android图像处理系列之四－－给图片添加边框（上）

图片处理时，有时需要为图片加一些边框，下面介绍一种为图片添加简单边框的方法。

基本思路是：将边框图片裁剪成八张小图片（图片大小最好一致，不然后面处理会很麻烦），分别对应左上角，左边，左下角，下边，右下角，右边，右上角，上边，其中左右上下只需要一个有效长度，就像重写水平进度条一样，只需要一个有效的长度，然后平铺，就达到了最后想要的效果，不错，左右上下边采用的也是这样的思路。也可以将八张图片组合在一起，然后读取整张图片，用代码裁剪，下面会给出相应的代码。下面的代码主要是给出第一种方法，后一种给出代码，有兴趣的可以自己试试。注意图片不要放到drawable目录下面，因为屏幕分辨率会影响图片的大小，所以最好是放在assets目录里面。下面代码为了简便所以没有那样做。后面一篇还会讲到另一种添加边框图片的方法。

下面贴图片：

原图片：

处理后：

代码(res参数为上面所说的八个边框组合图片资源)：

 

/**
     * 图片与边框组合
     * @param bm 原图片
     * @param res 边框资源
     * @return
     */
    private Bitmap combinateFrame(Bitmap bm, int[] res)
    {
        Bitmap bmp = decodeBitmap(res[0]);
        // 边框的宽高
        final int smallW = bmp.getWidth();
        final int smallH = bmp.getHeight();

        // 原图片的宽高
        final int bigW = bm.getWidth();
        final int bigH = bm.getHeight();

        int wCount = (int) Math.ceil(bigW * 1.0 / smallW);
        int hCount = (int) Math.ceil(bigH  * 1.0 / smallH);

        // 组合后图片的宽高
        int newW = (wCount + 2) * smallW;
        int newH = (hCount + 2) * smallH;

        // 重新定义大小
        Bitmap newBitmap = Bitmap.createBitmap(newW, newH, Config.ARGB_8888);
        Canvas canvas = new Canvas(newBitmap);
        Paint p = new Paint();
        p.setColor(Color.TRANSPARENT);
        canvas.drawRect(new Rect(0, 0, newW, newH), p);

        Rect rect = new Rect(smallW, smallH, newW - smallW, newH - smallH);
        Paint paint = new Paint();
        paint.setColor(Color.WHITE);
        canvas.drawRect(rect, paint);

        // 绘原图
        canvas.drawBitmap(bm, (newW - bigW - 2 * smallW) / 2 + smallW, (newH - bigH - 2 * smallH) / 2 + smallH, null);
        // 绘边框
        // 绘四个角
        int startW = newW - smallW;
        int startH = newH - smallH;
        Bitmap leftTopBm = decodeBitmap(res[0]); // 左上角
        Bitmap leftBottomBm = decodeBitmap(res[2]); // 左下角
        Bitmap rightBottomBm = decodeBitmap(res[4]); // 右下角
        Bitmap rightTopBm = decodeBitmap(res[6]); // 右上角

        canvas.drawBitmap(leftTopBm, 0, 0, null);
        canvas.drawBitmap(leftBottomBm, 0, startH, null);
        canvas.drawBitmap(rightBottomBm, startW, startH, null);
        canvas.drawBitmap(rightTopBm, startW, 0, null);

        leftTopBm.recycle();
        leftTopBm = null;
        leftBottomBm.recycle();
        leftBottomBm = null;
        rightBottomBm.recycle();
        rightBottomBm = null;
        rightTopBm.recycle();
        rightTopBm = null;

        // 绘左右边框
        Bitmap leftBm = decodeBitmap(res[1]);
        Bitmap rightBm = decodeBitmap(res[5]);
        for (int i = 0, length = hCount; i < length; i++)
        {
            int h = smallH * (i + 1);
            canvas.drawBitmap(leftBm, 0, h, null);
            canvas.drawBitmap(rightBm, startW, h, null);
        }

        leftBm.recycle();
        leftBm = null;
        rightBm.recycle();
        rightBm = null;

        // 绘上下边框
        Bitmap bottomBm = decodeBitmap(res[3]);
        Bitmap topBm = decodeBitmap(res[7]);
        for (int i = 0, length = wCount; i < length; i++)
        {
            int w = smallW * (i + 1);
            canvas.drawBitmap(bottomBm, w, startH, null);
            canvas.drawBitmap(topBm, w, 0, null);
        }

        bottomBm.recycle();
        bottomBm = null;
        topBm.recycle();
        topBm = null;

        canvas.save(Canvas.ALL_SAVE_FLAG);
        canvas.restore();

        return newBitmap;
    }

/**
	 * 图片与边框组合
	 * @param bm 原图片
	 * @param res 边框资源
	 * @return
	 */
	private Bitmap combinateFrame(Bitmap bm, int[] res)
	{
		Bitmap bmp = decodeBitmap(res[0]);
		// 边框的宽高
		final int smallW = bmp.getWidth();
		final int smallH = bmp.getHeight();
		
		// 原图片的宽高
		final int bigW = bm.getWidth();
		final int bigH = bm.getHeight();
		
		int wCount = (int) Math.ceil(bigW * 1.0 / smallW);
		int hCount = (int) Math.ceil(bigH  * 1.0 / smallH);
		
		// 组合后图片的宽高
		int newW = (wCount + 2) * smallW;
		int newH = (hCount + 2) * smallH;
		
