LinearGradient lg=new LinearGradien(0,0,100,100,Color.RED,Color.BLUE,Shader.TileMode.MIRROR);
两种颜色渐变。
LinearGradient shader = new LinearGradient(0, 0, endX, endY, new int[]{startColor, midleColor, endColor},new float[]{0 , 0.5f, 1.0f}, TileMode.MIRROR);
多种颜色渐变