[Android] 갤러리 이미지 가져오기 및 썸네일 생성

 

 

 

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <dimen name="imgSize">240dp</dimen>
</resources>

 

import androidx.activity.result.ActivityResult;
import androidx.activity.result.ActivityResultCallback;
import androidx.activity.result.ActivityResultLauncher;
import androidx.activity.result.contract.ActivityResultContracts;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.view.View;

import org.example.galleryfileprovider.databinding.ActivityMainBinding;

import java.io.InputStream;

public class MainActivity extends AppCompatActivity {

    String filePath = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        ActivityMainBinding binding = ActivityMainBinding.inflate(getLayoutInflater());
        setContentView(binding.getRoot());

        ActivityResultLauncher<Intent> galleryLauncher = registerForActivityResult(
              new ActivityResultContracts.StartActivityForResult()
            , new ActivityResultCallback<ActivityResult>()
        {
            @Override
            public void onActivityResult(ActivityResult result) {
                int calRatio = calculateInSampleSize(
                      result.getData().getData()
                    , getResources().getDimensionPixelSize(R.dimen.imgSize)
                    , getResources().getDimensionPixelSize(R.dimen.imgSize)
                );

                BitmapFactory.Options option = new BitmapFactory.Options();
                option.inSampleSize = calRatio;

                try {
                    InputStream inputStream = getContentResolver().openInputStream(result.getData().getData());
                    Bitmap bitmap = BitmapFactory.decodeStream(inputStream, null, option);
                    inputStream.close();
                    if(bitmap != null) {
                        binding.imgThumbnail.setImageBitmap(bitmap);
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });

        binding.btnGallery.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                Intent intent = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
                intent.setType("image/*");
                galleryLauncher.launch(intent);
            }
        });
    }

    private int calculateInSampleSize(Uri fileUri, int reqWidth, int reqHeight) {
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;

        try {
            InputStream inputStream = getContentResolver().openInputStream(fileUri);

            // inJustDecodeBounds 값을 true 로 설정한 상태에서 decodeXXX() 를 호출.
            // 로딩 하고자 하는 이미지의 각종 정보가 options 에 설정 된다.
            BitmapFactory.decodeStream(inputStream, null, options);
            inputStream.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

        // 비율 계산
        int width = options.outWidth;
        int height = options.outHeight;
        int inSampleSize = 1;

        //inSampleSize 비율 계산
        if (height > reqHeight || width > reqWidth) {

            int halfHeight = height / 2;
            int halfWidth = width / 2;

            while (halfHeight / inSampleSize >= reqHeight && halfWidth / inSampleSize >= reqWidth) {
                inSampleSize *= 2;
            }
        }
        return inSampleSize;
    }
}

 

 

 

 

 

<?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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/imgThumbnail"
        android:layout_width="240dp"
        android:layout_height="240dp"
        android:layout_marginTop="80dp"
        android:layout_weight="1"
        android:src="@drawable/user_thumbnail"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
    />

    <Button
        android:id="@+id/btnGallery"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:text="갤러리"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/imgThumbnail"
        tools:ignore="MissingConstraints"
    />

</androidx.constraintlayout.widget.ConstraintLayout>