嵌套滚动区 [英] Nested Scroll Areas
问题描述
我为WPF创建了一个控件,我想问一个关于WPF专家的问题.
I creating a control for WPF, and I have a question for you WPF gurus out there.
我希望控件能够扩展以适合可调整大小的窗口.
I want my control to be able to expand to fit a resizable window.
在我的控件中,我有一个想要随窗口扩展的列表框.列表框周围还有其他控件(按钮,文本等).
In my control, I have a list box that I want to expand with the window. I also have other controls around the list box (buttons, text, etc).
我希望能够在控件上设置一个最小尺寸,但是我希望通过创建用于查看控件的滚动条来使窗口的尺寸更小.
I want to be able to set a minimum size on my control, but I want the window to be able to be sized smaller by creating scroll bars for viewing the control.
这将创建嵌套的滚动区域:一个用于列表框,一个用于包装整个控件的ScrollViewer.
This creates nested scroll areas: One for the list box and a ScrollViewer wrapping the whole control.
现在,如果列表框设置为自动大小,则它将永远不会有滚动条,因为它始终在ScrollViewer中以全尺寸绘制.
Now, if the list box is set to auto size, it will never have a scroll bar because it is always drawn full size within the ScrollViewer.
我只希望在内容无法缩小的情况下滚动控件,否则,我不想滚动控件.相反,我想滚动控件内的列表框.
I only want the control to scroll if the content can't get any smaller, otherwise I don't want to scroll the control; instead I want to scroll the list box inside the control.
如何更改ScrollViewer类的默认行为?我尝试从ScrollViewer类继承并覆盖MeasureOverride和ArrangeOverride类,但是我不知道如何正确地测量和布置子级.看来安排必须以某种方式影响ScrollContentPresenter,而不是实际的内容子级.
How can I alter the default behavior of the ScrollViewer class? I tried inheriting from the ScrollViewer class and overriding the MeasureOverride and ArrangeOverride classes, but I couldn't figure out how to measure and arrange the child properly. It appears that the arrange has to affect the ScrollContentPresenter somehow, not the actual content child.
任何帮助/建议都将不胜感激.
Any help/suggestions would be much appreciated.
推荐答案
我创建了一个可解决此问题的类:
I've created a class to work around this problem:
public class RestrictDesiredSize : Decorator
{
Size lastArrangeSize = new Size(double.PositiveInfinity, double.PositiveInfinity);
protected override Size MeasureOverride(Size constraint)
{
Debug.WriteLine("Measure: " + constraint);
base.MeasureOverride(new Size(Math.Min(lastArrangeSize.Width, constraint.Width),
Math.Min(lastArrangeSize.Height, constraint.Height)));
return new Size(0, 0);
}
protected override Size ArrangeOverride(Size arrangeSize)
{
Debug.WriteLine("Arrange: " + arrangeSize);
if (lastArrangeSize != arrangeSize) {
lastArrangeSize = arrangeSize;
base.MeasureOverride(arrangeSize);
}
return base.ArrangeOverride(arrangeSize);
}
}
即使包含元素想要更大,它将始终返回期望的大小(0,0). 用法:
It will always return a desired size of (0,0), even if the containing element wants to be bigger. Usage:
<local:RestrictDesiredSize MinWidth="200" MinHeight="200">
<ListBox />
</local>
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