Windows QPA: Fix window frame calculation in multi-monitor setups

When introducing EnableNonClientDpiScaling() for QTBUG-53255, the window
frame calculation was not adapted. That is, window frames were calculated
from the style for the primary screen only, causing

- minimum size constraints not being calculated correctly for applications
  on secondary screens when populating the MINMAXINFO structure.
- warnings about not being able to apply a geometry when moving fixed
  size windows across screens.

The calculation of the frames for propagating size hints is also no longer
required after 3035400f36731c400adb9204b94e9afe346a71b7, which retrieves
them from the WM_NCCALCSIZE message; QWindowsWindow::fullFrameMargins() can
be used instead.

For newly created windows, use the newly added AdjustWindowRectExForDpi()
function to calculate the initial frame size.

Change QWindowsGeometryHint from a class to a collection of static functions
and add overloads to calculate the frame.

In checkForScreenChanged(), update the margins until WM_NCCALCSIZE is
received.

Task-number: QTBUG-67777
Task-number: QTBUG-65580
Task-number: QTBUG-53255
Change-Id: Iff2d382b2b316adec6c1a0622ae8015dba6de371
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>
Reviewed-by: Andre de la Rocha <andre.rocha@qt.io>

1 files changed, 3 insertions, 0 deletions

diff --git a/src/plugins/platforms/windows/qwindowsintegration.cpp b/src/plugins/platforms/windows/qwindowsintegration.cpp
index 2c90b0484e..5c1fa00088 100644
--- a/src/plugins/platforms/windows/qwindowsintegration.cpp
+++ b/src/plugins/platforms/windows/qwindowsintegration.cpp
@@ -353,6 +353,9 @@ QPlatformWindow *QWindowsIntegration::createPlatformWindow(QWindow *window) cons
     QWindowsWindow *result = createPlatformWindowHelper(window, obtained);
     Q_ASSERT(result);
 
+    if (window->isTopLevel() && !QWindowsContext::shouldHaveNonClientDpiScaling(window))
+        result->setFlag(QWindowsWindow::DisableNonClientScaling);
+
     if (QWindowsMenuBar *menuBarToBeInstalled = QWindowsMenuBar::menuBarOf(window))
         menuBarToBeInstalled->install(result);