Thursday, 13 September 2012

Android signature using Canvas

Signature which is used in many cases such as proof of delivery, inspection forms,to purchase new sim card.Here is sample program that how to make signature using canvas. 
And you can save this signature as png.


    public signature(Context context, AttributeSet attrs)
        {
            super(context, attrs);
            paint.setAntiAlias(true);
            paint.setColor(Color.BLACK);
            paint.setStyle(Paint.Style.STROKE);
            paint.setStrokeJoin(Paint.Join.ROUND);
            paint.setStrokeWidth(STROKE_WIDTH);
        }

        @Override
        protected void onDraw(Canvas canvas)
        {
            canvas.drawPath(path, paint);
        }

        @Override
        public boolean onTouchEvent(MotionEvent event)
        {
            float eventX = event.getX();
            float eventY = event.getY();
            mGetSign.setEnabled(true);

            switch (event.getAction())
            {
            case MotionEvent.ACTION_DOWN:
                path.moveTo(eventX, eventY);
                lastTouchX = eventX;
                lastTouchY = eventY;
                return true;

            case MotionEvent.ACTION_MOVE:

            case MotionEvent.ACTION_UP:

                resetDirtyRect(eventX, eventY);
                int historySize = event.getHistorySize();
                for (int i = 0; i < historySize; i++)
                {
                    float historicalX = event.getHistoricalX(i);
                    float historicalY = event.getHistoricalY(i);
                    expandDirtyRect(historicalX, historicalY);
                    path.lineTo(historicalX, historicalY);
                }
                path.lineTo(eventX, eventY);
                break;

            default;
                return false;
            }

            invalidate((int) (dirtyRect.left - HALF_STROKE_WIDTH),
                    (int) (dirtyRect.top - HALF_STROKE_WIDTH),
                    (int) (dirtyRect.right + HALF_STROKE_WIDTH),
                    (int) (dirtyRect.bottom + HALF_STROKE_WIDTH));

            lastTouchX = eventX;
            lastTouchY = eventY;

            return true;
        }

    
        private void expandDirtyRect(float historicalX, float historicalY)
        {
            if (historicalX < dirtyRect.left)
            {
                dirtyRect.left = historicalX;
            }
            else if (historicalX > dirtyRect.right)
            {
                dirtyRect.right = historicalX;
            }

            if (historicalY < dirtyRect.top)
            {
                dirtyRect.top = historicalY;
            }
            else if (historicalY > dirtyRect.bottom)
            {
                dirtyRect.bottom = historicalY;
            }
        }

        private void resetDirtyRect(float eventX, float eventY)
        {
            dirtyRect.left = Math.min(lastTouchX, eventX);
            dirtyRect.right = Math.max(lastTouchX, eventX);
            dirtyRect.top = Math.min(lastTouchY, eventY);
            dirtyRect.bottom = Math.max(lastTouchY, eventY);
        }
    }
}

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