Cách tạo Full-screen Custom Dialog trên Android

Giới thiệu về Full-screen Dialog

Full-screen Custom Dialog hiển thị dialog chiếm toàn bộ màn hình, phù hợp cho: onboarding, terms/conditions, image viewer, form phức tạp, bottom sheet style.

Cách tiếp cận: Tính toán kích thước màn hình, set minimum width/height cho dialog view.

Ví dụ minh họa

Bước 1: Tạo project

Android Studio → File → New Project.

Bước 2: Layout chính (res/layout/activity_main.xml)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
    android:id="@+id/parent"
    xmlns:tools="https://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:gravity="center"
    android:orientation="vertical">
    <Button
        android:id="@+id/customDialog"
        android:text="Custom Dialog"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</LinearLayout>

Bước 3: Layout Custom Dialog (res/layout/customview.xml)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:padding="16dp">
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Success"
            android:textAlignment="center"
            android:textAppearance="@style/TextAppearance.AppCompat.Headline" />
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:text="Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nulla eu erat tincidunt lacus fermentum rutrum."
            android:textAlignment="center"
            android:textAppearance="@style/TextAppearance.AppCompat.Medium" />
        <Button
            android:id="@+id/buttonOk"
            android:layout_width="200dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:layout_marginTop="15dp"
            android:background="@color/colorPrimary"
            android:text="Ok"
            android:textColor="#FFF" />
    </LinearLayout>
</LinearLayout>

Bước 4: Theme tùy chỉnh (res/values/styles.xml)

<style name="CustomAlertDialog" parent="Theme.AppCompat.Light.Dialog.Alert">
    <item name="android:windowBackground">@drawable/popup_background</item>
    <item name="android:windowMinWidthMajor">100%</item>
    <item name="android:windowMinWidthMinor">100%</item>
    <item name="android:windowIsFloating">false</item>
</style>

Bước 5: Drawable background (res/drawable/popup_background.xml)

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="https://schemas.android.com/apk/res/android">
    <solid android:color="#FFFFFF" />
    <corners android:radius="0dp" /> <!-- Full screen không bo góc -->
</shape>

Bước 6: Code (src/MainActivity.java)

package com.example.andy.myapplication;

import android.app.Activity;
import android.graphics.Rect;
import android.os.Build;
import android.os.Bundle;
import android.support.annotation.RequiresApi;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        findViewById(R.id.customDialog).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // 1. Lấy kích thước màn hình hiển thị
                Rect displayRectangle = new Rect();
                Window window = MainActivity.this.getWindow();
                window.getDecorView().getWindowVisibleDisplayFrame(displayRectangle);

                // 2. Tạo builder với custom theme
                AlertDialog.Builder builder = new AlertDialog.Builder(
                    MainActivity.this, R.style.CustomAlertDialog);

                // 3. Inflate custom view
                ViewGroup viewGroup = findViewById(android.R.id.content);
                View dialogView = LayoutInflater.from(v.getContext())
                    .inflate(R.layout.customview, viewGroup, false);

                // 4. QUAN TRỌNG: Set minimum width/height = màn hình
                dialogView.setMinimumWidth((int)(displayRectangle.width() * 1f));
                dialogView.setMinimumHeight((int)(displayRectangle.height() * 1f));

                builder.setView(dialogView);

                final AlertDialog alertDialog = builder.create();
                
                // 5. Xử lý nút OK
                Button buttonOk = dialogView.findViewById(R.id.buttonOk);
                buttonOk.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        alertDialog.dismiss();
                    }
                });

                alertDialog.show();
            }
        });
    }
}

Giải thích kỹ thuật quan trọng

// Lấy kích thước vùng hiển thị thực tế (trừ status/navigation bar)
Rect displayRectangle = new Rect();
getWindow().getDecorView().getWindowVisibleDisplayFrame(displayRectangle);

// Ép dialog view mở rộng toàn màn hình
dialogView.setMinimumWidth(displayRectangle.width());
dialogView.setMinimumHeight(displayRectangle.height());

// Theme hỗ trợ full screen
<item name="android:windowIsFloating">false</item>
<item name="android:windowMinWidthMajor">100%</item>

Cách hiện đại hơn - DialogFragment Full Screen

public class FullScreenDialogFragment extends DialogFragment {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setStyle(DialogFragment.STYLE_NORMAL, R.style.FullScreenDialogStyle);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        return inflater.inflate(R.layout.customview, container, false);
    }

    @Override
    public void onStart() {
        super.onStart();
        Dialog dialog = getDialog();
        if (dialog != null) {
            Window window = dialog.getWindow();
            if (window != null) {
                window.setLayout(ViewGroup.LayoutParams.MATCH_PARENT, 
                                 ViewGroup.LayoutParams.MATCH_PARENT);
                window.setBackgroundDrawableResource(android.R.color.transparent);
            }
        }
    }
}

// Style
<style name="FullScreenDialogStyle" parent="Theme.AppCompat.Dialog">
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowFullscreen">true</item>
    <item name="android:windowIsFloating">false</item>
</style>

So sánh các cách làm Full-screen Dialog

Lưu ý

• DialogFragment tự handle rotation, lifecycle
• Full-screen dialog nên có nút đóng rõ ràng (back button, close icon)
• Cân nhắc dùng BottomSheetDialog cho UX tốt hơn
• WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS cho edge-to-edge