Blur Background Behind AlertDialog

Question

As we know from API 14 the Below Blur has been deprecated

dialog.getWindow().addFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND);

Is there any alternative for this to make the Screen Blur behind Dialog I have tried FAST blur

score 53 · Accepted Answer · edited Jun 18 '23 at 15:23

Update:

We can also use renderscript api to blur background for API level >= 17 and uses fastblur for API level < 17. Please find below Github project.

- Github Project

- Blog

Steps Using FastBlur

Take the Snapshot of Your Background using Below Code

private static Bitmap takeScreenShot(Activity activity) {
    View view = activity.getWindow().getDecorView();
    view.setDrawingCacheEnabled(true);
    view.buildDrawingCache();
    Bitmap b1 = view.getDrawingCache();
    Rect frame = new Rect();
    activity.getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);
    int statusBarHeight = frame.top;
    int width = activity.getWindowManager().getDefaultDisplay().getWidth();
    int height = activity.getWindowManager().getDefaultDisplay().getHeight();

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

use it Like This Bitmap map=takeScreenShot(BlurImageView.this);// Your Actitvity Name

Call the Method Bitmap fast=fastblur(map, 10); Got it From Here

public 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];
  Log.e("pix", w + " " + h + " " + pix.length);
  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;
    }
  }

  Log.e("pix", w + " " + h + " " + pix.length);
  bitmap.setPixels(pix, 0, w, 0, 0, w, h);

  return (bitmap);
}

Finally on Button click

btnblur.setOnClickListener(new OnClickListener() {
  @Override
  public void onClick(View view) {

    AlertDialog.Builder builder=new AlertDialog.Builder(BlurImageView.this,R.style.Theme_D1NoTitleDim);
    builder.setTitle("Content");
    builder.setMessage("CLICK OK to Exit");
    builder.setPositiveButton("ON", new DialogInterface.OnClickListener() {
      @Override
      public void onClick(DialogInterface dialog, int which) {
        back_dim_layout.setVisibility(View.GONE);
        dialog.cancel();
      }
    });
    alert=builder.create();
    Bitmap map=takeScreenShot(BlurImageView.this);

    Bitmap fast=fastblur(map, 10);
    final Drawable draw=new BitmapDrawable(getResources(),fast);
    alert.getWindow().setBackgroundDrawable(draw);
    alert.show();
  }
});

That's It Now You can see the Blur Image Behind You Activity

Hope this could Help full for AnyOne...

does this implementation cause some lagging on the app ?? when i tried implementing this, the app was a little slow. — Rakeeb Rajbhandari, Jan 22 '14 at 17:55
@user2247689 This is becoz of the fastBlur method which takes a bit of time into exceution — Nitesh Tiwari, Jan 23 '14 at 05:01
Have you found any way around this ?? btw `back_dim_layout.setVisibility(View.GONE);` here ? — Rakeeb Rajbhandari, Jan 23 '14 at 05:04
@user2247689 You can try this tutorial for Reference http://nicolaspomepuy.fr/?p=18 .It actually store the Image to make it blur. — Nitesh Tiwari, Jan 23 '14 at 05:30
where does your dialog appear with this implementation btw ?? Mine appears at the top most of the screen. — Rakeeb Rajbhandari, Jan 23 '14 at 05:36
`getDefaultDisplay().getWidth()` and `getDefaultDisplay().getHeight()` are deprecated. Use the `getRealMetrics()` method instead: http://developer.android.com/reference/android/view/Display.html#getRealMetrics(android.util.DisplayMetrics) — Saket, Mar 01 '14 at 17:44
Has anybody got solution for making the alert dialog appear in center rather then top ? — Ajinkya S, Sep 12 '14 at 06:58
Thanks for an algorythm and fastblur. You can also take a screenshot like here: https://stackoverflow.com/a/33003645/2914140. — CoolMind, Aug 16 '16 at 20:11
This is a solution but it takes too much time to loads the alertdialog. Any solution? — Code Lover, Apr 27 '19 at 06:00
By this way dialog displays on top but we need dialog at bottom. Any solution for this ? — Gyan Swaroop Awasthi, May 12 '23 at 09:15

score 1 · Answer 2 · edited May 23 '17 at 12:26

This solution from nitesh works like below

But if you cannot make your alert to center(like me) check my answer as well, which is Here

What i did was,

used two alertDialogs one is for the blur effect(for the use of getWindow()) and it does not get display now(I removed its setContentView / can use transparent background)

The other one is the real alertDialog got display after the blur effect

Out put

score 0 · Answer 3 · answered Jul 31 '18 at 15:56

For a fast Blur and to solve the problem of Dialog to appear on the top of screen, I think there is an easier solution:

// Custom Dialog to be called in the Activity choosed.
public class CustomDialog {
    private Dialog dialog;

    public CustomDialog(AppCompatActivity activity) {
        dialog = new Dialog(activity);
        dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
        View viewCustomDialog = LayoutInflater.from(activity).inflate(R.layout.custom_dialog, null);
        dialog.setContentView(viewCustomDialog);

        RelativeLayout rootView = viewCustomDialog.findViewById(R.id.rootView);

        WindowManager.LayoutParams layoutParams = new WindowManager.LayoutParams();
        layoutParams.width = WindowManager.LayoutParams.MATCH_PARENT;
        layoutParams.height = WindowManager.LayoutParams.WRAP_CONTENT;
        layoutParams.gravity = Gravity.CENTER;
        dialog.getWindow().setAttributes(layoutParams);

