I've got a Silverlight 4 custom control that basically is several Canvas elements wrapped inside a ScrollViewer. The user can set a property to determine whether to scroll or zoom when using their mouses wheel. In the custom control's MouseWheel event, I check to see if they want to scroll or zoom. If zooming, I determine the delta and modify the custom control's zoom level (which then handles the zooming code for me).
The problem is that zooming won't start until the ScrollViewer's current position of the vertical scrollbar is at the top or bottom of the scrollbar. Once their, then the zooming works perfectly.
Does anyone have any suggestions on how I can prevent scrolling completely so that I only zoom (when the user wants to zoom, that is)?
Thanks!
Looks like one of my child elements was hogging the MouseWheel event. I traced this by adding Debug.WriteLine statements to each of the child element's MouseWheel event as well as the parent control's MouseWheel event.
So, I can't blame SL4. Just myself. :)
Related
In a Universal Windows App, I have a ScrollViewer, and inside it, I have a canvas.
The canvas is trying to handle its own TouchMove event but it's never fireed unless the parent ScrollViewer is disabled.
How can I make the ScrollViewer not stop the touch events from being passed to its children?
You can only set it to cover vertical, horizontal or both of the direction of the gesture by set the ManipulationMode. Or else you have to handle all the scrolling manually.
The UI for my WinForms app is centered around a DevExpress XtraGrid.
Usually, the first thing a user wants to do is scroll the grid, so the normal instinct is to move the mouse wheel.
But currently, you have to click a row in the grid first, which is annoying.
I tried to use BaseView.Focus method, but this did not work - still had to click a row before the wheel would work.
Any suggestions on how to accomplish this?
By default, the Grid is scrolled by mouse wheel only if the mouse pointer is above the grid. So, an attempt to focus it does not help. To change this behavior, you should change the static SmartMouseWheelProcessing property in the form's constructor as shown below:
DevExpress.XtraEditors.Drawing.MouseWheelHelper.SmartMouseWheelProcessing = false;
I'm working with a DataGrid in Silverlight.
If I have enough items so that the vertical scroll bar is visible for all sizes of the window, and I re-size the window a few times, the vertical scroll gets out of sync. The thumb gets to small as if the control thinks that there are more items then it is. When I drag the thumb towards the bottom or the top, the content starts to jump. It happens all the time, very frustrating. The DataGridis laying within a DockPanel that is re-sized according how large the window is (no specific size that is)
Anyone have any ideas?
I have some similar issues. Most of them could be resolved by calling UpdateLayout on the datagrid.
I too have a datagrid in a dockpanel. When I scroll down and select the bottom record and then reload my datagrid the horizontal scrollbar seems to cover the last record. And the vertical scrollbar appears to be as far down as possible and cannot be dragged down further.
If i use the scrollwheel on the mouse the last record can be brought into view.
This only occurs when i show my application in a maximized window.
Have you gotten anywhere with this?
I tried similar approach with the derived DataGrid.
The difference is that the OnApplyTemplate would only get the instance of VerticalScrollbar and the separate public method was introduced to invoke the UpdateLayout() on the scroll bar. Such method is to be called explicitly in the situations that may bring the scroll bar size out of sync (DataGridcontent resizing, etc.)
Sometimes the UpdateLayout() alone was not enough so I added flipping the scroll bar visibility - that worked better though still not in 100% of situations
This is a bug in the datagrid. You can solve this by inheriting from the datagrid and on the OnApplyTemplate method you search for the scrollbars and manually update their layout:
public override void OnApplyTemplate()
{
verticalScrollBar = this.GetTemplateChild("VerticalScrollbar") as ScrollBar;
if (verticalScrollBar != null)
{
verticalScrollBar.UpdateLayout();
}
}
If this still doesn't work then try calling the OnApplyTemplate method manuallty in code.
In data grid Style remove the vertical scroll bar and follow the Below Steps
Step1: Sorround the DataGridRowsPresenter with Scroll Viewer
Step2: Make HorizantalScrollBarVisibility to Disable
Step3: VerticalScrollBarVisibility to Auto
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?