Using what GetGlyphOutline returns...

[C.M. Rouleau]

Ok, with Dominic's help, my call to GetGlyphOutline is now returning a filled buffer and pointer to that buffer. From what I understand, this buffer is made up of a series of TTPOLYGONHEADER data structures, which are followed by as many TTPOLYCURVE data structures as required to describe the particular contour. In order to use the data in the buffer, my guess is I need to DIM a TTPOLYGONHEADER starting at the pointer, and then use information in this header to determine where I should DIM the next header, and so on. So, assuming I have this right, how does one go about overlaying structures onto this buffer?

-CMR

[Michael Mattias]

From what I understand, this buffer is made up of a series of TTPOLYGONHEADER data structures, which are followed by as many TTPOLYCURVE data structures

??

My SDK doc for GetGlyphOutline does not show that at all. Show the call with all values used .

Well, I found this..

The native buffer returned by GetGlyphOutline when GGO_NATIVE is specified is a glyph outline. A glyph outline is returned as a series of one or more contours defined by a TTPOLYGONHEADER structure followed by one or more curves. Each curve in the contour is defined by a TTPOLYCURVE structure followed by a number of POINTFX data points. POINTFX points are absolute positions, not relative moves. The starting point of a contour is given by the pfxStart member of the TTPOLYGONHEADER structure. The starting point of each curve is the last point of the previous curve or the starting point of the contour. The count of data points in a curve is stored in the cpfx member of TTPOLYCURVE structure. The size of each contour in the buffer, in bytes, is stored in the cb member of TTPOLYGONHEADER structure. Additional curve definitions are packed into the buffer following preceding curves and additional contours are packed into the buffer following preceding contours. The buffer contains as many contours as fit within the buffer returned by GetGlyphOutline.

.. so you must be using GGO_NATIVE in your call.

Meaning, you are on the correct track re your proposed access method.

Pointer variables are used to overlay structures on a memory block

 LOCAL pTTPH AS TTPOLYGONHEADER PTR, pTTPC as TTPOLYCURVE PTR

  pTTPH = Address of Header
  AnyValue =  @pTTPH.membername 
  pTTPC = @pTTPH.cpfx    ' address of first TTPOLYCURVE structure for this header
  ....

Then you just INCR your pointer variables to 'walk the list'

MCM

[C.M. Rouleau]

Michael,

What if the headers change size? This would seem to make walking quite difficult. What I mean is TTPOLYGONHEADER always seems to be the same size, but the TTPOLYCURVE structures that follow change size, depending on how many points are contained. So, the actual buffer could look like:

TTPOLYGONHEADER <--16 bytes
TTPOLYCURVE <--# of bytes depends on points involved
TTPOLYCURVE <--# of bytes depends on points involved
TTPOLYCURVE <--# of bytes depends on points involved
TTPOLYGONHEADER <--16 bytes
TTPOLYCURVE <--# of bytes depends on points involved
blah
blah
blah

The following link shows you what I mean: http://support.microsoft.com/kb/q87115/

[Michael Mattias]

It's almost like a treasure hunt: Start at the big oak tree; walk six paces west. There you will find the instructions for your next move... which will get you to the next set of instructions. Follow those to the next set of instructions, and so on.

True, walking a list of variable length elements or elements which aren't defined until you get there is more difficult than walking a list of a known qauntity of same-sized elements. But that's why programmers get the big bucks.

BTW.. using pointer variables is now essential to your task.

MCM

[Dominic Mitchell]

You both have the right idea but this is wrong

pTTPC = @pTTPH.cpfx    ' address of first TTPOLYCURVE structure for this header

The following shows how to access the data.

