Windows: Output resulting DPI awareness in debug and warning output.

Fix the signature of QWindowsShcoreDLL::GetProcessDpiAwareness and output the
value in the warning about failures of SetProcessDpiAwareness and in debug
output. Failures occur when Qt is embedded into another application, for
example Active Qt servers.

Task-number: QTBUG-41186
Task-number: QTBUG-50206
Change-Id: I3fd6cba26826ee8bbfa0a34f129deb64797c947f
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>

1 files changed, 17 insertions, 2 deletions

diff --git a/src/plugins/platforms/windows/qwindowscontext.cpp b/src/plugins/platforms/windows/qwindowscontext.cpp
index f2f6402889..4934b6c6e4 100644
--- a/src/plugins/platforms/windows/qwindowscontext.cpp
+++ b/src/plugins/platforms/windows/qwindowscontext.cpp
@@ -405,14 +405,29 @@ void QWindowsContext::setTabletAbsoluteRange(int a)
 #endif
 }
 
+int QWindowsContext::processDpiAwareness()
+{
+#ifndef Q_OS_WINCE
+    int result;
+    if (QWindowsContext::shcoredll.getProcessDpiAwareness
+        && SUCCEEDED(QWindowsContext::shcoredll.getProcessDpiAwareness(NULL, &result))) {
+        return result;
+    }
+#endif // !Q_OS_WINCE
+    return -1;
+}
+
 void QWindowsContext::setProcessDpiAwareness(QtWindows::ProcessDpiAwareness dpiAwareness)
 {
 #ifndef Q_OS_WINCE
     qCDebug(lcQpaWindows) << __FUNCTION__ << dpiAwareness;
     if (QWindowsContext::shcoredll.isValid()) {
         const HRESULT hr = QWindowsContext::shcoredll.setProcessDpiAwareness(dpiAwareness);
-        if (FAILED(hr))
-            qWarning() << "SetProcessDpiAwareness failed:" << QWindowsContext::comErrorString(hr);
+        if (FAILED(hr)) {
+            qWarning().noquote().nospace() << "SetProcessDpiAwareness("
+                << dpiAwareness << ") failed: " << QWindowsContext::comErrorString(hr)
+                << ", using " << QWindowsContext::processDpiAwareness();
+        }
     } else {
         if (dpiAwareness != QtWindows::ProcessDpiUnaware && QWindowsContext::user32dll.setProcessDPIAware) {
             if (!QWindowsContext::user32dll.setProcessDPIAware())