CODEWITHSUNDEEP
javacanvasjscrollpane
Phat RedDevil
Phat RedDevil

Reputation: 73

JScrollPane not repaint Canvas when scrolling?

I trying to make a game where I add a Canvas to a JScrollPane but the canvas is larger than the visible area of the JScrollPane. So when I scroll the JScrollPane to see the rest I only see the blank area even though my Canvas is continuously redrawn. Anybody can help me??

Upvotes: 2

Views: 3711

Answers (3)

freecoder
freecoder

Reputation: 141

It is common JScrollPane problem. To fix this with minimum fuss, call the following methods on your JScrollPane:

scrollpane.getViewport().setScrollMode(JViewport.SIMPLE_SCROLL_MODE);

Upvotes: 10

user1352813
user1352813

Reputation: 1

You need to use a lightweight JPanel and 2 heavyweight objects like:

JPanel foreground = new JPanel();
Panel frame = new Panel();
Cavas canvas = new Cavas();
foreground.add(frame);
frame.add(canvas);

Heavyweight objects might be AWT, or SWT (with OLE), or mixed, it does not matter.

Then get JScrollPane and add AdjustmentListener which calls method like:

private void updateLocation() {
    final JScrollPane scroll = getScrollPane();
    if (null == scroll) {
        // do nothing
        return;
    }
    final Point top = getLocation();
    final Rectangle visible = getVisibleRect();

    // set up new location
    frame.setSize(visible.width, visible.height);
    frame.setLocation(visible.x - top.x, visible.y - top.y);
    canvas.setSize(getWidth(), getHeight());
    canvas.setLocation(top.x - visible.x, top.y - visible.y);
}

Upvotes: 0

user1288739
user1288739

Reputation: 66

Swing components do not work with heavyweight AWT components like Canvas. Use a JComponent or a JPanel instead of a Canvas

Upvotes: 3

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