前一段时间用LinearGradient（线性渐变） 写了一个颜色变化闪动的文字控件和文字进度条http://blog.csdn.net/huweigoodboy/article/details/43088953，
最近在github上看到一个开源控件Titanic，特拿来分析一下，效果如下图：
private void createShader() {
if (wave == null) {
wave = getResources().getDrawable(R.drawable.wave);
}
int waveW = wave.getIntrinsicWidth();
int waveH = wave.getIntrinsicHeight();
Bitmap b = Bitmap.createBitmap(waveW, waveH, Bitmap.Config.ARGB_8888);
Canvas c = new Canvas(b);
c.drawColor(getCurrentTextColor());
wave.setBounds(0, 0, waveW, waveH);
wave.draw(c);
shader = new BitmapShader(b, Shader.TileMode.REPEAT, Shader.TileMode.CLAMP); //设置着色器的TileMode
getPaint().setShader(shader);
offsetY = (getHeight() - waveH) / 2; //计算偏移Y 默认放在textView的中间
}
@Override
protected void onDraw(Canvas canvas) {
// modify text paint shader according to sinking state
if (sinking && shader != null) {
// first call after sinking, assign it to our paint
if (getPaint().getShader() == null) {
getPaint().setShader(shader);
}
// translate shader accordingly to maskX maskY positions
// maskY is affected by the offset to vertically center the wave
shaderMatrix.setTranslate(maskX, maskY + offsetY); //平移变换，设置着色图片的坐标 ，maskX，maskY为shader的坐标变换值
// assign matrix to invalidate the shader
shader.setLocalMatrix(shaderMatrix);
} else {
getPaint().setShader(null);
}
super.onDraw(canvas);
}3，属性动画 // horizontal animation. 200 = wave.png width
//x方向上的变化,变换范围是从0-waveW
ObjectAnimator maskXAnimator = ObjectAnimator.ofFloat(textView, "maskX", 0, 200);
maskXAnimator.setRepeatCount(ValueAnimator.INFINITE); //变换次数设为不限制
maskXAnimator.setDuration(1000);
maskXAnimator.setStartDelay(0);
int h = textView.getHeight();
// vertical animation
// maskY = 0 -> wave vertically centered
// repeat mode REVERSE to go back and forth
//y方向是h/2 -> -h/2，折合偏移量，就是从textView底部到顶部。
ObjectAnimator maskYAnimator = ObjectAnimator.ofFloat(textView, "maskY", h/2, - h/2);
maskYAnimator.setRepeatCount(ValueAnimator.INFINITE);
maskYAnimator.setRepeatMode(ValueAnimator.REVERSE);
maskYAnimator.setDuration(10000);
maskYAnimator.setStartDelay(0);原文地址：http://blog.csdn.net/huweigoodboy/article/details/45369123
