I have in my application a data template that has a few buttons.
I want those buttons' even handler to be fired in the current page (I am using this template in many pages) rather than in the Application.xaml.vb/cs file, since I want different actions on each page.
I hope I am clear.
You can use commanding to achieve this. Have the Buttons in the DataTemplate execute specific Commands:
<Button Command="{x:Static MyCommands.SomeCommand}"/>
Then have each view that uses that DataTemplate handle the Command:
<UserControl>
<UserCommand.CommandBindings>
<CommandBinding Command="{x:Static MyCommands.SomeCommand}"
Executed="_someHandler"/>
</UserCommand.CommandBindings>
</UserControl>
EDIT after comments: Once you have created a code-behind for your ResourceDictionary as per these instructions, you can simply connect events in the usual fashion:
In MyResources.xaml:
<ListBox x:Key="myListBoxResource" ItemSelected="_listBox_ItemSelected"/>
Then in MyResources.xaml.cs:
private void _listBox_ItemSelected(object sender, EventArgs e)
{
...
}
If you use events and not commands, then in your Click event handler just write
private void Button_Click(object sender, RoutedEventArgs e)
{
var dataItem = (FrameworkElement)sender).DataContext;
// process dataItem
}
Related
I am trying to bind the IsEnabled property of a button to properties of the window's CollectionViewSource. I am doing this to implement First/Previous/Next/Last buttons and want the First and Previous to be disabled when the view is on the first item etc.
I have the collection view source set up, UI controls binding to it correctly, with access to its view in code so the click event handlers work fine in navigating through the view.
<CollectionViewSource x:Key="cvMain" />
The DockPanel is the root element of the window
<DockPanel DataContext="{StaticResource cvMain}">
FoJobs is an observable collection, cvJobs is a CollectionView that I use in the button's click handler
private void Window_Loaded(object sender, RoutedEventArgs e) {
((CollectionViewSource)Resources["cvMain"]).Source = FoJobs;
cvJobs = (CollectionView)((CollectionViewSource)Resources["cvMain"]).View;
}
I have tried this but get a binding error "BindingExpression path error: '' property not found on 'object' ''ListCollectionView'"
<Button Name="cbFirst" Click="cbMove_Click" IsEnabled="{Binding Source={StaticResource cvMain}, Converter={StaticResource CurrPos2BoolConverter}}" />
I am trying to do with a converter first but figure a style with triggers would be more efficient, but cant get access to the collection view. Even though the underlying datacontext is set to a collection view source, the binding is passed to the converter as the view's source (if I dont explicity set the binding's Source, as above), which has no currency properties (CurrentPosition, Count etc).
Any help would be greatly appreciated.
Why don't you use a RoutedCommand for this(even if you don't use MVVM that is)?
say something like:
<Button x:Name="nextButton"
Command="{x:Static local:MainWindow.nextButtonCommand}"
Content="Next Button" />
and in your code-behind:
public static RoutedCommand nextButtonCommand = new RoutedCommand();
public MainWindow() {
InitializeComponent();
CommandBinding customCommandBinding = new CommandBinding(
nextButtonCommand, ExecuteNextButton, CanExecuteNextButton);
nextButton.CommandBindings.Add(customCommandBinding); // You can attach it to a top level element if you wish say the window itself
}
private void CanExecuteNextButton(object sender, CanExecuteRoutedEventArgs e) {
e.CanExecute = /* Set to true or false based on if you want button enabled or not */
}
private void ExecuteNextButton(object sender, ExecutedRoutedEventArgs e) {
/* Move code from your next button click handler in here */
}
You can also apply one of the suggestions from Explicitly raise CanExecuteChanged() to manually re-evaluate Button.isEnabled state.
This way your encapsulating logic relating to the button in one area.
I am building a composite WPF application with Prism and using the Ribbon Library. One thing I am having a very difficult time with is with region-crossing commands.
