// RoundButton.cpp : implementation file
//
// Round Buttons!
//
//
// This code may be used in compiled form in any way you desire. This
// file may be redistributed unmodified by any means PROVIDING it is 
// not sold for profit without the authors written consent, and 
// providing that this notice and the authors name is included. If 
// the source code in this file is used in any commercial application 
// then a simple email would be nice.
//
// This file is provided "as is" with no expressed or implied warranty.
// The author accepts no liability if it causes any damage to your
// computer, causes your pet cat to fall ill, increases baldness or
// makes you car start emitting strange noises when you start it up.
//
// Expect bugs.
// 
// Please use and enjoy. Please let me know of any bugs/mods/improvements 
// that you have found/implemented and I will fix/incorporate them into this
// file. 
//
/////////////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "math.h"
#include "RoundButton.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

// prototypes
COLORREF GetColour(double dAngle, COLORREF crBright, COLORREF crDark);
void DrawCircle(CDC* pDC, CPoint p, LONG lRadius, COLORREF crColour, BOOL bDashed = FALSE);
void DrawCircleLeft(CDC* pDC, CPoint p, LONG lRadius, COLORREF crBright, COLORREF crDark);
void DrawCircleRight(CDC* pDC, CPoint p, LONG lRadius, COLORREF crBright, COLORREF crDark);


// Calculate colour for a point at the given angle by performing a linear
// interpolation between the colours crBright and crDark based on the cosine
// of the angle between the light source and the point.
//
// Angles are measured from the +ve x-axis (i.e. (1,0) = 0 degrees, (0,1) = 90 degrees )
// But remember: +y points down!

COLORREF GetColour(double dAngle, COLORREF crBright, COLORREF crDark)
{
#define Rad2Deg	180.0/3.1415 

// For better light-continuity along the edge of a stretched button: 
//	LIGHT_SOURCE_ANGLE == -1.88
	
//#define LIGHT_SOURCE_ANGLE	-2.356		// -2.356 radians = -135 degrees, i.e. From top left
#define LIGHT_SOURCE_ANGLE	-1.88

	ASSERT(dAngle > -3.1416 && dAngle < 3.1416);
	double dAngleDifference = LIGHT_SOURCE_ANGLE - dAngle;

	if (dAngleDifference < -3.1415) dAngleDifference = 6.293 + dAngleDifference;
	else if (dAngleDifference > 3.1415) dAngleDifference = 6.293 - dAngleDifference;

	double Weight = 0.5*(cos(dAngleDifference)+1.0);

	BYTE Red   = (BYTE) (Weight*GetRValue(crBright) + (1.0-Weight)*GetRValue(crDark));
	BYTE Green = (BYTE) (Weight*GetGValue(crBright) + (1.0-Weight)*GetGValue(crDark));
	BYTE Blue  = (BYTE) (Weight*GetBValue(crBright) + (1.0-Weight)*GetBValue(crDark));

	//TRACE("LightAngle = %0.0f, Angle = %3.0f, Diff = %3.0f, Weight = %0.2f, RGB %3d,%3d,%3d\n", 
	//	  LIGHT_SOURCE_ANGLE*Rad2Deg, dAngle*Rad2Deg, dAngleDifference*Rad2Deg, Weight,Red,Green,Blue);

	return RGB(Red, Green, Blue);
}

void DrawCircle(CDC* pDC, CPoint p, LONG lRadius, COLORREF crColour, BOOL bDashed)
{
	const int nDashLength = 1;
	LONG lError, lXoffset, lYoffset;
	int  nDash = 0;
	BOOL bDashOn = TRUE;

	//Check to see that the coordinates are valid
	ASSERT( (p.x + lRadius <= LONG_MAX) && (p.y + lRadius <= LONG_MAX) );
	ASSERT( (p.x - lRadius >= LONG_MIN) && (p.y - lRadius >= LONG_MIN) );

	//Set starting values
	lXoffset = lRadius;
	lYoffset = 0;
	lError   = -lRadius;

	do {
		if (bDashOn) {
			pDC->SetPixelV(p.x + lXoffset, p.y + lYoffset, crColour);
			pDC->SetPixelV(p.x + lXoffset, p.y - lYoffset, crColour);
			pDC->SetPixelV(p.x + lYoffset, p.y + lXoffset, crColour);
			pDC->SetPixelV(p.x + lYoffset, p.y - lXoffset, crColour);
			pDC->SetPixelV(p.x - lYoffset, p.y + lXoffset, crColour);
			pDC->SetPixelV(p.x - lYoffset, p.y - lXoffset, crColour);
			pDC->SetPixelV(p.x - lXoffset, p.y + lYoffset, crColour);
			pDC->SetPixelV(p.x - lXoffset, p.y - lYoffset, crColour);
		}

		//Advance the error term and the constant X axis step
		lError += lYoffset++;

		//Check to see if error term has overflowed
		if ((lError += lYoffset) >= 0)
			lError -= --lXoffset * 2;

		if (bDashed && (++nDash == nDashLength)) {
			nDash = 0;
			bDashOn = !bDashOn;
		}

	} while (lYoffset <= lXoffset);	//Continue until halfway point
} 

// The original Drawcircle function is split up into DrawCircleRight and DrawCircleLeft
// to make stretched buttons
//
void DrawCircleRight(CDC* pDC, CPoint p, LONG lRadius, COLORREF crBright, COLORREF crDark)
{
	LONG lError, lXoffset, lYoffset;

