I have UserControl, which contains Canvas (in Grid).
When I just clicked on canvas event PreviewMouseLeftButtonDown or MouseLeftButtonDown works perfectly, but when I set canvas.Background = new ImageBrush(imgs); and try to click on canvas, events doesn't raising. I tried to make same events for grid (canvas parent), but result was the same.
UPD1: canvas has children - rectangle (from System.Windows.Shapes) around cursor, maybe it somehow affect on events.
In wpf there are two possible scenarios where hit testing (clicking with mouse somewhere) is not working. These two are ment to be that way and it is by design. I am talking about when your Background is NULL or when you have the property IsHitTestVisible set to false.
In any other case hit testing/clicking will work.
I assume your background is null somehow. Maybe imgs throws error which will be catched in an empty try/catch block internally at render time.
Tell us is the background property of your canvas null?
There is a nice tool called Snoop which allows you to snoop an wpf app and change properties at runtime. Use that tool to change the background and tell us about the results.
EDIT:
First of all the default value of Canvas Background is null therefore by default you can click as often you wish on Canvas and nothing will happen.
As soon you change the Background to Yellow it clicking will work and your handler will be called.
Related
I have created a custom popup to decorate my buttons with animated tooltips. I track Button.MouseEnter for the button to decide when to display the popup. I use Button.MouseLeave to determine when to hide the popup.
Problem is Button.MouseLeave is fired prematurely if the popup moves over the mouse cursor (its appearance is animated) despite the fact that I have set IsHitTestVisible = false for the popup and all its visual children.
Is this the way WPF is designed to work? I need MouseLeave to only fire when the cursor moves away from the button itself and not be influenced by the popup.
Thanks
I believe that the Popup control is actually contained within a window, which is why the popup can extend beyond the window bounds in some cases. (It's also why popup transparency is not supported in Silverlight.)
I believe that while the popup control is no longer processing "hits", the container window is, which is why you are losing your button's mouse focus.
I've not tested this, but you might try creating a template for your button and actually declaring the popup as part of the button (rather than below it). This may cause WPF to view the popup control as part of the button and eliminate the problem of losing mouse focus. This works in other scenarios, but I'm not 100% sure how this will work with a Popup.
EDIT: As a side note, the deault WPF tooltip allows you to override the template. I'm not sure what your goals are, but you may find it easier to change the appearance and behavior of the default tooltip than to try to roll your own, as a lot of these sorts of problems have already been solved in the default Tooltip.
I am working out of the 3.5 .Net Framework. I have a textbox next to a scroll bar in a stackpanel. I would like it to be that when the user clicks the "up" arrow of the scrollbar, the contents of the textbox are incremented, and decremented when the click the "down" arrow of the scrollbar. The problem is I am not sure which event I need to fire to do this. I've tried MouseDown, MouseUp, PreviewMouseDown (which fires but I don't know how to differentiate whether the up or down arrow was clicked), PreviewMouseUp (same problem), StylusUp, StylusDown, PreviewStylusDown, PreviewStylusUp, StylusButtonDown, StylusButtonUp, and the previews for that also. As I am debugging, I am using messageboxes to let me know I've entered that event, but none have shown (expcept for the PreviewMouseDown). Being fairly new to WPF, I am basically baffled.
Does anyone know which event I should be looking for? Thanks.
You should not abuse the ScrollBar for this but create a new control with two buttons.
In a Silverlight 2 app, I am using Rectangles on a Canvas to draw a representation of data. I would like to have mouse clicks on the Rectangles be passed on to the control that owns the Canvas. I would also like to be able to show a tooltip with a summary of the data when the mouse is over a Rectangle.
So far I've only been able to achieve one item or the other. If I make the Rectangles have their IsHitTestVisible property = false, the tooltips don't work, but the owning control will receive the mouse clicks. If I set it to true, then tooltips do work, but the clicks don't get passed on.
Is there a way to have a Silverlight item be IsHitTestvisible = true, and pass on the mouse clicks?
I'm not sure why the tooltip and mouse left down / up is being linked, In SL3 the mouse left down / up will bubble unless it gets marked as handled by a routine / object. It sounds more like the event is not bubbling thru the parent controls. AFAIK SL2 does the same. (could be wrong on that one)
What is the visual tree from the outer parent to the inner rectangle?
Have Canvas pass a reference of itself to Rectangles when they're constructed. When a rectangle is clicked, call a method on Canvas.
Edit:
If Rectangles and Canvas are library classes, subclass them to add functionality you need.
I'm writing an XBAP with a complex Popup (Canvas Z-index of 99 with a grid on it...) that I would like to "attach" to the button that opens it and follow that button around wherever it goes on the screen. For example, if the button is in a ListBox or an XamDataGrid I would like the popup to follow the button as it scrolls through. If it is beneath an Expander I want it to stay attached to the button when the expander forces it to move, etc.
Any Ideas?
When using a Popup, neither PlacementTarget nor CustomPopupPlacementCallback is used after the popup has originally appeared. So any use of these properties will not allow the popup to track the button as it moves.
Several ways occur to me of achieving what you desire:
Attach a custom Adorner to the button and put the popup inside it. Disadvantage: Popup is not connected to Button or surrounding elements, so it won't inherit properties & DataContext from them.
Attach a custom Adorner to the button. This adorner will get measure and arrange calls when the button moves relative to the AdornerLayer, allowing you to manually update the Popup position. As long as your AdornerDecorator doesn't move relative to your Window (eg if it is the direct child of the Window), you can easily detect the AdornerLayer being moved by monitoring changes to Window size. Disadvantage: Complex to code & get right.
Don't use a Popup at all. Instead wrap the button in a <Grid> alongside a <Canvas> with zero width and height and the desired position. Inside the <Canvas> add the UserControl for the popup with an appropriate ZIndex. It will extend past the edge f the Canvas, which is just fine in WPF. Instead of using a Popup control just control the visibility of the UserControl. Disadvantage: Will not really be totally on top of all other objects, can't extend off edge of window (may not be an issue for XBAP, though).
I'm not sure if it will auto-update for you or not, but the PlacementTarget property allows you to specify a control to position the popup relative to. If that doesn't work, then maybe CustomPopupPlacementCallback will do the trick?
When the WPF ComboBox is clicked and in-focus, the only interaction that occurs after that can be with the ComboBox. If anything else is interacted with, including the window functions (minimize, restore, close, resize) and any control in the window, the action is ignored and the ComboBox loses focus.
In addition, MouseEnter and MouseLeave on the window buttons are still active, but when MouseEnter on the window border(?) occurs, the mouse pointer does not change to the resize pointer. This behavior makes sense because of the ComboBox's use of the popup control. The popup control exists independently of the main visual tree and if i.e. the window moves or gets resized, the popup remains fixed floating above the main window.
I have tried using Reflector, to see what the ComboBox is doing, but I have not been able to find what I am looking for. Basically, I do not know if this behavior is coming from the window, the ComboBox, or if it has something to do with the popup. How can I solve this problem?
You're right on in your description there, the popup keeps all action focus until it itself loses focus. If you're trying to change the functionality of the ComboBox you may want to look at creating your own ControlTemplate that behaves differently and does not keep the default action of the popup control.
Hope this helps, not entirely sure what you're trying to do.
I know this question is old, but for anyone coming here looking for the answer, it is to use Mouse.Capture.
The ComboBox sets Mouse.Capture(comboBox, CaptureMode.SubTree) in OnIsDropDownOpenChanged. This ensures that all mouse events are captured by the ComboBox. When the Popup is closed Mouse.Capture(null) releases the mouse capture.