CaptureScreen error

[Divaite-zz]

Hi.

First of all, thanks for the great library, works perfectly.
Unfortunately sometimes this error occurs:

"The parameter value must be greater than zero.\r\nParameter name: pixelWidth"
   at System.Windows.Media.Imaging.RenderTargetBitmap..ctor(Int32 pixelWidth, Int32 pixelHeight, Double dpiX, Double dpiY, PixelFormat pixelFormat)
   at GongSolutions.Wpf.DragDrop.DragDrop.CaptureScreen(Visual target, FlowDirection flowDirection, Double dpiX, Double dpiY) in d:\projects\git\gong-wpf-dragdrop\GongSolutions.Wpf.DragDrop\DragDrop.cs:line 502
   at GongSolutions.Wpf.DragDrop.DragDrop.CreateDragAdorner() in d:\projects\git\gong-wpf-dragdrop\GongSolutions.Wpf.DragDrop\DragDrop.cs:line 432
   at GongSolutions.Wpf.DragDrop.DragDrop.DropTarget_PreviewDragOver(Object sender, DragEventArgs e) in d:\projects\git\gong-wpf-dragdrop\GongSolutions.Wpf.DragDrop\DragDrop.cs:line 857
   at GongSolutions.Wpf.DragDrop.DragDrop.DropTarget_PreviewDragEnter(Object sender, DragEventArgs e) in d:\projects\git\gong-wpf-dragdrop\GongSolutions.Wpf.DragDrop\DragDrop.cs:line 825
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   at System.Windows.OleDropTarget.RaiseDragEvent(RoutedEvent dragEvent, Int32 dragDropKeyStates, Int32& effects, DependencyObject target, Point targetPoint)
   at System.Windows.OleDropTarget.MS.Win32.UnsafeNativeMethods.IOleDropTarget.OleDragEnter(Object data, Int32 dragDropKeyStates, Int64 point, Int32& effects)

After such error UI is unresponsive until user minimizes and restores application.

[punker76]

@Divaite With which version is this happened?

[Divaite-zz]

Latest stable 1.0.0

[punker76]

@Divaite This is just curious, the CaptureScreen method is converting the bounds of VisualTreeHelper.GetDescendantBounds(target) with DpiHelper.LogicalRectToDevice(bounds) and it seems that it gives us negative size. So what is your DPI OS setting? Or can you explain what do you try to drag (which element)? Thx.

[Divaite-zz]

@punker76, OS Windows 7, DPI 96 (100%)
We have a TreeView, in each node representing folder there is a ListBox, each node representing an item is a Grid with Image and TextBlock controls inside.
We use DragDrop with this configuration on ListBox and TreeView:

dd:DragDrop.IsDragSource="True"
dd:DragDrop.IsDropTarget="True"
dd:DragDrop.DropHandler="{Binding}"
dd:DragDrop.UseDefaultDragAdorner="True" 

It's not easy to catch, but happens when user manipulates with lowest element (Grid with Image and TextBlock).

[punker76]

@Divaite I'll make this more robust against negative values, but it's curious to get these negative values from your elements...

[punker76]

@Divaite I handle now negative values to prevent this exception (available in v1.1.0). Nevertheless, it would be helpful if you can create a short repro app to demonstrate the issue.