Steps to customize Android controls

Original intention of learning: During the actual development process of work, the original Android controls can no longer meet the actual functional needs, and some applications also require some unique display effects. At this time, custom controls are needed to customize the controls to meet our needs.

Steps to customize the control

Step 1: First, create a new class CustomView inherits from View

public class CustomView extends View{}

Step 2: Add a constructor, using the constructor with the AttributeSet parameter

public CustomView(Context context,AttributeSet attrs){
  //Attribute attribute, custom attributes set in the layout file  //attrs must be passed to the parent class so that the parent class knows the specific parameters to be drawn  super(context,attrs);
}

Step 3: Draw the interface and rewrite the onDraw() method

@Override
protected void onDraw(Canvas canvas){
  //Draw the background and create a new brush  Paint pain=new Paint();
  (48);
  ();
  //Create a rectangle, at this time, you need the width and height of a rectangle. The values of viewWidth and viewHeight are obtained through the following steps  Rect rect=new Rect(0,0,viewWidth,viewHeight);
  //Draw a rectangle, the parameters are rectangle objects and brush objects  (rect,paint);
}

Step 4: Obtain the width and height of an interface

int viewHeight,viewWidth;
@Override
protected void onSizeChanged(int w,int h,int oldw,int oldh){
  //When the interface changes, that is, the current width and height when cutting the screen  (w,h,oldw,oldh);
  viewHeight=h;
  viewWidth=w;
}

Finally, I got a picture with a red background

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