For example, I have my ribbon in my 'RibbonRegion' and a grid view in my 'MainRegion'. Lets say I want a button in my ribbon to pop up a message box with the currently selected item in the grid view, how do I do this?
The easy way is using EventAggregator but I fear that if I have a bunch of subscribers hooked up just for button clicks I am just asking for memory leak issues.
Is there a way to have a cross-region command, so that clicking a button in my 'RibbonRegion' will get the selected item in the grid view and pop up a message box with that value?
You can use a System.Windows.Input.RoutedUICommand
First you need to declare your Command as below:
public static class Commands
{
public static readonly RoutedUICommand TestCommand = new RoutedUICommand("Test Command",
"Test Command", typeof(Commands));
}
Then in your RibbonRegion xaml:
<my:RibbonButton Command="{x:Static cmd:Commands.TestCommand}" ...
Then in your MainRegion xaml:
<UserControl.CommandBindings>
<CommandBinding CanExecute="OnTestCanExecute"
Command="{x:Static cmd:Commands.TestCommand}"
Executed="OnTestExecute" />
</UserControl.CommandBindings>
Then in your xaml.cs:
public void OnTestRouteCanExecute(object sender, System.Windows.Input.CanExecuteRoutedEventArgs e)
{
e.CanExecute = true;
}
public void OnTestRouteExecute(object sender, System.Windows.Input.ExecutedRoutedEventArgs e)
{
// do some stuff here
}
I have an UserControl. In my UserControl i have a button that I want bind its command to my ViewModel command. Can I do this?
Yes, you could add a routed event to your user control which gets invoked when the button is pressed.
You can then use various techniques to invoke the view model verb when the user control event fires.
E.g. you could use an attached property, or I would recommend using an MVVM framework such as Caliburn.Micro which has Actions that makes it even more straightforward.
I found it...I can define a DependensyProperty typof RelayCommand in my usercontrol and bind my DependensyProperty to my ViewModel Command
I'm not really sure what you mean but I take a shot.
In your code behind, define a RoutedCommand:
public partial class MyUserControl : UserControl
{
public static RoutedCommand Click =
new RoutedCommand("Click", typeof(UserControl));
}
Then it the xaml, set up a command binding:
<UserControl.CommandBindings>
<CommandBinding
Command="{x:Static MyNameSpace:MyUserControl.Click}"
CanExecute="ClickCanExecute"
Executed="ClickExecuted"/>
</UserControl.CommandBindings>
Then add the handlers in the code behind:
private void ClickCanExecute(object sender, CanExecuteRoutedEventArgs e)
{
e.CanExecute = true;
}
private void ClickExecuted(object sender, ExecutedRoutedEventArgs e)
{
// TODO execution logic goes here
}
Was I close? :)
I have a ContentControl element whose ContentTemplate is determined at run time from the Resource Dictionary. In the datatemplate I have a visual (Convas) and what I want is to also have a button in datatemplate which when clicked should print the visual element(canvas).
As I said that the DateTemplate is inside the Resource Dictionary so How can I write a Code on Click Event of that button and where it should be?
Any response would be much appreciated.
Sounds like you can use the Button.Click attached event. Just add it to the ContentControl.
<ContentControl
Button.Click="Button_Click"
ContentTemplate="<template with a button>"
/>
and the handler:
private void Button_Click(object sender, RoutedEventArgs e)
{
}
If you have multiple buttons in your template, you can use e.Source to figure it out. And I think you can use MouseButtonEventArgs instead.
Thanks to this question (click me!), I have the Source property of my WebBrowser binding correctly to my ViewModel.
Now I'd like to achieve two more goals:
Get the IsEnabled property of my Back and Forward buttons to correctly bind to the CanGoBack and CanGoForward properties of the WebBrowser.
Figure out how to call the GoForward() and GoBack() methods without resorting to the code-behind and without the ViewModel having to know about the WebBrowser.
