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From: Cecil Westerhof <Cecil@decebal.nl>
Newsgroups: comp.lang.java.programmer
Subject: Making a cross-hair visible
Date: Thu, 11 Aug 2016 23:14:34 +0200
Organization: Decebal Computing
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I am dabbling with Swing to do some GUI stuff. This is relatively new
for me. At the moment I draw a rectangle for cropping an image. The
position is selected by clicking on the centre from where I think the
rectangle should be placed. This can be a little of, so I have to
fine-tune it. For this I draw a little cross in the centre. Problem is
that I paint it in black and when the centre is black, I will not see
it. And with every colour I choose I can have this problem. Is there a
smart way to make the cross always visible?

I was thinking about a timer function which would alternate the colour
of the cross between black and white, but was wondering if there is a
better way.

At the moment my code is:
    protected void paintComponent(Graphics g) {
        Graphics2D g2       = (Graphics2D) g;
        int        centerX  = x + cropWidth  / 2;
        int        centerY  = y + cropHeight / 2;

        super.paintComponent(g);
        g2.setStroke(stroke);
        g.setColor(rectColor);
        g.drawImage(image, 0, 0, imageWidth, imageHeight, null);
        g.drawRect(x, y, cropWidth, cropHeight);
        g.drawLine(centerX - crossLength, centerY, centerX + crossLength, centerY);
        g.drawLine(centerX, centerY - crossLength, centerX, centerY + crossLength);
    }

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof