在JFrame的玻璃窗格上使用paintComponent（Graphics g）

Question

I am trying to draw on the glass pane part of a JFrame with a marker using g.fillPolygon(xValues, yValues, numPoints) after making the background of the JFrame transparent.

I am using a method to find the location of the cursor and can get the right locations. To force the call of paintComponent(Graphics g) , I am using myGlassPane.repaint() but this deletes the previous part of the segment that I drew.

I am wondering if there is a way to retain what was previously drawn through the paintComponent(Graphics g) method.

Answer 1

I am wondering if there is a way to retain what was previously drawn through the paintComponent(Graphics g) method.

Yes, add whatever you drew before either to a BufferedImage or a List which can allow you to create it...

For example

• Trouble with JApplets and calling paint/paintComponent
• Calling paintComponent() with parameters using repaint()
• MouseEvent is not registering a release when I release the mouse button
• Drawing a rectangle that won't disappear in next paint