画圈

Question

How to draw four circles in java, so all four are in the angles of panel?I have radius a, but my main problem is to find coordinates of upper left point of rectangle. I found this for the down left corner:

g.fillOval(0-(2*a/2-((int)(2*a/2*Math.sqrt(2)/2))),0-(2*a/2-((int)(2*a/2*Math.sqrt(2)/2))), 2*a, 2*a).

Is there easiest way?

Answer 1

so all four are in the angles of panel

Do you mean the 4 corners of the panel?

If so, then you know:

1. the size of your circle because you are painting the circle
2. the width/height of the panel by using the getWidth() and getHeight() methods of the panel.

but my main problem is to find coordinates of upper left point of rectangle

Painting the upper left is easy since the circle will always start at (0,0).

So in the paintComponent(...) method the code would be:

g.FillOval(0, 0, circleWidth, circleHeight);

To paint the circle at the bottom/left you also know the x value will be 0, so you only need to calculate the y value which will be:

int y = getHeight() - circleHeight;
g.fillOval(0, y, circleWidth, circleHeight);

The same basic logic will apply for the top/right and bottom/right.