SWT MouseDown事件对于自定义选择控件太占优势

Question

我已经制作了UI /编辑器，您可以在下面的图片中看到。文本显示为StyledText s。黑色线条是自定义边框，实际上是Label，其上绘制有线条。

现在我的目标是提供一个选择，允许用户选择Control s到删除或者添加一些给他们。第二张图显示了一个示例选择。所以从各种各样的MouseEvent开始，这比我最初想象的更复杂。

当MouseDown事件上的任何Control解雇我不能够跟踪任何其他Control s表示用户希望选择，因为MouseMove事件包含引发该事件MouseDown，直到鼠标得到释放相同的控制。我需要追踪到正在进行的选择，以便为选定的Control提供视觉反馈。下面的代码显示了一个演示行为的最小示例。

public class Tester { 

    public static void main(String[] args) 
    { 
     Display display = new Display(); 
     final Shell shell = new Shell(display); 
     shell.setLayout(new FillLayout()); 
     shell.setText("Stackoverflow"); 

     Composite comp = new Composite(shell, SWT.NONE); 
     comp.setLayout(new GridLayout(1, true)); 
     SelectionListener listener = new SelectionListener(); 

     StyledText text = new StyledText(comp, SWT.NONE); 
     text.setText("first text"); 
     attachListener(text, listener); 
     text = new StyledText(comp, SWT.NONE); 
     text.setText("second text"); 
     attachListener(text, listener); 


     shell.pack(); 
     shell.open(); 
     while (!shell.isDisposed()) 
     { 
      if (!display.readAndDispatch()) 
       display.sleep(); 
     } 
     display.dispose(); 
    } 

    private static void attachListener(Control control, Listener listener) { 
     if(control != null && !control.isDisposed()){ 
      control.addListener(SWT.MouseDown, listener); 
      control.addListener(SWT.MouseMove, listener); 
      control.addListener(SWT.MouseEnter, listener); 
      control.addListener(SWT.MouseUp, listener); 
     } 
    } 

    static class SelectionListener implements Listener { 

     Event lastEvent = null; 

     @Override 
     public void handleEvent(Event event) { 
      switch(event.type){ 

      case SWT.MouseDown: 
       lastEvent = event; 
       break; 

      case SWT.MouseMove: 
       if(lastEvent != null){ 
        if(event.widget == lastEvent.widget) 
         System.out.println("the same!!!"); 
        else 
         System.out.println("not the same!!!"); 
       } 
       break; 

      case SWT.MouseEnter: 
       //this also does not fire when MouseDown is fired 
       System.out.println("entering"); 
       break; 

      case SWT.MouseUp: 
       lastEvent = null; 
       break; 
      } 
     } 

    } 
} 

因此，基本上我正在寻求帮助。也许有更好/更简单的方法来实现这一点。我还试图弄清楚swt是如何在支持多选的表格或其他控件中执行此操作。但是很难找到特定的代码，或者他们为诸如表格之类的nativ控件调用本地方法。所以如果有人有想法请分享。

Answer 1

我找到了我的问题的解决方案。您可以自行发布MouseUp事件。之后，所有事件都会再次出现。唯一困难的部分是区分您自己的自定义事件和普通用户/系统事件。我能够创建/找到一些标准来识别自定义事件。下面的代码/文档更详细地解释了这一点：

/** 
    * Sets up a custom {@code SWT.MouseUp} event and fires it. This is needed because a {@code SWT.MouseDown} is consuming all 
    * other events until a {@code SWT.MouseUp} event is fired. This means that it is not possible to get a e.g. 
    * {@code SWT.MouseEnter} event when entering a certain StyledText which is needed for selection. Therefore a custom {@code SWT.MouseUp} 
    * event is fired to simulate the releasing of the button on system level so that all other events can come through again. The real problem here 
    * is to distinguish between the custom event for simulation and a normal event produced by the user. Firing the event via Display.post(Event) 
    * does not fire the handed over event parameter. The system actually creates a new event instance. Therefore 2 criteria are used to distinguish the custom event: 
    * <ul> 
    *  <ol>1. The selection can only be started by dragging a border control. 
    *   A {@code SWT.DragDetect} event starts the hole selection process. All events coming in before this event are ignored.</ol> 
    *  <ol>2. The actual distinguishing of the {@code SWT.MouseUp} is performed on the cursor coordinates and the referenced/dragged {@code widget}. 
    *   The dragging event has to be started on this widget.</ol> 
    * </ul> 
    * @param the starting {@code SWT.DragDetect} event 
    * @see #isCustomMouseUpEvent(Event) 
    */ 
    private void fireCustomMouseUpEvent(Event dragDetectEvent){ 
     customMouseUpEvent = new Event(); 
     customMouseUpEvent.type = SWT.MouseUp; 
     customMouseUpEvent.button = 1; //left mouse button 
     customMouseUpEvent.widget = dragDetectEvent.widget; 

     if(dragDetectEvent.widget instanceof Control){ 
      startingControl = (Control) dragDetectEvent.widget; 
      //get cursor location relative to widget to be comparable later with the event fired by the system 
      Point cursorLocation = startingControl.toControl(startingControl.getDisplay().getCursorLocation()); 
      customMouseUpEvent.x = cursorLocation.x; 
      customMouseUpEvent.y = cursorLocation.y; 
     } 

     /* 
     * note: set attributes like Event.data or Event.x are not present 
     * in the actually firing event. SWT or the system is creating a complete new 
     * event instance without those manually added information. 
     */ 
//  mouseUpEvent.data = SELECTION_START_EVENT_IDENTIFIER; 
     if(dragDetectEvent.widget.getDisplay().post(customMouseUpEvent)) 
      System.out.println("custom MouseUp event fired!"); 
    } 

    private boolean isCustomMouseUpEvent(Event event) { 
     return customMouseUpEvent != null && event.widget == customMouseUpEvent.widget && 
       customMouseUpEvent.x == event.x && customMouseUpEvent.y == event.y; 
    }