Drawing lines, rectangles and circles as objects onto a JPanel.

Question

Hi. I have to complete a task in school. The work is to create some simple 2D graphical editor. I'm new to java and I have some problems with this job, so I'm looking for help where it is possible...
I created a JFrame and using it as a window. Into this JFrame I've added a toolbox (JToolBox) and "drawpad" - a JPanel. The toolbox wasn't any problem, but I aim to use the JPanel for drawing 2D objects. I tought about creating some container of objects, where I could put lines, rectangles or circles, each one with its properties (color, [x; y] coordinates on the scene, filling and drawing width) and then, draw this scene onto the JPanel.
It should be something like windows Paintbrush. Can be simplier, but including the possibility to move and change properties of drawn objects.

Answer 1

Well, there are two approaches to this that come to mind:
1. Create an image. If this program is supposed to be like Windows Paint, the tools you are describing are only there for the sake of modifying a two dimensional image. In that case, I would recommend using a BufferedImage.
The JPanel can contain a single JLabel. The JLabel is constructed in the following fashion:
JLabel image_label = new JLabel(new ImageIcon(bufferedImage));...where bufferedImage is the image on which you will be storing the data. You can use bufferedImage.getGraphics() to get an object which will quite happily draw geometric shapes for you. Then, after each draw, you tell the panel to repaint itself.
2. Store the shapes and create a component to draw them for you. You'd create a new JComponent class that would accept objects representing geometric shapes. You then override the paintComponent method on this new class to have it render itself according to the contents of the geometry objects. It would also probably be advisable to have all of these classes implement a common interface (which you would also create) so the rendering component could treat them identically.