我有两个用于显示评论和签名集合的自定义控件。每个控件都有一个用于更改显示样式的按钮 - 显示整个集合或仅显示前4个元素。
当我将这些控件放在默认的WrapPanel中时 - 它们可以正常工作:根据用户的操作进行扩展或折叠。 在我自己的带有新ArrangeOverride功能的自定义WrapPanel中,它们也可以正常工作。
现在我需要WrapPanel选项" LastChildFill" (我在这里找到了例子)并使用自定义" WrapDirection" (类似于FlowDirection)。 WrapPanel中的第一个或最后一个元素必须填充所有剩余空间,同时它超过元素的MinWidth。 所以我用自定义的MeasureOverride和ArrangeOverride创建了第三个WrapPanel。并且它可以按照我的需要工作,但是当我更改控件显示样式时,控件内的集合会发生变化,但是我的WrapPanel中的MeasureOverride在我更改窗口大小之前不会启动。
更新:MeasureOverride不会开始扩展填充剩余空间的第一个或最后一个元素。折叠此元素可以正常工作。
我不明白我用自定义MeasureOverride打破了什么?
更新2: 我觉得我的问题与此类似:MeasureOverride not always called on children's property changes。
并附上MeasureOverride代码。
public class WrapPanelFlowDirection : WrapPanel
{
public bool LastChildFill
{
get { return (bool)GetValue(LastChildFillProperty); }
set { SetValue(LastChildFillProperty, value); }
}
public static readonly DependencyProperty LastChildFillProperty =
DependencyProperty.Register("LastChildFill", typeof(bool), typeof(WrapPanelFlowDirection), new FrameworkPropertyMetadata(true, FrameworkPropertyMetadataOptions.AffectsMeasure));
public WrapDirection WrapDirection
{
get { return (WrapDirection)GetValue(WrapDirectionProperty); }
set { SetValue(WrapDirectionProperty, value); }
}
public static readonly DependencyProperty WrapDirectionProperty =
DependencyProperty.Register("WrapDirection", typeof(WrapDirection), typeof(WrapPanelFlowDirection), new FrameworkPropertyMetadata(WrapDirection.LeftToRight, FrameworkPropertyMetadataOptions.AffectsMeasure));
#region Measure Override
protected override Size MeasureOverride(Size availableSize)
{
var panelSize = new Size(availableSize.Width, 0);
double minWidth = 0;
foreach (FrameworkElement child in this.InternalChildren)
{
child.Measure(availableSize);
minWidth += child.DesiredSize.Width;
}
int firstChildInLine = 0;
double currLineHeight = 0;
double currLineWidth = 0;
UIElementCollection children = this.InternalChildren;
for (int i = 0; i < children.Count; i++)
{
FrameworkElement child = children[i] as FrameworkElement;
if (child == null)
continue;
double w = 0;
if (child.MinWidth == 0)
w = child.DesiredSize.Width;
else
w = child.MinWidth;
if (currLineWidth + w <= availableSize.Width)
{
currLineWidth += w;
currLineHeight = Math.Max(currLineHeight, child.DesiredSize.Height);
}
else
{
MeasureOneLine(firstChildInLine, i - 1, ref currLineHeight, availableSize.Width);
panelSize.Height += currLineHeight;
currLineWidth = w;
currLineHeight = child.DesiredSize.Height;
if (w > availableSize.Width)
{
MeasureOneLine(i, i, ref currLineHeight, availableSize.Width);
panelSize.Height += currLineHeight;
currLineHeight = currLineWidth = 0;
firstChildInLine = i + 1;
}
else
{
firstChildInLine = i;
}
}
}
if (firstChildInLine < children.Count)
{
MeasureOneLine(firstChildInLine, children.Count - 1, ref currLineHeight, availableSize.Width);
panelSize.Height += currLineHeight;
}
if (double.IsInfinity(panelSize.Width))
panelSize.Width = minWidth;
return panelSize;
}
private void MeasureOneLine(int start, int end, ref double height, double totalWidth)
{
UIElementCollection children = this.InternalChildren;
if (WrapDirection == WrapDirection.LeftToRight)
{
for (int i = start; i < end; i++)
{
FrameworkElement child = children[i] as FrameworkElement;
if (child == null)
continue;
double w = 0;
if (child.MinWidth == 0)
w = child.DesiredSize.Width;
else
w = child.MinWidth;
if (i < end)
{
child.Measure(new Size(w, height));
totalWidth -= w;
}
else
{
child.Measure(new Size(totalWidth, double.PositiveInfinity));
height = Math.Max(height, child.DesiredSize.Height);
}
}
}
else
{
for (int i = end; i >= start; i--)
{
FrameworkElement child = children[i] as FrameworkElement;
if (child == null)
continue;
double w = 0;
if (child.MinWidth == 0)
w = child.DesiredSize.Width;
else
w = child.MinWidth;
if (i > start)
{
child.Measure(new Size(w, height));
totalWidth -= w;
}
else
{
child.Measure(new Size(totalWidth, double.PositiveInfinity));
height = Math.Max(height, child.DesiredSize.Height);
}
}
}
}
#endregion
答案 0 :(得分:0)
我在这里找到了解决方案:How does a container know when a child has called InvalidateArrange?
它对我有用。
public static void OnPropertyChanged(DependencyObject source, DependencyPropertyChangedEventArgs e)
{
UIElement panel= VisualTreeHelper.GetParent(source) as UIElement;
if(panel != null)
{
panel.InvalidateMeasure();
panel.InvalidateArrange();
}
}