android dialog背景模糊化效果实现方法

private Bitmap takeScreenShot(Activity activity) {
  View view = activity.getWindow().getDecorView();
  view.setDrawingCacheEnabled(true);
  view.buildDrawingCache();
  Bitmap b1 = view.getDrawingCache();

  // 获取屏幕长和高
  int width = activity.getResources().getDisplayMetrics().widthPixels;
  int height = activity.getResources().getDisplayMetrics().heightPixels;

  Bitmap bmp = Bitmap.createBitmap(b1, 0, 0, width, height);
  view.destroyDrawingCache();
  return bmp;
 }

//blurBackgroundDrawer为模糊后的背景图片
 Window window = getWindow();
 window.setBackgroundDrawable(new BitmapDrawable(mContext.getResources(), blurBackgroundDrawer));

public class FastBlurUtility {
/**
* 获得模糊化的背景图片
* @param activity 获取模糊化的背景activity
* @return 模糊化的背景图片
*/
public static Bitmap getBlurBackgroundDrawer(Activity activity) {
Bitmap bmp = takeScreenShot(activity);
return startBlurBackground(bmp);
}
/**
* 截屏
* @param activity 截屏的activity
* @return 截屏图片
*/
private static Bitmap takeScreenShot(Activity activity) {
View view = activity.getWindow().getDecorView();
view.setDrawingCacheEnabled(true);
view.buildDrawingCache();
Bitmap b1 = view.getDrawingCache();
// 获取屏幕长和高
int width = activity.getResources().getDisplayMetrics().widthPixels;
int height = activity.getResources().getDisplayMetrics().heightPixels;
Bitmap bmp = Bitmap.createBitmap(b1, 0, 0, width, height);
view.destroyDrawingCache();
return bmp;
}
private static Bitmap startBlurBackground(Bitmap bkg) {
long startMs = System.currentTimeMillis();
float radius = 20; //模糊程度
Bitmap overlay = fastblur(small(bkg), (int) radius);
Log.i("FastBlurUtility", "=====blur time:" + (System.currentTimeMillis() - startMs));
return big(overlay);
}
/**
* 放大图片
* @param bitmap 需要放大的图片
* @return 放大的图片
*/
private static Bitmap big(Bitmap bitmap) {
Matrix matrix = new Matrix();
matrix.postScale(4f, 4f);
Bitmap resizeBmp = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
return resizeBmp;
}
/**
* 缩小图片
* @param bitmap 需要缩小的图片
* @return 缩小的图片
*/
private static Bitmap small(Bitmap bitmap) {
Matrix matrix = new Matrix();
matrix.postScale(0.25f, 0.25f);
Bitmap resizeBmp = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
return resizeBmp;
}
/**
* 将图片模糊化
* @param sentBitmap 需要模糊的图片
* @param radius  模糊程度
* @return 模糊后的图片
*/
private static Bitmap fastblur(Bitmap sentBitmap, int radius) {
Bitmap 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++) {
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);
}
}