My code: public class MainActivity extends GraphicsActivity{ @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);

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Asked: June 13, 20262026-06-13T08:22:53+00:00 2026-06-13T08:22:53+00:00

My code: public class MainActivity extends GraphicsActivity{ @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);

0

My code:

public class MainActivity extends GraphicsActivity{    

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new MyView(this));

        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setDither(true);
        mPaint.setColor(0xffffffff);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeJoin(Paint.Join.ROUND);
        mPaint.setStrokeCap(Paint.Cap.ROUND);
        mPaint.setStrokeWidth(12);

        mEmboss = new EmbossMaskFilter(new float[] { 1, 1, 1 },
                                       0.4f, 6, 3.5f);
        mPaint.setMaskFilter(mEmboss);

        //mBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.NORMAL);
    }

    private Paint       mPaint;
    private MaskFilter  mEmboss;

    public class MyView extends View {

        private Bitmap  mBitmap;
        private Canvas  mCanvas;
        private Path    mPath;
        private Paint   mBitmapPaint;

        public MyView(Context c) {
            super(c);

            Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.t01);
            Display  display = getWindowManager().getDefaultDisplay();
            int height = display.getWidth();
            int width = display.getHeight();
            mBitmap = Bitmap.createScaledBitmap(bmp, height, width, true);
            //mBitmap = Bitmap.createBitmap(320, 480, Bitmap.Config.ARGB_8888);
            mCanvas = new Canvas(mBitmap);
            mPath = new Path();
            mBitmapPaint = new Paint(Paint.DITHER_FLAG);
        }

        @Override
        protected void onDraw(Canvas canvas) {

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

            canvas.drawPath(mPath, mPaint);
        }

        private float mX, mY;
        private static final float TOUCH_TOLERANCE = 4;

        private void touch_start(float x, float y) {
            mPath.reset();
            mPath.moveTo(x, y);
            mX = x;
            mY = y;
        }
        private void touch_move(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 touch_up() {
            mPath.lineTo(mX, mY);
            // commit the path to our offscreen
            mCanvas.drawPath(mPath, mPaint);
            // kill this so we don't double draw
            mPath.reset();
        }

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

            switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    touch_start(x, y);
                    invalidate();
                    break;
                case MotionEvent.ACTION_MOVE:
                    touch_move(x, y);
                    invalidate();
                    break;
                case MotionEvent.ACTION_UP:
                    touch_up();
                    invalidate();
                    break;
            }
            return true;
        }
    }

}

My xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <ImageView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:src="@drawable/t01"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true" />

</RelativeLayout>

Now I want add the view in the activity to this xml and also I want to place this view over the layout such that the image must be seen and also the view. Actually I’m trying to draw inside the lines of the letter in the image. Something like tracing the letter.
And also I don’t want my canvas draw to exclude the outline of my Letter in the image. If it crosses, then I want to put some warning sound.
enter image description here
Please help me how to do this?
Thanks in advance.

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1 Answer

Editorial Team · Answer 1 · 2026-06-13T08:22:54+00:00

When I tried the answer given by MarvinLabs, I get Inflate Exception. So tried to write the code using java itself. My code that worked out for me:

public class MainActivity extends GraphicsActivity{

    private Button clearButton;
    MyView signature;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        signature = new MyView(this);

        RelativeLayout myLayout = new RelativeLayout(this);
        myLayout.setLayoutParams(new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));

        clearButton = new Button(this);
        clearButton.setText("Clear");
        clearButton.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {
                // To clear the drawn lines with finger.
                Intent intent = new Intent(MainActivity.this, MainActivity.class);
            startActivity(intent);
            finish();
            }
        });

        myLayout.addView(signature);
        myLayout.addView(clearButton);

        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(100, LayoutParams.WRAP_CONTENT);
        params.addRule(RelativeLayout.ALIGN_PARENT_TOP);
        params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
        clearButton.setLayoutParams(params);

        clearButton.bringToFront();
        this.setContentView(myLayout);

        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setDither(true);
        mPaint.setColor(0xffffffff);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeJoin(Paint.Join.ROUND);
        mPaint.setStrokeCap(Paint.Cap.ROUND);
        mPaint.setStrokeWidth(12);

        mEmboss = new EmbossMaskFilter(new float[] { 1, 1, 1 },
                                       0.4f, 6, 3.5f);
        mPaint.setMaskFilter(mEmboss);

    }

    private Paint       mPaint;
    private MaskFilter  mEmboss;


    public class MyView extends View {

        private static final float MINP = 0.25f;
        private static final float MAXP = 0.75f;

        private Bitmap  mBitmap;
        private Canvas  mCanvas;
        private Path    mPath;
        private Paint   mBitmapPaint;

        public MyView(Context c) {
            super(c);

            Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.t01);
            Display  display = getWindowManager().getDefaultDisplay();
            int height = display.getWidth();
            int width = display.getHeight();
            mBitmap = Bitmap.createScaledBitmap(bmp, height, width, true);
            mCanvas = new Canvas(mBitmap);
            mPath = new Path();
            mBitmapPaint = new Paint(Paint.DITHER_FLAG);
        }


        @Override
        protected void onDraw(Canvas canvas) {

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

            canvas.drawPath(mPath, mPaint);
        }

        private float mX, mY;
        private static final float TOUCH_TOLERANCE = 4;

        private void touch_start(float x, float y) {
            mPath.reset();
            mPath.moveTo(x, y);
            mX = x;
            mY = y;
        }
        private void touch_move(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 touch_up() {
            mPath.lineTo(mX, mY);
            // commit the path to our offscreen
            mCanvas.drawPath(mPath, mPaint);
            // kill this so we don't double draw
            mPath.reset();
        }

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

            switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    touch_start(x, y);
                    invalidate();
                    break;
                case MotionEvent.ACTION_MOVE:
                    touch_move(x, y);
                    invalidate();
                    break;
                case MotionEvent.ACTION_UP:
                    touch_up();
                    invalidate();
                    break;
            }
            return true;
        }
    }
}

Thanks for the support and help.

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My code: public class MainActivity extends GraphicsActivity{ @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);

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