Android文本视图的颜色滚动效果

public class FlashTextView extends android.support.v7.widget.AppCompatTextView { 
 private Paint mPaint; 
 private int mViewWidth; 
 private LinearGradient mLinearGradient; 
 private Matrix mGradientMatrix; 
 private int mTransalte; 
 
 public FlashTextView(Context context, @Nullable AttributeSet attrs) { 
  super(context, attrs); 
 } 
 
 @Override 
 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 
  super.onSizeChanged(w, h, oldw, oldh); 
  if (mViewWidth == 0) { 
   mViewWidth = getMeasuredWidth(); 
   if (mViewWidth > 0) { 
    mPaint = getPaint();//获得当前绘制的Paint对象 
    mLinearGradient = new LinearGradient( 
      0,//渐变起始点x坐标 
      0,//渐变起始点y坐标 
      mViewWidth,//渐变结束点x点坐标 
      0,//渐变结束点y坐标 
      new int[]{ 
        Color.BLUE, 0xffffffff, 
        Color.BLUE,Color.RED,Color.YELLOW},//颜色的int数组 
      null,//相对位置的颜色数组,可为null, 若为null,可为null,颜色沿渐变线均匀分布 
      Shader.TileMode.MIRROR);//平铺模式 
    mPaint.setShader(mLinearGradient);//给这个paint设置linearFradient属性 
    mGradientMatrix = new Matrix(); 
   } 
  } 
 } 
 
 @Override 
 protected void onDraw(Canvas canvas) { 
  super.onDraw(canvas); 
 
  if (mGradientMatrix != null) { 
   mTransalte += mViewWidth / 5; 
   if (mTransalte > 2 * mViewWidth) { 
    mTransalte -= mViewWidth; 
   } 
   mGradientMatrix.setTranslate(mTransalte, 0); 
   mLinearGradient.setLocalMatrix(mGradientMatrix);//通过矩阵的方式不断平移产生渐变效果 
   postInvalidateDelayed(100); 
 
  } 
 
 } 
}