今年刚开始接触Surface的时候就遇到过这个问题，当时想了很多办法，但是一直没有成功，看到Silverlight里面可以直接新建事件实在是非常的羡慕，后来还尝试了CommandBinding的方法，虽然可以用了但还是感觉很麻烦。
今天无意中在MSDN看到有段代码里在DataTemplate中添加了事件，就又实验了一下，终于找到了原因。
先创建一个项目便于说明：
<s:SurfaceWindow x:Class="ScatterViewItemScale.SurfaceWindow1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:s="http://schemas.microsoft.com/surface/2008"
Title="ScatterViewItemScale"
>
<s:SurfaceWindow.Resources>
<DataTemplate x:Key="ScatterViewItemDataTemplate" >
<Border BorderThickness="2" BorderBrush="White" Margin="10">
<StackPanel Background="{DynamicResource {x:Static s:SurfaceColors.Accent3BrushKey}}">
<Label Content="{Binding Name}"
HorizontalAlignment="Center"
VerticalAlignment="Center"
FontSize="20"/>
<s:SurfaceButton Content="{Binding CanDrag}" Click="SurfaceButton_Click"
HorizontalAlignment="Center"
VerticalAlignment="Center"
FontSize="18"/>
</StackPanel>
</Border>
</DataTemplate>
</s:SurfaceWindow.Resources>
<Grid>
<s:ScatterView
Name="DragSource"
ItemTemplate="{StaticResource ScatterViewItemDataTemplate}"
ItemsSource="{Binding Path=SourceItems}"
PreviewMouseDown="DragSourcePreviewInputDeviceDown"
PreviewTouchDown="DragSourcePreviewInputDeviceDown"
s:SurfaceDragDrop.DragCanceled="DragCanceled"
s:SurfaceDragDrop.DragCompleted="DragCompleted"/>
</Grid>
</s:SurfaceWindow>
具体后台代码我就偷个懒不贴了，有朋友需要的话可以到这里参考一下：http://msdn.microsoft.com/en-us/library/ff727736
private void SurfaceButton_Click(object sender, RoutedEventArgs e)
{
Console.WriteLine(sender);
}
数据类：
public class DataItem
{
private string name;
private bool canDrag;
public string Name
{
get { return name; }
}
public bool CanDrag
{
get { return canDrag; }
}
public object DraggedElement
{
get;
set;
}
public DataItem(string name, bool canDrag)
{
this.name = name;
this.canDrag = canDrag;
}
}
现在开始说重点，在对代码完全不做修改的情况下，点击每个ScatterViewItem中的Button，只有canDrag为false的item的事件被触发了。原因是在ScatterView的PreviewTouchDown事件中有如下定义：
// If the data has not been specified as draggable,
// or the ScatterViewItem cannot move, return.
if (data == null || !data.CanDrag || !draggedElement.CanMove)
{
return;
}
这里的return使得touch跳过了对ScatterViewItem的操作，进入了VisualTree的下一级，所以ButtonClick就可以被触发了。
所以概念上的解决办法就是当touchpoint的originalsource是需要触发事件的控件时，PreviewTouchDown返回就好了。
可以写成：
private void DragSourcePreviewInputDeviceDown(object sender, InputEventArgs e)
{
FrameworkElement findSource = e.OriginalSource as FrameworkElement;
ScatterViewItem draggedElement = null;
/////////////////////////////////////////////重点
SurfaceButton sb = null;
sb = FindContainer<SurfaceButton>(sb, findSource);
if (sb != null)
{
return;
}
//////////////////////////////////////////////重点
// Find the ScatterViewItem object that is being touched.
while (draggedElement == null && findSource != null)
{
if ((draggedElement = findSource as ScatterViewItem) == null)
{
findSource = VisualTreeHelper.GetParent(findSource) as FrameworkElement;
}
}
if (draggedElement == null)
{
return;
}
DataItem data = draggedElement.Content as DataItem;
// If the data has not been specified as draggable,
// or the ScatterViewItem cannot move, return.
if (data == null || !data.CanDrag || !draggedElement.CanMove)
{
return;
}
// Set the dragged element. This is needed in case the drag operation is canceled.
data.DraggedElement = draggedElement;
// Create the cursor visual.
ContentControl cursorVisual = new ContentControl()
{
Content = draggedElement.DataContext,
Style = FindResource("CursorStyle") as Style
};
// Create a list of input devices,
// and add the device passed to this event handler.
List<InputDevice> devices = new List<InputDevice>();
devices.Add(e.Device);
// If there are touch devices captured within the element,
// add them to the list of input devices.
foreach (InputDevice device in draggedElement.TouchesCapturedWithin)
{
if (device != e.Device)
{
devices.Add(device);
}
}
// Get the drag source object.
ItemsControl dragSource = ItemsControl.ItemsControlFromItemContainer(draggedElement);
// Start the drag-and-drop operation.
SurfaceDragCursor cursor =
SurfaceDragDrop.BeginDragDrop(
// The ScatterView object that the cursor is dragged out from.
dragSource,
// The ScatterViewItem object that is dragged from the drag source.
draggedElement,
// The visual element of the cursor.
cursorVisual,
// The data attached with the cursor.
draggedElement.DataContext,
// The input devices that start dragging the cursor.
devices,
// The allowed drag-and-drop effects of the operation.
DragDropEffects.Move);
// If the cursor was created, the drag-and-drop operation was successfully started.
if (cursor != null)
{
// Hide the ScatterViewItem.
draggedElement.Visibility = Visibility.Hidden;
// This event has been handled.
e.Handled = true;
}
}
下面是FindContainer的代码，用来返回指定类型的控件（找不到时返回null）；
public T FindContainer<T>(T containerElement, FrameworkElement findsource) where T : DependencyObject
{
while (containerElement == null && findsource != null)
{
if ((containerElement = findsource as T) == null)
{
findsource = VisualTreeHelper.GetParent(findsource) as FrameworkElement;
}
}
return containerElement;
}
上面的代码中添加的部分我已经加了标记，很大的重点两个字;-)。但是还有缺点就是这几行代码必须每次都要写出，还在想更通用的方法，希望各位达人如果看到了可以帮帮忙。
转载于:https://www.cnblogs.com/icyfantasy/archive/2012/07/18/2597215.html