android how to draw on a canvas through touch events

I want to make android-screen as white-board so that by touch on screen I able to draw something on screen. I know I have to use canvas, Path all these things. But how I can make that screen so that i able to draw a dot there? For that what should i do开发者_开发百科 with my activity? How can I do that plz give me some sample code.

Thank you

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So maybe you should take a look to this example:

http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/graphics/TouchPaint.html