Java - Set JPanel to fixed size and scale it to window

Question

I want my JPanel to be fixed size of 800x600, but if JFrame size changes, JPanel will scale, keeping original size of 800x600. For example, if I draw a string on JPanel, and stretch window 2 times, string will be stretched 2 times too.

I tried

g2d.scale(frame.getWidth() / 800, frame.getHeight() / 600);

But if I change width of frame to 0.5, the color on background (used g2d.fillRect after g2d.scale ) will cover only half of frame.

Answer 1

First thing i can say in Swing, never paint by yourself and use LayoutManager for layouting. When you really have to draw by yourself, create a new Graphics2d from the original and dispose after usage. On this Graphics you can set your properties.

At first i would consider putting the Panel in a BorderLayout(Center) inside the Frame. Without your code its quite hard to know how to help you.

Answer 2

Found a solution to this problem.

Created BufferedImage at creation of Panel, ie

bimg = new BufferedImage(800, 600, BufferedImage.TYPE_INT_RGB);

Got graphics out of it, ie

g2d = bimg.createGraphics();

Performed all drawing operations on it, then drawn the scaled image on JPanel.

    g.drawImage(bimg, 0, 0, getWidth(), getHeight(), null);

(Where getXX() returns XX of panel). After resizing the window, it clearly looks that background and string, drawn on BufferedImage, are stretched, keeping original size same.