WPF 图层管理

玩过phtoshop或者blend的人都知道里面都一个图层管理器，管理图层的遮挡顺序，有置顶层、置底层、置下一层、置上一层四个管理方式。

那么在wof中我们应该怎么玩呢? 请看代码，支持多个图层同时操作。

首先置顶：

private void BringToFront(List<UIElement> CurrentSelection ,UIElementCollection childrens)
{
List<UIElement> selectionSorted = (from item in CurrentSelection
orderby Canvas.GetZIndex(item as UIElement) ascending
select item as UIElement).ToList();

List<UIElement> childrenSorted = (from UIElement item in childrens
orderby Canvas.GetZIndex(item as UIElement) ascending
select item as UIElement).ToList();

int i = 0;
int j = 0;
foreach (UIElement item in childrenSorted)
{
if (selectionSorted.Contains(item))
{
int idx = Canvas.GetZIndex(item);
Canvas.SetZIndex(item, childrenSorted.Count - selectionSorted.Count + j++);
}
else
{
Canvas.SetZIndex(item, i++);
}
}
}

置底类似：

private void SendToBack(List<UIElement> CurrentSelection ,UIElementCollection childrens)
{
List<UIElement> selectionSorted = (from item in CurrentSelection
orderby Canvas.GetZIndex(item as UIElement) ascending
select item as UIElement).ToList();

List<UIElement> childrenSorted = (from UIElement item in childrens

orderby Canvas.GetZIndex(item as UIElement) ascending
select item as UIElement).ToList();
int i = 0;
int j = 0;
foreach (UIElement item in childrenSorted)
{
if (selectionSorted.Contains(item))
{
int idx = Canvas.GetZIndex(item);
Canvas.SetZIndex(item, j++);

}
else
{
Canvas.SetZIndex(item, selectionSorted.Count + i++);
}
}
}

　置下一层：

private void SendBackward(List<UIElement> CurrentSelection ,UIElementCollection childrens)

{
List<UIElement> ordered = (from item in CurrentSelection
orderby Canvas.GetZIndex(item as UIElement) ascending
select item as UIElement).ToList();

int count = childrens.Count;

for (int i = 0; i < ordered.Count; i++)
{
int currentIndex = Canvas.GetZIndex(ordered[i]);
int newIndex = Math.Max(i, currentIndex - 1);
if (currentIndex != newIndex)
{
Canvas.SetZIndex(ordered[i], newIndex);
IEnumerable<UIElement> it =childrens.OfType<UIElement>().Where(item => Canvas.GetZIndex(item) == newIndex);

foreach (UIElement elm in it)
{
if (elm != ordered[i])
{
Canvas.SetZIndex(elm, currentIndex);
break;
}
}
}
}
}

　置上一层：

private void BringForward(List<UIElement> CurrentSelection ,UIElementCollection childrens)

{
List<UIElement> ordered = (from item in CurrentSelection
orderby Canvas.GetZIndex(item as UIElement) descending
select item as UIElement).ToList();

int count = childrens.Count;

for (int i = 0; i < ordered.Count; i++)
{
int currentIndex = Canvas.GetZIndex(ordered[i]);
int newIndex = Math.Min(count - 1 - i, currentIndex + 1);
if (currentIndex != newIndex)
{
Canvas.SetZIndex(ordered[i], newIndex);
IEnumerable<UIElement> it = this.Children.OfType<UIElement>().Where(item => Canvas.GetZIndex(item) == newIndex);

foreach (UIElement elm in it)
{
if (elm != ordered[i])
{
Canvas.SetZIndex(elm, currentIndex);
break;
}
}
}
}
}