SWT：刪除複合中的不可見組件空間

Question

我在一個composite0中放置了三個複合（1,2,3），因此它們都根據composite0.setLayout(new FormLayout())設置了它們的佈局。現在我遇到的問題是，我將composite3隱藏起來：composite3.setVisible(false);（我不想刪除數據，仍然需要該組件，但不希望它顯示在UI上），現在componite2之後存在很大差距。如何消除較大的差距（用於放置composite2）？先進的謝謝你！

Answer 1

 FormData data = new FormData(); 
     data.left = new FormAttachment(0, 100, EditorPanel.SPACING); 
     data.top = new FormAttachment(section1, EditorPanel.SPACING); 
     data.height = 0; 
     data.width = 0; 
     addSectionFormData(a, b, c); 
     a.setLayoutData(data); 
     b.setLayoutData(data); 

這個問題解決了！ :)

Answer 2

Snippet 313官方的SWT例子應該可以幫到你。您基本上在composite3上設置了不同的FormData，具體取決於您是要顯示還是隱藏它。

Answer 3

我有一個數據綁定可觀察的，但它假定控件在一個GridLayout。我使用它來顯示和隱藏嚮導頁面中的組合和小部件，具體取決於複選框的選擇狀態。

要使用它，像這樣的東西設置它：

DataBindingContext dbc = new DataBindingContext(); 
Button button = new Button(composite, SWT.CHECK); 
IObservableValue target = SWTObservables.observeSelection(button); 
dbc.bindValue(target, new HideControlObservable(someControl)); 

這裏是觀察到：

/** 
* Observable to control the presence (visibility and size) of any control 
* within a grid layout. 
* <p> 
* Changing the value of this observable will do two things: 
* <ol> 
* <li>Set the visibility of the control</li> 
* <li>Set the size of the control to zero when the control is invisible.</li> 
* </ol> 
* So, when using this observable, the control will not only be invisible, 
* but it will be gone, completely. Normally, when setting the visibility of 
* a control to <code>false</code>, the control will not be displayed but 
* will still take all the space on the screen. 
* </p> 
* <p> 
* <strong>Note:</strong> this observable works for controls within a 
* <strong>GridLayout only</strong>. 
* </p> 
*/ 
public class HideControlObservable extends WritableValue implements IValueChangeListener { 
    private final DataBindingContext dbc = new DataBindingContext(); 
    private final ISWTObservableValue sizeObservable; 
    private final Point size = new Point(0, 0); 
    private final Control control; 

    public HideControlObservable(Control control) { 
     super(control.getVisible(), Boolean.class); 
     this.control = control; 

     UpdateValueStrategy never = new UpdateValueStrategy(UpdateValueStrategy.POLICY_NEVER); 
     dbc.bindValue(SWTObservables.observeVisible(control), this, never, null); 

     sizeObservable = SWTObservables.observeSize(control); 
     sizeObservable.addValueChangeListener(this); 

     if (!control.isVisible()) { 
      GridData gd = (GridData) control.getLayoutData(); 
      if (gd == null) { 
       gd = new GridData(); 
      } 
      gd.exclude = true; 
      control.setLayoutData(gd); 
      control.setSize(new Point(0, 0)); 
     } 
    } 

    @Override 
    public void doSetValue(Object value) { 
     super.doSetValue(value); 
     Boolean bool = (Boolean) value; 
     if (bool) { 
      GridData gd = (GridData) control.getLayoutData(); 
      if (gd == null) { 
       gd = new GridData(); 
      } 
      gd.exclude = false; 
      control.setLayoutData(gd); 
      control.setSize(size); 
      control.getParent().layout(); 
     } else { 
      GridData gd = (GridData) control.getLayoutData(); 
      if (gd == null) { 
       gd = new GridData(); 
      } 
      gd.exclude = true; 
      control.setLayoutData(gd); 
      control.setSize(new Point(0, 0)); 
      control.getParent().layout(); 
     } 
    } 

    @Override 
    public synchronized void dispose() { 
     sizeObservable.dispose(); 
     super.dispose(); 
    } 

    @Override 
    public void handleValueChange(ValueChangeEvent event) { 
     Point newSize = (Point) event.getObservableValue().getValue(); 
     if (newSize.x > size.x) { 
      size.x = newSize.x; 
     } 
     if (newSize.y > size.y) { 
      size.y = newSize.y; 
     } 
    } 
}