The point is that I want to be able to draw to an image thus creating my custom rendering canvas. The image is then to be placed into a custom GUI window. Thus the result will be a window inside my program, which holds an area, dedicated for graphical output. The main idea is to create a resizable and moveable rendering viewport inside my main programs window... How can I do this? Is there any better way than rendering to an image?

EDIT: I have found that an instruction like

PGraphics pg = createGraphics();

might save me but it confuses me that the reference says that the createGraphics() method returns Pimage!!! So should I manage to use these methods somehow? I want to be able to use the standard line(), image() and other functions for this my custom context..