        // First get bitmap with blur filter applied, using the function blur presented here,  
        // or another function.
        // Activity parameter is the Activity for which you call dialog.show();
        Bitmap bitmap = Utils.blur(activity);

        // Get bitmap height.
        int bitmapHeight = bitmap.getHeight();

        dialog.setOnShowListener(dialogInterface -> {
            // When dialog is shown, before set new blurred image for background drawable, 
            // the root view height and dialog margin are saved.
            int rootViewHeight = rootView.getHeight();
            int marginLeftAndRight = dialog.getWindow().getDecorView().getPaddingLeft();

            // Set new blurred image for background drawable.
            dialog.getWindow().setBackgroundDrawable(new BitmapDrawable(builder.context.getResources(), bitmap));

            // After get positions and heights, recover and rebuild original marginTop position, 
            // that is (bitmapHeight - rootViewHeight) / 2.
            // Also recover and rebuild Dialog original left and right margin.
            FrameLayout.LayoutParams rootViewLayoutParams = (FrameLayout.LayoutParams)rootView.getLayoutParams();
            rootViewLayoutParams.setMargins(marginLeftAndRight, (bitmapHeight - rootViewHeight) / 2, marginLeftRight, 0);
        });

        dialog.show();
    }
}

Blur method:

public static Bitmap blur(AppCompatActivity activity) {
   Bitmap bitmap = Utils.takeScreenShot(activity);

   RenderScript renderScript = RenderScript.create(activity);

   // This will blur the bitmapOriginal with a radius of 16 and save it in bitmapOriginal
   final Allocation input = Allocation.createFromBitmap(renderScript, bitmap); // Use this constructor for best performance, because it uses USAGE_SHARED mode which reuses memory
   final Allocation output = Allocation.createTyped(renderScript, input.getType());
   final ScriptIntrinsicBlur script = ScriptIntrinsicBlur.create(renderScript, Element.U8_4(renderScript));
   script.setRadius(16f);
   script.setInput(input);
   script.forEach(output);
   output.copyTo(bitmap);

   return bitmap;
}

TakeScreenShot method:

public static Bitmap takeScreenShot(AppCompatActivity activity) {
    View view = activity.getWindow().getDecorView();
    view.setDrawingCacheEnabled(true);
    view.buildDrawingCache();
    Bitmap bitmap = view.getDrawingCache();
    Rect frame = new Rect();
    activity.getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);
    int statusBarHeight = frame.top;
    int[] widthHeight = getScreenSize(activity);
    Bitmap bitmapResult = Bitmap.createBitmap(bitmap, 0, statusBarHeight, widthHeight[0], widthHeight[1]  - statusBarHeight);
    view.destroyDrawingCache();
    return bitmapResult;
}

GetScreenSize method:

public static int[] getScreenSize(Context context) {
    int[] widthHeight = new int[2];
    widthHeight[WIDTH_INDEX] = 0;
    widthHeight[HEIGHT_INDEX] = 0;

    WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
    Display display = windowManager.getDefaultDisplay();

    Point size = new Point();
    display.getSize(size);
    widthHeight[WIDTH_INDEX] = size.x;
    widthHeight[HEIGHT_INDEX] = size.y;

    if (!isScreenSizeRetrieved(widthHeight)) {
        DisplayMetrics metrics = new DisplayMetrics();
        display.getMetrics(metrics);
        widthHeight[0] = metrics.widthPixels;
        widthHeight[1] = metrics.heightPixels;
    }

    if (!isScreenSizeRetrieved(widthHeight)) {
        widthHeight[0] = display.getWidth(); // deprecated
        widthHeight[1] = display.getHeight(); // deprecated
    }

    return widthHeight;
}   

private static boolean isScreenSizeRetrieved(int[] widthHeight) {
    return widthHeight[WIDTH_INDEX] != 0 && widthHeight[HEIGHT_INDEX] != 0;
}

And for use RenderScript (To blur), in the App's build.gradle you must add:

defaultConfig {
    ...     
    renderscriptTargetApi 19
    renderscriptSupportModeEnabled true
}

score 0 · Answer 4 · answered Apr 22 '20 at 18:45

Try this

    dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
    dialog.setContentView(view);
    dialog.setCancelable(true);
    Window window = dialog.getWindow();
    WindowManager.LayoutParams wlp = window.getAttributes();

    wlp.gravity = Gravity.CENTER;
    wlp.flags &= WindowManager.LayoutParams.FLAG_DIM_BEHIND;
    window.setAttributes(wlp);
    dialog.getWindow().setLayout(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
    dialog.show();
}

Try to explain your answer in more detail instead of *just* providing code. *Why* does your code work? *Why* would this be the preferred solution? — kumaheiyama, Apr 23 '20 at 07:37

score 0 · Answer 5 · answered May 04 '23 at 10:50

        Dialog dialog = new Dialog(this); 
        alertDialogView = LayoutInflater.from(KycActivity.this).inflate(R.layout.indian_user_layout, null); 
dialog.setContentView(alertDialogView); 
    dialog.getWindow().setLayout(WindowManager.LayoutParams.MATCH_PARENT,WindowManager.LayoutParams.MATCH_PARENT); 
    dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT)); 
    diaog.getWindow().addFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND); 
    dialog.show();
        
        ------------------------------------------------------------------------

Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer). — Community, May 04 '23 at 13:09

Blur Background Behind AlertDialog

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