mNavigationDrawerFragment = (NavigationDrawerFragment)
getSupportFragmentManager().findFragmentById(R.id.navigation_drawer);这个NavigationDrawerFragment就是我们的侧滑菜单实现的类，可以不去管它。mNavigationDrawerFragment.getView().getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
});这个OnPreDrawListener需要实现OnPreDraw方法，就在这个方法中，对当前的View，进行截图，并且高斯模糊。private FrameLayout view; private Bitmap bitmap;对view初始化后，开始对view进行截图，对view截图的方式如下：
view.buildDrawingCache(); bitmap = view.getDrawingCache();这样，bitmap中就保存了当前的view的截图，接下来我们要对图片进行高斯模糊，关于高斯模糊的算法，网上有很多，我就随便贴一个（复制来的）：
public static Bitmap doBlur(Bitmap sentBitmap, int radius, boolean canReuseInBitmap) {
// Stack Blur v1.0 from
// http://www.quasimondo.com/StackBlurForCanvas/StackBlurDemo.html
//
// Java Author: Mario Klingemann <mario at quasimondo.com>
// http://incubator.quasimondo.com
// created Feburary 29, 2004
// Android port : Yahel Bouaziz <yahel at kayenko.com>
// http://www.kayenko.com
// ported april 5th, 2012
// This is a compromise between Gaussian Blur and Box blur
// It creates much better looking blurs than Box Blur, but is
// 7x faster than my Gaussian Blur implementation.
//
// I called it Stack Blur because this describes best how this
// filter works internally: it creates a kind of moving stack
// of colors whilst scanning through the image. Thereby it
// just has to add one new block of color to the right side
// of the stack and remove the leftmost color. The remaining
// colors on the topmost layer of the stack are either added on
// or reduced by one, depending on if they are on the right or
// on the left side of the stack.
//
// If you are using this algorithm in your code please add
// the following line:
//
// Stack Blur Algorithm by Mario Klingemann <mario@quasimondo.com>
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);
}第一个参数为需要高斯模糊的图片，第二个参数可以理解为模糊效果大小，第三个参数表示位图是否可以重复使用。
int[] location = new int[2]; mNavigationDrawerFragment.getView().getLocationInWindow(location); blur(bitmap, listView, location[0]);//只传x坐标blur函数就是我们处理位置的细节了，传的listView是Fragment里的唯一一个view：
private void blur(Bitmap bkg, View view,int width) {
float scaleFactor = 4;//缩放图片，缩放之后模糊效果更好
float radius = 2;
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);
float visibleWidth = slideMenuWidth +width;//可见宽
int visibleHeight = view.getHeight();//可见高
//从view的截图中截取的区域，+10和下面-10的原因是，高斯模糊的边有时会有黑影，所以增大模糊区域
Rect src = new Rect(0,0, (int)(visibleWidth)+10, visibleHeight);
RectF dest = new RectF(-width - 10, 0, slideMenuWidth, visibleHeight);//设置Drawer背景的区域
canvas.drawBitmap(bkg, src, dest, paint);
overlay = ImageUtils.doBlur(overlay, (int)radius, true);//进行高斯模糊操作
if (Build.VERSION.SDK_INT < 16) {//16level以前使用这个方法，在16中被废弃
view.setBackgroundDrawable(new BitmapDrawable(getResources(), overlay));
} else {
view.setBackground(new BitmapDrawable(getResources(), overlay));
}
}
整个的事件监听代码如下：mNavigationDrawerFragment.getView().getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
@Override
public boolean onPreDraw() {
if (bitmap == null) {
view.buildDrawingCache();
bitmap = view.getDrawingCache();
}
int[] location = new int[2];
mNavigationDrawerFragment.getView().getLocationInWindow(location);
blur(bitmap, listView, location[0]);//只传x坐标
return true;
}
});到这里，侧滑菜单的毛玻璃效果就已经完成了。原文地址：http://blog.csdn.net/xjyzxx/article/details/38740143
