Saving a file in drawing app

Question

I am making a notes app where a user can draw on the screen and save it as an image. I am following the following tutorial https://www.ssaurel.com/blog/learn-to-create-a-paint-application-for-android/
In this I am having 2 problems:
1. I can't figure out how to save the drawn figure as Image.
2. The Image formed should be saved as an external file or is it better to save in SQLite Database

Code of MainActivity.java

    public class MainActivity extends AppCompatActivity {

private PaintView paintView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    paintView = (PaintView) findViewById(R.id.paintView);
    DisplayMetrics metrics = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(metrics);
    paintView.init(metrics);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater menuInflater = getMenuInflater();
    menuInflater.inflate(R.menu.main, menu);
    return super.onCreateOptionsMenu(menu);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch(item.getItemId()) {
        case R.id.normal:
            paintView.normal();
            return true;
        case R.id.emboss:
            paintView.emboss();
            return true;
        case R.id.blur:
            paintView.blur();
            return true;
        case R.id.clear:
            paintView.clear();
            return true;
    }

    return super.onOptionsItemSelected(item);
}
}

PaintView.class

    public class PaintView extends View {

public static int BRUSH_SIZE = 20;
public static final int DEFAULT_COLOR = Color.RED;
public static final int DEFAULT_BG_COLOR = Color.WHITE;
private static final float TOUCH_TOLERANCE = 4;
private float mX, mY;
private Path mPath;
private Paint mPaint;
private ArrayList<FingerPath> paths = new ArrayList<>();
private int currentColor;
private int backgroundColor = DEFAULT_BG_COLOR;
private int strokeWidth;
private boolean emboss;
private boolean blur;
private MaskFilter mEmboss;
private MaskFilter mBlur;
private Bitmap mBitmap;
private Canvas mCanvas;
private Paint mBitmapPaint = new Paint(Paint.DITHER_FLAG);

public PaintView(Context context) {
    this(context, null);
}

public PaintView(Context context, AttributeSet attrs) {
    super(context, attrs);
    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setDither(true);
    mPaint.setColor(DEFAULT_COLOR);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setXfermode(null);
    mPaint.setAlpha(0xff);

    mEmboss = new EmbossMaskFilter(new float[] {1, 1, 1}, 0.4f, 6, 3.5f);
    mBlur = new BlurMaskFilter(5, BlurMaskFilter.Blur.NORMAL);
}

public void init(DisplayMetrics metrics) {
    int height = metrics.heightPixels;
    int width = metrics.widthPixels;

    mBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
    mCanvas = new Canvas(mBitmap);

    currentColor = DEFAULT_COLOR;
    strokeWidth = BRUSH_SIZE;
}

public void normal() {
    emboss = false;
    blur = false;
}

public void emboss() {
    emboss = true;
    blur = false;
}

public void blur() {
    emboss = false;
    blur = true;
}

public void clear() {
    backgroundColor = DEFAULT_BG_COLOR;
    paths.clear();
    normal();
    invalidate();
}

@Override
protected void onDraw(Canvas canvas) {
    canvas.save();
    mCanvas.drawColor(backgroundColor);

    for (FingerPath fp : paths) {
        mPaint.setColor(fp.color);
        mPaint.setStrokeWidth(fp.strokeWidth);
        mPaint.setMaskFilter(null);

        if (fp.emboss)
            mPaint.setMaskFilter(mEmboss);
        else if (fp.blur)
            mPaint.setMaskFilter(mBlur);

        mCanvas.drawPath(fp.path, mPaint);

    }

    canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
    canvas.restore();
}

private void touchStart(float x, float y) {
    mPath = new Path();
    FingerPath fp = new FingerPath(currentColor, emboss, blur, strokeWidth, mPath);
    paths.add(fp);

    mPath.reset();
    mPath.moveTo(x, y);
    mX = x;
    mY = y;
}

private void touchMove(float x, float y) {
    float dx = Math.abs(x - mX);
    float dy = Math.abs(y - mY);

    if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
        mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
        mX = x;
        mY = y;
    }
}

private void touchUp() {
    mPath.lineTo(mX, mY);
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    float x = event.getX();
    float y = event.getY();

    switch(event.getAction()) {
        case MotionEvent.ACTION_DOWN :
            touchStart(x, y);
            invalidate();
            break;
        case MotionEvent.ACTION_MOVE :
            touchMove(x, y);
            invalidate();
            break;
        case MotionEvent.ACTION_UP :
            touchUp();
            invalidate();
            break;
    }

    return true;
}
}

score 0 · Accepted Answer · answered Jun 20 '18 at 15:49

0

I think the Image is stored in mBitmap.

Describing how to save a bitmap in Android to internal storage or SD-Card: Save bitmap to location

FileOutputStream out = null;
try {
    out = new FileOutputStream(filename);
    mBitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
    // PNG is a lossless format, the compression factor (100) is ignored
} catch (Exception e) {
    e.printStackTrace();
} finally {
    try {
        if (out != null) {
            out.close();
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

Hope it helps

answered Jun 20 '18 at 15:49

Jannis

31
1

Thanks it did work! However, is there a way to load a given bitmap into the canvas? – Akshra Gupta Jun 22 '18 at 06:51
try `canvas= new Canvas(bitmap)` – Jannis Jun 22 '18 at 13:41

Saving a file in drawing app

1 Answers1