	//Check to see that the coordinates are valid
	ASSERT( (p.x + lRadius <= LONG_MAX) && (p.y + lRadius <= LONG_MAX) );
	ASSERT( (p.x - lRadius >= LONG_MIN) && (p.y - lRadius >= LONG_MIN) );

	//Set starting values
	lXoffset = lRadius;
	lYoffset = 0;
	lError   = -lRadius;

	do {
		const double Pi = 3.141592654, 
					 Pi_on_2 = Pi * 0.5,
					 Three_Pi_on_2 = Pi * 1.5;
		COLORREF crColour;
		double   dAngle = atan2(lYoffset, lXoffset);

		//Draw the current pixel, reflected across all four arcs

		crColour = GetColour(dAngle, crBright, crDark);
		pDC->SetPixelV(p.x + lXoffset, p.y + lYoffset, crColour);

		crColour = GetColour(Pi_on_2 - dAngle, crBright, crDark);
		pDC->SetPixelV(p.x + lYoffset, p.y + lXoffset, crColour);

		crColour = GetColour(-Pi_on_2 + dAngle, crBright, crDark);
		pDC->SetPixelV(p.x + lYoffset, p.y - lXoffset, crColour);

		crColour = GetColour(-dAngle, crBright, crDark);
		pDC->SetPixelV(p.x + lXoffset, p.y - lYoffset, crColour);

		//Advance the error term and the constant X axis step
		lError += lYoffset++;

		//Check to see if error term has overflowed
		if ((lError += lYoffset) >= 0)
			lError -= --lXoffset * 2;

	} while (lYoffset <= lXoffset);	//Continue until halfway point
} 

// The original Drawcircle function is split up into DrawCircleRight and DrawCircleLeft
// to make stretched buttons
//
void DrawCircleLeft(CDC* pDC, CPoint p, LONG lRadius, COLORREF crBright, COLORREF crDark)
{
	LONG lError, lXoffset, lYoffset;

	//Check to see that the coordinates are valid
	ASSERT( (p.x + lRadius <= LONG_MAX) && (p.y + lRadius <= LONG_MAX) );
	ASSERT( (p.x - lRadius >= LONG_MIN) && (p.y - lRadius >= LONG_MIN) );

	//Set starting values
	lXoffset = lRadius;
	lYoffset = 0;
	lError   = -lRadius;

	do {
		const double Pi = 3.141592654, 
					 Pi_on_2 = Pi * 0.5,
					 Three_Pi_on_2 = Pi * 1.5;
		COLORREF crColour;
		double   dAngle = atan2(lYoffset, lXoffset);

		//Draw the current pixel, reflected across all eight arcs

		crColour = GetColour(Pi_on_2 + dAngle, crBright, crDark);
		pDC->SetPixelV(p.x - lYoffset, p.y + lXoffset, crColour);

		crColour = GetColour(Pi - dAngle, crBright, crDark);
		pDC->SetPixelV(p.x - lXoffset, p.y + lYoffset, crColour);

		crColour = GetColour(-Pi + dAngle, crBright, crDark);
		pDC->SetPixelV(p.x - lXoffset, p.y - lYoffset, crColour);

		crColour = GetColour(-Pi_on_2 - dAngle, crBright, crDark);
		pDC->SetPixelV(p.x - lYoffset, p.y - lXoffset, crColour);

		//Advance the error term and the constant X axis step
		lError += lYoffset++;

		//Check to see if error term has overflowed
		if ((lError += lYoffset) >= 0)
			lError -= --lXoffset * 2;

	} while (lYoffset <= lXoffset);	//Continue until halfway point
} 

static void	CreateButtonRgn(CRgn & rgn, const CRect & rect, const CPoint & ptLeft, const CPoint & ptRight, int nRadius) {
	CBrush brush;
	brush.CreateSolidBrush(::GetSysColor(COLOR_BTNFACE));

	// left circle
	CRgn rgnLeftCircle;
	VERIFY(rgnLeftCircle.CreateEllipticRgn(ptLeft.x-nRadius, ptLeft.y-nRadius, ptLeft.x+nRadius, ptLeft.y+nRadius));
	VERIFY(rgn.CreateEllipticRgn(ptLeft.x-nRadius, ptLeft.y-nRadius, ptLeft.x+nRadius, ptLeft.y+nRadius));
	CRgn rgnLeftPart;
	VERIFY(rgnLeftPart.CreateEllipticRgn(ptLeft.x-nRadius, ptLeft.y-nRadius, ptLeft.x+nRadius, ptLeft.y+nRadius));

	// main body
	CRgn rgnMainBody;
	VERIFY(rgnMainBody.CreateRectRgn(rect.left+nRadius, rect.top, rect.right-nRadius, rect.bottom));

	CRgn rgnRightCircle;
	VERIFY(rgnRightCircle.CreateEllipticRgn(ptRight.x+2+nRadius, ptRight.y+nRadius, ptRight.x+2-nRadius, ptRight.y-nRadius));

	// OK now combine the regions
	VERIFY(rgnLeftPart.CombineRgn(&rgnLeftCircle, &rgnMainBody, RGN_OR) != ERROR);

	VERIFY(rgn.CombineRgn(&rgnLeftPart, &rgnRightCircle, RGN_OR) != ERROR);
}

/////////////////////////////////////////////////////////////////////////////
// CRoundButton

CRoundButton::CRoundButton()
{
	m_bDrawDashedFocusCircle = TRUE;
}

CRoundButton::~CRoundButton()
{
	m_rgn.DeleteObject();