/// <summary>
/// 尝试焦点移动到目标元素
/// </summary>
/// <param name="target"></param>
public void FlowTo(ComponentBase target)
{
//如果目标不在列表中，则不处理
var targetIndex = FlowList.IndexOf(target);
if (targetIndex < 0)
{
return;
}
//若当前要素为空，则重置到顶点
var currentIndex = FlowList.IndexOf(CurrentElement);
if (currentIndex < 0)
{
MoveFocusHost(FlowNavigation.Top);
return;
}
//开始组织焦点移动
if (currentIndex > targetIndex)
{
//尝试往目标进行转移
SetFlow(target);
}
else if (currentIndex < targetIndex)
{
//检查是否允许跳过控制
if (GetCanSkipFlow(target))
{
SetFlow(target);
}
else
{
while (true)
{
if (!MoveFocusHost(FlowNavigation.Forward))
{
break;
}
var index = FlowList.IndexOf(CurrentElement);
if (targetIndex <= index)
{
break;
}
}
}
}
}
/// <summary>
/// 按照参数指定的方向进行一次移动
/// </summary>
public bool MoveFocusHost(FlowNavigation navigation)
{
//当前焦点元素的位置
var currentIndex = FlowList.IndexOf(CurrentElement);
switch (navigation)
{
case FlowNavigation.Top:
//清除当前焦点元素，然后重新往下移动
CurrentElement = null;
return(MoveFocusHost(FlowNavigation.Forward));
case FlowNavigation.Backward:
//若当前元素不存在，则移动到顶端
if (currentIndex < 0)
{
return(MoveFocusHost(FlowNavigation.Top));
}
//从当前位置倒序查找回退位置，若当前位置为0，则不移动
while (currentIndex > 0)
{
currentIndex--;
var target = FlowList[currentIndex];
if (IsFlowable(target))
{
//位置合适，进行移动，此时触发Enter系列事件
if (!RaiseEnterEvent(target))
{
return(false);
}
CurrentElement = target;
return(true);
}
}
FlowToTop?.Invoke(this, new RoutedEventArgs());
return(false);
case FlowNavigation.Forward:
if (CurrentElement != null && !RaiseLeaveEvent(CurrentElement))
{
return(false);
}
//沿着流程列表往下找焦点控件
while (currentIndex + 1 < FlowList.Count)
{
currentIndex++;
var target = FlowList[currentIndex];
if (IsFlowable(target))
{
if (!RaiseEnterEvent(target))
{
return(false);
}
CurrentElement = target;
return(true);
}
}
//触发移动到最后的事件
FlowToEnd?.Invoke(this, new RoutedEventArgs());
return(false);
default: return(false);
}
}
