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, 1 deletions

diff --git a/src/plugins/platforms/windows/qwindowscontext.cpp b/src/plugins/platforms/windows/qwindowscontext.cpp
index 6c1f5c8f93..8d1ef9f34a 100644
--- a/src/plugins/platforms/windows/qwindowscontext.cpp
+++ b/src/plugins/platforms/windows/qwindowscontext.cpp
@@ -210,6 +210,7 @@ void QWindowsUser32DLL::init()
 
     if (QOperatingSystemVersion::current()
         >= QOperatingSystemVersion(QOperatingSystemVersion::Windows, 10, 0, 14393)) {
+        adjustWindowRectExForDpi = (AdjustWindowRectExForDpi)library.resolve("AdjustWindowRectExForDpi");
         enableNonClientDpiScaling = (EnableNonClientDpiScaling)library.resolve("EnableNonClientDpiScaling");
         getWindowDpiAwarenessContext = (GetWindowDpiAwarenessContext)library.resolve("GetWindowDpiAwarenessContext");
         getAwarenessFromDpiAwarenessContext = (GetAwarenessFromDpiAwarenessContext)library.resolve("GetAwarenessFromDpiAwarenessContext");
@@ -977,7 +978,7 @@ static inline bool resizeOnDpiChanged(const QWindow *w)
     return result;
 }
 
-static bool shouldHaveNonClientDpiScaling(const QWindow *window)
+bool QWindowsContext::shouldHaveNonClientDpiScaling(const QWindow *window)
 {
     return QOperatingSystemVersion::current() >= QOperatingSystemVersion::Windows10
         && window->isTopLevel()
@@ -1589,6 +1590,7 @@ extern "C" LRESULT QT_WIN_CALLBACK qWindowsWndProc(HWND hwnd, UINT message, WPAR
             marginsFromRects(ncCalcSizeFrame, rectFromNcCalcSize(message, wParam, lParam, 0));
         if (margins.left() >= 0) {
             if (platformWindow) {
+                qCDebug(lcQpaWindows) << __FUNCTION__ << "WM_NCCALCSIZE for" << hwnd << margins;
                 platformWindow->setFullFrameMargins(margins);
             } else {
                 const QSharedPointer<QWindowCreationContext> ctx = QWindowsContext::instance()->windowCreationContext();