[Points]Canvas and Drawables

origin article: http://developer.android.com/guide/topics/graphics/2d-graphics.html

translation: http://www.cnblogs.com/jsaint/articles/3427728.html

Draw style

• bind layout view
• canvans draw

On the View

1. do draw in View onDraw() function
2. invalidate() request system call onDraw
3. postInvalidate() not in Ui thread

On a SurfaceView

• async draw

Drawables

creaet function

• saved as res images
• create in xml(AnimationDrawable and so on)
• new using constructors
• notice image res may be automatically compression if you do not want put in res/raw/

create form resource images

• using resouce id (both in code and xml)

drawables

• ShapeDrawable(basic shape)
• NinePatchDrawable(can be stretch)