在ScrollViewer中封装自定义画布
本文关键字:自定义 封装 ScrollViewer | 更新日期: 2023-09-27 17:50:35
我需要有一个自定义面板,作为一个画布,但实际上是一个ScrollViewer与画布里面。用户应该能够像在画布中一样添加控件;我需要ScrollViewer包装器来处理缩放和平移行为。
所以,我开始写控件:[ContentProperty("Children")]
public class MyContainer : ScrollViewer, IAddChild
{
private Canvas _innerCanvas;
[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
public UIElementCollection Children
{
get { return _innerCanvas.Children; }
}
public MyContainer()
{
this._innerCanvas = new Canvas();
this.Content = _innerCanvas;
_innerCanvas.Height = this.ActualHeight;
_innerCanvas.Width = this.ActualWidth;
}
void IAddChild.AddChild(object value)
{
_innerCanvas.Children.Add(value as UIElement);
}
void IAddChild.AddText(string text)
{
;
}
}
但它不起作用。如果我想在XAML
中使用它<Controls:MyContainer>
<TextBlock Height="92" Canvas.Left="324" TextWrapping="Wrap" Text="TextBlock 1" Canvas.Top="267" Width="284"/>
<TextBlock Height="92" Canvas.Left="462" TextWrapping="Wrap" Text="TextBlock 1" Canvas.Top="267" Width="284"/>
</Controls:MyContainer>
子元素不可见。
怎么了?
在Ctor处将画布的大小设置为ActualWidth
和ActualHeight
,但此时它们尚未初始化。ActualWidth
和ActualHeight
只有在屏幕上显示控制时才有意义。尝试订阅ScrollViewer的Loaded事件,然后更改Canvas的大小:
public MyContainer()
{
this._innerCanvas = new Canvas();
this.Content = _innerCanvas;
this.Loaded += ScrollViewer_Loaded;
}
public void ScrollViewer_Loaded(object sender, EventArgs e)
{
_innerCanvas.Height = this.ActualHeight;
_innerCanvas.Width = this.ActualWidth;
}