java - 如何在 SWT ListViewer 上捕获 Ctrl 键按下和释放

Question

我正在尝试根据 Ctrl 按键在 SWT ListViewer 上对元素进行多重选择。我想区分使用 Ctrl 键的选择和 ListViewer 上的简单选择。我没有找到如何查看 Ctrl 键是否被按下或释放的方法。我没有看到任何有用的监听器补充。有没有办法通过 SWT ListViewer 上的按键和释放来了解选择。这是我尝试过的示例代码。

public class DummyListViewer {

private ListViewer dummyViewer;

    public DummyListViewer (Composite parent) {
            dummyViewer = createListViewer(parent);
        }

        private ListViewer createListViewer(Composite parent) {
            GridData data = new GridData(SWT.LEFT, SWT.LEFT, false, false);
            ScrolledComposite scrolledParent = (ScrolledComposite) createScrolledComposite(parent, SWT.NONE);
            final ListViewer dummyViewer= new ListViewer(scrolledParent, SWT.BORDER | SWT.H_SCROLL | SWT.V_SCROLL| SWT.MULTI);
            dummyViewer.getList().addKeyListener(new CtrlKeyListener());
            dummyViewer.setContentProvider(new ListViewerContentProvider());
            dummyViewer.setLabelProvider(new ListViewerLabelProvider());
            scrolledParent.setContent(dummyViewer.getControl());
            scrolledParent.setMinSize(dummyViewer.getControl().computeSize(SWT.DEFAULT, SWT.DEFAULT));
            dummyViewer.getControl().setLayoutData(new GridData(SWT.LEFT, SWT.FILL, false, true));
            return dummyViewer;
        }

        private Composite createScrolledComposite(Composite parent, int style) {
            ScrolledComposite scrolledComposite = new ScrolledComposite(parent, SWT.H_SCROLL | SWT.V_SCROLL);
            scrolledComposite.setLayout(new GridLayout(1, false));
            GridData gridData = new GridData(SWT.FILL, SWT.FILL, true, true);
            gridData.widthHint = 400;
            gridData.heightHint = 700;
            scrolledComposite.setLayoutData(gridData);
            scrolledComposite.setExpandVertical(true);
            scrolledComposite.setExpandHorizontal(true);
            return scrolledComposite;
        }

        public void setInput(List<Object> input) {
            filterViewer.setInput(input);
        }

        private class ListViewerContentProvider implements IStructuredContentProvider {

            @Override
            public void dispose() {

            }

            @Override
            public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {

            }

            @Override
            public Object[] getElements(Object inputElement) {
                if (inputElement instanceof List) {
                    return ((List)inputElement).toArray();
                }
                return null;
            }

        }

        private ColumnViewerFilter filter;



        private class ColumnViewerFilter extends ViewerFilter {

            String value=""; //$NON-NLS-1$

            /**
             * Constructor for ColumnViewerFilter to set the String on which
             * the viewer has to be filtered on.
             * @param value - String on which
             * the viewer has to be filtered on.
             */
            public ColumnViewerFilter(String value) {
                this.value = value;
            }

            @Override
            public boolean select(Viewer viewer, Object parentElement, Object element) {
                if (value != null && value instanceof String && element instanceof String) {
                    if (value.equals(element))
                        return true;
                }
                return false;
            }

        }

        private class ListViewerLabelProvider extends ColumnLabelProvider {

            @Override
            public String getText(Object element) {
                if(element instanceof String)
                    return (String)element;
                return null;
            }

        }



        private boolean CtrlkeyPressed = false;
        private class CtrlKeyListener implements KeyListener{

            @Override
            public void keyPressed(KeyEvent e) {
            if (e.keyCode == SWT.CTRL)
                CtrlkeyPressed = true;

            }

            @Override
            public void keyReleased(KeyEvent e) {
               if (e.keyCode == SWT.CTRL)
                CtrlkeyPressed = false;
            }

        }
    }

Answer 1

您可以使用 ListViewer 中包含的 List 控件上的 addKeyListener 监听按键事件:

viewer.getList().addKeyListener(new KeyListener() {

  @Override
  public void keyPressed(final KeyEvent e)
  {
    if (e.keyCode == SWT.CTRL)
      // TODO control pressed
   }

  @Override
  public void keyReleased(final KeyEvent e)
  {
    if (e.keyCode == SWT.CTRL)
      // TODO control release
  }

});

请注意，在某些平台上，多重选择不使用 Ctrl 键。在 Mac 上，使用 ⌘ 键 (SWT.COMMAND)。