When drawing on my extended JPanel I want the size to be variable. I've worked out the code to always outline a 1 pixel margin. My code works but I don't understand why I must adjust the height and width and height of the dimension by -1 when drawing the rectangle.
If I draw a rectangle that has 1,1 as a size it draws a single pixel square so shouldn't drawing the width and the height work without the -1 modifier.
If any one can explain why there is a discrepancy between the size of my extended JPanel or explain a better way to get the exact dimensions of the drawing area I would appreciate it.
public class Engine extends JPanel {
Engine(){
}
@Override
public void paintComponent(Graphics g){
Dimension a = this.getSize();
g.setColor(Color.RED);
g.drawRect(0, 0, a.width-1, a.height-1);
}
}
Remember, most values are 0 based. But instead of having to say, " I want the width of my panel to be 199" so you get a panel that is 200 pixels wide (0-199), Swing allows you to specify 1 based values and makes adjustments internally
If you create a rectangle of 1, 1, 1, 1, your actually creating a rectangle at position 1x1, whose width & height is 1 pixel (1 + 1 would be 2)