I have a listbox with DrawMode = OwnerDraw.
I have noticed a flicker that is the result of the listbox background being drawn before my custom DrawItem is called. Thus even if I use a single e.Graphics.FillRectangle call it would still cause flicker.
Is there anything that can be done to prevent this flicker, perhaps preventing the listbox backgroundcolor from being drawn?
Related
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.
I'm wanting to have a tooltip for disabled TabItems in a TabControl. The standard way of putting tooltips onto disabled controls in Silverlight is by wrapping the control in a dummy element that has the tooltip, but I can't get at the TabItem like that. The TabItems' host control is a TabPanel, which doesn't seem to expose any useful properties.
Any ideas?
I had the same problem with putting a Toolip on a disabled menu item, i solved it by changing the VisualState of my menu item to Disabled and then disabling the MouseButton events.
VisualStateManager.GoToState(tabitem, "Disabled", true);
You'll have to be careful with other events though, because the VisualState will change according to different events. It's not a perfect solution, but it will work for certain scenarios.
Hope this helps
My current workaround for my own problem:
I've got a TabControl Behavior that finds the "TabPanelTop" template part (or left, right, or bottom depending on TabStripPlacement), along with the "TemplateTop". I add a Canvas into the TemplateTop (which is a Grid), and fill it with Transparent Rectangles whose positions (using TransformToVisual) and sizes are calculated (and updated) to be the same as the TabItems, which are the children of the TabPanelTop.
The visibility of the Rectangles is bound to the inverse of TabItem IsEnabled, and the ToolTipService.ToolTip is bound to the ToolTipService.ToolTip on the TabItem.
It's a bit scary but it works and is easy to use.
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'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
I have WPF ListBox that shows a lot of data. I need smooth scrolling, so I've set ListBox.ScrollViewer.CanContentScroll to False that disables virtualization. Now when I open the tab where this ListBox is placed, I see nothing for few seconds because ListBox is loading/creating items/rendering. I also have a control that shows some animation that indicates that application is running and user should wait a bit.
How can I show this control while ListBox is not available?
Add a Grid in the location of your list box and place inside it your ListBox and your animation control. This way they are placed in the same location. The animation control should be on the top of the z-order and so displayed. Once the ListBox has finished loading you would then hide the animation control and so the ListBox would show instead. Any time you need to perform another long operation you set the animation control to visible again.
Clean shutdown in Silverlight and WPF applications
Check how the author of this application did it via code maybe it can help you though it is different scenario.