CODEWITHSUNDEEP
javaswing
Get Off My Lawn
Get Off My Lawn

Reputation: 36351

Getting a JPanel graphics color is always the same color

I have a vertical color bar, it has 7 main colors all combined as a gradient. I then take that and paint it to a JPanel like this:

@Override
public void paintComponent(Graphics g){
    super.paintComponent(g);
    Graphics2D g2d = (Graphics2D)g;
    int w = getWidth();
    int h = getHeight();

    Point2D start = new Point2D.Float(0, 0);
    Point2D end = new Point2D.Float(0, h);
    float[] dist = {
        0.02f,
        0.28f,
        0.42f,
        0.56f,
        0.70f,
        0.84f,
        1.0f
    };

    Color[] colors = {
        Color.red,
        Color.magenta,
        Color.blue,
        Color.cyan,
        Color.green,
        Color.yellow,
        Color.red
    };

    LinearGradientPaint p = new LinearGradientPaint(start, end, dist, colors);

    g2d.setPaint(p);
    g2d.fillRect(0, 0, w, h);
}

I then have have a click event in the same class, which looks like this:

public void mouseClick(MouseEvent evt){
    BufferedImage img = (BufferedImage)this.createImage(getWidth(), getHeight());
    int[] colors = new int[3];
    int x = evt.getX();
    int y = evt.getY();
    img.getRaster().getPixel(evt.getX(), evt.getY(), colors);
    ColorPickerDialog.sldColor = new Color(colors[0], colors[1], colors[2]);
    getParent().invalidate();
    getParent().repaint();
}

The line img.getRaster().getPixel(evt.getX(), evt.getY(), colors); always returns the RGB colors:

And I can click anywhere, on the Red, Yellow, Green, Cyan, etc. and I always get those RGB colors back. Why?

Upvotes: 1

Views: 1093

Answers (2)

Get Off My Lawn
Get Off My Lawn

Reputation: 36351

I got it!

I replaced this line:

BufferedImage img = (BufferedImage)this.createImage(getWidth(), getHeight());

With this:

BufferedImage img = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB);
Graphics2D g = img.createGraphics();
this.paint(g);

And now it works perfectly!

Upvotes: 0

Sam Hazleton
Sam Hazleton

Reputation: 462

I think I see the problem. The line

img.getRaster().getPixel(evt.getX(), evt.getY(), colors);

returns an int[] corresponding to the RGB colors. The getPixel method takes in your array as a parameter, but it returns its own array. It never actually touches your array. what you want to do is this.

int[] colors = img.getRaster().getPixel(evt.getX(), evt.getY(), new int[3]);

that should store the return value of the method in your array instead of whatever it's default value is.

Upvotes: 3

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