Detect image skew angle and deskew image

// SkewManager.h: interface for the SkewManager class.
//
//////////////////////////////////////////////////////////////////////

#ifndef __SKEWMANAGER_H__
#define __SKEWMANAGER_H__

#include "ImageData.h"

#define M_PI 3.14159265358979323846


class SkewManager
{
public:
	SkewManager();
	virtual ~SkewManager();
	
	bool GetSkewAngle(bool isTextImage, ImageData& image, double& outAngle, int canny_slices = 0);

private:
	
	enum EdgeType
	{
		ET_LEFT = 0,
		ET_TOP,
		ET_RIGHT,
		ET_BOTTOM
	};
	struct SlopeInfo
	{
		double x;
		double y;
		double slope;
		double rounded_slope;
		int frequency;

		SlopeInfo()
		{
			x = INFINITE;
			y = INFINITE;
			slope = INFINITE;
			rounded_slope = INFINITE;
			frequency = INFINITE;
		}
	};
	
	bool IsText(ImageData& image);
	double GetTextSkewAngle(ImageData& image, int sample_skip = 10);
	double GetImageSkewAngle(ImageData& image, int slices, EdgeType edge_type, int edge_depth, double* indicator1, double* indicator2);
	
	double Histogram(ImageData& image, double angle);	
	//DJP 07Feb13 Changed int row to unsigned int row to avoid compiler warning
	unsigned int CastRay(ImageData& raster, unsigned int row, const double &dx, int dy);
	unsigned int bit_count(unsigned char* buf, unsigned int start, unsigned int end);
	
	double sqr(double x)
	{
		return x * x;
	}
	
	double m_skew;
	int m_sample_skip;
	// DJP 07Feb13 Changed int m_max_rows to unsigned int m_max_rows to avoid compiler warning
	unsigned int m_max_rows;
	unsigned int* m_rows;
};

#endif // __SKEWMANAGER_H__