Truyền Drawable giữa các Activity Android Kotlin

Hướng dẫn này minh họa cách truyền Drawable (hình ảnh) giữa các Activity trong Android sử dụng Kotlin.

Bước 1: Tạo dự án mới

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

Bước 2: Thiết kế giao diện MainActivity (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"
    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" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="Transfer Bitmap to 2nd Activity" />

</RelativeLayout>

Bước 3: Viết code MainActivity.kt

import android.content.Intent
import android.os.Bundle
import android.widget.Button
import androidx.appcompat.app.AppCompatActivity

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

        val button: Button = findViewById(R.id.button)
        button.setOnClickListener {
            val intent = Intent(this@MainActivity, NewActivity::class.java)
            intent.putExtra("picture", R.drawable.ic_baseline_directions_walk_24)
            startActivity(intent)
        }
    }
}

Bước 4: Tạo Activity thứ hai (NewActivity.kt)

import android.os.Bundle
import android.widget.ImageView
import androidx.appcompat.app.AppCompatActivity

class NewActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_new)
        title = "KotlinApp"

        val imageView: ImageView = findViewById(R.id.imageView)
        val bundle = intent.extras
        if (bundle != null) {
            val pictureResId = bundle.getInt("picture")
            imageView.setImageResource(pictureResId)
        }
    }
}

Layout cho NewActivity (activity_new.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"
    tools:context=".NewActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="25sp"
        android:text="Second Activity"
        android:textSize="16sp"
        android:textStyle="bold" />

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true" />

</RelativeLayout>

Bước 5: Khai báo Activity trong 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>
                
                
            </intent-filter>
        </activity>

        <activity android:name=".NewActivity" />

    </application>
</manifest>

Chạy ứng dụng

Kết nối thiết bị, nhấn Run. Nhấn button "Transfer Bitmap to 2nd Activity" → Chuyển sang NewActivity hiển thị icon ic_baseline_directions_walk_24.

Các cách truyền Drawable/Bitmap

Truyền Bitmap thực tế (Parcelable)

// Gửi
val bitmap = BitmapFactory.decodeResource(resources, R.drawable.large_image)
intent.putExtra("bitmap", bitmap) // Bitmap implements Parcelable

// Nhận
val bitmap = intent.getParcelableExtra("bitmap")
imageView.setImageBitmap(bitmap)

Truyền Uri (Khuyên dùng cho ảnh lớn)

// Gửi - dùng FileProvider
val uri = FileProvider.getUriForFile(this, "${packageName}.provider", imageFile)
intent.putExtra("image_uri", uri)
intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)

// Nhận
val uri = intent.getParcelableExtra("image_uri")
imageView.setImageURI(uri)