Custom Controls (3): How the View is drawn

Custom UI controls inherit the subclass of the view class or view and overload some methods in the view class without overloading, but at least overloading OnDraw ().

category	Method	Description
Creation	Constructors
	Onfinishinflate ()	This method is called after view and all its child objects are imported from XML
Layout	onmeasure (int, int)	View calls this method to confirm the size of itself and all child objects
	OnLayout (boolean, int, int, int, int, int, int)	This method is called when view wants to allocate size and position for all child objects
	onsizechanged (int, int, int, int)	This method is called when the view size changes
Drawing	OnDraw (Canvas)	This method is called when the view wants to draw its contents.
Event processing	OnKeyDown (int, keyevent)	This method is called when a new keystroke event occurs
	onKeyUp (int, keyevent)	This method is called when a key-release event occurs
	Onmotionevent (motionevent)	This method is called when an action event (such as touch) occurs
Focus	Onfocuschanged (boolean, int)	This method is called when the view Gets or loses focus
Attaching	Onattachedtowindow ()	This method is called when the view is attached to a form
	Ondetachedfromwindow ()	This method is called when the view leaves its form

View Drawing process: Onattachedtowindow, Onmeasrue, onsizechanged, OnLayout, OnDraw
Activity in drawing view: The root node reference to the hierarchy tree passed through the Setcontentview () activity is activated and gets focus---Request root node calculation and drawing tree The ViewGroup combines its own effective space with the layoutparams of the sub-view requirements to lay out the child view and call the child View's draw () method to draw the

Custom Controls (3): How the View is drawn