threshold.cpp

barcode readers [ from Image]

//
// Threshold
//   If bLessThan is true, output is 0 if pixel is < threshold, 255 otherwise.
//   If bLessThan is false, output is 0 if pixel is > threshold, 255 otherwise.
//   Output overwrites input.
//
// Copyright (C) 2003, 2006 by Jon A. Webb (Contact via GMail; username is jonawebb)
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
// 
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
// 
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
//

#include "Threshold.h"

#include "Debug.h"
#include "GrayImageIter.h"
#include "GrayIndex.h"
#include "Image.h"
#include "ImageSize.h"
#include "Replicate.h"

#include <e32std.h>
#include <fbs.h>

using namespace Core;

namespace Algorithm
{

	EXPORT_C CThreshold* CThreshold::NewL(int nThreshold, bool bLessThan)
	{	
		return new (ELeave) CThreshold(nThreshold, bLessThan);	
	}

	CThreshold::~CThreshold()
	{
	}

	CThreshold::CThreshold(int nThreshold, bool bLessThan) :
		ibEmpty(true),
		ibLessThan(bLessThan),
		mnThreshold(nThreshold)
	{
	}

	CImage CThreshold::FrontL() 
	{
		if (ibEmpty) {
			User::Leave(KErrGeneral);
			return CImage();
		}
		ibEmpty = true;
		return iImage;
	}

	void CThreshold::PushL(CImage image)
	{
		image.LockLC();
		IGrayImageIter it(image);
		for (it.Reset(); !it.End(); it.NextRow()) {
			if (ibLessThan) {
				for (; !it.REnd(); it++) {
					if (it() < mnThreshold) {
						it() = 0;
					} else {
						it() = 255;
					}
				}
			} else {
				for (; !it.REnd(); it++) {
					if (it() > mnThreshold) {
						it() = 0;
					} else {
						it() = 255;
					}
				}
			}
		}
		CleanupStack::PopAndDestroy(); // unlock bitmaps
		iImage = image;
		CDebug::ShowImage(iImage);
		ibEmpty = false;
	}

	bool CThreshold::Empty() const
	{
		return ibEmpty;
	}

};