Bug 1854473 - Use screen's scale factor when providing accessible bounds in ATK. r=nlapre

Differential Revision: https://phabricator.services.mozilla.com/D188883

accessible/atk/nsMaiInterfaceComponent.cpp

@@ -10,10 +10,12 @@
 #include "AccessibleWrap.h"
 #include "nsAccUtils.h"
 #include "nsMai.h"
+#include "nsWindow.h"
 #include "mozilla/Likely.h"
 #include "mozilla/a11y/DocAccessibleParent.h"
 #include "mozilla/a11y/RemoteAccessible.h"
 #include "mozilla/dom/BrowserParent.h"
+#include "mozilla/dom/Document.h"
 #include "nsAccessibilityService.h"
 
 using namespace mozilla;
@@ -107,6 +109,36 @@ AtkObject* refAccessibleAtPointHelper(AtkObject* aAtkObj, gint aX, gint aY,
   return atkObj;
 }
 
+static double getScaleFactor(Accessible* aAccessible) {
+  DocAccessible* docAcc = nullptr;
+  if (LocalAccessible* localAcc = aAccessible->AsLocal()) {
+    docAcc = localAcc->Document();
+  } else {
+    RemoteAccessible* remote = aAccessible->AsRemote();
+    LocalAccessible* outerDoc = remote->OuterDocOfRemoteBrowser();
+    if (outerDoc) {
+      docAcc = outerDoc->Document();
+    }
+  }
+
+  if (!docAcc || !docAcc->DocumentNode()) {
+    return 1.0;
+  }
+
+  nsCOMPtr<nsIWidget> rootWidget =
+      nsContentUtils::WidgetForDocument(docAcc->DocumentNode());
+  if (!rootWidget) {
+    return 1.0;
+  }
+
+  if (RefPtr<nsWindow> window =
+          static_cast<nsWindow*>(rootWidget->GetTopLevelWidget())) {
+    return window->FractionalScaleFactor();
+  }
+
+  return 1.0;
+}
+
 void getExtentsHelper(AtkObject* aAtkObj, gint* aX, gint* aY, gint* aWidth,
                       gint* aHeight, AtkCoordType aCoordType) {
   *aX = *aY = *aWidth = *aHeight = -1;
@@ -128,10 +160,12 @@ void getExtentsHelper(AtkObject* aAtkObj, gint* aX, gint* aY, gint* aWidth,
     screenRect.y -= winCoords.y;
   }
 
-  *aX = screenRect.x;
-  *aY = screenRect.y;
-  *aWidth = screenRect.width;
-  *aHeight = screenRect.height;
+  double scaleFactor = getScaleFactor(acc);
+
+  *aX = screenRect.x / scaleFactor;
+  *aY = screenRect.y / scaleFactor;
+  *aWidth = screenRect.width / scaleFactor;
+  *aHeight = screenRect.height / scaleFactor;
 }
 
 void componentInterfaceInitCB(AtkComponentIface* aIface) {