I am designing a code viewer using a virtualized ListView control to display code lines.
Now I want to create a highlight effect when the user clicks a link which takes them to a particular line. I want the target line to be highlighted.
The effect will be either an "underline" appearing (and disappearing) or a semi-transparent overlay (like a marker pen) appearing (and disappearing). The actual graphical effect itself is unimportant, that's not the problem.
What is the best approach to achieve this? I'm not quite sure where to start.
Some technical requirements might be that I need to:
find the right events to react to - or use databinding
obtain the absolute bounding rectangle of the virtualized target item (although when brought into view the item should be available)
absolutely position a canvas effect on top, fade in and fade out
...Ideally some state changes in a view model, a piece of XAML is animated via a triggered storyboard to appear (fade in) above the relevant ListViewItem and then animates away again (fade out). Of course before the fade in, the element must already be correctly positioned over the relevant ListViewItem...
I have worked on a search feature for a Listview where every ListViewItem had few textbocks. When the user types something in a search textbox, all the matches in the listview was supposed to get highlighted.
I created Run objects based on the search string (used Regex to find the match) and then set the Background to some color. Also, held the reference of the ListViewItem in the tag of the Run object which helped me to use call ScrollIntoView. Hope this will be of some help in your case.
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I have a WPF RichTextBox in my application that sits in Grid. It gets updated every second or two as it displays logs (though sometimes there are no logs for up to a minute depending on the load).
The grid is not always visible, as it sits in its own tab. If the user is on another tab, the logger is not visible.
My problem is that I want the RichTextBox to scroll to the end every time a new paragraph is added. It seemed simple as there is a 'ScrollToEnd' method on the RichTextBox control and so I call that method every time text is added to the control.
The problem is that that method only works if the control is visible, if the user is on another tab, the RichTextBox will not scroll to the end and it looks weird when you click on the tab with the logger and after a couple of seconds or longer it scrolls to the bottom when it should already be at the bottom.
Is there a way around this annoying "feature" of the control? I would like to ALWAYS have the RichTextBox be at the bottom unless the user is manually taking control of the scroll bar.
Thanks!
By default, the TabControl actually doesn't change its contents visibility, it removes them from the view completely when you change tabs and then "re-attachs" them when you navigate back to the previous tab.
That's why the Visibility change doesn't get fired. Instead, you should handle the Loaded event, which should get fired right before the view is re-rendered.
Is there a reason you cannot simply call ScrollToEnd in response to the text box becoming visible? That seems like the simplest approach. Did you try it and run into an issue?
Edit: If you are using a TabControl, each TabItem has an IsSelected property you can bind to from the ItemContainerStyle. You could probably scroll your text box in response to the tab becoming selected.
As a separate note: if you are planning to make a custom control for this, here are some things to consider.
I wrote an auto-scrolling version of a FlowDocumentScrollViewer. (I never needed a RichTextBox specifically, but they display similar content.) I can tell you that there are a lot of things to account for, such as knowing when and when not to auto-scroll based on what the user is currently doing.
For example:
If the user takes over the scrolling themselves via the scrollbar or mousewheel, you don't want the control to fight with them.
If they start selecting text, you don't want to scroll it away from them mid selection.
If they scroll to the bottom, you probably want it to start auto-scrolling again.
Also, determining what the user is doing to begin with can sometimes be a complex process on its own.
I'm making a custom dropdown button (since the one included in wpf requires too much hacking to style right). Now that i got the button bit out of the way i need to add the drop down part.
My first thought was to add a stackpanel and use that to contain the items but it gets cut off if it leaves the borders of the grid that the button is in. Next up was the popup primitive, it gets on top of everything nicely enough but position wise it just free floats and i haven't figured out how to make it follow the button it was spawned by. I also tried using contextmenu but that seems to have no positioning controls at all and just sits where the mouse made it..
Anyways wpf is a big package and I'm just getting into it, anybody know which direction i might find what I'm looking for?
Preferred approach normally is to use a Popup. You got two very important properties with a Popup
PlacementTarget and Placement
Setup a binding for PlacementTarget on the Popup to your custom Button and then use Placement to position the Popup accordingly w.r.t to the PlacementTarget(Button)
Placement accepts an enum of type PlacementMode which gives you quite a few options to position the Popup.
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 have a ListBox bound to a collection of custom objects. I have an ItemTemplate set up for displaying those items. Each item takes up a large rectangular area, so what I want to do is actually only display one item at a time. After ten seconds, I want to animate (maybe slide in/out or fade in/out) to the next item so that only that one is displayed and so on.
I can't get to grips with how to achieve this, can anyone help please?
Maybe a listbox isn't even the right approach?
If you are not dead set on using a listbox, you can get this effect using a TransitioningContentContol instead. How-to Video here (the control is in system.Windows.Controls.Layout.Toolkit). It is now part of the released toolkit (the video is old).
Part of the demo shows how to emulate exactly the behaviour you are after. You can add a slider to the side if you still want it to look a bit like a listbox (and change the selection in response to the slider value changes).
I have an ItemsControl with a number of elements, each one with its own ViewModel instance. Each item's ViewModel knows whether that item should be visible (currently each ViewModel has a Visibility property that the UI binds to). When my window first opens, some of these items are visible, others are collapsed. Later, some items' visibility might change in response to user interaction. The window sizes to its content, so the window resizes when items are shown or hidden. And the window is initially centered on the screen (which means everything has to be arranged properly right away, so the window knows its initial size and can center itself accordingly).
Now I want to add animations whenever an item is shown or hidden -- but I only want to animate if the item's visibility changes after the window is already shown. So if the window is already open, and the user does something that makes one of the ViewModels want to appear, it animates in; if the user does something to make one of the ViewModels disappear, it animates out. But when the window first opens, I want everything to start out rock-solid -- no lingering animations.
And I want the window to still set its initial size based on its initially-visible content, and I still want it to be initially centered onscreen. (Although actually, in this case, it would be acceptable if it centered itself as if all items were visible, if event ordering made it work out that way.)
I know a fair bit about WPF, but I admit I'm lost when it comes to triggers and storyboards. I haven't really done anything with WPF animations before, and I'm not sure where to begin.
I already tried using Reveal from the Bag of Tricks, but I had several problems with it, the biggest being that it doesn't have the "only use animations after the window is shown" behavior that I want -- my window would appear and the initially-visible elements would still be animating in. It also didn't play well with my layout (it was centering the elements horizontally, instead of stretching them to the ItemsControl's width), and a few other problems that might or might not be fixable.
I'm not too picky about whether I animate by stretching (e.g. by animating a LayoutTransform from SizeX=1 SizeY=0 to SizeX=1 SizeY=1, thus starting with squished text and expanding to normal size) or by just changing the Height (thus starting with only part of the content visible and revealing more as the animation progresses) -- I'm fine with either.
I'm open to writing my own Panel descendant (I've done it before) if that's the best way to solve this, and I can always steal code from Reveal and hack until I get it working -- but it seems like there should already be an easier way to do this, if I just knew what it was. I'm open to learning about triggers and storyboards, or whatever, if someone can point me in the right direction.