java - 你能帮我解决一些 SWT 列表布局和渲染问题吗

Question

我一直在努力修复一个错误，即向 SWT 列表添加大约 2500 个项目会导致布局中断，我相信这是 SWT 中渲染的一个错误，因为几乎不会出错，但是当您滚动时使用滚动组合向下滚动列表，在某个时刻，组合中的下一个项目将在列表上呈现，并且滚动将停止(在 2100 左右)，列表中的项目就会消失。如果您注释掉 151 附近的行或我的代码，您可以自己看到这种效果。

但是我意识到，如果我向列表的布局数据添加高度提示，它将添加它自己的滚动条，这将解决渲染问题，但引入了一个新问题，那就是我无法解决列表贪婪地占据水平空间，使滚动条位于面板的右侧，有谁知道如何让列表以这种方式拉伸(stretch)？

import java.util.Collection;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

import org.eclipse.jface.dialogs.Dialog;
import org.eclipse.jface.layout.GridDataFactory;
import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.ScrolledComposite;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.ToolBar;
import org.eclipse.swt.widgets.ToolItem;
import org.eclipse.swt.widgets.Widget;

public class FilterLayoutDialog extends Dialog {

    private ListDisplayer keyWordListDisplay;
    private ScrolledComposite scroll;
    private Composite parent;

    public FilterLayoutDialog(final Shell parentShell) {
    super(parentShell);
    }

    @Override
    protected void configureShell(final Shell shell) {

    super.configureShell(shell);
    shell.setSize(new Point(450, 550));
    shell.setText("FML"); //$NON-NLS-1$
    }

    @Override
    public Control createDialogArea(final Composite comp) {

    scroll = new ScrolledComposite(comp, SWT.V_SCROLL);

    parent = new Composite(scroll, SWT.NONE);
    parent.setLayout(new GridLayout(1, true));

    scroll.setContent(parent);
    scroll.setExpandHorizontal(true);
    scroll.setExpandVertical(true);

    scroll.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, true));

    final ToolBar keywordBar = new ToolBar(parent, SWT.RIGHT | SWT.FLAT);
    ToolItem addText = new ToolItem(keywordBar, SWT.RIGHT | SWT.FLAT);

    addText.setToolTipText("Add 3000");
    addText.setText("Add 3000");
    addText.addSelectionListener(new SelectionAdapter() {

        @Override
        public void widgetSelected(final SelectionEvent e) {

        keyWordListDisplay
            .setContent(IntStream.range(0, 3000).mapToObj(i -> i + "").collect(Collectors.toList()));
        parent.layout();
        setScrollSize();
        }
    });
    addText = new ToolItem(keywordBar, SWT.RIGHT | SWT.FLAT);

    addText.setToolTipText("Add 12");
    addText.setText("Add 12");
    addText.addSelectionListener(new SelectionAdapter() {

        @Override
        public void widgetSelected(final SelectionEvent e) {

        keyWordListDisplay
            .setContent(IntStream.range(0, 12).mapToObj(i -> i + "").collect(Collectors.toList()));
        parent.layout();
        setScrollSize();
        }
    });

    final ToolItem reset = new ToolItem(keywordBar, SWT.RIGHT | SWT.FLAT);

    reset.setToolTipText("Reset");
    reset.setText("Reset");
    reset.addSelectionListener(new SelectionAdapter() {

        @Override
        public void widgetSelected(final SelectionEvent e) {
        keyWordListDisplay.setEmpty();
        parent.layout();
        setScrollSize();
        }
    });

    final GridData barData = new GridData(SWT.LEFT, SWT.CENTER, true, false);
    keywordBar.setLayoutData(barData);

    Label sep = new Label(parent, SWT.HORIZONTAL | SWT.SEPARATOR);

    sep.setLayoutData(GridDataFactory.fillDefaults().grab(true, false).span(1, 1).create());

    final Composite keywordList = new Composite(parent, SWT.NONE);
    keywordList.setLayout(new GridLayout(1, true));
    keyWordListDisplay = new ListDisplayer(keywordList, "None Selected");

    sep = new Label(parent, SWT.HORIZONTAL | SWT.SEPARATOR);
    sep.setLayoutData(GridDataFactory.fillDefaults().grab(true, false).span(1, 1).create());

    setScrollSize();
    return scroll;
    }

    public static void main(final String[] args) {
    new Display();

    final FilterLayoutDialog fml = new FilterLayoutDialog(new Shell());
    fml.open();
    }

    private void setScrollSize() {
    scroll.setMinSize(parent.computeSize(SWT.DEFAULT, SWT.DEFAULT));
    }

    private class ListDisplayer {

    String emptyIndicator;
    Composite parent;
    Widget w;

    public ListDisplayer(final Composite parent, final String emptyIndicator) {
        this.parent = parent;
        this.emptyIndicator = emptyIndicator;
        setEmpty();
    }

    void setContent(final Collection<String> content) {
        disposeWidget();

        Composite fill = new Composite(parent, SWT.NONE);
        fill.setLayout(new FillLayout());
        final GridData gd = new GridData(SWT.FILL, SWT.FILL, true, true);

        // Comment this out
        if (content.size() > 20) {
        GC gc = new GC(parent);
        gd.heightHint = gc.getFontMetrics().getHeight() * 20;
        }
        // End of comment

        fill.setLayoutData(gd);

        final org.eclipse.swt.widgets.List box = new org.eclipse.swt.widgets.List(fill, SWT.V_SCROLL | SWT.SINGLE);
        box.addSelectionListener(new SelectionAdapter() {

        @Override
        public void widgetSelected(final SelectionEvent e) {
            box.setSelection(new int[] {});
        }
        });

        for (final String row : content) {
        box.add(row);
        }
        w = fill;
    }

    void setEmpty() {
        disposeWidget();
        final Label a = new Label(parent, SWT.NONE | SWT.WRAP);
        a.setText(emptyIndicator);
        w = a;
    }

    void disposeWidget() {
        if (w != null) {
        w.dispose();
        }
    }
    }
}

Answer 1

您还没有在keywordList Composite 上设置布局数据，因此它的布局尽可能小。

keywordList.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));

有效。

注意:在调试布局时将 SWT.BORDER 指定为复合样式通常会有所帮助，这样您就可以看到它们占用的空间(o 设置背景颜色)。