Android Shader application development: neon flashing text effect

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/**
 * Created by apple on 2017/5/10.
 */

public class LinearGradientTextView extends TextView {
 private TextPaint mPaint;

 private LinearGradient mLinearGradient ;
 private Matrix mMatrix;

 private float mTranslate;
 private float DELTAX = 20;
 private int mGradientSize;

 public LinearGradientTextView(Context context) {
  super(context);
 }

 public LinearGradientTextView(Context context, @Nullable AttributeSet attrs) {
  super(context, attrs);
 }

 /**
   * Priority is given to onDraw execution, here we get the brush that system draws TextView, and then set a shader for this brush
   * In this way, when executing onDraw, you use a brush with a Shader effect.
   * @param w
   * @param h
   * @param oldw
   * @param oldh
   */
 @Override
 protected void onSizeChanged(int w, int h, int oldw, int oldh) {
  (w, h, oldw, oldh);
  // ★Get the brush of the system TextView  mPaint = getPaint();
// Get text  String text = getText().toString();
// Use a brush to measure the length of the text  float textWith = (text);
  // Width of 3 text  mGradientSize = (int) (textWith / () * 3);

  // Start from the left-gradientSize, that is, the left-hand distance from the text gradientSize starts to change.  // A gradient unit is: start from the distance between 3 characters before the first character and end before the first character  //Then keep moving the gradient unit from left to right dx displacement until the rightmost side and move to the left  // CLAMP means: Since you are only changing the length of 3 characters in the gradient, then the remaining space is filled with the edge color  mLinearGradient = new LinearGradient(-mGradientSize,0,0,0,new int[]{
    0xffff0000, 0xff00ff00, 0xff00ffff},null, 
  );

  (mLinearGradient);
 }

 @Override
 protected void onDraw(Canvas canvas) {
// Call super, which means to complete the textview drawing first according to the process of drawing the textview in the system  (canvas);

// I will draw some effects based on the system

  mTranslate += DELTAX;
  float textWidth = getPaint().measureText(getText().toString());
// When it reaches the boundary dx, reverse  if(mTranslate > textWidth + mGradientSize || mTranslate < 0){
   DELTAX = - DELTAX;
  }
// Continuously translate to get a flashing effect  mMatrix = new Matrix();
  (mTranslate, 0);
  (mMatrix);
// Delay repaint  postInvalidateDelayed(50);

 }
}