Tạo Animation bằng file XML trong Android Kotlin

Giới thiệu

Ví dụ này minh họa cách tạo hiệu ứng animation (Zoom và Blink) bằng file XML trong thư mục res/anim/ và áp dụng lên View (TextView) trong Android Kotlin.

Các bước thực hiện

Bước 1: Tạo dự án mới

Mở Android Studio, chọn File → New Project, điền thông tin.

Bước 2: Giao diện (res/layout/activity_main.xml)

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="https://schemas.android.com/apk/res/android"
    xmlns:tools="https://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="4dp"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="50dp"
        android:text="Tutorials Point"
        android:textAlignment="center"
        android:textColor="@android:color/holo_green_dark"
        android:textSize="32sp"
        android:textStyle="bold" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="Have a Wonderful day!"
        android:textColor="@android:color/holo_purple"
        android:textSize="24sp"
        android:textStyle="bold" />

    <Button
        android:id="@+id/buttonZoom"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@id/buttonBlink"
        android:text="Zoom" />

    <Button
        android:id="@+id/buttonBlink"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:text="Blink" />

</RelativeLayout>

Bước 3: Tạo thư mục anim và file animation

1. Chuột phải res → New → Android Resource Directory, Resource type: anim, Directory name: anim.
2. Chuột phải anim → New → Animation Resource File.

res/anim/zoom.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="https://schemas.android.com/apk/res/android"
    android:fillAfter="true">
    <scale
        android:duration="1000"
        android:fromXScale="1.0"
        android:fromYScale="1.0"
        android:pivotX="50%"
        android:pivotY="50%"
        android:toXScale="3.0"
        android:toYScale="3.0" />
</set>

res/anim/blink.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="https://schemas.android.com/apk/res/android">
    <alpha
        android:duration="600"
        android:fromAlpha="0.0"
        android:toAlpha="1.0"
        android:repeatCount="infinite"
        android:repeatMode="reverse"
        android:interpolator="@android:anim/accelerate_interpolator" />
</set>

Bước 4: MainActivity.kt

import android.os.Bundle
import android.view.View
import android.view.animation.Animation
import android.view.animation.AnimationUtils
import android.widget.Button
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity(), Animation.AnimationListener {
    private lateinit var textView: TextView
    private lateinit var buttonZoom: Button
    private lateinit var buttonBlink: Button
    private lateinit var zoomAnim: Animation
    private lateinit var blinkAnim: Animation

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        title = "KotlinApp"

        textView = findViewById(R.id.textView)
        buttonZoom = findViewById(R.id.buttonZoom)
        buttonBlink = findViewById(R.id.buttonBlink)

        zoomAnim = AnimationUtils.loadAnimation(this, R.anim.zoom)
        zoomAnim.setAnimationListener(this)

        blinkAnim = AnimationUtils.loadAnimation(this, R.anim.blink)
        blinkAnim.setAnimationListener(this)

        buttonZoom.setOnClickListener {
            textView.visibility = View.VISIBLE
            textView.startAnimation(zoomAnim)
        }

        buttonBlink.setOnClickListener {
            textView.visibility = View.VISIBLE
            textView.startAnimation(blinkAnim)
        }
    }

    override fun onAnimationStart(animation: Animation) {}
    override fun onAnimationEnd(animation: Animation) {}
    override fun onAnimationRepeat(animation: Animation) {}
}

Bước 5: AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="https://schemas.android.com/apk/res/android"
    package="com.example.q11">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
</manifest>

Chạy ứng dụng

Kết nối thiết bị, nhấn Run. Nhấn nút "Zoom" → TextView phóng to 3 lần. Nhấn "Blink" → TextView nhấp nháy vô hạn.

Lưu ý: Hệ thống View Animation (XML) cũ, hạn chế. Nên dùng Property Animation (ObjectAnimator, ValueAnimator) hoặc MotionLayout cho animation phức tạp, hiệu năng tốt hơn.