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POAdding Undo and Deletion to FingerPaint.java
 

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  1. POAdding Undo and Deletion to FingerPaint.java
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    <p>I have worked on the fingerpaint class before and I was very much comfortable but this time I found myself in deep trouble implementing both these functionalities of Undo and deletion</p> <p>This is my drawing view</p> <pre><code>public class MyView extends View { private Bitmap mBitmap; private Canvas mCanvas; private Path mPath; private Paint mBitmapPaint; public MyView(Context c) { super(c); mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888); mCanvas = new Canvas(mBitmap); mPath = new Path(); mBitmapPaint = new Paint(Paint.DITHER_FLAG); } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); } @Override protected void onDraw(Canvas canvas) { /*canvas.drawColor(Color.WHITE); canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);*/ for (int i=0;i&lt;paths.size();i++){ canvas.drawPath(paths.get(i).path, paths.get(i).paint); } canvas.drawPath(mPath, mPaint); } private float mX, mY; private static final float TOUCH_TOLERANCE = 4; private void touch_start(float x, float y) { if ( erase == true ) { mPath.reset(); } undonePaths.clear(); 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 (check == 1 || (selectedId == ERASE_MENU_ID) ) { if (dx &gt;= TOUCH_TOLERANCE || dy &gt;= TOUCH_TOLERANCE) { mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2); mX = x; mY = y; mCanvas.drawPath(mPath, mPaint); } } if(selectedId == ERASE_MENU_ID) { mCanvas.drawPath(mPath, mPaint); mPath=new Path(); mX = x; mY = y; mPath.moveTo(x, y); } } public void onClickUndo () { if (paths.size()&gt;0) { paths.remove(paths.size()-1); invalidate(); } else { } //toast the user } private void touch_up() { mCanvas.drawPath(mPath, mPaint); MyDataHolder md=new MyDataHolder(); md.paint=mPaint; md.path=mPath; paths.add(md); mPath=new Path(); } @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; } } </code></pre> <p>Now the problem is when I change mPaint's mode to clear</p> <pre><code> erase=true; mPaint.setXfermode(null); mPaint.setStrokeWidth(25.0f); //mPaint.setColor(Color.TRANSPARENT); mPaint.setXfermode(new PorterDuffXfermode(Mode.CLEAR)); </code></pre> <p>every drawn path turns black with 25 width somebody suggested that I am using same paint so I made a wrapper class to store paint and path object but it's not working.</p>
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    1. USAashish Bhatnagar
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