// 构建Dialog
val dialog = Dialog(context)
val contentView: View =
    LayoutInflater.from(view.context).inflate(R.layout.dialog_wish_product, null)
// 获取自定义View里的控件并传值
val tvWishValue: TextView = contentView.findViewById(R.id.tv_wish_value)
tvWishValue.text = "1980"
val textView: TextView = contentView.findViewById(R.id.tv_back)

textView.setOnClickListener { dialog.dismiss() }
dialog.setContentView(contentView)
dialog.setCanceledOnTouchOutside(true)
dialog.setCancelable(true);

val window: Window? = dialog.window
window?.let {
    window.decorView.setPadding(0, 0, 0, 0) // 设置弹窗跟原始padding为0

    val lp: WindowManager.LayoutParams? = window.attributes
    lp?.let {
        it.gravity = Gravity.CENTER
        it.width = WindowManager.LayoutParams.MATCH_PARENT
        it.height = WindowManager.LayoutParams.MATCH_PARENT
        it.horizontalMargin = 0F
        window.attributes = it

    }
    window.decorView.minimumWidth = view.context.resources.displayMetrics.widthPixels
    window.decorView.setBackgroundColor(Color.TRANSPARENT) // 颜色要设置，不然不能全屏，所以设置透明
}
dialog.show()

布局文件：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#B3000000">

    <LinearLayout
        android:layout_width="275dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="50dp"
        android:layout_marginTop="50dp"
        android:layout_marginEnd="50dp"
        android:orientation="vertical"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <androidx.constraintlayout.widget.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="112dp"
            android:background="@mipmap/wish_product_dialog_head">

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginBottom="17dp"
                android:text="@string/my_wish"
                android:textColor="@color/white"
                android:textSize="20sp"
                android:textStyle="bold"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent" />

        </androidx.constraintlayout.widget.ConstraintLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@color/white"
            android:orientation="vertical">

            <androidx.constraintlayout.widget.ConstraintLayout
                android:layout_width="match_parent"
                android:layout_height="85dp"
                android:layout_marginStart="10dp"
                android:layout_marginTop="14dp"
                android:layout_marginEnd="10dp"
                android:background="@mipmap/wish_product_dialog_box">

                <ImageView
                    android:id="@+id/iv_img"
                    android:layout_width="55dp"
                    android:layout_height="55dp"
                    android:layout_marginStart="14dp"
                    android:contentDescription="@string/cover"
                    android:src="@mipmap/bbb"
                    app:layout_constraintBottom_toBottomOf="parent"
                    app:layout_constraintStart_toStartOf="parent"
                    app:layout_constraintTop_toTopOf="parent" />

                <TextView
                    android:layout_width="160dp"
                    android:layout_height="wrap_content"
                    android:layout_marginStart="7dp"
                    android:layout_marginTop="14dp"
                    android:layout_marginEnd="21dp"
                    android:maxLines="2"
                    android:src="@mipmap/bbb"
                    android:text="连帽加厚棉衣男冬季外套 潮牌港风军绿大衣"
                    android:textColor="@color/black"
                    android:textSize="14sp"
                    android:textStyle="bold"
                    app:layout_constraintEnd_toEndOf="parent"
                    app:layout_constraintLeft_toRightOf="@id/iv_img"
                    app:layout_constraintRight_toRightOf="parent"
                    app:layout_constraintStart_toEndOf="@id/iv_img"
                    app:layout_constraintTop_toTopOf="parent" />

                <TextView
                    android:id="@+id/tv_wish_value_text"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginStart="7dp"
                    android:layout_marginEnd="21dp"
                    android:layout_marginBottom="17dp"
                    android:text="@string/wish_value"
                    android:textColor="@color/black"
                    android:textSize="12sp"
                    app:layout_constraintBottom_toBottomOf="parent"
                    app:layout_constraintStart_toEndOf="@id/iv_img" />

                <TextView
                    android:id="@+id/tv_wish_value"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginStart="7dp"
                    android:layout_marginEnd="21dp"
                    android:layout_marginBottom="17dp"
                    android:text="@string/wish_value"
                    android:textColor="@color/c1"
                    android:textSize="12sp"
                    app:layout_constraintBottom_toBottomOf="parent"
                    app:layout_constraintStart_toEndOf="@id/tv_wish_value_text" />
            </androidx.constraintlayout.widget.ConstraintLayout>

            <TextView
                android:id="@+id/tv_tip"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginStart="17dp"
                android:layout_marginTop="24dp"
                android:layout_marginEnd="17dp"
                android:textColor="@color/text_color1" />

            <TextView
                android:layout_width="match_parent"
                android:layout_height="34dp"
                android:layout_marginStart="20dp"
                android:layout_marginTop="26dp"
                android:layout_marginEnd="20dp"
                android:background="@drawable/btn_bg1"
                android:gravity="center"
                android:text="@string/start_wish"
                android:textColor="@color/white"
                android:textSize="15sp" />

            <TextView
                android:id="@+id/tv_back"
                android:layout_width="match_parent"
                android:layout_height="34dp"
                android:layout_marginStart="20dp"
                android:layout_marginTop="10dp"
                android:layout_marginEnd="20dp"
                android:layout_marginBottom="17dp"
                android:background="@drawable/btn_bg1"
                android:gravity="center"
                android:text="@string/back"
                android:textColor="@color/white"
                android:textSize="15sp" />
        </LinearLayout>
    </LinearLayout>

</androidx.constraintlayout.widget.ConstraintLayout>