Android图片添加水印的实现方法

 /*
   添加全屏斜着45度的文字
   /
  public static Bitmap drawCenterLable(Context context, Bitmap bmp, String text) {
    float scale = context.getResources().getDisplayMetrics().density;
    //创建一样大小的图片
    Bitmap newBmp = Bitmap.createBitmap(bmp.getWidth(), bmp.getHeight(), Config.ARGB_8888);
    //创建画布
    Canvas canvas = new Canvas(newBmp);
    canvas.drawBitmap(bmp, 0, 0, null);  //绘制原始图片
    canvas.save();
    canvas.rotate(45); //顺时针转45度
    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    paint.setColor(Color.argb(50, 255, 255, 255)); //白色半透明
    paint.setTextSize(100 scale);
    paint.setDither(true);
    paint.setFilterBitmap(true);
    Rect rectText = new Rect();  //得到text占用宽高， 单位：像素
    paint.getTextBounds(text, 0, text.length(), rectText);
    double beginX = (bmp.getHeight()/2 - rectText.width()/2) * 1.4;  //45度角度值是1.414
    double beginY = (bmp.getWidth()/2 - rectText.width()/2) * 1.4;
    canvas.drawText(text, (int)beginX, (int)beginY, paint);
    canvas.restore();
    return newBmp;
  }

long begin = System.currentTimeMillis();
Bitmap destBmp = ImageUtil.drawCenterLable(this, sourBitmap, "某某公司专用");
long end = System.currentTimeMillis();
Log.d("brycegao", "打水印用时：" + (end-begin) + "毫秒");
mWartermarkImage.setImageBitmap(destBmp);

 java.lang.OutOfMemoryError: Failed to allocate a 467251212 byte allocation with 16767536 free bytes and 110MB until OOM
                                        at dalvik.system.VMRuntime.newNonMovableArray(Native Method)
                                        at android.graphics.BitmapFactory.nativeDecodeAsset(Native Method)
                                        at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:613)
                                        at android.graphics.BitmapFactory.decodeResourceStream(BitmapFactory.java:446)
                                        at android.graphics.BitmapFactory.decodeResource(BitmapFactory.java:469)
                                        at android.graphics.BitmapFactory.decodeResource(BitmapFactory.java:501)