Implement heightForWidth().

Add a virtual function QWindowPrivate::closestAcceptableGeometry()
which is called from the platform plugin.

Task-number: QTBUG-36220
Task-number: QTBUG-36318
Change-Id: I2b3d205e2c75f1d4dd2ba1d333b0d89bc0fcf13a
Reviewed-by: Jan Arve Sæther <jan-arve.saether@theqtcompany.com>

4 files changed, 46 insertions, 1 deletions

diff --git a/src/plugins/platforms/windows/qtwindowsglobal.h b/src/plugins/platforms/windows/qtwindowsglobal.h
index 99c97d156f..90e6d6ab9d 100644
--- a/src/plugins/platforms/windows/qtwindowsglobal.h
+++ b/src/plugins/platforms/windows/qtwindowsglobal.h
@@ -72,7 +72,8 @@ enum WindowsEventType // Simplify event types
     ShowEventOnParentRestoring = WindowEventFlag + 20,
     HideEvent = WindowEventFlag + 8,
     DestroyEvent = WindowEventFlag + 9,
-    MoveEvent = WindowEventFlag + 10,
+    GeometryChangingEvent = WindowEventFlag + 10,
+    MoveEvent = WindowEventFlag + 11,
     ResizeEvent = WindowEventFlag + 12,
     QuerySizeHints = WindowEventFlag + 15,
     CalculateSize = WindowEventFlag + 16,
@@ -146,6 +147,10 @@ inline QtWindows::WindowsEventType windowsEventType(UINT message, WPARAM wParamI
     case WM_MOUSEWHEEL:
     case WM_MOUSEHWHEEL:
         return QtWindows::MouseWheelEvent;
+#ifndef Q_OS_WINCE
+    case WM_WINDOWPOSCHANGING:
+        return QtWindows::GeometryChangingEvent;
+#endif
     case WM_MOVE:
         return QtWindows::MoveEvent;
     case WM_SHOWWINDOW:
diff --git a/src/plugins/platforms/windows/qwindowscontext.cpp b/src/plugins/platforms/windows/qwindowscontext.cpp
index 22a4dbb09f..4f1a1a375f 100644
--- a/src/plugins/platforms/windows/qwindowscontext.cpp
+++ b/src/plugins/platforms/windows/qwindowscontext.cpp
@@ -995,6 +995,8 @@ bool QWindowsContext::windowsProc(HWND hwnd, UINT message,
         return QWindowsGeometryHint::handleCalculateSize(platformWindow->customMargins(), msg, result);
     case QtWindows::NonClientHitTest:
         return platformWindow->handleNonClientHitTest(QPoint(msg.pt.x, msg.pt.y), result);
+    case QtWindows::GeometryChangingEvent:
+        return platformWindow->QWindowsWindow::handleGeometryChanging(&msg);
 #endif // !Q_OS_WINCE
     case QtWindows::ExposeEvent:
         return platformWindow->handleWmPaint(hwnd, message, wParam, lParam);
diff --git a/src/plugins/platforms/windows/qwindowswindow.cpp b/src/plugins/platforms/windows/qwindowswindow.cpp
index 8a80729354..0b4bb9b09d 100644
--- a/src/plugins/platforms/windows/qwindowswindow.cpp
+++ b/src/plugins/platforms/windows/qwindowswindow.cpp
@@ -1783,6 +1783,43 @@ void QWindowsWindow::propagateSizeHints()
     qCDebug(lcQpaWindows) << __FUNCTION__ << this << window();
 }
 
+bool QWindowsWindow::handleGeometryChanging(MSG *message) const
+{
+#ifndef Q_OS_WINCE
+    QWindow *qWin = window();
+    if (!qWin->isTopLevel())
+        return false;
+    WINDOWPOS *windowPos = reinterpret_cast<WINDOWPOS *>(message->lParam);
+    if ((windowPos->flags & (SWP_NOCOPYBITS | SWP_NOSIZE)))
+        return false;
+    const QMargins marginsDp = frameMarginsDp();
+    const QRect suggestedFrameGeometryDp(windowPos->x, windowPos->y,
+                                         windowPos->cx, windowPos->cy);
+    const qreal factor = QWindowsScaling::factor();
+    const QRect suggestedGeometryDp = suggestedFrameGeometryDp - marginsDp;
+    const QRectF suggestedGeometry = QRectF(QPointF(suggestedGeometryDp.topLeft()) / factor,
+                                            QSizeF(suggestedGeometryDp.size()) / factor);
+    const QRectF correctedGeometryF =
+        qt_window_private(qWin)->closestAcceptableGeometry(suggestedGeometry);
+    if (!correctedGeometryF.isValid())
+        return false;
+    const QRect correctedFrameGeometryDp
+        = QRectF(correctedGeometryF.topLeft() * factor,
+                 correctedGeometryF.size() * factor).toRect()
+          + marginsDp;
+    if (correctedFrameGeometryDp == suggestedFrameGeometryDp)
+        return false;
+    windowPos->x = correctedFrameGeometryDp.left();
+    windowPos->y = correctedFrameGeometryDp.top();
+    windowPos->cx = correctedFrameGeometryDp.width();
+    windowPos->cy = correctedFrameGeometryDp.height();
+    return true;
+#else // !Q_OS_WINCE
+    Q_UNUSED(message)
+    return false;
+#endif
+}
+
 QMargins QWindowsWindow::frameMarginsDp() const
 {
     // Frames are invalidated by style changes (window state, flags).
diff --git a/src/plugins/platforms/windows/qwindowswindow.h b/src/plugins/platforms/windows/qwindowswindow.h
index edba992b19..a63a9f56e3 100644
--- a/src/plugins/platforms/windows/qwindowswindow.h
+++ b/src/plugins/platforms/windows/qwindowswindow.h
@@ -183,6 +183,7 @@ public:
     void windowEvent(QEvent *event);
 
     void propagateSizeHints() Q_DECL_OVERRIDE;
+    bool handleGeometryChanging(MSG *message) const;
     QMargins frameMarginsDp() const;
     QMargins frameMargins() const Q_DECL_OVERRIDE { return frameMarginsDp() / QWindowsScaling::factor(); }