All the documentation seems to suggest that setting the RenderTransform isn't supposed to impact arrange. But that's not exactly the behavior I'm seeing.
I have an odd requirement for a control layout. I wanted to leave as much of wpf's layout system as I could, so I created an element that inherits Decorator.I have an attached property that marks the elements I'm interested in.
During arrange, I call the base ArrangeOverride method, which layouts out the elements using the normal process. Next, I crawl through the controls with the attached attribute and, using the render transform, I re-position the controls where I want them.
All of this works fine, until I use an items control. Assigning the RenderTransform is causing the arrange to be invalidated and my arrange method is being called repeatedly. The documentation seems to suggest setting the RenderTransform has no impact on Arrange.
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I recently used a TranslateTransform in my WPF application to implement dragging a UserControl across the screen. There is a new bug in that after the first time you drag it somewhere else on the screen, when you click on the "Title bar" on the control, it jumps back to where it was originally displayed. It will still follow the mouse, but that initial jump is disconcerting.
I don't know what's going on, but this got me to wondering. Since WPF controls don't have a left or top property of their own, unless you put them into a Canvas, and those are attached properties anyway, just what properties are being modified by the TranslateTransform?
WPF's layout and render passes have intrinsic knowledge of transforms. By modifying the X and Y properties of the TranslateTransform, you're causing the layout/render pass to take those new values into consideration when positioning the associated FrameworkElement.
To put it another way: the TranslateTransform is not modifying other properties, but by modifying its properties you are triggering another layout/render pass and thus affecting the on-screen positioning of the associated FrameworkElement.
Read here for more information.
I am working on a WPF panel derivative with custom layout logic and sometimes it might be that component should be visible in two places, when following that layouting logic. Both instances of the same component will be partially cropped. Is it possible to do this - lay out a child component in two different places during the arrange pass?
I think that the panels behaviors are for arrange items in a view, and not for copy the items. I think this is not possible. If you copy a visual element then it will not be the same. If you want get this effect you may use a VisualBrush and paint some region with that, and set to the brush the control that you may want to copy. Using VisualBursh you will see a control copy, but you will not be able to modify it. The other way is using a custom control for making this effect. Other way could be using two different custom panels, both with the same items source (in the case that be the ItemsPanel for some collection).
Hope this answer helps to you...
I am making a search app in wp7. Every record's data is bound to a user control. I have introduced an infinite loading instead giving page numbers. So when the number of instances of the UserControl is increased in the screen the transition from one page to another page (like the preview or settings pages) or coming back from that page to the current page is getting slower. I cannot change the design (infinite loading concept).
What are the ways to handle this scenario? How about changing the visibility of the controls? And reference or suggestion will be highly appreciated.
Note I tagged WPF and Silverlight because the binding happens the same way in them, expected those to have dealt with scenarios like these.
EDIT Check this question, which is asked by me. Because of having UserControl's in the listbox the vertical offset is not being maintained. So I had no option other than using ItemsControl with scrollViewer around it. ItemsControl contains a list of 5 - 6 usercontrols which intern have itemsControls inside them, I thought virtualization may not happen in such cases. Am I right?
In WPF, this is done by Virtualization
Using Virtualization, only one copy (or a few copies) of the UserControl actually gets created, and switching to another user control actually just swaps out the DataContext that the control is bound to. It doesn't actually create a new UserControl.
For example, if you have an VirtualizingStackPanel with 100,000 items, and only 10 are visible at a time, it will only render about 14 items (extra items for a scroll buffer). When you scroll, the DataContext behind those 14 controls gets changed, but the actual controls themselves will never get replaced. In contrast, a regular StackPanel would actually render 100,000 items when it gets loaded, which would dramatically decrease the performance of your application.
This question about Virtualizing an ItemsControl can probably get you going in the right direction.
Take a look at this post, I believe the solution provided by Rico is what you are looking for. :)
So much reading, and so much about inheritance, I can't find any direct answers, so here goes.
If you have a base-class derived to do certain things, look or act a certain way, you can subclass it and get all the functionality of the parent class with only slightly modified differential. The same does not appear to be the same for working with WPF Themes... more specifically, the combobox control (similar issues with textbox, but that's obviously less complex).
By looking at the Control Template Examples, they discuss the entire structure of it, the borders, backgrounds, glyphs, actions, properties, etc.
If the ONLY thing I want to do with a combobox is to change the border of it to Red if there is an error in it, it appears, I have to basically redefine the entire thing and somehow put in my custom trigger setting / color to be implemented.
Somewhat similar is that of the textbox control and how its created. It has the named control when trying to nuts around with the background color... you can't just say... background = some static brush value.
What shortcuts are out there to only allow overriding these small elements without having to re-create the entire template control. I can just imagine what would go on with grids, tabbed controls, and others that could get extremely messed up if you miss one simple thing.
I also see that some controls are made up of OTHER Control.Templates, so how might I be able to attach to changing the property setting on just the single element of the control template... Such as the combobox has the control template for the Toggle Button. From that, it has a border via x:Name="Border" and I want to change THAT element within a derived style.
Thanks
I might not understand your question here. But from what i get is:
Yes you can't partially implement Templates, in fact i wouldn't know how this could be possible. But, if you want to change certain things, you can of course do that. You can create Styles, Templates, Brushes etc. as DependencyProperties and use TemplateBinding to bind to them, on the given child control.
Remember that WPF allows always to change the template on the fly. if we could partially change the template this would might hurt performance or could get messy and complicated. Still, you can do that using ContentControls and TemplateBinding or simply Triggers.
For my custom controls, which might contain multiple part sub controls, i usually add a style for them. For example, a custom ComboBox would contain a ToggleButtonStyle.
One thing that would be nice though, would be to add control template triggers without the need to reimplement the template.
I want to make a custom Panel to (amongst other things) insert spacing between all children. To inherit from Panel seemed very complicated and perhaps unnecessary. What I want is close to StackPanel so I figured I could inherit from StackPanel and modify the ArrangeOverride and MeasureOverride to get what I want.
I got the implementation of these from Reflector but immediately noticed that one property was not accessible at all from a inherited class, namely IsScrolling (and the field _scrollData). My question is if I can skip this or if there is any other way of implementing identical behaviour? Im not sure I will need scrolling for this custom panel but I may do some day and I dont want to paint myself into a corner...
if all you want is just that all elements inside a container would automatically contain margin definitions, you're much better off just creating a custom behavior that implements that functionality.
to create a custom behavior, just implement Behavior<Panel>. It's rather self-explanatory, but if you don't know how then ask.