【转】六、android图片特效处理之图片叠加

这篇将讲到图片特效处理的图片叠加效果。跟前面一样是对像素点进行处理，可参照前面的android图像处理系列之七－－图片涂鸦，水印－图片叠加和android图像处理系列之六－－给图片添加边框（下）－图片叠加两篇文章，此篇所讲的与之前有一点区别。叠加原理是两张图片的像素点按透明度叠加，不会进行颜色过滤。叠加图片可以是JPG格式，跟前在一样，最好是放大assets目录。下面看效果图：

+=

代码：

/**

     * 图片效果叠加

     * @param bmp 限制了尺寸大小的Bitmap

     * @return

     */

    private Bitmap overlay(Bitmap bmp)

    {

        long start = System.currentTimeMillis();

        int width = bmp.getWidth();

        int height = bmp.getHeight();

        Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);

// 对边框图片进行缩放

        Bitmap overlay = BitmapFactory.decodeResource(mContext.getResources(), R.drawable.rainbow_overlay);

        int w = overlay.getWidth();

        int h = overlay.getHeight();

        float scaleX = width * 1F / w;

        float scaleY = height * 1F / h;

        Matrix matrix = new Matrix();

        matrix.postScale(scaleX, scaleY);
Bitmap overlayCopy = Bitmap.createBitmap(overlay, 0, 0, w, h, matrix, true);
int pixColor = 0;

        int layColor = 0;
int pixR = 0;

        int pixG = 0;

        int pixB = 0;

        int pixA = 0;
int newR = 0;

        int newG = 0;

        int newB = 0;

        int newA = 0;
int layR = 0;

        int layG = 0;

        int layB = 0;

        int layA = 0;
final float alpha = 0.5F;
int[] srcPixels = new int[width * height];

        int[] layPixels = new int[width * height];

        bmp.getPixels(srcPixels, 0, width, 0, 0, width, height);

        overlayCopy.getPixels(layPixels, 0, width, 0, 0, width, height);
int pos = 0;

        for (int i = 0; i < height; i++)

        {

            for (int k = 0; k < width; k++)

            {

                pos = i * width + k;

                pixColor = srcPixels[pos];

                layColor = layPixels[pos];
pixR = Color.red(pixColor);

                pixG = Color.green(pixColor);

                pixB = Color.blue(pixColor);

                pixA = Color.alpha(pixColor);
layR = Color.red(layColor);

                layG = Color.green(layColor);

                layB = Color.blue(layColor);

                layA = Color.alpha(layColor);
newR = (int) (pixR * alpha + layR * (1 - alpha));

                newG = (int) (pixG * alpha + layG * (1 - alpha));

                newB = (int) (pixB * alpha + layB * (1 - alpha));

                layA = (int) (pixA * alpha + layA * (1 - alpha));
newR = Math.min(255, Math.max(0, newR));

                newG = Math.min(255, Math.max(0, newG));

                newB = Math.min(255, Math.max(0, newB));

                newA = Math.min(255, Math.max(0, layA));
srcPixels[pos] = Color.argb(newA, newR, newG, newB);

            }

        }
bitmap.setPixels(srcPixels, 0, width, 0, 0, width, height);

        long end = System.currentTimeMillis();

        Log.d("may", "overlayAmeliorate used time="+(end - start));

        return bitmap;

    }

叠加的边框图片还是大点比较好，也要控制被叠加图片大小。alpha变量值可以根据需求修改，建议还是大于0.5比较好，不然原图会看不清楚。

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