CODEWITHSUNDEEP
javaswt
Link19
Link19

Reputation: 606

ScrolledComposite rendering incorrectly when adding a large amount of content

When trying to add a lot of labels on to a Composite that is contained in a ScrolledComposite after a certain number (1638) for me, it just seems to give up and stop drawing the components after it. Is this a hard limit on a number of things that can be displayed or something I'm doing wrong.

This also happens if I just add one label with 2000 lines of text in.

public class LoadsOfLabelsTestDialog extends Dialog
{
    List<Label> displaylabels = new ArrayList<>();
    Composite content, list;
    ScrolledComposite scroll;

    public LoadsOfLabelsTestDialog(Shell parentShell)
    {
        super(parentShell);
    }

    @Override
    protected void configureShell(Shell shell)
    {
        super.configureShell(shell);
        shell.setSize(new Point(700, 500));
        shell.setText("FML"); //$NON-NLS-1$
    }

    @Override
    public Control createDialogArea(final Composite comp)
    {
        content = (Composite) super.createDialogArea(comp);
        content.setLayout(new GridLayout(1, false));
        content.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));

        Button set1 = new Button(content, SWT.PUSH);
        set1.setText("Display List 1");
        set1.addSelectionListener(new SelectionAdapter() {

            @Override
            public void widgetSelected(SelectionEvent e) {
                List<String> rows = new ArrayList<>();
                for (int i = 0; i < 2000; i++) {
                    rows.add(i +" row");
                }
                updateList(rows);
            }
        });




        scroll = new ScrolledComposite(content, SWT.V_SCROLL);
        list = new Composite(scroll, SWT.NONE);
        list.setLayout(new GridLayout(1, true));

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

        scroll.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, true));
        new Label(content, SWT.HORIZONTAL | SWT.SEPARATOR);
        setScrollSize();
        return content;
    }

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

    private void updateList(List<String> rows) {
        if (this.displaylabels == null) {
            this.displaylabels = new ArrayList<>();
        }
        for (Label l : displaylabels) {
            l.dispose();
        }
        this.displaylabels.clear();


        for (String item : rows) {
            addListLabel(item);
        }
        content.layout(true, true);
        setScrollSize();
    }

    private void addListLabel(String whoText) {
        Label a = new Label(list, SWT.NONE);
        a.setText(whoText);
        this.displaylabels.add(a);
    }

    public static void main(String[] args)
    {
        Display d = new Display();
        Shell s = new Shell();

        LoadsOfLabelsTestDialog fml = new LoadsOfLabelsTestDialog(s);
        fml.open();
    }

}

Upvotes: 0

Views: 49

Answers (1)

R&#252;diger Herrmann
R&#252;diger Herrmann

Reputation: 20985

You hit a hard limit, probably the maximum size of a control. While this limit may differ slightly on other platforms, you can't size a control arbitrarily.

As @greg-449 suggested, prefer using a Table. If the content per table row is more than just an image and text, you can add a paint listener to draw the row contents yourself.

Upvotes: 1

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