/*
typedef struct {
    DWORD lStructSize; 4
    HWND hwndOwner; 4
    HDC hDC; 4
    LPLOGFONT lpLogFont; 4
    INT iPointSize; 4
    DWORD Flags; 4
    COLORREF rgbColors; 4
    LPARAM lCustData; 4
    LPCFHOOKPROC lpfnHook; 4
    LPCTSTR lpTemplateName; 4
    HINSTANCE hInstance; 4
    LPTSTR lpszStyle; 4 
    WORD nFontType; 2
    INT nSizeMin; 4 
    INT nSizeMax; 4
} CHOOSEFONT, *LPCHOOSEFONT;
*/

//flags
var CF_INITTOLOGFONTSTRUCT = 0x40;
var CF_SCREENFONTS = 0x1;

var CHOOSEFONT = Interop.Allocate(60);
CHOOSEFONT.WriteDWORD(0, CHOOSEFONT.Size); //lStructSize
CHOOSEFONT.WriteDWORD(4, 0); //hwndOwner
CHOOSEFONT.WriteDWORD(8, 0); //hDC

/*
typedef struct tagLOGFONT { 
  LONG lfHeight; 4
  LONG lfWidth;  4
  LONG lfEscapement; 4
  LONG lfOrientation;  4
  LONG lfWeight;  4
  BYTE lfItalic;  1
  BYTE lfUnderline;  1
  BYTE lfStrikeOut;  1
  BYTE lfCharSet;  1
  BYTE lfOutPrecision;  1
  BYTE lfClipPrecision;  1
  BYTE lfQuality;  1
  BYTE lfPitchAndFamily; 1
  TCHAR lfFaceName[LF_FACESIZE];  64
} LOGFONT, *PLOGFONT; 
*/

var LOGFONT = Interop.Allocate(92);
LOGFONT.WriteDWORD(0,0); //lfHeight
LOGFONT.WriteDWORD(4,0); //lfWidth
LOGFONT.WriteDWORD(8,0); //lfEscapement
LOGFONT.WriteDWORD(12,0); //lfOrientation
LOGFONT.WriteDWORD(16,0); //lfWeight
LOGFONT.SetAt(20,0); //lfItalic
LOGFONT.SetAt(21,0); //lfUnderline
LOGFONT.SetAt(22,0); //lfCharSet
LOGFONT.SetAt(23,0); //lfOutPrecision
LOGFONT.SetAt(24,0); //lfClipPrecision
LOGFONT.SetAt(25,0); //lfQuality
LOGFONT.SetAt(26,0); //lfPitchAndFamily
LOGFONT.WriteString(27, ""); // lfFaceName

CHOOSEFONT.WriteDWORD(12, LOGFONT.DataPtr); //LPLOGFONT

var iPointSize = Interop.Allocate(4);
CHOOSEFONT.WriteDWORD(16, iPointSize.DataPtr); //iPointSize


CHOOSEFONT.WriteDWORD(20, CF_INITTOLOGFONTSTRUCT | CF_SCREENFONTS ); //Flags
CHOOSEFONT.WriteDWORD(24, 0); // rgbColors
CHOOSEFONT.WriteDWORD(28, 0); // lCustData
CHOOSEFONT.WriteDWORD(32, 0); // lpfnHook
CHOOSEFONT.WriteDWORD(36, 0); // lpTemplateName
CHOOSEFONT.WriteDWORD(40, 0); // hInstance

var lpszStyle = Interop.Allocate(514);
CHOOSEFONT.WriteDWORD(44, lpszStyle.DataPtr); // lpszStyle
CHOOSEFONT.WriteWORD(48, 0x2000); // nFontType
CHOOSEFONT.WriteDWORD(50, 0); // nSizeMin
CHOOSEFONT.WriteDWORD(54, 0); // nSizeMax

Interop.Call("comdlg32.dll", "ChooseFontW", CHOOSEFONT);