Description Jim Hayes 2009-05-13 14:42:32 EDT

Created attachment 135654 [details]
screenshot of example

Eclipse build id or SWT version: SWT 3.4.2

Platform(s) tested on: Windows XP

Snippet title: A Re-sizable Text Field Example.

Snippet code:

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.ModifyEvent;
import org.eclipse.swt.events.ModifyListener;
import org.eclipse.swt.graphics.FontMetrics;
import org.eclipse.swt.graphics.GC;
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.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;

public class ResizableTextExample extends Composite {

    // maximum number of lines in the re-sizable text field.
    private int maxLineCount = 15;
    // minimum number of lines in the re-sizable text field.
    private int minLineCount = 3;
    // the width of the re-sizable text field.
    private int width = 500;
    // the height of a row of text.
    private int fontHeight;

    public ResizableTextExample(Composite parent, int style) {
        super(parent, style);

        setLayout(new GridLayout(2, false));

        // ///////////////////////////////////////////////////////////////
        // Add some stuff before the re-sizable text.
        // ///////////////////////////////////////////////////////////////

        Label label1 = new Label(this, SWT.NONE);
        label1.setText("A non-resizable text field:");

        Text text1 = new Text(this, SWT.MULTI | SWT.BORDER 
                | SWT.H_SCROLL | SWT.V_SCROLL);
        text1.setText("non-resizable text non-resizable text"
                        + "\nnon-resizable text non-resizable"
                        + "\nnon-resizable text non-resizable");
        text1.setLayoutData(new GridData(width, 100));

        // ///////////////////////////////////////////////////////////////
        // Add the re-sizable text
        // ///////////////////////////////////////////////////////////////

        Label label2 = new Label(this, SWT.NONE);
        label2.setText("The resizable text field:");

        final Text resizableText = new Text(this, SWT.BORDER
                | SWT.MULTI | SWT.H_SCROLL | SWT.V_SCROLL);
        resizableText.setText("This text field will become larger as you add lines of text,"
                + "\nand smaller as you remove lines of text."
                + "\nThis text field will become larger as you add lines of text,"
                + "\nand smaller as you remove lines of text.");

        // Figure out how tall the font is. We use this value to determine how
        // large to make the text field.
        GC gc = new GC(resizableText);
        FontMetrics fm = gc.getFontMetrics();
        fontHeight = fm.getHeight();

        updateTextSize(resizableText);

        // Add a modify listener to the text field so that we can 
        // resize it whenever the contents change.
        resizableText.addModifyListener(new ModifyListener() {
            public void modifyText(ModifyEvent e) {
                if (updateTextSize(resizableText)) {
                    // re-layout the composite because the size of 
                    // the field has changed.
                    layout();
                }
            }
        });

        // ///////////////////////////////////////////////////////////////
        // Add some stuff after the re-sizable text.
        // ///////////////////////////////////////////////////////////////

        Label label3 = new Label(this, SWT.NONE);
        label3.setText("A non-resizable text field:");

        Text text3 = new Text(this, SWT.MULTI | SWT.BORDER 
                | SWT.H_SCROLL | SWT.V_SCROLL);
        text3.setText("non-resizable text non-resizable text"
                        + "\nnon-resizable text non-resizable text"
                        + "\nnon-resizable text non-resizable text");
        text3.setLayoutData(new GridData(width, 100));
    }

    private boolean updateTextSize(Text resizableText) {
        int lineCount = resizableText.getLineCount();
        
        // Add a line so that there will always be a blank line after the last line.
        lineCount++;

        // Limit the height of the text field to a minimum and maximum.
        int height;
        if (lineCount > maxLineCount) {
            height = maxLineCount * fontHeight;
        }
        else if (lineCount < minLineCount) {
            height = minLineCount * fontHeight;
        }
        else {
            height = lineCount * fontHeight;
        }
        
        // See if the new size is different from the current size.
        // The size of the text only changes when lines are added or removed, 
        // so we usually do not need to resize.
        GridData gridData = (GridData) resizableText.getLayoutData();        
        if (gridData != null && gridData.widthHint == width 
                && gridData.heightHint == height) {
            return false;
        }

        resizableText.setLayoutData(new GridData(width, height));
        return true;
    }

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

        // Add the UI to the shell.
        new ResizableTextExample(shell, SWT.NONE);

        shell.setSize(800, 600);
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
        display.dispose();
    }
}