如何禁用DocumentViewer控件中的「打印」按钮？

有两种常用方法可以禁用DocumentViewer控件中的打印按钮：

方法一：修改控件模板 #

提取DocumentViewer的默认控件模板，找到打印按钮（默认名称为PrintButton），直接设置其IsEnabled="False"。示例代码如下：

<DocumentViewer x:Name="viewerDocument" Document="{Binding GeneratedDocument}">
    <DocumentViewer.Template>
        <ControlTemplate TargetType="{x:Type DocumentViewer}">
            <Border BorderThickness="{TemplateBinding BorderThickness}" BorderBrush="{TemplateBinding BorderBrush}" Focusable="False">
                <Grid Background="{TemplateBinding Background}">
                    <Grid.RowDefinitions>
                        <RowDefinition Height="Auto"/>
                        <RowDefinition Height="*"/>
                        <RowDefinition Height="Auto"/>
                    </Grid.RowDefinitions>
                    <ToolBar ToolBarTray.IsLocked="True" Focusable="False">
                        <Button Command="ApplicationCommands.Print" x:Name="PrintButton" IsEnabled="False" Content="打印"/>
                        <Button Command="ApplicationCommands.Copy" x:Name="CopyButton" Content="复制"/>
                        <Separator/>
                        <Button Command="NavigationCommands.IncreaseZoom" x:Name="IncreaseZoomButton" Content="放大"/>
                        <Button Command="NavigationCommands.DecreaseZoom" x:Name="DecreaseZoomButton" Content="缩小"/>
                        <Separator/>
                        <Button Command="NavigationCommands.GoToPage" x:Name="GoToPageButton" Content="转到页面"/>
                        <Button Command="NavigationCommands.Find" x:Name="FindButton" Content="查找"/>
                        <Separator/>
                        <Button Command="NavigationCommands.PreviousPage" x:Name="PreviousPageButton" Content="上一页"/>
                        <Button Command="NavigationCommands.NextPage" x:Name="NextPageButton" Content="下一页"/>
                        <Separator/>
                        <Button Command="NavigationCommands.FirstPage" x:Name="FirstPageButton" Content="首页"/>
                        <Button Command="NavigationCommands.LastPage" x:Name="LastPageButton" Content="尾页"/>
                    </ToolBar>
                    <ScrollViewer Grid.Row="1" CanContentScroll="True" HorizontalScrollBarVisibility="Auto" x:Name="PART_ContentHost" VerticalScrollBarVisibility="Auto"/>
                    <StatusBar Grid.Row="2" Focusable="False">
                        <TextBlock x:Name="PageNumber" Text="{Binding PageNumber, RelativeSource={RelativeSource TemplatedParent}}"/>
                        <TextBlock Text=" / "/>
                        <TextBlock x:Name="PageCount" Text="{Binding PageCount, RelativeSource={RelativeSource TemplatedParent}}"/>
                    </StatusBar>
                </Grid>
            </Border>
        </ControlTemplate>
    </DocumentViewer.Template>
</DocumentViewer>

方法二：通过后台代码查找并禁用按钮 #

在DocumentViewer的Loaded事件中，遍历控件的可视化树，找到打印按钮并设置其IsEnabled为false。示例C#代码如下：

private void viewerDocument_Loaded(object sender, RoutedEventArgs e)
{
    var printButton = FindVisualChild<Button>(viewerDocument, "PrintButton");
    if (printButton != null)
    {
        printButton.IsEnabled = false;
    }
}

private T FindVisualChild<T>(DependencyObject parent, string name) where T : FrameworkElement
{
    for (int i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
    {
        var child = VisualTreeHelper.GetChild(parent, i);
        if (child is T element && element.Name == name)
        {
            return element;
        }
        else
        {
            var result = FindVisualChild<T>(child, name);
            if (result != null)
                return result;
        }
    }
    return null;
}

记得在XAML中绑定Loaded事件：

<DocumentViewer x:Name="viewerDocument" 
                Document="{Binding GeneratedDocument}" 
                Loaded="viewerDocument_Loaded"/>

内容的提问来源于stack exchange，提问作者Fabrizio Ciavatta