I have a sidebar in an application I am writing that displays information about the application's state to the user. In certain cases, the user can hover over various elements in the sidebar to view more specific details. These details are shown to the user using a control that mimics the behavior of Bootstrap's Popover control. I accomplish this using an invisible Canvas overlay that spans the entire window, and the "Popover" itself is placed relatively on this Canvas using computed Canvas.Left and Canvas.Top properties.
Here's a (very simplified) look at the current XAML of my application:
<Window>
<Grid x:Name="container">
<.. a lot of various nested elements ..>
<StackPanel x:Name="sidepanel">
.. content of the sidepanel control ..
</StackPanel>
</.. a lot of various nested elements ..>
<Canvas x:Name="overlay">
.. content of the Popover control ..
</Canvas>
</Grid>
</Window>
This works great, except that I'd like to refactor this functionality into a single control. However, I'm not sure how to proceed - if the custom UserControl includes the Canvas overlay in its XAML definition, I'll be unable to position the sidepanel portion of the control in the same way as it currently is positioned within the application. However, the Canvas overlay can't be nested inside of the sidepanel, as it needs to span the entire window in order to operate properly.
Is there a way to define a single UserControl that can sit in different parts of the logical tree? Or is there a better way to accomplish this effect?
You can't split a single UserControl into different places in the logical tree, but you can inject other code into a Control and place it around the internal components it defines. This is the model used by HeaderedContentControl: two content properties, Content and Header, which are injected into two different ContentPresenters in the control's template. Hence things like Expander and TabItem with externally defined content in multiple locations around intrinsic parts of the controls. In the case of a UserControl you would be placing them in the main XAML instead of a template so the bindings are a little different but the principle is the same.
Define two Dependency properties of type object on your UserControl and then bind those into ContentPresenters placed in the exact spots where you have "a lot of various nested elements" in your sample. Then when you use the UserControl you can just define whatever other elements you want under the UserControl element inside like <MyUserControl.MyContentProperty1> tags and they'll get placed inside your UserControl content.
Related
Based on this mechanism, I created a dialog window of which I can dynamically assign the content by a <ContentPresenter Content="{Binding .}">
The content I want to assign is an user control with a corresponding ViewModel. This works as I can render the DialogView in other usercontrols
<DataTemplate DataType="{x:Type ViewModels:DialogViewModel}">
<Views:DialogView/>
</DataTemplate>
)
However, in the DialogWindow, DialogView cannot be rendered but instead, only the string representation of DialogViewModel is visible. What might be the reason why I cannot render the view of contentpresenter's content?
Any help is much appreciated!
Thanks in advance
Where did you define the Data Template? It sounds like you are creating them as Window resources, and did not include it in your DialogWindow. If you're defining them as Window resources, the Data Template definition needs to be included on every Window you want to render this way. If the ViewModel/View pair is global to the application, it is easier to just define it in the App.xaml where it will be picked up by any Window or UserControl throughout the application.
I have an application with minimizable controls. Minimized items are displayed in a horizontal stackpanel. On resize (shrink) of the application items could be chopped because of too little space.
To avoid this my idea was to move chopped elements to an expandable control (like this)
The application follows the MVVM pattern, the items in the panel are in an ItemsControl bound to the view model.
My implementation for now is to use a custom panel where the chopped elements are handed out with a property "SpillOverElements". I wanted to bind another control (panel, expander or popup) to this property. The problem is that I am not able to bind to the "SpillOverElements" property of the "SpillOverPanel" inside the ItemsControl.
<ItemsControl>
ItemTemplate="{StaticResource DummyContentDataTemplate}"
ItemsSource="{Binding DisplayElementsCollection}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<local:SpillOverPanel />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
So the question is how could I bind to "SpillOverElements" property of the "SpillOverPanel". Any other ideas how to implement this are welcome, too. I am not sure if my way is the right approach.
Thanks in advance for your help!
Forgive me, there's a lot of spitballing in the text below.
A Single, Reusable ItemsControl class
This will probably be a rather involved implementation. You will likely need to create entirely new WPF Controls, in the form of both a "SpilloverItemsControl" class and a "SpilloverItem" class to serve as the item container, for items displayed in the spillover control. The SpilloverItemsControl class would of course inherit from ItemsControl.
The SpilloverItem container will expose a property - "IsSpilledOver" (or something like that), which the parent control will automatically set to true or false based on various size and visibility calculations.
Your SpilloverItemsControl class will be layed out as a sort of composite control, providing 2 different ItemsControls within its ControlTemplate - one whose items' Visibility will be set to Visible if "IsSpilledOver" set to 'false', and set to 'Collapsed' if not; and another one to serve as the 'spillover' area, which will display only the items with "IsSpilledOver" set to true.
An Alternate Approach
An alternative approach, but slightly less reusable, is to have the "IsSpilledOver" property exist in your item ViewModel, and create a minimal Behavior to determine when it should be set to true or false. Then in your View, you would again just have two different ItemsControls bound to the same collection. One to display the 'non spilled-over' items and one to display the 'spilled-over' items. The visibility here, would be set in your ItemTemplate.
