How to select a database blob and transform into bitmap?

Question

I have the following error in my project, I select an image of the gallery turn it into byte register in the database, but at the moment of loading it to imageView it does not appear and not the application error, I’m not touching the part of the photo taking code but if someone has some better code because that the image loses quality, I appreciate the help.

public class Main extends AppCompatActivity {

    private int REQUEST_CAMERA = 0, SELECT_FILE = 1;
    private Button btnSelect;
    private Button btnCamera;
    private Button btnSave;
    private ImageView ivImage;
    private String Chave;
    banco db = new banco(this);
    SQLiteDatabase banco;
    String local;
    byte[] imagem;

    Bitmap bitmap;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ivImage = (ImageView) findViewById(R.id.ivImage);
        btnSelect = (Button) findViewById(R.id.btnSelect);
        btnCamera = (Button) findViewById(R.id.btnCamera);
        btnSave = (Button) findViewById(R.id.btnSalvar);


        btnSelect.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                Chave = "Selecionar";
                galleryIntent();

            }
        });

        btnCamera.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                Chave = "Camera";
                cameraIntent();

            }
        });

        btnSave.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {

                banco = db.getReadableDatabase();
                banco.execSQL("insert into tabela (imagem) values('"+imagem+"')");
                Toast.makeText(Main.this, imagem+" Imagem salva!", Toast.LENGTH_SHORT).show();
                banco.close();

            }
        });

        carregar();

    }


    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        switch (requestCode) {
            case Utility.MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE:
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    if(Chave.equals("Camera"))
                        cameraIntent();
                    else if(Chave.equals("Selecionar"))
                        galleryIntent();
                }
                break;
        }
    }

    private void galleryIntent()
    {
        Intent intent = new Intent();
        intent.setType("image/*");
        intent.setAction(Intent.ACTION_GET_CONTENT);
        startActivityForResult(Intent.createChooser(intent, "Select File"),SELECT_FILE);
    }

    private void cameraIntent()
    {
        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        startActivityForResult(intent, REQUEST_CAMERA);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (resultCode == Activity.RESULT_OK) {
            if (requestCode == SELECT_FILE)
                onSelectFromGalleryResult(data);
            else if (requestCode == REQUEST_CAMERA)
                onCaptureImageResult(data);
        }

    }

    private void onCaptureImageResult(Intent data) {
        bitmap = (Bitmap) data.getExtras().get("data");
        ByteArrayOutputStream bytes = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.JPEG, 90, bytes);

        File destination = new File(Environment.getExternalStorageDirectory(), System.currentTimeMillis() + ".jpg");

        local = destination.getName();

        FileOutputStream fo;
        try {
            destination.createNewFile();
            fo = new FileOutputStream(destination);
            fo.write(bytes.toByteArray());
            fo.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        ivImage.setImageBitmap(bitmap);

    }

    @SuppressWarnings("deprecation")
    private void onSelectFromGalleryResult(Intent data) {

        bitmap = null;
        if (data != null) {
            try {

                bitmap = MediaStore.Images.Media.getBitmap(getApplicationContext().getContentResolver(), data.getData());

            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        ivImage.setImageBitmap(bitmap);

        Bitmap bitmap2 = ((BitmapDrawable)ivImage.getDrawable()).getBitmap();
        ByteArrayOutputStream saida = new ByteArrayOutputStream();
        bitmap2.compress(Bitmap.CompressFormat.PNG,100,saida);
        imagem = saida.toByteArray();

        Toast.makeText(Main.this, imagem.toString(), Toast.LENGTH_SHORT).show();
    }




    public void carregar() {

        banco = db.getReadableDatabase();

        Cursor cur = banco.rawQuery("select * from tabela", null);

        cur.moveToFirst();

        if(cur.isAfterLast()== false) {

            cur.moveToLast();

            byte[] image = cur.getBlob(cur.getColumnIndex("imagem"));

            if (image != null) {
                Bitmap bmp = BitmapFactory.decodeByteArray(image, 0, image.length);
                ivImage.setImageBitmap(bmp);
            }
        }

    }


}

Answer 1

Your image is certainly too big to be drawn on surface of a bitmap, because it bursts the maximum allowed size for the texture memory of Android. If you use the Android Monitor within the Android Studio will see a lot of warning like "Bitmap Too large to be uploaded into a Texture". You need to do downsampling of the same. Avoid manipulating bitmaps directly, use a library for this. It is much more complicated to deal with bitmaps on android than one imagines. Very much!

Note: In cases of low remaining system memory, read file operations to an array of bytes in memory may fail. In extreme situations of low memory, not even using a library with Glide can prevent these errors from occurring, but Glide handles them gracefully, another advantage of using a library like this.

So study the library Glide, that does all the work for you of reading the image in a background thread (avoiding crashing the user interface) and still considers screen orientation rotations (which would give you an exception of NullReferenceException), and also implements an image cache to improve application performance.

Install Glide by adding the following line to your Gradle:

dependencies {
    compile 'com.github.bumptech.glide:glide:3.7.0'
    compile 'com.android.support:support-v4:19.1.0'
}

Once installed Glide modify its display routine to:

public void carregar() {

    banco = db.getReadableDatabase();

    Cursor cur = banco.rawQuery("select * from tabela", null);

    cur.moveToFirst();

    if(cur.isAfterLast()== false) {

        cur.moveToLast();

        byte[] image = cur.getBlob(cur.getColumnIndex("imagem"));

        if (image != null) {

            Glide.with(this)
                .load(image)
                .asBitmap()
                .into(ivImage);

        }
    }

Note: I noticed an error in your implementation of capturing the image by the camera. You are only taking the thumbnail of the captured image. This is a common mistake/prank from anyone who starts working with the camera on Android. I have an answer on exactly what you can see here: Working with the camera or gallery

Answer 2

Here’s a basic example of how to manipulate images in Sqlite:

IMAGE:

public void add( byte[] image) throws SQLiteException{
    ContentValues cv = new  ContentValues();
    cv.put(KEY_IMAGE,   image);
    database.insert( DB_TABLE, null, cv );
}

To load the image use the method getBlob :

byte[] image = cursor.getBlob(1);