本文使用仅仅是使用Blurring Github库实现高斯模糊效果,在这里自己做下笔记。
具体实现步骤,如下:
1、截屏当前显示页并处理状态栏和标题栏是否显示
2、对截屏后的图片做高斯模糊处理
3、根据情况释放cache资源

先看下我们公司的App-回家吃饭高斯处理后的效果图

###截屏当前显示页并处理状态栏和标题栏是否显示

private boolean isBlur; //防止重复高斯处理
private View blurView; //Activity的根view即DecorView

private void applyBlur() {
    isBlur = false;
    blurView = getActivity().getWindow().getDecorView();
    blurView.setDrawingCacheEnabled(true);
    //获取当前窗口快照,相当于截屏
    Bitmap blurBmp1 = blurView.getDrawingCache();
    int height = getOtherHeight();
    //除去状态栏和标题栏
    final Bitmap blurBmp2 = Bitmap.createBitmap(blurBmp1, 0, height, blurBmp1.getWidth(), blurBmp1.getHeight() - height);
    blurView.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
        @Override
        public boolean onPreDraw() {
            if (!isBlur) {
                blur(blurBmp2, ivBlurBg);
                isBlur = true;
            }
            return true;
        }
    });
}

/**
 * 获取状态栏、标题栏和ListView上面的View高度
 * @return
 */
private int getOtherHeight() {
    Rect frame = new Rect();
    getActivity().getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);
    int statusBarHeight = frame.top;
    int contentTop = getActivity().getWindow().findViewById(Window.ID_ANDROID_CONTENT).getTop();
    int titleBarHeight = contentTop - statusBarHeight;
    return statusBarHeight + titleBarHeight + llLocation.getHeight() + llTag.getHeight();
}

###对截屏后的图片做高斯模糊处理

private void blur(Bitmap bkg, View view) {
    float scaleFactor = 20; //迷糊度设置
    float radius = 20;

    Bitmap overlay = Bitmap.createBitmap((int) (view.getMeasuredWidth() / scaleFactor),
            (int) (view.getMeasuredHeight() / scaleFactor), Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(overlay);
    canvas.translate(-view.getLeft() / scaleFactor, -view.getTop() / scaleFactor);
    canvas.scale(1 / scaleFactor, 1 / scaleFactor);
    Paint paint = new Paint();
    paint.setFlags(Paint.FILTER_BITMAP_FLAG);
    canvas.drawBitmap(bkg, 0, 0, paint);

    overlay = BlurUtil.doBlur(overlay, (int) radius, true);
    view.setBackground(new BitmapDrawable(getResources(), overlay));
}

BlurUtil.java文件下的java高斯算法

public static Bitmap doBlur(Bitmap sentBitmap, int radius, boolean canReuseInBitmap) {
    Bitmap bitmap;
    if (canReuseInBitmap) {
        bitmap = sentBitmap;
    } else {
        bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);
    }

    if (radius < 1) {
        return (null);
    }

    int w = bitmap.getWidth();
    int h = bitmap.getHeight();

    int[] pix = new int[w * h];
    bitmap.getPixels(pix, 0, w, 0, 0, w, h);

    int wm = w - 1;
    int hm = h - 1;
    int wh = w * h;
    int div = radius + radius + 1;

    int r[] = new int[wh];
    int g[] = new int[wh];
    int b[] = new int[wh];
    int rsum, gsum, bsum, x, y, i, p, yp, yi, yw;
    int vmin[] = new int[Math.max(w, h)];

    int divsum = (div + 1) >> 1;
    divsum *= divsum;
    int dv[] = new int[256 * divsum];
    for (i = 0; i < 256 * divsum; i++) {
        dv[i] = (i / divsum);
    }

    yw = yi = 0;

    int[][] stack = new int[div][3];
    int stackpointer;
    int stackstart;
    int[] sir;
    int rbs;
    int r1 = radius + 1;
    int routsum, goutsum, boutsum;
    int rinsum, ginsum, binsum;

