wpf 研习1-24小时自学wpf10

Commands

In WPF, a command is a function or action(f.e,making the selected text bold) that can be bound to an input gesture(user actions,some way that a user provides input to an application，the gestures are all routed events).

 

four central concepts underlying commands:

The command itself is the action that’s going to be executed;

The source is the object that is invoking the command, such as a button or menu;

The target is the subject that the command is affecting, such as the currently selected text;

Finally, the binding is the object that links the actual implementation of the action to the command.

 

 

Built-In Command Libraries in WPF

ApplicationCommands	commonly used commands such as Cut, Copy, Paste, New, Open, Save, Undo, Close etc
ComponentCommands	for moving around inside an application,more general use than editing commands as well as navigation commands,commands such as MoveDown, ExtendSelectionLeft, ScrollByLine,SelectToEnd,etc
EditingCommands	helpful for dealing with text,includes commands for alignment, formatting, and the navigation of text,such as ToggleBold, AlignLeft, and DecreaseFontSize
MediaCommands	commands for controlling audio and video in your applications. Some typical commands are Play,Pause, and IncreaseVolume
NavigationCommands	useful for navigating in an application built around a web browser metaphor.Commands include BrowseForward, NextPage,PreviousPage, Refresh, and Search.

 

<ToggleButton x:Name=”boldButton”
                           Command=”EditingCommands.ToggleBold”
                           ToolTip=”Bold”> 

 

<Button Command=”ApplicationCommands.Cut”
              ToolTip=”Cut”>
              <Image Source=”Icons/cut.png” />
</Button> 

 

Building commands to the menu

<MenuItem Header=”_Edit”>
   <MenuItem Command=”ApplicationCommands.Undo” />
   <MenuItem Command=”ApplicationCommands.Redo” />
   <Separator />
   <MenuItem Command=”ApplicationCommands.Cut” />
   <MenuItem Command=”ApplicationCommands.Copy” />
   <MenuItem Command=”ApplicationCommands.Paste” />
   <MenuItem Command=”EditingCommands.Delete” />
</MenuItem> 

 

CommandBindings

is a library of commands available to UIElement and any of its child elements.It's a collection;

 

map the command bindings to event handlers 

 

MainWindow.xaml:

<Window.CommandBindings>
      <CommandBinding Command=”ApplicationCommands.New”

                                           Executed=”NewDocument” />
</Window.CommandBindings>

 

The command binding must point to an event handler with an ExecutedRoutedEventArgs parameter.

 

MainWindow.xaml.cs:

 

private void NewDocument(object sender,ExecutedRoutedEventArgs e)

{

   _documentManager.NewDocument(); status.Text = “New Document”;

   status.Text = “New Document”;

}

 

TextEditorMenu.xaml:

<MenuItem Command=”ApplicationCommands.New” />

 

CanExecute event判断是否可执行

mainwindow.xaml

<CommandBinding Command=”ApplicationCommands.Save”
                               CanExecute=”SaveDocument_CanExecute”
                               Executed=”SaveDocument” />

 

DocumentManager

public bool CanSaveDocument()
{
      return !string.IsNullOrEmpty(_currentFile);
}

 

mainwindow.xaml.cs

private void SaveDocument_CanExecute(object sender,CanExecuteRoutedEventArgs e)
{
      e.CanExecute = _documentManager.CanSaveDocument();
}

 

input binding:

Input bindings are similar to the command bindings,UIElement defines a collection of input bindings that are automatically available to all of the element’s children;

 

two types,KeyBinding and MouseBinding(KeyBinding is for activating commands with the keyboard,and MouseBinding is for activating them with the mouse);

 

Gesture attribute

Gesture = MouseAction [+  ModifierKeys]

 

<Window.InputBindings>
   <MouseBinding Gesture=”Control+WheelClick”
                                Command=”ApplicationCommands.SaveAs” />
</Window.InputBindings> 

 

Key,Modifiers attribute(Key is the required attribute, whereas Modifiers is optional;Modifiers expects a value from the same ModifierKeys enumeration we used in the MouseBinding)

<Window.InputBindings>
  <KeyBinding Key=”S”
                           Modifiers=”Shift”
                           Command=”ApplicationCommands.SaveAs” />
</Window.InputBindings> 

 

结合标志，可以是"＋"也可以是"｜";其实，通常情况下，除了ModifiersKeys，wpf中都是使用管道结合标志符。

 

小结：

到目前为止，已经出现了多种绑定(binding)-databinding、CommandBinding、InputBinding(KeyBinding、MouseBinding).