when does the View.ondraw method get called
a View's onDraw() is called when:
- The view is initially drawn
- Whenever invalidate() is called on the view
Invalidate can be called by you or the system whenever needed. For example, a lot of Views change how they look onTouch, like an EditText getting an outline and cursor, or a button being in the pressed state. Due to this, Views are redrawn on touch.
I agree that it would be nice to have a document that detailed the working of Views, and if one exists and somebody knows where to find it, please let us know.
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If you set a background drawable for a View, then the View will draw it for you before calling back to its onDraw() method.
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onAttachedToWindow () is called when the view is attached to a window. At this point it has a Surface and will start drawing. Note that this function is guaranteed to be called before onDraw(android.graphics.Canvas), however it may be called any time before the first onDraw -- including before or after onMeasure(int, int).
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invalidate() mark the area defined by dirty as needing to be drawn. If the view is visible, onDraw(android.graphics.Canvas) will be called at some point in the future.
see also:
http://stackoverflow.com/questions/11912406/view-ondraw-when-does-it-get-called
posted on 2013-10-20 20:59 malaikuangren 阅读(173) 评论(0) 编辑 收藏 举报