Windows Accessibility: Recurse up to find a window.

Not all classes inheriting QAccessibleInterface implement
QAccessibleInterface::window(), so, go up the hierarchy to find
one that does.
The window is required to be able to determine the correct
scale factor for the screen when High DPI scaling is active.
Fixes multimonitor issues for QtWidgets.

Amends change d7a3b6145999d015997e26e12a7345f774b053f3.

Task-number: QTBUG-52943
Change-Id: I81733765faee4d296bd6ea046bc2cecb018eb28d
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@theqtcompany.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/src/plugins/platforms/windows/accessible/qwindowsmsaaaccessible.cpp b/src/plugins/platforms/windows/accessible/qwindowsmsaaaccessible.cpp
index 5ca83fa9f2..71c197a32c 100644
--- a/src/plugins/platforms/windows/accessible/qwindowsmsaaaccessible.cpp
+++ b/src/plugins/platforms/windows/accessible/qwindowsmsaaaccessible.cpp
@@ -470,6 +470,15 @@ HRESULT STDMETHODCALLTYPE QWindowsMsaaAccessible::Invoke(long dispIdMember,
     return hr;
 }
 
+static const QWindow *windowOf(const QAccessibleInterface *ai)
+{
+    for ( ; ai; ai = ai->parent()) {
+        if (const QWindow *window = ai->window())
+            return window;
+    }
+    return Q_NULLPTR;
+}
+
 /*
   IAccessible
 
@@ -498,7 +507,7 @@ HRESULT STDMETHODCALLTYPE QWindowsMsaaAccessible::accHitTest(long xLeft, long yT
     if (!accessible)
         return E_FAIL;
 
-    const QPoint pos = QHighDpi::fromNativeLocalPosition(QPoint(xLeft, yTop), accessible->window());
+    const QPoint pos = QHighDpi::fromNativeLocalPosition(QPoint(xLeft, yTop), windowOf(accessible));
     QAccessibleInterface *child = accessible->childAt(pos.x(), pos.y());
     if (child == 0) {
         // no child found, return this item if it contains the coordinates
@@ -541,7 +550,7 @@ HRESULT STDMETHODCALLTYPE QWindowsMsaaAccessible::accLocation(long *pxLeft, long
     QAccessibleInterface *acc = childPointer(accessible, varID);
     if (!acc || !acc->isValid())
         return E_FAIL;
-    const QRect rect = QHighDpi::toNativePixels(acc->rect(), accessible->window());
+    const QRect rect = QHighDpi::toNativePixels(acc->rect(), windowOf(accessible));
 
     *pxLeft = rect.x();
     *pyTop = rect.y();