roundsliderctrl.cpp

一个非常好的圆形Slider Control类,对我们非常实用.

// RoundSliderCtrl.cpp: Implementation file
//
// Copyright (c) 1999 Daniel Frey
//
// Partially based on CRoundButton, copyright (c) 1997,1998 by Chris Maunder.
//
// Distribute and use freely, except:
// a) Don't alter or remove this notice.
// b) Mark the changes you make.
//
// This file is provided "as is" with no expressed or implied warranty.
// May not be sold for profit. Use at your own risk. Expect bugs.
//
// History:
//
//  v1.2  13.09.1999  Added knob-only drag-activation (suggested by Kevin Shale)
//
//  v1.1  11.05.1999  Added/fixed mouse-wheel support
//                    Added volume-button-look (thanks to Noam Rathaus)
//                    Added color and font support (thanks to John Gann)
//                    Fixed text position in OnPaint()
//
//  v1.0  19.04.1999  Initial release

#include "stdafx.h"
#include "RoundSliderCtrl.h"

#include <math.h>

#include "MemDC.h"
#define USE_MEM_DC // Comment this out, if you don't want to use CMemDC

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

static const double pi = 3.141592653589793238462643383279;

// The following 3 functions were taken from 'CRoundButton.cpp', written and
// copyright (c) 1997,1998 by Chris Maunder.

// To be honest, I never had a look at their implementation, I just use them.
// This is cut-and-paste-programming at its best... if it works... :)   (Daniel)

// prototypes
COLORREF GetColour(double dAngle, COLORREF crBright, COLORREF crDark);
void DrawCircle(CDC* pDC, CPoint p, LONG lRadius, COLORREF crColour, BOOL bDashed = FALSE);
void DrawCircle(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 
#define LIGHT_SOURCE_ANGLE	-2.356		// -2.356 radians = -135 degrees, i.e. From top left

	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
} 

void DrawCircle(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(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(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);

		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
} 

/////////////////////////////////////////////////////////////////////////////
// CRoundSliderCtrl

IMPLEMENT_DYNAMIC(CRoundSliderCtrl, CSliderCtrl)

CRoundSliderCtrl::CRoundSliderCtrl()
{
	m_strText = "%ld