Set command target to template part

问题

1) Custom DataGrid with CommandBindings.

2) A RoutedCommand Definition.

3) A Command Target Definition. (XAML)

CS :

    //(1)
    public class CustomDataGrid : DataGrid
    {
         this.CommandBindings.Add(new CommandBinding(Commands.ClearInputCommand, 
                     ClearFilter, ClearFilterCanExecute));                      
    }

    //(2)
    public static class Commands
    {
        public static RoutedCommand ClearInputCommand = new RoutedCommand("ClearInputCommand", typeof(Commands));   
    }

XAML :

    <!-- (3) -->
    <local:CustomDataGrid x:Name="grid" />                                                                                  
    <Button Command="{x:Static p:Commands.ClearInputCommand}" 
            CommandTarget="{Binding ElementName=grid}"/>

I would like to transfer the CommandBindings to a child of my CustomDataGrid (an Element in it's Template) , thus dissolving the need for a this "Custom" DataGrid and only a change in a template of a regular DataGrid.

XAML : CustomDataGridTemplate.

       <Template TargetType="{x:Type p:CustomDataGrid}" >
            ......
            <p:SomeCustomElement x:Name="I WANT TO BE THE COMMAND TARGET !" />
            ......
       </Template>

how can i achieve this ? is there a was of registering SomeCustomElement to that command ?

回答1:

Ok , so along side all the type of RoutedCommands i placed a few extension methods to register the routed command with the type it self ,

public static class Commands
{
    public static RoutedCommand ClearInputCommand = new RoutedCommand("ClearInputCommand", typeof(Commands));

    public static void RegisterCommand(this UIElement uiElement, RoutedCommand command, ExecutedRoutedEventHandler execute, CanExecuteRoutedEventHandler canExecute = null)
    {
        uiElement.RegisterCommand(new CommandBinding(command, execute, canExecute));
    }

    public static void RegisterCommand(this UIElement uiElement, CommandBinding commandBinding)
    {
        CommandManager.RegisterClassCommandBinding(typeof(object), commandBinding);         
    }

    public static void UnRegisterCommand(this UIElement uiElement, RoutedCommand command)
    {
        for (int i = 0; i < uiElement.CommandBindings.Count; i++)
        {
            CommandBinding c = uiElement.CommandBindings[i];
            if (c.Command == command)
            {
                uiElement.CommandBindings.RemoveAt(i);
            }
        }           
    }

    public static void UnRegisterCommand(this UIElement uiElement, CommandBinding commandBinding)
    {
        uiElement.CommandBindings.Remove(commandBinding);                               
    }
}

and then just called it from the constructor of that class , i'm not sure if i need to unregister this tough it seems to me that this can cause memory leaks , since it holds a reference to the Execute and CanExecute delegates.

in order to Unregister them i would have to keep track of all the registered uielements and clear there CommandBindings on application shut down.

i think a better solution would be to use something like prisms CompositeCommand. but this would do for now.

来源：https://stackoverflow.com/questions/21511674/set-command-target-to-template-part

标签

wpf

routed-commands