    for (y = 0; y < h; y++) {
        rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
        for (i = -radius; i <= radius; i++) {
            p = pix[yi + Math.min(wm, Math.max(i, 0))];
            sir = stack[i + radius];
            sir[0] = (p & 0xff0000) >> 16;
            sir[1] = (p & 0x00ff00) >> 8;
            sir[2] = (p & 0x0000ff);
            rbs = r1 - Math.abs(i);
            rsum += sir[0] * rbs;
            gsum += sir[1] * rbs;
            bsum += sir[2] * rbs;
            if (i > 0) {
                rinsum += sir[0];
                ginsum += sir[1];
                binsum += sir[2];
            } else {
                routsum += sir[0];
                goutsum += sir[1];
                boutsum += sir[2];
            }
        }
        stackpointer = radius;

        for (x = 0; x < w; x++) {

            r[yi] = dv[rsum];
            g[yi] = dv[gsum];
            b[yi] = dv[bsum];

            rsum -= routsum;
            gsum -= goutsum;
            bsum -= boutsum;

            stackstart = stackpointer - radius + div;
            sir = stack[stackstart % div];

            routsum -= sir[0];
            goutsum -= sir[1];
            boutsum -= sir[2];

            if (y == 0) {
                vmin[x] = Math.min(x + radius + 1, wm);
            }
            p = pix[yw + vmin[x]];

            sir[0] = (p & 0xff0000) >> 16;
            sir[1] = (p & 0x00ff00) >> 8;
            sir[2] = (p & 0x0000ff);

            rinsum += sir[0];
            ginsum += sir[1];
            binsum += sir[2];

            rsum += rinsum;
            gsum += ginsum;
            bsum += binsum;

            stackpointer = (stackpointer + 1) % div;
            sir = stack[(stackpointer) % div];

            routsum += sir[0];
            goutsum += sir[1];
            boutsum += sir[2];

            rinsum -= sir[0];
            ginsum -= sir[1];
            binsum -= sir[2];

            yi++;
        }
        yw += w;
    }
    for (x = 0; x < w; x++) {
        rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
        yp = -radius * w;
        for (i = -radius; i <= radius; i++) {
            yi = Math.max(0, yp) + x;

            sir = stack[i + radius];

            sir[0] = r[yi];
            sir[1] = g[yi];
            sir[2] = b[yi];

            rbs = r1 - Math.abs(i);

            rsum += r[yi] * rbs;
            gsum += g[yi] * rbs;
            bsum += b[yi] * rbs;

            if (i > 0) {
                rinsum += sir[0];
                ginsum += sir[1];
                binsum += sir[2];
            } else {
                routsum += sir[0];
                goutsum += sir[1];
                boutsum += sir[2];
            }

            if (i < hm) {
                yp += w;
            }
        }
        yi = x;
        stackpointer = radius;
        for (y = 0; y < h; y++) {
            // Preserve alpha channel: ( 0xff000000 & pix[yi] )
            pix[yi] = (0xff000000 & pix[yi]) | (dv[rsum] << 16) | (dv[gsum] << 8) | dv[bsum];

            rsum -= routsum;
            gsum -= goutsum;
            bsum -= boutsum;

            stackstart = stackpointer - radius + div;
            sir = stack[stackstart % div];

            routsum -= sir[0];
            goutsum -= sir[1];
            boutsum -= sir[2];

            if (x == 0) {
                vmin[y] = Math.min(y + r1, hm) * w;
            }
            p = x + vmin[y];

            sir[0] = r[p];
            sir[1] = g[p];
            sir[2] = b[p];

            rinsum += sir[0];
            ginsum += sir[1];
            binsum += sir[2];

            rsum += rinsum;
            gsum += ginsum;
            bsum += binsum;

            stackpointer = (stackpointer + 1) % div;
            sir = stack[stackpointer];

            routsum += sir[0];
            goutsum += sir[1];
            boutsum += sir[2];

            rinsum -= sir[0];
            ginsum -= sir[1];
            binsum -= sir[2];

            yi += w;
        }
    }

    bitmap.setPixels(pix, 0, w, 0, 0, w, h);
    return (bitmap);
}

###根据情况释放cache资源

blurView为Activity的根view即DecorView

if (blurView != null) {
    blurView.setDrawingCacheEnabled(false);
}