Try this just change the width of your root frame layout

<FrameLayout xmlns_android="http://schemas.android.com/apk/res/android"
   android_layout_width="match_parent"
   android_layout_height="wrap_content">

SAMPLE CODE

    <?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns_android="http://schemas.android.com/apk/res/android"
android_layout_width="match_parent"
android_layout_height="wrap_content">

<ImageView
    android_layout_width="wrap_content"
    android_layout_height="wrap_content"
    android_background="@drawable/popup_img"
    android_contentDescription="@string/todo" />

<LinearLayout
    android_layout_width="match_parent"
    android_layout_height="wrap_content"
    android_layout_gravity="center"
    android_layout_marginTop="32dp"
    android_orientation="vertical">

   // TextView's

</LinearLayout>


<FrameLayout
    android_id="@+id/btn_ok"
    android_layout_width="wrap_content"
    android_layout_height="wrap_content"
    android_layout_gravity="center_horizontal|bottom">

    <ImageView
        //  />

    <TextView
        //     />

</FrameLayout>


</FrameLayout>

Hey as you already have centered the content you can set the dialog’s window to transparent and then show the dialog to remove that white background.

alert.getWindow().setBackgroundDrawableResource(android.R.color.transparent);
alert.show();

I want to get an alert dialog view when button clicked like this

my layout file

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns_android="http://schemas.android.com/apk/res/android"
android_layout_width="wrap_content"
android_layout_height="wrap_content">

<ImageView
    android_layout_width="wrap_content"
    android_layout_height="wrap_content"
    android_background="@drawable/popup_img"
    android_contentDescription="@string/todo" />

<LinearLayout
    android_layout_width="wrap_content"
    android_layout_height="wrap_content"
    android_layout_gravity="center"
    android_layout_marginTop="32dp"
    android_orientation="vertical">

   // TextView's

</LinearLayout>


<FrameLayout
    android_id="@+id/btn_ok"
    android_layout_width="wrap_content"
    android_layout_height="wrap_content"
    android_layout_gravity="center_horizontal|bottom">

    <ImageView
        //  />

    <TextView
        //     />

</FrameLayout>


</FrameLayout>

However at the end when I clicked button I get this image;

It has white backround which one I don’t want to get it and it is not centered. Can anyone help me? Should I use AlertDialog?

My code for AlertDialog is;

     AlertDialog.Builder builder = new AlertDialog.Builder(this);
        View view = getLayoutInflater().inflate(R.layout.layout_congratulations, null);
        builder.setView(view);
        AlertDialog alert = builder.create();
        alert.show();