Android添加水印的正确方法只要三步!

 private static Bitmap createWaterMaskBitmap(Bitmap src, Bitmap watermark,
            int paddingLeft, int paddingTop) {
  if (src == null) {
   return null;
  }
  int width = src.getWidth();
  int height = src.getHeight();
  //创建一个bitmap
  Bitmap newBitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);// 创建一个新的和SRC长度宽度一样的位图
  //将该图片作为画布
  Canvas canvas = new Canvas(newBitmap);
  //在画布 0，0坐标上开始绘制原始图片
  canvas.drawBitmap(src, 0, 0, null);
  //在画布上绘制水印图片
  canvas.drawBitmap(watermark, paddingLeft, paddingTop, null);
  // 保存
  canvas.save(Canvas.ALL_SAVE_FLAG);
  // 存储
  canvas.restore();
  return newBitmap;
 }

/**
  * 绘制文字到中间
  *
  * @param context
  * @param bitmap
  * @param text
  * @param size
  * @param color
  * @return
  */
 public static Bitmap drawTextToCenter(Context context, Bitmap bitmap, String text,
           int size, int color) {
  Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
  paint.setColor(color);
  paint.setTextSize(dp2px(context, size));
  Rect bounds = new Rect();
  paint.getTextBounds(text, 0, text.length(), bounds);
  return drawTextToBitmap(context, bitmap, text, paint, bounds,
    (bitmap.getWidth() - bounds.width()) / 2,
    (bitmap.getHeight() + bounds.height()) / 2);
 }

 /**
  * 图片上绘制文字
  */
 private static Bitmap drawTextToBitmap(Context context, Bitmap bitmap, String text,
           Paint paint, Rect bounds, int paddingLeft, int paddingTop) {
  Config bitmapCOnfig= bitmap.getConfig();

  paint.setDither(true); // 获取跟清晰的图像采样
  paint.setFilterBitmap(true);// 过滤一些
  if (bitmapCOnfig== null) {
   bitmapCOnfig= Config.ARGB_8888;
  }
  bitmap = bitmap.copy(bitmapConfig, true);
  Canvas canvas = new Canvas(bitmap);

  canvas.drawText(text, paddingLeft, paddingTop, paint);
  return bitmap;
 }