WPF Layout Windows Form Elements Inside ScrollViewer

Question

when placing the ScrollViewer inside the window (without saving all window sizes) inside the ScrollViewer there is (with other materials) WinFormsHost and a control inside (say, DateTimePicker). when scrolling, the internal control of winforms remains visible when there is no more reason (it is outside the scroll area), so it “floats” over what's outside of the ScrollViewer

any solutions for this?

Answer 1

According to this msdn link

WindowsFormsHost elements are always drawn on top of other WPF elements, and they are not affected by z-order

I do not think this is a simple solution. You might want to think about window shape management handling scrolling, rather than using WPF ScrollViewer.

Answer 2

Yes, there is a solution. Use the following custom WindowsFormsHost class.

class WindowsFormsHostEx : WindowsFormsHost { private PresentationSource _presentationSource; public WindowsFormsHostEx() { PresentationSource.AddSourceChangedHandler(this, SourceChangedEventHandler); } protected override void OnWindowPositionChanged(Rect rcBoundingBox) { base.OnWindowPositionChanged(rcBoundingBox); ParentScrollViewer.ScrollChanged += ParentScrollViewer_ScrollChanged; ParentScrollViewer.SizeChanged += ParentScrollViewer_SizeChanged; ParentScrollViewer.Loaded += ParentScrollViewer_Loaded; if (Scrolling || Resizing) { if (ParentScrollViewer == null) return; GeneralTransform tr = RootVisual.TransformToDescendant(ParentScrollViewer); var scrollRect = new Rect(new Size(ParentScrollViewer.ViewportWidth, ParentScrollViewer.ViewportHeight)); var intersect = Rect.Intersect(scrollRect, tr.TransformBounds(rcBoundingBox)); if (!intersect.IsEmpty) { tr = ParentScrollViewer.TransformToDescendant(this); intersect = tr.TransformBounds(intersect); } else intersect = new Rect(); int x1 = (int)Math.Round(intersect.Left); int y1 = (int)Math.Round(intersect.Top); int x2 = (int)Math.Round(intersect.Right); int y2 = (int)Math.Round(intersect.Bottom); SetRegion(x1, y1, x2, y2); this.Scrolling = false; this.Resizing = false; } } private void ParentScrollViewer_Loaded(object sender, RoutedEventArgs e) { this.Resizing = true; } private void ParentScrollViewer_SizeChanged(object sender, SizeChangedEventArgs e) { this.Resizing = true; } private void ParentScrollViewer_ScrollChanged(object sender, ScrollChangedEventArgs e) { if (e.VerticalChange != 0 || e.HorizontalChange != 0 || e.ExtentHeightChange != 0 || e.ExtentWidthChange != 0) Scrolling = true; } protected override void Dispose(bool disposing) { base.Dispose(disposing); if (disposing) PresentationSource.RemoveSourceChangedHandler(this, SourceChangedEventHandler); } private void SourceChangedEventHandler(Object sender, SourceChangedEventArgs e) { ParentScrollViewer = FindParentScrollViewer(); } private ScrollViewer FindParentScrollViewer() { DependencyObject vParent = this; ScrollViewer parentScroll = null; while (vParent != null) { parentScroll = vParent as ScrollViewer; if (parentScroll != null) break; vParent = LogicalTreeHelper.GetParent(vParent); } return parentScroll; } private void SetRegion(int x1, int y1, int x2, int y2) { SetWindowRgn(Handle, CreateRectRgn(x1, y1, x2, y2), true); } private Visual RootVisual { get { _presentationSource = PresentationSource.FromVisual(this); return _presentationSource.RootVisual; } } private ScrollViewer ParentScrollViewer { get; set; } private bool Scrolling { get; set; } private bool Resizing { get; set; } [DllImport("User32.dll", SetLastError = true)] static extern int SetWindowRgn(IntPtr hWnd, IntPtr hRgn, bool bRedraw); [DllImport("gdi32.dll")] static extern IntPtr CreateRectRgn(int nLeftRect, int nTopRect, int nRightRect, int nBottomRect); } 

Answer 3

Just add the ScrollViewer control property:

 VerticalScrollBarVisibility="Auto" 

and set the height to maximum height. It's all.