Android 图片添加水印图片或者文字

给图片添加水印的基本思路都是载入原图，添加文字或者载入水印图片，保存图片这三个部分

添加水印图片：

private Bitmap createWaterMaskImage(Context gContext, Bitmap src, Bitmap watermark)
	{

		String tag = "createBitmap";
		Log.d(tag, "create a new bitmap");
		if (src == null)
		{
			return null;
		}
		int w = src.getWidth();
		int h = src.getHeight();
		int ww = watermark.getWidth();
		int wh = watermark.getHeight();
		// create the new blank bitmap
		Bitmap newb = Bitmap.createBitmap(w, h, Config.ARGB_8888);// 创建一个新的和SRC长度宽度一样的位图
		Canvas cv = new Canvas(newb);
		// draw src into
		cv.drawBitmap(src, 0, 0, null);// 在 0，0坐标开始画入src
		// draw watermark into
		cv.drawBitmap(watermark, 20, 20, null);// 在src的右下角画入水印
		// save all clip
		cv.save(Canvas.ALL_SAVE_FLAG);// 保存
		// store
		cv.restore();// 存储
		return newb;
	}

添加文字

  public static Bitmap scaleWithWH(Bitmap src, double w, double h) {
	        if (w == 0 || h == 0 || src == null) {
	            return src;
	        } else {
	            // 记录src的宽高
	            int width = src.getWidth();
	            int height = src.getHeight();
	            // 创建一个matrix容器
	            Matrix matrix = new Matrix();
	            // 计算缩放比例
	            float scaleWidth = (float) (w / width);
	            float scaleHeight = (float) (h / height);
	            // 开始缩放
	            matrix.postScale(scaleWidth, scaleHeight);
	            // 创建缩放后的图片
	            return Bitmap.createBitmap(src, 0, 0, width, height, matrix, true);
	        }
	    }

	public Bitmap drawTextToBitmap(Context gContext,
			  int gResId,
			  String gText) {
			  Resources resources = gContext.getResources();
			  float scale = resources.getDisplayMetrics().density;
			  Bitmap bitmap =
			      BitmapFactory.decodeResource(resources, gResId);  

			  bitmap = scaleWithWH(bitmap, 300*scale, 300*scale);

			  android.graphics.Bitmap.Config bitmapConfig =
			      bitmap.getConfig();  

			  // set default bitmap config if none
			  if(bitmapConfig == null) {
			    bitmapConfig = android.graphics.Bitmap.Config.ARGB_8888;
			  }
			  // resource bitmaps are imutable,
			  // so we need to convert it to mutable one
			  bitmap = bitmap.copy(bitmapConfig, true);  

			  Canvas canvas = new Canvas(bitmap);
			  // new antialised Paint
			  Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
			  // text color - #3D3D3D
			  paint.setColor(Color.RED);
			  paint.setTextSize((int) (18 * scale));
		       paint.setDither(true); //获取跟清晰的图像采样
		       paint.setFilterBitmap(true);//过滤一些
			  Rect bounds = new Rect();
			  paint.getTextBounds(gText, 0, gText.length(), bounds);
			  int x = 30;
			  int y = 30;
			  canvas.drawText(gText, x * scale, y * scale, paint);
			  return bitmap;
			}