Overview of Graphics 2D

To make the Graphics 2D API portable across platform, the API is designed indepandant on any native graphics system (like LCDUI or LWUIT etc). It's "Canvas" actaully is a 2 demension integer arrary.

The constructor Graphics2D(int width,int height) creates an internal buffer of type 32-bit integer ,each element is a ARGB value ,stand for one pixel.

All the drawing primitives like draw a line, fill a rectange etc is actually modifying pixel (ARGB value) in the 2 demesional array.
After all rendering work is done, call Graphics2D.getRGB() to get the int [] buffer, and then call any native render method to actually render the buffer to the physical device screen.

so typical usage of Graphics 2D API is as following

 Graphics2D graphics2d=new Graphics2D(width,height)
graphics2d.clear(backgroundColor)
...any render primitives

int []rgb=graphics2d.getRGB();

//call native graphics to render the buffer to screen
graphics.drawImage(rgb, ...);