From 9ebc51ed4807a19ed63ab9ea1c39d9ab71572d11 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emilio=20Cobos=20=C3=81lvarez?= <emilio@crisal.io>
Date: Wed, 23 Nov 2022 14:52:12 +0000
Subject: [PATCH] Bug 1801032 - Keep reading lowercase screenx/y when loading
 XUL window positions. r=smaug

The early blank first-paint stuff[1] manually sets these attributes in
lowercase in an about:blank window, marvelous o.O

[1]: https://searchfox.org/mozilla-central/rev/650c19c96529eb28d081062c1ca274bc50ef3635/browser/components/BrowserGlue.jsm#1507-1523

Differential Revision: https://phabricator.services.mozilla.com/D162745
---
 xpcom/ds/StaticAtoms.py     |  2 ++
 xpfe/appshell/AppWindow.cpp | 55 +++++++++++++++++++++----------------
 2 files changed, 34 insertions(+), 23 deletions(-)

diff --git a/xpcom/ds/StaticAtoms.py b/xpcom/ds/StaticAtoms.py
index f6f44dad05e2..ec3bab7b7ff4 100644
--- a/xpcom/ds/StaticAtoms.py
+++ b/xpcom/ds/StaticAtoms.py
@@ -1107,7 +1107,9 @@ STATIC_ATOMS = [
     Atom("scoped", "scoped"),
     Atom("screen", "screen"),
     Atom("screenX", "screenX"),
+    Atom("screenx", "screenx"),
     Atom("screenY", "screenY"),
+    Atom("screeny", "screeny"),
     Atom("script", "script"),
     Atom("scrollbar", "scrollbar"),
     Atom("scrollbarThumb", "scrollbar-thumb"),
diff --git a/xpfe/appshell/AppWindow.cpp b/xpfe/appshell/AppWindow.cpp
index 55a57be7d41d..0c085c26cde4 100644
--- a/xpfe/appshell/AppWindow.cpp
+++ b/xpfe/appshell/AppWindow.cpp
@@ -1210,6 +1210,22 @@ void AppWindow::RemoveTooltipSupport() {
   listener->RemoveTooltipSupport(docShellElement);
 }
 
+static Maybe<int32_t> ReadIntAttribute(const Element& aElement,
+                                       nsAtom* aPrimary,
+                                       nsAtom* aSecondary = nullptr) {
+  nsAutoString attrString;
+  if (!aElement.GetAttr(aPrimary, attrString)) {
+    if (aSecondary) {
+      return ReadIntAttribute(aElement, aSecondary);
+    }
+    return Nothing();
+  }
+
+  nsresult res = NS_OK;
+  int32_t ret = attrString.ToInteger(&res);
+  return NS_SUCCEEDED(res) ? Some(ret) : Nothing();
+}
+
 // If aSpecWidth and/or aSpecHeight are > 0, we will use these CSS px sizes
 // to fit to the screen when staggering windows; if they're negative,
 // we use the window's current size instead.
@@ -1222,8 +1238,8 @@ bool AppWindow::LoadPositionFromXUL(int32_t aSpecWidth, int32_t aSpecHeight) {
     return false;
   }
 
-  nsCOMPtr<dom::Element> windowElement = GetWindowDOMElement();
-  NS_ENSURE_TRUE(windowElement, false);
+  RefPtr<dom::Element> root = GetWindowDOMElement();
+  NS_ENSURE_TRUE(root, false);
 
   const LayoutDeviceIntRect devRect = GetPositionAndSize();
 
@@ -1246,19 +1262,23 @@ bool AppWindow::LoadPositionFromXUL(int32_t aSpecWidth, int32_t aSpecHeight) {
   }
 
   // Obtain the position information from the <xul:window> element.
-  nsAutoString posString;
   DesktopIntPoint specPoint = curPoint;
-  nsresult errorCode;
-  windowElement->GetAttr(nsGkAtoms::screenX, posString);
-  int32_t temp = posString.ToInteger(&errorCode);
-  if (NS_SUCCEEDED(errorCode)) {
-    specPoint.x = temp;
+
+  // Also read lowercase screenx/y because the front-end sometimes sets these
+  // via setAttribute on HTML documents like about:blank, and stuff gets
+  // lowercased.
+  //
+  // TODO(emilio): We should probably rename screenX/Y to screen-x/y to
+  // prevent this impedance mismatch.
+  if (auto attr =
+          ReadIntAttribute(*root, nsGkAtoms::screenX, nsGkAtoms::screenx)) {
+    specPoint.x = *attr;
     gotPosition = true;
   }
-  windowElement->GetAttr(nsGkAtoms::screenY, posString);
-  temp = posString.ToInteger(&errorCode);
-  if (NS_SUCCEEDED(errorCode)) {
-    specPoint.y = temp;
+
+  if (auto attr =
+          ReadIntAttribute(*root, nsGkAtoms::screenY, nsGkAtoms::screeny)) {
+    specPoint.y = *attr;
     gotPosition = true;
   }
 
@@ -1282,17 +1302,6 @@ bool AppWindow::LoadPositionFromXUL(int32_t aSpecWidth, int32_t aSpecHeight) {
   return gotPosition;
 }
 
-static Maybe<int32_t> ReadIntAttribute(const Element& aElement, nsAtom* aAtom) {
-  nsAutoString attrString;
-  if (!aElement.GetAttr(aAtom, attrString)) {
-    return Nothing();
-  }
-
-  nsresult res = NS_OK;
-  int32_t ret = attrString.ToInteger(&res);
-  return NS_SUCCEEDED(res) ? Some(ret) : Nothing();
-}
-
 static Maybe<int32_t> ReadSize(const Element& aElement, nsAtom* aAttr,
                                nsAtom* aMinAttr, nsAtom* aMaxAttr) {
   Maybe<int32_t> attr = ReadIntAttribute(aElement, aAttr);