roundbutton.cpp

深入剖析Visual C++编程技术及应用实例

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

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

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);

COLORREF GetColour(double dAngle, COLORREF crBright, COLORREF crDark)
{
#define Rad2Deg	180.0/3.1415 
#define LIGHT_SOURCE_ANGLE	-2.356

	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));

	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;

	ASSERT( (p.x + lRadius <= LONG_MAX) && (p.y + lRadius <= LONG_MAX) );
	ASSERT( (p.x - lRadius >= LONG_MIN) && (p.y - lRadius >= LONG_MIN) );

	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);
		}

		lError += lYoffset++;

		if ((lError += lYoffset) >= 0)
			lError -= --lXoffset * 2;

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

	} while (lYoffset <= lXoffset);	
} 

void DrawCircle(CDC* pDC, CPoint p, LONG lRadius, COLORREF crBright, COLORREF crDark)
{
	LONG lError, lXoffset, lYoffset;

	ASSERT( (p.x + lRadius <= LONG_MAX) && (p.y + lRadius <= LONG_MAX) );
	ASSERT( (p.x - lRadius >= LONG_MIN) && (p.y - lRadius >= LONG_MIN) );

	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);

		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);

		lError += lYoffset++;

		if ((lError += lYoffset) >= 0)
			lError -= --lXoffset * 2;

	} while (lYoffset <= lXoffset);
} 


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

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

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

BEGIN_MESSAGE_MAP(CRoundButton, CButton)
	//{{AFX_MSG_MAP(CRoundButton)
	//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CRoundButton message handlers

void CRoundButton::PreSubclassWindow() 
{
	CButton::PreSubclassWindow();

	ModifyStyle(0, BS_OWNERDRAW);

	CRect rect;
	GetClientRect(rect);

	rect.bottom = rect.right = min(rect.bottom,rect.right);

	m_ptCentre = rect.CenterPoint();
	m_nRadius  = rect.bottom/2-1;

	m_rgn.DeleteObject(); 
	SetWindowRgn(NULL, FALSE);
	m_rgn.CreateEllipticRgnIndirect(rect);
	SetWindowRgn(m_rgn, TRUE);

	ClientToScreen(rect);
	CWnd* pParent = GetParent();
	if (pParent) pParent->ScreenToClient(rect);

	MoveWindow(rect.left, rect.top, rect.Width(), rect.Height(), TRUE);
}

void CRoundButton::DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct) 
{
	ASSERT(lpDrawItemStruct != NULL);
	
	CDC* pDC   = CDC::FromHandle(lpDrawItemStruct->hDC);
	CRect rect = lpDrawItemStruct->rcItem;
	UINT state = lpDrawItemStruct->itemState;
	UINT nStyle = GetStyle();
	int nRadius = m_nRadius;

	int nSavedDC = pDC->SaveDC();

	pDC->SelectStockObject(NULL_BRUSH);
	pDC->FillSolidRect(rect, ::GetSysColor(COLOR_BTNFACE));

	if ((state & ODS_FOCUS) && m_bDrawDashedFocusCircle)
		DrawCircle(pDC, m_ptCentre, nRadius--, RGB(0,0,0));

	if (nStyle & BS_FLAT) {
		DrawCircle(pDC, m_ptCentre, nRadius--, RGB(0,0,0));
		DrawCircle(pDC, m_ptCentre, nRadius--, ::GetSysColor(COLOR_3DHIGHLIGHT));
	} else {
		if ((state & ODS_SELECTED))	{
			DrawCircle(pDC, m_ptCentre, nRadius--, 
					   ::GetSysColor(COLOR_3DDKSHADOW), ::GetSysColor(COLOR_3DHIGHLIGHT));
			DrawCircle(pDC, m_ptCentre, nRadius--, 
					   ::GetSysColor(COLOR_3DSHADOW), ::GetSysColor(COLOR_3DLIGHT));
		} else {
			DrawCircle(pDC, m_ptCentre, nRadius--, 
					   ::GetSysColor(COLOR_3DHIGHLIGHT), ::GetSysColor(COLOR_3DDKSHADOW));
			DrawCircle(pDC, m_ptCentre, nRadius--, 
					   ::GetSysColor(COLOR_3DLIGHT), ::GetSysColor(COLOR_3DSHADOW));
		}
	}
	
	CString strText;
	GetWindowText(strText);

	if (!strText.IsEmpty())
	{
		CRgn rgn;
		rgn.CreateEllipticRgn(m_ptCentre.x-nRadius, m_ptCentre.y-nRadius, 
							  m_ptCentre.x+nRadius, m_ptCentre.y+nRadius);
		pDC->SelectClipRgn(&rgn);

		CSize Extent = pDC->GetTextExtent(strText);
		CPoint pt = CPoint( m_ptCentre.x - Extent.cx/2, m_ptCentre.x - Extent.cy/2 );

		if (state & ODS_SELECTED) pt.Offset(1,1);

		pDC->SetBkMode(TRANSPARENT);

		if (state & ODS_DISABLED)
			pDC->DrawState(pt, Extent, strText, DSS_DISABLED, TRUE, 0, (HBRUSH)NULL);
		else
			pDC->TextOut(pt.x, pt.y, strText);

		pDC->SelectClipRgn(NULL);
		rgn.DeleteObject();
	}

	if ((state & ODS_FOCUS) && m_bDrawDashedFocusCircle)
		DrawCircle(pDC, m_ptCentre, nRadius-2, RGB(0,0,0), TRUE);

	pDC->RestoreDC(nSavedDC);
}