		// 重新定义大小
		Bitmap newBitmap = Bitmap.createBitmap(newW, newH, Config.ARGB_8888);
		Canvas canvas = new Canvas(newBitmap);
		Paint p = new Paint();
		p.setColor(Color.TRANSPARENT);
		canvas.drawRect(new Rect(0, 0, newW, newH), p);
		
		Rect rect = new Rect(smallW, smallH, newW - smallW, newH - smallH);
		Paint paint = new Paint();
		paint.setColor(Color.WHITE);
		canvas.drawRect(rect, paint);
		
		// 绘原图
		canvas.drawBitmap(bm, (newW - bigW - 2 * smallW) / 2 + smallW, (newH - bigH - 2 * smallH) / 2 + smallH, null);
		// 绘边框
		// 绘四个角
		int startW = newW - smallW;
		int startH = newH - smallH;
		Bitmap leftTopBm = decodeBitmap(res[0]); // 左上角
		Bitmap leftBottomBm = decodeBitmap(res[2]); // 左下角
		Bitmap rightBottomBm = decodeBitmap(res[4]); // 右下角
		Bitmap rightTopBm = decodeBitmap(res[6]); // 右上角
		
		canvas.drawBitmap(leftTopBm, 0, 0, null);
		canvas.drawBitmap(leftBottomBm, 0, startH, null);
		canvas.drawBitmap(rightBottomBm, startW, startH, null);
		canvas.drawBitmap(rightTopBm, startW, 0, null);
		
		leftTopBm.recycle();
		leftTopBm = null;
		leftBottomBm.recycle();
		leftBottomBm = null;
		rightBottomBm.recycle();
		rightBottomBm = null;
		rightTopBm.recycle();
		rightTopBm = null;
		
		// 绘左右边框
		Bitmap leftBm = decodeBitmap(res[1]);
		Bitmap rightBm = decodeBitmap(res[5]);
		for (int i = 0, length = hCount; i < length; i++)
		{
			int h = smallH * (i + 1);
			canvas.drawBitmap(leftBm, 0, h, null);
			canvas.drawBitmap(rightBm, startW, h, null);
		}
		
		leftBm.recycle();
		leftBm = null;
		rightBm.recycle();
		rightBm = null;
		
		// 绘上下边框
		Bitmap bottomBm = decodeBitmap(res[3]);
		Bitmap topBm = decodeBitmap(res[7]);
		for (int i = 0, length = wCount; i < length; i++)
		{
			int w = smallW * (i + 1);
			canvas.drawBitmap(bottomBm, w, startH, null);
			canvas.drawBitmap(topBm, w, 0, null);
		}
		
		bottomBm.recycle();
		bottomBm = null;
		topBm.recycle();
		topBm = null;
		
		canvas.save(Canvas.ALL_SAVE_FLAG);
		canvas.restore();
		
		return newBitmap;
	}

如果边框是在一张图片里面，下面给出从一张图片取中间200X200的区域。如何类似边框过多，可以将裁剪的信息写入到指定的文件，裁剪时可先将边框图片信息读取出来，然后再裁剪出边框。如果处理的原图片太大，可能会出内存溢出。可先将图片缩小到一定尺寸再处理，具体缩小方法，参见android图像处理系列之二－－图片旋转、缩放、反转的图片缩放。

/**
 * 截取图片的中间的200X200的区域
 * @param bm
 * @return
 */
private Bitmap cropCenter(Bitmap bm)
{
    int dstWidth = 200;
       int dstHeight = 200;
       int startWidth = (bm.getWidth() - dstWidth)/2;
       int startHeight = ((bm.getHeight() - dstHeight) / 2);
       Rect src = new Rect(startWidth, startHeight, startWidth + dstWidth, startHeight + dstHeight);
       return dividePart(bm, src);
}

/**
 * 剪切图片
 * @param bmp 被剪切的图片
 * @param src 剪切的位置
 * @return 剪切后的图片
 */
private Bitmap dividePart(Bitmap bmp, Rect src)
{
    int width = src.width();
    int height = src.height();
    Rect des = new Rect(0, 0, width, height);
    Bitmap croppedImage = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
    Canvas canvas = new Canvas(croppedImage);
    canvas.drawBitmap(bmp, src, des, null);
    return croppedImage;
}

	/**
	 * 截取图片的中间的200X200的区域
	 * @param bm
	 * @return
	 */
	private Bitmap cropCenter(Bitmap bm)
	{
		int dstWidth = 200;
        int dstHeight = 200;
        int startWidth = (bm.getWidth() - dstWidth)/2;
        int startHeight = ((bm.getHeight() - dstHeight) / 2);
        Rect src = new Rect(startWidth, startHeight, startWidth + dstWidth, startHeight + dstHeight);
        return dividePart(bm, src);
	}
	
	/**
	 * 剪切图片
	 * @param bmp 被剪切的图片
	 * @param src 剪切的位置
	 * @return 剪切后的图片
	 */
	private Bitmap dividePart(Bitmap bmp, Rect src)
	{
		int width = src.width();
		int height = src.height();
		Rect des = new Rect(0, 0, width, height);
		Bitmap croppedImage = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
		Canvas canvas = new Canvas(croppedImage);
		canvas.drawBitmap(bmp, src, des, null);
		return croppedImage;
	}

处理后图片（原图片还是上面的图片）：