mfc作图问题求解，新手

Question

CClientDC画出图形，如何计算图形面积？dc都包含那些函数？

Answer 1

 class CDC : public CObject
{
    DECLARE_DYNCREATE(CDC)
public:

// Attributes
    HDC m_hDC;          // The output DC (must be first data member)
    HDC m_hAttribDC;    // The Attribute DC
    operator HDC() const;
    HDC GetSafeHdc() const; // Always returns the Output DC
    CWnd* GetWindow() const;

    static CDC* PASCAL FromHandle(HDC hDC);
    static void PASCAL DeleteTempMap();
    BOOL Attach(HDC hDC);   // Attach/Detach affects only the Output DC
    HDC Detach();

    virtual void SetAttribDC(HDC hDC);  // Set the Attribute DC
    virtual void SetOutputDC(HDC hDC);  // Set the Output DC
    virtual void ReleaseAttribDC();     // Release the Attribute DC
    virtual void ReleaseOutputDC();     // Release the Output DC

    BOOL IsPrinting() const;            // TRUE if being used for printing

    CPen* GetCurrentPen() const;
    CBrush* GetCurrentBrush() const;
    CPalette* GetCurrentPalette() const;
    CFont* GetCurrentFont() const;
    CBitmap* GetCurrentBitmap() const;

    // for bidi and mirrored localization
    DWORD GetLayout() const;
    DWORD SetLayout(DWORD dwLayout);

// Constructors
    CDC();
    BOOL CreateDC(LPCTSTR lpszDriverName, LPCTSTR lpszDeviceName,
        LPCTSTR lpszOutput, const void* lpInitData);
    BOOL CreateIC(LPCTSTR lpszDriverName, LPCTSTR lpszDeviceName,
        LPCTSTR lpszOutput, const void* lpInitData);
    BOOL CreateCompatibleDC(CDC* pDC);

    BOOL DeleteDC();

// Device-Context Functions
    virtual int SaveDC();
    virtual BOOL RestoreDC(int nSavedDC);
    int GetDeviceCaps(int nIndex) const;
    UINT SetBoundsRect(LPCRECT lpRectBounds, UINT flags);
    UINT GetBoundsRect(LPRECT lpRectBounds, UINT flags);
    BOOL ResetDC(const DEVMODE* lpDevMode);

// Drawing-Tool Functions
    CPoint GetBrushOrg() const;
    CPoint SetBrushOrg(int x, int y);
    CPoint SetBrushOrg(POINT point);
    int EnumObjects(int nObjectType,
            int (CALLBACK* lpfn)(LPVOID, LPARAM), LPARAM lpData);

// Type-safe selection helpers
public:
    virtual CGdiObject* SelectStockObject(int nIndex);
    CPen* SelectObject(CPen* pPen);
    CBrush* SelectObject(CBrush* pBrush);
    virtual CFont* SelectObject(CFont* pFont);
    CBitmap* SelectObject(CBitmap* pBitmap);
    int SelectObject(CRgn* pRgn);       // special return for regions
    CGdiObject* SelectObject(CGdiObject* pObject);
        // CGdiObject* provided so compiler doesn't use SelectObject(HGDIOBJ)

// Color and Color Palette Functions
    COLORREF GetNearestColor(COLORREF crColor) const;
    CPalette* SelectPalette(CPalette* pPalette, BOOL bForceBackground);
    UINT RealizePalette();
    void UpdateColors();

// Drawing-Attribute Functions
    COLORREF GetBkColor() const;
    int GetBkMode() const;
    int GetPolyFillMode() const;
    int GetROP2() const;
    int GetStretchBltMode() const;
    COLORREF GetTextColor() const;

    virtual COLORREF SetBkColor(COLORREF crColor);
    int SetBkMode(int nBkMode);
    int SetPolyFillMode(int nPolyFillMode);
    int SetROP2(int nDrawMode);
    int SetStretchBltMode(int nStretchMode);
    virtual COLORREF SetTextColor(COLORREF crColor);

    BOOL GetColorAdjustment(LPCOLORADJUSTMENT lpColorAdjust) const;
    BOOL SetColorAdjustment(const COLORADJUSTMENT* lpColorAdjust);

#if (_WIN32_WINNT >= 0x0500)

    COLORREF GetDCBrushColor() const;
    COLORREF SetDCBrushColor(COLORREF crColor);

    COLORREF GetDCPenColor() const;
    COLORREF SetDCPenColor(COLORREF crColor);

#endif

    // Graphics mode
    int SetGraphicsMode(int iMode);
    int GetGraphicsMode() const;

    // World transform
    BOOL SetWorldTransform(const XFORM* pXform);
    BOOL ModifyWorldTransform(const XFORM* pXform,DWORD iMode);
    BOOL GetWorldTransform(XFORM* pXform) const;

    // Mapping Functions
    int GetMapMode() const;
    CPoint GetViewportOrg() const;
    virtual int SetMapMode(int nMapMode);
    // Viewport Origin
    virtual CPoint SetViewportOrg(int x, int y);
            CPoint SetViewportOrg(POINT point);
    virtual CPoint OffsetViewportOrg(int nWidth, int nHeight);

    // Viewport Extent
    CSize GetViewportExt() const;
    virtual CSize SetViewportExt(int cx, int cy);
            CSize SetViewportExt(SIZE size);
    virtual CSize ScaleViewportExt(int xNum, int xDenom, int yNum, int yDenom);

    // Window Origin
    CPoint GetWindowOrg() const;
    CPoint SetWindowOrg(int x, int y);
    CPoint SetWindowOrg(POINT point);
    CPoint OffsetWindowOrg(int nWidth, int nHeight);

    // Window extent
    CSize GetWindowExt() const;
    virtual CSize SetWindowExt(int cx, int cy);
            CSize SetWindowExt(SIZE size);
    virtual CSize ScaleWindowExt(int xNum, int xDenom, int yNum, int yDenom);

// Coordinate Functions
    void DPtoLP(LPPOINT lpPoints, int nCount = 1) const;
    void DPtoLP(LPRECT lpRect) const;
    void DPtoLP(LPSIZE lpSize) const;
    void LPtoDP(LPPOINT lpPoints, int nCount = 1) const;
    void LPtoDP(LPRECT lpRect) const;
    void LPtoDP(LPSIZE lpSize) const;

// Special Coordinate Functions (useful for dealing with metafiles and OLE)
    void DPtoHIMETRIC(LPSIZE lpSize) const;
    void LPtoHIMETRIC(LPSIZE lpSize) const;
    void HIMETRICtoDP(LPSIZE lpSize) const;
    void HIMETRICtoLP(LPSIZE lpSize) const;

// Region Functions
    BOOL FillRgn(CRgn* pRgn, CBrush* pBrush);
    BOOL FrameRgn(CRgn* pRgn, CBrush* pBrush, int nWidth, int nHeight);
    BOOL InvertRgn(CRgn* pRgn);
    BOOL PaintRgn(CRgn* pRgn);

// Clipping Functions
    virtual int GetClipBox(LPRECT lpRect) const;
    virtual BOOL PtVisible(int x, int y) const;
            BOOL PtVisible(POINT point) const;
    virtual BOOL RectVisible(LPCRECT lpRect) const;
            int SelectClipRgn(CRgn* pRgn);
            int ExcludeClipRect(int x1, int y1, int x2, int y2);
            int ExcludeClipRect(LPCRECT lpRect);
            int ExcludeUpdateRgn(CWnd* pWnd);
            int IntersectClipRect(int x1, int y1, int x2, int y2);
            int IntersectClipRect(LPCRECT lpRect);
            int OffsetClipRgn(int x, int y);
            int OffsetClipRgn(SIZE size);
    int SelectClipRgn(CRgn* pRgn, int nMode);

// Line-Output Functions
    CPoint GetCurrentPosition() const;
    CPoint MoveTo(int x, int y);
    CPoint MoveTo(POINT point);
    BOOL LineTo(int x, int y);
    BOOL LineTo(POINT point);
    BOOL Arc(int x1, int y1, int x2, int y2, int x3, int y3, int x4, int y4);
    BOOL Arc(LPCRECT lpRect, POINT ptStart, POINT ptEnd);
    BOOL Polyline(const POINT* lpPoints, int nCount);

    BOOL AngleArc(int x, int y, int nRadius, float fStartAngle, float fSweepAngle);
    BOOL ArcTo(int x1, int y1, int x2, int y2, int x3, int y3, int x4, int y4);
    BOOL ArcTo(LPCRECT lpRect, POINT ptStart, POINT ptEnd);
    int GetArcDirection() const;
    int SetArcDirection(int nArcDirection);

    BOOL PolyDraw(const POINT* lpPoints, const BYTE* lpTypes, int nCount);
    BOOL PolylineTo(const POINT* lpPoints, int nCount);
    BOOL PolyPolyline(const POINT* lpPoints,
        const DWORD* lpPolyPoints, int nCount);

    BOOL PolyBezier(const POINT* lpPoints, int nCount);
    BOOL PolyBezierTo(const POINT* lpPoints, int nCount);

// Simple Drawing Functions
    void FillRect(LPCRECT lpRect, CBrush* pBrush);
    void FrameRect(LPCRECT lpRect, CBrush* pBrush);
    void InvertRect(LPCRECT lpRect);
    BOOL DrawIcon(int x, int y, HICON hIcon);
    BOOL DrawIcon(POINT point, HICON hIcon);
    BOOL DrawState(CPoint pt, CSize size, HBITMAP hBitmap, UINT nFlags,
        HBRUSH hBrush = NULL);
    BOOL DrawState(CPoint pt, CSize size, CBitmap* pBitmap, UINT nFlags,
        CBrush* pBrush = NULL);
    BOOL DrawState(CPoint pt, CSize size, HICON hIcon, UINT nFlags,
        HBRUSH hBrush = NULL);
    BOOL DrawState(CPoint pt, CSize size, HICON hIcon, UINT nFlags,
        CBrush* pBrush = NULL);
    BOOL DrawState(CPoint pt, CSize size, LPCTSTR lpszText, UINT nFlags,
        BOOL bPrefixText = TRUE, int nTextLen = 0, HBRUSH hBrush = NULL);
    BOOL DrawState(CPoint pt, CSize size, LPCTSTR lpszText, UINT nFlags,
        BOOL bPrefixText = TRUE, int nTextLen = 0, CBrush* pBrush = NULL);
    BOOL DrawState(CPoint pt, CSize size, DRAWSTATEPROC lpDrawProc,
        LPARAM lData, UINT nFlags, HBRUSH hBrush = NULL);
    BOOL DrawState(CPoint pt, CSize size, DRAWSTATEPROC lpDrawProc,
        LPARAM lData, UINT nFlags, CBrush* pBrush = NULL);

// Ellipse and Polygon Functions
    BOOL Chord(int x1, int y1, int x2, int y2, int x3, int y3,
        int x4, int y4);
    BOOL Chord(LPCRECT lpRect, POINT ptStart, POINT ptEnd);
    void DrawFocusRect(LPCRECT lpRect);
    BOOL Ellipse(int x1, int y1, int x2, int y2);
    BOOL Ellipse(LPCRECT lpRect);
    BOOL Pie(int x1, int y1, int x2, int y2, int x3, int y3, int x4, int y4);
    BOOL Pie(LPCRECT lpRect, POINT ptStart, POINT ptEnd);
    BOOL Polygon(const POINT* lpPoints, int nCount);    
    BOOL PolyPolygon(const POINT* lpPoints, const INT* lpPolyCounts, int nCount);
    BOOL Rectangle(int x1, int y1, int x2, int y2);
    BOOL Rectangle(LPCRECT lpRect);
    BOOL RoundRect(int x1, int y1, int x2, int y2, int x3, int y3);
    BOOL RoundRect(LPCRECT lpRect, POINT point);

