SWT: Get sub image from image

Question

Assuming I have the Rectangle selection (x,y, width and height). Is it possible to get a Sub Image from an image in Java SWT?

I have an Image on a Canvas . The user selects a section of the image. I would like to replace the image with the users selection.

I cannot find a way to achieve this. Is the problem that I am using a Canvas ?

Update: This is my current method of doing it using drawImage. I guess this is a bit of a hack as I am not getting a Subset of the image and creating a new image - I am just drawing part of the Image:

            int minX = Math.min(startX, endX);
            int minY = Math.min(startY, endY);

            int maxX = Math.max(startX, endX);
            int maxY = Math.max(startY, endY);

            int width = maxX - minX;
            int height = maxY - minY;
            gc.drawImage(image, minX, minY, width, height, image.getBounds().x,  
            image.getBounds().y, image.getBounds().width, image.getBounds().height );

Answer 1

You can use the method Canvas#copyArea(Image, int, int) to copy just the area you're interested in to the given Image . Then set the Image to the Label :

private static boolean drag = false;

private static int xStart;
private static int yStart;

private static int xEnd;
private static int yEnd;
private static Image outputImage = null;

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

    Image inputImage = new Image(display, "baz.png");
    Label output = new Label(shell, SWT.NONE);

    Canvas canvas = new Canvas(shell, SWT.DOUBLE_BUFFERED);

    canvas.addListener(SWT.Paint, e -> e.gc.drawImage(inputImage, 0, 0));

    canvas.addListener(SWT.MouseDown, e -> {
        xStart = e.x;
        yStart = e.y;
        drag = true;
    });

    canvas.addListener(SWT.MouseUp, e -> {
        drag = false;

        int x = Math.min(xStart, xEnd);
        int y = Math.min(yStart, yEnd);

        if (outputImage != null && !outputImage.isDisposed())
            outputImage.dispose();

        outputImage = new Image(display, new Rectangle(x, y, Math.abs(xEnd - xStart), Math.abs(yEnd - yStart)));
        GC gc = new GC(inputImage);

        gc.copyArea(outputImage, x, y);
        output.setImage(outputImage);

        gc.dispose();
    });
    canvas.addListener(SWT.MouseExit, e -> drag = false);

    canvas.addListener(SWT.MouseMove, e -> {
        if (drag)
        {
            xEnd = e.x;
            yEnd = e.y;
        }
    });

    shell.pack();
    shell.open();

    while (!shell.isDisposed())
    {
        if (!display.readAndDispatch())
            display.sleep();
    }
    display.dispose();
    inputImage.dispose();
    if (outputImage != null && !outputImage.isDisposed())
        outputImage.dispose();
}

Looks like this: