Java2d: Translate the axes

Question

Hi,

I am developing an application using Java2d. The weird thing I noticed is, the origin is at the top left corner and positive x goes right and positive y increases down.

Is there a way to move the origin bottom left?

Thank you.

Answer 1

Have you tried Graphics2D.translate()?

Answer 2

You are going to need to do a Scale and a translate.

in your paintComponent method you could do this:

public void paintComponent(Graphics g)
{
    Graphics2D g2d = (Graphics2D) g;
    g2d.translate(0, -height);
    g2d.scale(1.0, -1.0);
    //draw your component with the new coordinates

    //you may want to reset the transforms at the end to prevent
    //other controls from making incorrect assumptions
    g2d.scale(1.0, -1.0);
    g2d.translate(0, height);
}

my Swing is a little rusty but this should accomplish the task.

Answer 3

You're going to want to just get used to it. Like luke mentioned, you technically CAN apply a transform to the graphics instance, but that will end up affecting performance negatively.

Just doing a translate could move the position of 0,0 to the bottom left, but movement along the positive axes will still be right in the x direction and down in the y direction, so the only thing you would accomplish is drawing everything offscreen. You'd need to do a rotate to accomplish what you're asking, which would add the overhead of radian calculations to the transform matrix of the graphics instance. That is not a good tradeoff.