Android Bitmap 倒影

public Bitmap invertedImg() {//1. 倒立图Matrix matrix = new Matrix();matrix.preScale(1, -1);int w = mBitmap.getWidth();int h = mBitmap.getHeight();Bitmap reflectionImg = Bitmap.createBitmap(mBitmap, 0, h / 2, w, h / 2, matrix, false);//2. 要生成原图加倒立图，先生成一个可变的Bitmap，高度为1.5倍原hint gap = 10; //间隙 空白Bitmap newBitmap = Bitmap.createBitmap(w, h + h / 2 + gap, Bitmap.Config.ARGB_8888);Paint paint = new Paint();Canvas canvas = new Canvas(newBitmap);canvas.drawBitmap(mBitmap, 0, 0, paint);  //绘制原图canvas.drawBitmap(reflectionImg, 0, h + gap, paint); //绘制倒立图//3. 画笔使用 LinearGradient 线性渐变渲染LinearGradient lg = new LinearGradient(0, h + gap, w, newBitmap.getHeight(), 0xabff0000,0x00ffff00, Shader.TileMode.MIRROR);paint.setShader(lg);//4. 指定画笔的Xfermode  即绘制的模式(不同的模式，绘制的区域不同)paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_ATOP));//5. 在倒立图区，绘制矩形渲染图层canvas.drawRect(0, h + gap, w, newBitmap.getHeight(), paint);paint.setXfermode(null);return newBitmap;
}