Let me explain you my situation.
I have a base class called Shape, and several concrete classes like Triangle, Square, etc.
I have several data templates.
I'm building just one object. So I wouldn't use an ItemControl control, I would like to use a normal panel like the grid, and show the respective data template (in DataContext has the concrete item)..
The only way to do this is using an ItemsControl? Or there's another way.. because I'm just using one item and not a collection and display the correct template.
DataTemplates are used in much more than just ItemsControls
They are used to tell WPF how to draw any object in the Visual Tree. For example, if you stick a User class object in the VisualTree, a DataTemplate can be used to tell WPF how to draw that User object
They are most frequently used in controls with an ItemsSource or Content properties, because those are the most common way of inserting data objects into the VisualTree.
In your specific case where you only want to insert one data item into the VisualTree, I would suggest a ContentControl
<ContentControl Content="{Binding MyDataObject}" />
To tell WPF how to draw MyDataObject you can either use the ContentTemplate property and set it to a DataTemplate
<ContentControl Content="{Binding MyDataObject}"
ContentTemplate="{StaticResource MyDataTemplate}" />
or define an implicit DataTemplate that tells WPF to draw any object of a specific type using a specific template.
<DataTemplate DataType="{x:Type local:MyDataObject}">
<!-- Tell WPF how to draw MyDataObject here -->
</DataTemplate>
If you want to display a single item with a data template that is selected based on the item's type, you should use ContentControl or any of its derived classes.
This is a tough question, but I'll try to explain anyway...
I have a custom control window that is used all over my applicaton. The reason I did this is because I wanted the various windows and dialog boxes to be fully customizable across my program. I.e., the minimize, maximize, close button and frame are all custom. This window is templated inside my generic.xaml. Now this works and it's all good. The idea I got was from http://www.codeproject.com/KB/WPF/CustomFrames.aspx
Now the users of this custom window are user controls in their xaml they basically use MyWindow as their root element:
<MyWindow>
....
</MyWindow>
But now what I'm trying to do is "inject" certain elements into MyWindow from the User Control's xaml. MyWindow would simply have a container for hosting them. For example, they might want to inject a toolbar button that appears right next to the minimize button. So for example, I might have a user control that does the following (where MyWindow is the root element):
<MyWindow>
<MyWindow.ToolBar>
<Button x:Name="BlaBla"/>
</MyWindow.ToolBar>
</MyWindow>
This would put "blabla" right next to the minimize button for example. But I'm wondering if it's even possible to do this. I.e., the whole MyWindow.ToolBar thing. Is there a construct for this, is this an attached property or something weirder?
It definitely is possible, depends on your choice of types for the DependencyProperty. You could use IEnumerable and bind the MyWindow.ToolBar dp to the ItemsSource on your internal ToolBar.
<ControlTemplate>
<!-- ... snipped down to the ToolBar ... -->
<ToolBarTray>
<ToolBar x:Name="PART_ToolBar" />
</ToolBarTray>
</ControlTemplate>
With the appropriate code in OnApplyTemplate to pull PART_ToolBar and create new Binding for the ItemsSource.
EDIT: rereading your question it appears that I missed that you wanted to add this elsewhere. My suggestion then would be to use this as an object dependency property, with a ContentPresenter bound to the MyWindow.ToolBar with a Visibility set if the binding is not {x:Null}.
Is it possible to open another Window in a TabControl's TabItem?
The reason I want to do this is that if I have 5 TabItems in my TabControl, the one Window file I'm coding all these TabItems and their associated actions will get very large. So it would be nice if it was possible to to give each TabItem its own Window file.
Or how do you solve the problem where theWindow file controlling the TabControl gets too large?
<Window ...
xmlns:local="clr-namespace:MyNamespace"
>
<TabControl>
<TabItem Header="FirstTab">
<local:MyFirstTabUserControl/>
</TabItem>
<TabItem Header="SecondTab">
<local:MySecondTabUserControl/>
</TabItem>
<TabItem Header="ThirdTab">
<local:MyThirdTabUserControl/>
</TabItem>
</TabControl>
</Window>
Your each TabUserControl is actually simple UserControl, since TabItem can host any control as its own child.
You have several choices:
add one or more resource dictionaries to your app that contain resources with templates and styles for the various views you host in your tabs. This approach works well if you just need to maintain separation of the visual trees only.
create user controls for each view (with own XAML and class file) and use one instance for each different view in the tabs. This approach allows you to encapsulated specific business logic and the corresponding visual tree together.
generate some of the UI from code. This one has no advantages, except t makes you XAML smaller. And is your .cs files become too big, you can always split them in multiple code files and use partial classes. (just had to throw in this one for completeness :-))
You can also set the TabItem Content equals to your Window content
ex: [WindowType is your window]
WindowsType oWindow = new WindowType();
TabItem oTab = new TabItem();
oTab.Content = oWindow.Content;
Make a UserControl for each TabItem.
You can use a UserControl as was mentioned already.
But you can also use the Page control. Each "Window" would be a page, and the tab would have a NavigationControl in it. I've used this approach before and it works well. I prefer the UserControl route, but both are valid.