最近换了工作，由于工作中要使用一些自己以前不是很了解的知识，就没有时间更新博客了。

由于最近做了一些很有意思的小demo，不吐不快，再加上还是认为技术需要沉淀和梳理，所以再次把写博客这件事拾起来。

已经不是第一次遇到设计师要求使用毛玻璃效果了，但是做带毛玻璃效果背景的Dialog还是第一次。考虑实现的逻辑，弹出Dialog之前对当前屏幕截图，做高斯模糊处理，设为Dialog背景，显示Dialog。

屏幕截图核心代码public static Bitmap takeScreenShot(Activity activity) {

// View是你需要截图的View

View view = activity.getWindow().getDecorView();

view.setDrawingCacheEnabled(true);

view.buildDrawingCache();

Bitmap b1 = view.getDrawingCache();

// 获取状态栏高度

Rect frame = new Rect();

activity.getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);

int statusBarHeight = frame.top;

// 获取屏幕长和高

int width = activity.getWindowManager().getDefaultDisplay().getWidth();

int height = activity.getWindowManager().getDefaultDisplay()

.getHeight();

// 去掉标题栏

Bitmap b = Bitmap.createBitmap(b1, 0, statusBarHeight, width, height - statusBarHeight);

Matrix matrix = new Matrix();

matrix.postScale(0.2f,0.2f); //长和宽放大缩小的比例

// 压缩 丢弃一部分像素点

b = Bitmap.createBitmap(b,0,0,b.getWidth(),b.getHeight(),matrix,true);

b = FastBlur.doBlur(b, 4, true);

view.destroyDrawingCache();

return b;

}

做压缩的目的是丢弃一部分像素点，保证做高斯模糊处理时的效率。既然要做高斯模糊，那么就意味着图片对精度的要求极低。

FastBlur类(高斯模糊)

这个类来自于开源项目StackBlur的早期源码，感兴趣的可以使用最新的源码来替换。public class FastBlur {

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

// http://incubator.quasimondo.com

// created Feburary 29, 2004

// Android port : Yahel Bouaziz

// 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

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);

}

}

Dialog的布局我就不赘述了，另外可以根据需要修改Stylefalse

true

@android:color/transparent

得到自己想要的效果。

最后，附上效果图

本文出自Yang，转载时请注明出处及相应链接。