Question

我正在构建一个Videoplayer自定义控件（名为WpfCustomControlLibrary1的项目），并希望添加一个加载命令。

这是我在课堂上添加以获取此命令的内容：

Public Class VideoPlayer
Inherits Control
...
Public Shared ReadOnly LoadCommad As RoutedUICommand
....

Shared Sub New()
    'This OverrideMetadata call tells the system that this element wants to provide a style that is different than its base class.
    'This style is defined in Themes\Generic.xaml
    DefaultStyleKeyProperty.OverrideMetadata(GetType(VideoPlayer), New FrameworkPropertyMetadata(GetType(VideoPlayer)))

    LoadCommad = New RoutedUICommand("Load", "Load Video", GetType(VideoPlayer))
    CommandManager.RegisterClassCommandBinding(GetType(VideoPlayer), New CommandBinding(LoadCommad, AddressOf OnLoadExecuted))
End Sub
...

这就是我从我的XAML中调用它的方式：

<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfCustomControlLibrary1">
.....
<Button Command="local:VideoPlayer.LoadCommand"
        DockPanel.Dock="Right" Margin="0 5 5 0"
        Width="30" HorizontalAlignment="Left"
        Content="..." />
.....

但是当我将这个Usercontrol添加到这样的新项目时：

<Window x:Class="Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:bibli="clr-namespace:EigeneControllsBibli;assembly=EigeneControllsBibli"
xmlns:uc="clr-namespace:WpfCustomControlLibrary1;assembly=WpfCustomControlLibrary1"
Title="Window1" Height="442" Width="804">
<Grid>
    <uc:VideoPlayer Source="C:\Users\Public\Videos\Sample Videos\Bear.wmv" Margin="0,106,369,0"></uc:VideoPlayer>
</Grid>

我得到一个错误，他无法将属性“命令”中的字符串转换为类型为“System.Windows.Input.ICommand

的对象

有人看到有什么问题吗？

感谢您的帮助，尼科

Answer 1

你有拼写错误：

LoadCommad = New RoutedUICommand("Load", "Load Video", GetType(VideoPlayer))

应该是

LoadCommand = New RoutedUICommand("Load", "Load Video", GetType(VideoPlayer))

我不知道这是否会产生错误，但也许。

Answer 2

我认为您要做的是将LoadCommand声明为实例而不是共享变量，因此：

Public Class VideoPlayer
Inherits Control
...
Private ReadOnly m_LoadCommand As RoutedUICommand
....

Shared Sub New()
    'This OverrideMetadata call tells the system that this element wants to provide a style that is different than its base class.
    'This style is defined in Themes\Generic.xaml
    DefaultStyleKeyProperty.OverrideMetadata(GetType(VideoPlayer), New FrameworkPropertyMetadata(GetType(VideoPlayer)))
End Sub

Sub New()
    m_LoadCommand = New RoutedUICommand("Load", "Load Video", GetType(VideoPlayer))
End Sub

Public Property LoadCommand As ICommand
   Get
      Return m_LoadCommand
   End Get
End Property 
...

然后绑定XAML中的Button.Command属性，所以：

<StackPanel>
    <uc:VideoPlayer x:Name="myPlayer" Source="C:\Users\Public\Videos\Sample Videos\Bear.wmv" Margin="0,106,369,0"></uc:VideoPlayer>
    <Button Command="{Binding ElementName=myPlayer, Path=LoadCommand"
        Width="30"
        Content="..." />
</StackPanel>

wpf命令自定义控件绑定xaml

2 个答案: