within WPF I have created a ListView which displays a list of messages in chronological order using a custom ItemsPanel class which uses the time of the messages to correct space them apart when laying out the items;
Is there an easy way to go one step further and add 'other drawing items', for example a timeline (line, ticks and text), to the background of the ListView which scrolls with it? What's the best approach?
Thanks for your comments, but my solution was to add an ItemsControl which binds to a Timeline collection of integers (one every 100ms) that's sits on top of the ListView (and scrolls with it) which simply has two lines it the ItemTemplate to get the following result:
ListView with added timeline markings
Related
I'm having a problem with a TreeView in WPF C#.
I have a TreeView with two TreeViewItems defined in XAML.
On the second TreeViewItem, I have a list of items defined by a binding.
When the list is too long, a vertical scrollbar appears and allows the entire TreeView to scroll.
But the two TreeViewItems must stay at the same place, so I'd like the content of the second to scroll instead, rather than the entire TreeView.
Left : what I get, and the two first items are scrolled out; Right what I'd like, with the two first items staying at the same spot. (The scrollbar is the red zone).
I look forward to hearing from you guys, and thanks in advance,
Raekh.
EDIT :
Found a solution : I removed the two treeviewitems and used a treeview with a item source obtained by binding, so the treeview starts after the treeviewitems and is scrolled properly.
I recently wrote a routine that displayed a grid of images from files in a folder. I used a vertically-oriented ListBox where each row in the ListBox was a horizontally-oriented StackPanel of the images. I just had to walk the folder tree and populate the StackPanel. It was simple, quick and easy to implement.
Now I have a new requirement. I'll be receiving the images one-at-a-time from a piece of factory equipment that will be sending one every few seconds and I need to display it as I get it. I still need to display these in a grid but the images start from the lower left and proceed to the right until a row is filled up, then we start a new row directly above it. We WILL know at the start the final dimensions, but it may be more than we can fit on a screen so scrolling will have to be enabled.
What are the right controls to use for this in WPF? Is there a way to reuse my ListBox/StackPanel scheme or are there more appropriate controls for this? Remember, the images must be displayed as I get them - I can't fill up a whole StackPanel and then do a
listBoxImages.Items.Add(myStackPanel)
... or can I - can I add an empty StackPanel to a parent and then populate one image at a time afterwards? What's the right way to go about this?
Based on the fact the number of images is known at the start of the routine, I would create a view model with a collection of collections.
The first is an observable collection with elements for each row, inside the element is another collection for each column. This can be bound to an items control where the content template has a second items control with horizontal orientation.
Then, as your images arrive, you start to fill the last element first with your image references and work back up. That should create the desired effect. Not sure how that works with scrolling as you effectively want the last element to be in view first, so scrolled to the end.
Another option, using a single collection is to bind to an items control with a uniform grid panel template. This can be wired up with a DataTemplateSelector which when the data is null, displays an empty template, otherwise shows an image box. This will allow you to again add elements to your collection in any order and it mirror on the UI.
An example of the data template selector can be found here. Or search SO.
I'm building a WPF application to visualize a load of items (a few thousand). For this i'm using an ItemsControl of which the ItemsSource is set to a BindingList.
I've noticed that it takes some time to initialize the screen... The main bottleneck is the creation of TextBlock elements (the data template of the items contains 4 TextBlock elements). Once the screen is initialized (when all WPF elements are created), rendering is quite OK.
I've implemented zooming and panning, so i was thinking about making the appearance of the items dependent on the zoom level and the center point (a bit like Google Maps: data is only visualized for regions that are into the view).
How can this be done? Is there any way in WPF to ask the item or item container if it is currently clipped?
You can make your list virtualized. This way only the items that are visible will have UI controls created for them.
Check the ListView documentation, or this link may help:
http://www.codeproject.com/KB/WPF/WpfDataVirtualization.aspx
Jogy
I have a ListBox that contains a number of User items that are DataTemplated to appear as UserControls in the ListBox. Each UserControl can be expanded in size. To start with, the ListBox is big enough to display them all in their unexpanded state. The problem that I have is that when a number of these UserControls are expanded together, they extend out of the ListBox's visible area. The ListBox does not recognise this fact and no ScrollBars appear, even when they are set to Visible.
I am using DoubleAnimations to alter the UserControl heights when the user clicks on a button in each one. Is there something that I have to do, or some setting on the ListBox that must be set to get it to register the size changes of the UserControls that represent its items and display ScrollBars when needed?
Edit>>>
I have tracked down the problem to a custom WrapPanel that I am using in the ListBox.ItemsPanel. When I remove it, or replace it with a standard WrapPanel, ScrollBars appear when required. I got the code for the Panel from a good article about creating custom WPF panels. Can anyone see what's missing from the code given in the article and why it might stop the ScrollBars from displaying?
I wonder whether ListBoxes normally do what you are expecting? You might try calling InvalidateMeasure/Layout on the ListBox if you know when the item sizes change, just to see?
I decided to write the custom WrapPanel code again completely and this time it worked correctly! When comparing the new version with the previous version, I could see that a + was missing from a += in a measuring calculation and so the Panel thought that the items were much smaller than they really were... hence no ScrollBars.
So, if you have this problem, check your measuring code carefully.
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).