async () => {
+    await Promise.resolve();
+  });
+
+  EventUtils.synthesizeMouseAtPoint(
+    positionInBrowser.x / window.devicePixelRatio,
+    positionInBrowser.y / window.devicePixelRatio,
+    { type: "mousedown", button: 1 }
+  );
+  await mouseDownPromise;
+
+  Assert.ok(true, "LayoutUtils.rectToBrowserRect() works as expected");
+
+  BrowserTestUtils.removeTab(tab);
+});