// Bitmap Functions
    BOOL PatBlt(int x, int y, int nWidth, int nHeight, DWORD dwRop);
    BOOL BitBlt(int x, int y, int nWidth, int nHeight, CDC* pSrcDC,
        int xSrc, int ySrc, DWORD dwRop);
    BOOL StretchBlt(int x, int y, int nWidth, int nHeight, CDC* pSrcDC,
        int xSrc, int ySrc, int nSrcWidth, int nSrcHeight, DWORD dwRop);
    COLORREF GetPixel(int x, int y) const;
    COLORREF GetPixel(POINT point) const;
    COLORREF SetPixel(int x, int y, COLORREF crColor);
    COLORREF SetPixel(POINT point, COLORREF crColor);
    BOOL FloodFill(int x, int y, COLORREF crColor);
    BOOL ExtFloodFill(int x, int y, COLORREF crColor, UINT nFillType);
    BOOL MaskBlt(int x, int y, int nWidth, int nHeight, CDC* pSrcDC,
        int xSrc, int ySrc, CBitmap& maskBitmap, int xMask, int yMask,
        DWORD dwRop);
    BOOL PlgBlt(LPPOINT lpPoint, CDC* pSrcDC, int xSrc, int ySrc,
        int nWidth, int nHeight, CBitmap& maskBitmap, int xMask, int yMask);
    BOOL SetPixelV(int x, int y, COLORREF crColor);
    BOOL SetPixelV(POINT point, COLORREF crColor);
   BOOL GradientFill(TRIVERTEX* pVertices, ULONG nVertices, 
      void* pMesh, ULONG nMeshElements, DWORD dwMode);
   BOOL TransparentBlt(int xDest, int yDest, int nDestWidth, int nDestHeight,
      CDC* pSrcDC, int xSrc, int ySrc, int nSrcWidth, int nSrcHeight, 
      UINT clrTransparent);
   BOOL AlphaBlend(int xDest, int yDest, int nDestWidth, int nDestHeight,
      CDC* pSrcDC, int xSrc, int ySrc, int nSrcWidth, int nSrcHeight, 
      BLENDFUNCTION blend);

// Text Functions
    virtual BOOL TextOut(int x, int y, LPCTSTR lpszString, int nCount);
            BOOL TextOut(int x, int y, const CString& str);
    virtual BOOL ExtTextOut(int x, int y, UINT nOptions, LPCRECT lpRect,
                LPCTSTR lpszString, UINT nCount, LPINT lpDxWidths);
            BOOL ExtTextOut(int x, int y, UINT nOptions, LPCRECT lpRect,
                const CString& str, LPINT lpDxWidths);
    virtual CSize TabbedTextOut(int x, int y, LPCTSTR lpszString, int nCount,
                int nTabPositions, LPINT lpnTabStopPositions, int nTabOrigin);
            CSize TabbedTextOut(int x, int y, const CString& str,
                int nTabPositions, LPINT lpnTabStopPositions, int nTabOrigin);

#pragma push_macro("DrawText")
#pragma push_macro("DrawTextEx")
#undef DrawText
#undef DrawTextEx
    virtual int _AFX_FUNCNAME(DrawText)(LPCTSTR lpszString, int nCount, LPRECT lpRect,
                UINT nFormat);
            int _AFX_FUNCNAME(DrawText)(const CString& str, LPRECT lpRect, UINT nFormat);

    virtual int _AFX_FUNCNAME(DrawTextEx)(LPTSTR lpszString, int nCount, LPRECT lpRect,
                UINT nFormat, LPDRAWTEXTPARAMS lpDTParams);
            int _AFX_FUNCNAME(DrawTextEx)(const CString& str, LPRECT lpRect, UINT nFormat, LPDRAWTEXTPARAMS lpDTParams);

            int DrawText(LPCTSTR lpszString, int nCount, LPRECT lpRect,
                UINT nFormat);
            int DrawText(const CString& str, LPRECT lpRect, UINT nFormat);

            int DrawTextEx(LPTSTR lpszString, int nCount, LPRECT lpRect,
                UINT nFormat, LPDRAWTEXTPARAMS lpDTParams);
            int DrawTextEx(const CString& str, LPRECT lpRect, UINT nFormat, LPDRAWTEXTPARAMS lpDTParams);
#pragma pop_macro("DrawText")
#pragma pop_macro("DrawTextEx")