I have the following (non-working) XAML markup at the moment:
<WebBrowser
x:Name="_instructionsWebBrowser"
x:FieldModifier="private"
clwm:WebBrowserUtility.AttachedSource="{Binding InstructionsSource}" />
<Button
Style="{StaticResource Button_Style}"
Grid.Column="2"
IsEnabled="{Binding ElementName=_instructionsWebBrowser, Path=CanGoBack}"
Command="{Binding GoBackCommand}"
Content="< Back" />
<Button
Style="{StaticResource Button_Style}"
Grid.Column="4"
IsEnabled="{Binding ElementName=_instructionsWebBrowser, Path=CanGoForward}"
Command="{Binding GoForwardCommand}"
Content="Forward >" />
I'm pretty sure the problem is that CanGoBack and CanGoForward are not dependency properties (and don't implement INotifyChanged), but I'm not quite sure how to get around that.
Questions:
Is there any way to hook up attached properties (as I did with Source) or something similar to get the CanGoBack and CanGoForward bindings to work?
How do write the GoBackCommand and GoForwardCommand so they are independent of the code-behind and ViewModel and can be declared in markup?
For anyone who comes across this question and wants a complete solution, here it is. It combines all of the suggestions made in this thread and the linked threads (and others those link to).
XAML:
http://pastebin.com/aED9pvW8
C# class:
http://pastebin.com/n6cW9ZBB
Example XAML usage:
http://pastebin.com/JpuNrFq8
Note: The example assumes your view binds to a ViewModel that provides the source URL to the browser. A very rudimentary navigation bar with back, forward, and refresh buttons and address bar is provided just for demonstration.
Enjoy. I have set the expiration on those pastebin's to never, so they should be available for as long as pastebin exists.
I used this in my bindable webbrowser wrapper:
CommandBindings.Add(new CommandBinding(NavigationCommands.BrowseBack, BrowseBack, CanBrowseBack));
CommandBindings.Add(new CommandBinding(NavigationCommands.BrowseForward, BrowseForward, CanBrowseForward));
CommandBindings.Add(new CommandBinding(NavigationCommands.BrowseHome, GoHome, TrueCanExecute));
CommandBindings.Add(new CommandBinding(NavigationCommands.Refresh, Refresh, TrueCanExecute));
CommandBindings.Add(new CommandBinding(NavigationCommands.BrowseStop, Stop, TrueCanExecute));
Note that I created my bindable webbrowser as FrameworkElement that exposes DependencyProperties and calls methods on the actual browser element, so i can set CommandBindings on it.
That way, you can use the default NavigationCommands in your View.
The used handlers are:
private void CanBrowseBack(object sender, CanExecuteRoutedEventArgs e) {
e.CanExecute = webBrowser.CanGoBack;
}
private void BrowseBack(object sender, ExecutedRoutedEventArgs e) {
webBrowser.GoBack();
}
private void CanBrowseForward(object sender, CanExecuteRoutedEventArgs e) {
e.CanExecute = webBrowser.CanGoForward;
}
private void BrowseForward(object sender, ExecutedRoutedEventArgs e) {
webBrowser.GoForward();
}
private void TrueCanExecute(object sender, CanExecuteRoutedEventArgs e) { e.CanExecute = true; }
private void Refresh(object sender, ExecutedRoutedEventArgs e) {
try { webBrowser.Refresh(); }
catch (Exception ex) { PmsLog.LogException(ex, true); }
}
private void Stop(object sender, ExecutedRoutedEventArgs e) {
mshtml.IHTMLDocument2 doc = WebBrowser.Document as mshtml.IHTMLDocument2;
if (doc != null)
doc.execCommand("Stop", true, null);
}
private void GoHome(object sender, ExecutedRoutedEventArgs e) {
Source = new Uri(Home);
}
Your question seems to imply that in order to correctly implement an MVVM pattern you are not allowed to have any code-behind. But perhaps adding some code-behind to your view will make it much easier to hook it up with your view-model. You can add dependency properties to the view and let it listen for INotifyPropertyChanged events.