Imitation WeChat radar scanning

Source code introduction: Imitate WeChat radar scanning, imitate Android WeChat, cloud broadcast radar scanning animation effect. Click the black circle in the middle to start the scanning animation, and click again to reset. Friends who need this effect can download it and have a look.

Source code effect:

Source code snippet:

 package com.example.tz_demo_8_7; 
  
 import android.content.Context;
 import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Matrix;
 import android.graphics.Paint;
 import android.graphics.Paint.Style;
 import android.graphics.Shader;
 import android.graphics.SweepGradient;
 import android.os.Handler;
 import android.util.AttributeSet;
 import android.widget.FrameLayout; 
  
 public   class MyRadarView extends FrameLayout { 
      
 private Paint mPaintNormal; // Brush for drawing normal circles and lines  
 private Paint mPaintCircle; // Draw a gradient circle  
 private   int w,h; // width and height of the mobile phone screen, width and height of the parent container of the radar view  
 private Matrix matrix;
 private Handler handler= new Handler();
 private   int start;
 private Runnable r= new Runnable() { 
          
 @Override  
 public   void run() {
 // Execute the loop rotation animation and refresh the UI  
 start=start+ 2 ;
            matrix= new Matrix();
 matrix.postRotate(start, w/ 2 , h/ 2 ); // Set the canvas rotation  
 MyRadarView. this .invalidate(); // Refresh UI  
            handler.postDelayed(r, 20 );
 }
 }; 
      
  
 public MyRadarView(Context context, AttributeSet attrs) {
 super (context, attrs);
 // Initialize the brush  
 initPaint();
        setBackgroundResource(R.drawable.bg);
 // Get the width and height of the mobile phone screen  
 this .w=context.getResources().getDisplayMetrics().widthPixels;
 this .h=context.getResources().getDisplayMetrics().heightPixels;
 handler.post(r);
 } 
  
 /**
     * @author Xubin Single QQ:215298766
 */  
 private   void initPaint() {
 mPaintNormal = new Paint(); // Create a brush  
        mPaintNormal.setColor(Color.parseColor( "#A1A1A1" ));
 mPaintNormal.setStrokeWidth( 3 ); // Set the line  
 mPaintNormal.setAntiAlias( true ); // Set anti-aliasing  
        mPaintNormal.setStyle(Style.STROKE); 
          
 // Draw a gradient circle  
        mPaintCircle= new Paint();
 mPaintCircle.setColor( 0x9D00ff00 ); // Hexadecimal  
        mPaintCircle.setAntiAlias( true );
 } 
      
 /**
 * Measure the width and height of the control
 */  
 @Override  
 protected   void onMeasure( int widthMeasureSpec, int heightMeasureSpec) {
 // Set the width and height of this view  
        setMeasuredDimension(w, h);
 } 
      
 /**
 * Determine the view of the control
 */  
 @Override  
 protected   void onDraw(Canvas canvas) {
 // Screen center, x:w/2, y:h/2  
 canvas.drawCircle(w/ 2 , h/ 2 , w/ 6 , mPaintNormal); // Draw a small circle  
 canvas.drawCircle(w/ 2 , h/ 2 , 2 *w/ 6 , mPaintNormal); // Draw the circle  
 canvas.drawCircle(w/ 2 , h/ 2 , 11 *w/ 20 , mPaintNormal); // Draw the large circle  
 canvas.drawCircle(w/ 2 , h/ 2 , 7 *h/ 16 , mPaintNormal); // Draw a large circle   
          
 // Draw a gradient circle  
        Shader shader= new SweepGradient(w/ 2 , h/ 2 , Color.TRANSPARENT, Color.parseColor( "#AAAAAAAAA" ));
        mPaintCircle.setShader(shader);
        canvas.concat(matrix);
 canvas.drawCircle(w/ 2 , h/ 2 , 7 *h/ 16 , mPaintCircle); //Draw a gradient circle   
          
 super .onDraw(canvas);
 }
 }