    CSize GetTextExtent(LPCTSTR lpszString, int nCount) const;
    CSize GetTextExtent(const CString& str) const;
    CSize GetOutputTextExtent(LPCTSTR lpszString, int nCount) const;
    CSize GetOutputTextExtent(const CString& str) const;
    CSize GetTabbedTextExtent(LPCTSTR lpszString, int nCount,
        int nTabPositions, LPINT lpnTabStopPositions) const;
    CSize GetTabbedTextExtent(const CString& str,
        int nTabPositions, LPINT lpnTabStopPositions) const;
    CSize GetOutputTabbedTextExtent(LPCTSTR lpszString, int nCount,
        int nTabPositions, LPINT lpnTabStopPositions) const;
    CSize GetOutputTabbedTextExtent(const CString& str,
        int nTabPositions, LPINT lpnTabStopPositions) const;
    virtual BOOL GrayString(CBrush* pBrush,
        BOOL (CALLBACK* lpfnOutput)(HDC, LPARAM, int), LPARAM lpData,
            int nCount, int x, int y, int nWidth, int nHeight);
    UINT GetTextAlign() const;
    UINT SetTextAlign(UINT nFlags);
    int GetTextFace(_In_ int nCount, _Out_z_cap_post_count_(nCount, return) LPTSTR lpszFacename) const;
    int GetTextFace(CString& rString) const;
#pragma push_macro("GetTextMetrics")
#undef GetTextMetrics
    BOOL _AFX_FUNCNAME(GetTextMetrics)(LPTEXTMETRIC lpMetrics) const;
    BOOL GetTextMetrics(LPTEXTMETRIC lpMetrics) const;
#pragma pop_macro("GetTextMetrics")
    BOOL GetOutputTextMetrics(LPTEXTMETRIC lpMetrics) const;
    int SetTextJustification(int nBreakExtra, int nBreakCount);
    int GetTextCharacterExtra() const;
    int SetTextCharacterExtra(int nCharExtra);

    DWORD GetCharacterPlacement(LPCTSTR lpString, int nCount, int nMaxExtent, LPGCP_RESULTS lpResults, DWORD dwFlags) const;
    DWORD GetCharacterPlacement(CString& str, int nMaxExtent, LPGCP_RESULTS lpResults, DWORD dwFlags) const;

#if (_WIN32_WINNT >= 0x0500)

    BOOL GetTextExtentExPointI(LPWORD pgiIn, int cgi, int nMaxExtent, LPINT lpnFit, LPINT alpDx, _Out_opt_ LPSIZE lpSize) const;
    BOOL GetTextExtentPointI(LPWORD pgiIn, int cgi, _Out_opt_ LPSIZE lpSize) const;

#endif



// Advanced Drawing
    BOOL DrawEdge(LPRECT lpRect, UINT nEdge, UINT nFlags);
    BOOL DrawFrameControl(LPRECT lpRect, UINT nType, UINT nState);

// Scrolling Functions
    BOOL ScrollDC(int dx, int dy, LPCRECT lpRectScroll, LPCRECT lpRectClip,
        CRgn* pRgnUpdate, LPRECT lpRectUpdate);

// Font Functions
    BOOL GetCharWidth(UINT nFirstChar, UINT nLastChar, LPINT lpBuffer) const;
    BOOL GetOutputCharWidth(UINT nFirstChar, UINT nLastChar, LPINT lpBuffer) const;
    DWORD SetMapperFlags(DWORD dwFlag);
    CSize GetAspectRatioFilter() const;

