vaadin drag n drop组件

Question

我有一个垂直布局，我需要在垂直布局中上下移动组件。我使用DragAndDropWrapper，但我不确定在DropHandler的拖放函数下实现什么。我找到了绝对布局的例子，它工作。

class MoveHandler implements DropHandler 
    { 
     public AcceptCriterion getAcceptCriterion() 
     { 
      return AcceptAll.get(); 
     } 

     public void drop(DragAndDropEvent event) 
     { 
      WrapperTransferable t = (WrapperTransferable) event.getTransferable(); 
      WrapperTargetDetails details = (WrapperTargetDetails) event.getTargetDetails(); 

      // Calculate the drag coordinate difference 
      int xChange = details.getMouseEvent().getClientX() - t.getMouseDownEvent().getClientX(); 
      int yChange = details.getMouseEvent().getClientY() - t.getMouseDownEvent().getClientY(); 

      // Move the component in the absolute layout 
      ComponentPosition pos = ((AbsoluteLayout) 
      questionButtonLayout).getPosition(t.getSourceComponent()); 
      pos.setLeftValue(pos.getLeftValue() + xChange); 
      pos.setTopValue(pos.getTopValue() + yChange); 
     } 
    } 

以上是抽象布局的代码。不知道如何做垂直布局。

Answer 1

vaadin 7.4.5中存在拖放n拖放功能的错误。如果在拖放n包装器的布局中有多个文本框，它将永远不会将鼠标放在它上面（这意味着您将无法使用鼠标选择它，以便在其中键入任何内容）。其固定在7.7.5。所以，我用了下面的方法

class MoveHandler implements DropHandler 
{ 
    private static final long  serialVersionUID = -5709370299130660699L; 
    private AbstractOrderedLayout layout; 
    private Level     level; 

    public MoveHandler(AbstractOrderedLayout layout, Level level) 
    { 
     this.layout = layout; 
     this.level = level; 
    } 

    public AcceptCriterion getAcceptCriterion() 
    { 
     return AcceptAll.get(); 
    } 

    @SuppressWarnings("deprecation") 
    public void drop(DragAndDropEvent dropEvent) 
    { 
     Transferable transferable = dropEvent.getTransferable(); 
     Component sourceComponent = transferable.getSourceComponent(); 
     TargetDetails dropTargetData = dropEvent.getTargetDetails(); 
     DropTarget target = dropTargetData.getTarget(); 

     // First question cann't be dragged. 
     if (layout.getComponent(0).equals(sourceComponent)) 
      return; 

     // find the location of the dragged component 
     Iterator<Component> componentIterator = layout.getComponentIterator(); 
     Component next = null; 
     int indexSourceComponent = 0; 
     while (componentIterator.hasNext()) 
     { 
      next = componentIterator.next(); 
      if (next == sourceComponent) 
       break; 
      indexSourceComponent++; 
     } 

     // find the location where to move the dragged component 
     boolean sourceWasAfterTarget = true; 
     int index = 0; 
     componentIterator = layout.getComponentIterator(); 
     next = null; 

     while (next != target && componentIterator.hasNext()) 
     { 
      next = componentIterator.next(); 

      if (next != sourceComponent) 
      { 
       index++; 
      } 
      else 
      { 
       sourceWasAfterTarget = false; 
      } 
     } 
     if (next == null || next != target) 
     { 
      // component not found - if dragging from another layout 
      return; 
     } 

     // drop on top of target? 
     if (dropTargetData.getData("verticalLocation").equals(VerticalDropLocation.MIDDLE.toString())) 
     { 
      if (sourceWasAfterTarget) 
      { 
       index--; 
      } 
     } 

     // drop before the target? 
     else if (dropTargetData.getData("verticalLocation").equals(VerticalDropLocation.TOP.toString())) 
     { 
      index--; 
      if (index < 0) 
      { 
       index = 0; 
      } 
     } 

     // Nothing can be dragged to 1st position. 1st positions is secured for default question. 
     if (index == 0) 
      return; 

     // move component within the layout 
     layout.removeComponent(sourceComponent); 
     layout.addComponent(sourceComponent, index); 

    } 
}