Graphics coordinates problem

[Jim Longmore]

Hi all,

I'm fiddling around with Swing, and decided to create a simple program that will graph a set of data you provide it. In order to do this, I created a subclass of JPanel so I could override the paint() method and use the Graphics class to draw lines etc straight to the panel. However, when I try to add it to my JFrame, and size it to the exact size of the JFrame, it extends over the edge of the JFrame, and the entire panel is only shown when I enlarge the frame to fit.

The code I'm using is below.

//Abridged version
JFrame frame = new JFrame("Grapher");
Graph graph = new Graph();
frame.setSize(200,200);
graph.setSize(frame.getSize().width, frame.getSize().height);
 
//Code below is in the paint method of Graph
gc.drawRect(1,1,this.getSize().width-1, this.getSize().height-1);

I'm not particularly experienced with Swing/AWT, so I may well be using methods incorrectly. Any help is appreciated.


Jim

[Craig Wood]

You do not need to call 'setSize' on 'graph'. The general practice is to limit the use of 'setSize' to top–level containers. You can let the JFrame maximize the size of your graphic component by adding it to the center section of the JFrames default BorderLayout.

Graph graph = new Graph();
JFrame frame = new JFrame("Grapher");
frame.add(graph);
frame.setSize(200,200);

[Jim Longmore]

I've changed tact slightly (now using panels and layout managers), now the only problem I'm having is still the co-ordinate thing. Where my problem lies (I'm guessing) is getting the width of a component? I've been using the getSize() method, but I'm self-taught, so I don't know what the standard practice is.

Any ideas?

[colin shuker]

I kind of get the same problem too, if I set a frame size as 500 by 500,
then using the mouse, you can see the grey area starts at x=4 to x=496(more or less), so I just compensate by using a wider frame.
I find using the mouse a good way to check your screen is the right size.
But I'm no expert either

[Jim Longmore]

Colin,

I think your problem might be solved by the use of the Inset class. The Inset class records the margins for a particular component, see the Java documentation for more details.

I may be wrong, but i guess its worth a try.