    BOOL GetCharABCWidths(UINT nFirstChar, UINT nLastChar, LPABC lpabc) const;
    DWORD GetFontData(DWORD dwTable, DWORD dwOffset, LPVOID lpData, DWORD cbData) const;
    int GetKerningPairs(int nPairs, LPKERNINGPAIR lpkrnpair) const;
    UINT GetOutlineTextMetrics(UINT cbData, LPOUTLINETEXTMETRIC lpotm) const;
    DWORD GetGlyphOutline(UINT nChar, UINT nFormat, LPGLYPHMETRICS lpgm,
        DWORD cbBuffer, LPVOID lpBuffer, const MAT2* lpmat2) const;

    BOOL GetCharABCWidths(UINT nFirstChar, UINT nLastChar,
        LPABCFLOAT lpABCF) const;
    BOOL GetCharWidth(UINT nFirstChar, UINT nLastChar,
        float* lpFloatBuffer) const;

    DWORD GetFontLanguageInfo() const;

#if (_WIN32_WINNT >= 0x0500)

    BOOL GetCharABCWidthsI(UINT giFirst, UINT cgi, LPWORD pgi, LPABC lpabc) const;
    BOOL GetCharWidthI(UINT giFirst, UINT cgi, LPWORD pgi, LPINT lpBuffer) const;

#endif

// Printer/Device Escape Functions
    virtual int Escape(_In_ int nEscape, _In_ int nCount,
        _In_bytecount_(nCount) LPCSTR lpszInData, _In_ LPVOID lpOutData);
    int Escape(_In_ int nEscape, _In_ int nInputSize, _In_bytecount_(nInputSize) LPCSTR lpszInputData,
        _In_ int nOutputSize, _Out_bytecap_(nOutputSize) LPSTR lpszOutputData);
    int DrawEscape(int nEscape, int nInputSize, LPCSTR lpszInputData);

    // Escape helpers
    int StartDoc(LPCTSTR lpszDocName);  // old Win3.0 version
    int StartDoc(LPDOCINFO lpDocInfo);
    int StartPage();
    int EndPage();
    int SetAbortProc(BOOL (CALLBACK* lpfn)(HDC, int));
    int AbortDoc();
    int EndDoc();

// MetaFile Functions
    BOOL PlayMetaFile(HMETAFILE hMF);
    BOOL PlayMetaFile(HENHMETAFILE hEnhMetaFile, LPCRECT lpBounds);
    BOOL AddMetaFileComment(UINT nDataSize, const BYTE* pCommentData);
        // can be used for enhanced metafiles only

// Path Functions
    BOOL AbortPath();
    BOOL BeginPath();
    BOOL CloseFigure();
    BOOL EndPath();
    BOOL FillPath();
    BOOL FlattenPath();
    BOOL StrokeAndFillPath();
    BOOL StrokePath();
    BOOL WidenPath();
    float GetMiterLimit() const;
    BOOL SetMiterLimit(float fMiterLimit);
    int GetPath(LPPOINT lpPoints, LPBYTE lpTypes, int nCount) const;
    BOOL SelectClipPath(int nMode);

// Misc Helper Functions
    static CBrush* PASCAL GetHalftoneBrush();
    void DrawDragRect(LPCRECT lpRect, SIZE size,
        LPCRECT lpRectLast, SIZE sizeLast,
        CBrush* pBrush = NULL, CBrush* pBrushLast = NULL);
    void FillSolidRect(LPCRECT lpRect, COLORREF clr);
    void FillSolidRect(int x, int y, int cx, int cy, COLORREF clr);
    void Draw3dRect(LPCRECT lpRect, COLORREF clrTopLeft, COLORREF clrBottomRight);
    void Draw3dRect(int x, int y, int cx, int cy,
        COLORREF clrTopLeft, COLORREF clrBottomRight);

// Implementation
public:
    virtual ~CDC();
#ifdef _DEBUG
    virtual void AssertValid() const;
    virtual void Dump(CDumpContext& dc) const;
#endif

    // advanced use and implementation
    BOOL m_bPrinting;
    HGDIOBJ SelectObject(HGDIOBJ);      // do not use for regions

protected:
    // used for implementation of non-virtual SelectObject calls
    static CGdiObject* PASCAL SelectGdiObject(HDC hDC, HGDIOBJ h);
};