 
FUNCTION Form1_TextBtn1_Clicked _
  ( _
  BYVAL hWndParent  AS DWORD, _ ' handle of parent window
  BYVAL hWndCtrl    AS DWORD _  ' handle of control
  ) AS LONG

  LOCAL szOut           AS ASCIIZ * 32768
  LOCAL GlyphMets       AS GLYPHMETRICS
  LOCAL xformation      AS MAT2
  LOCAL PolygonHeader   AS TTPOLYGONHEADER PTR
  LOCAL PolyCurve       AS TTPOLYCURVE PTR
  LOCAL PtFx            AS POINTFX PTR
  LOCAL bufferPointer   AS DWORD
  LOCAL curPointer      AS DWORD
  LOCAL endPointer      AS DWORD
  LOCAL curPoly         AS DWORD
  LOCAL endPoly         AS DWORD
  LOCAL ipfx            AS LONG
  LOCAL ihdr            AS LONG
  LOCAL ipoly           AS LONG
  LOCAL hDC             AS DWORD
  LOCAL hFont           AS DWORD
  LOCAL hOldFont        AS DWORD
  LOCAL point_size      AS LONG
  LOCAL points_per_inch AS LONG
  LOCAL pixels_per_inch AS LONG
  LOCAL logical_height  AS LONG
  LOCAL bufferSize      AS DWORD

  hDC = GetDC(hWndParent)

  point_size      =24 '30
  points_per_inch =72
  pixels_per_inch =GetDeviceCaps(hDC, %LOGPIXELSY)

  logical_height = -MulDiv(point_size, pixels_per_inch, points_per_inch)

  hFont = CreateFont(logical_height,0,0,0,0,%TRUE,0,0,%ANSI_CHARSET,0,0,0,0,"Arial")
  hOldFont=SelectObject(hDC, hFont)

  xformation.eM11.value   =1
  xformation.eM11.fract   =0
  xformation.eM12.value   =0
  xformation.eM12.fract   =0
  xformation.eM21.value   =0
  xformation.eM21.fract   =0
  xformation.eM22.value   =1
  xformation.eM22.fract   =0

  bufferSize=GetGlyphOutline(hDC, ASC("j"), %GGO_NATIVE, GlyphMets, 0, BYVAL %NULL, xformation)
  MSGBOX FORMAT$(bufferSize)
  bufferPointer = HeapAlloc(GetProcessHeap(), %HEAP_ZERO_MEMORY, bufferSize)
  IF bufferPointer THEN
    IF GetGlyphOutline(hDC, ASC("j"), %GGO_NATIVE, GlyphMets, bufferSize, BYVAL bufferPointer, xformation) <> %GDI_ERROR THEN
      OPEN "Glyph.txt" FOR OUTPUT AS #1      
      curPointer = bufferPointer
      endPointer = curPointer + bufferSize
      
      ' Walk PolygonHeader structs 
      WHILE curPointer < endPointer
        ' Get PolygonHeader at current address
        PolygonHeader = curPointer
        endPoly = curPointer + @PolygonHeader.cb
        ' Get first PolyCurve associated with current PolygonHeader
        curPoly = curPointer + SIZEOF(@PolygonHeader)
        
        szOut = "TTPOLYGONHEADER #" + FORMAT$(ihdr + 1) + $CRLF + _
                "cb      " + $TAB + "= " + FORMAT$(@PolygonHeader.cb) + $CRLF + _
                "dwType  " + $TAB + "= " + FORMAT$(@PolygonHeader.dwType) + $CRLF + _
                "pfxStart" + $TAB + "= " + FORMAT$(@PolygonHeader.pfxStart.x.value) + "." + FORMAT$(@PolygonHeader.pfxStart.x.fract * 100 \ 65536) + "," + _
                                          FORMAT$(@PolygonHeader.pfxStart.y.value) + "." + FORMAT$(@PolygonHeader.pfxStart.y.fract * 100 \ 65536) + $CRLF
        PRINT #1, szOut
        
        ' Walk PolyCurve structs
        WHILE curPoly < endPoly
          PolyCurve = curPoly

          szOut = "TTPOLYCURVE #" + FORMAT$(ipoly + 1) + $CRLF + _
                  "wType" + $TAB + "= " + FORMAT$(@PolyCurve.wType) + $CRLF + _
                  "cpfx " + $TAB + "= " + FORMAT$(@PolyCurve.cpfx) 
          PRINT #1, szOut
        
          SELECT CASE @PolyCurve.wType
            CASE %TT_PRIM_LINE
              PtFx = curPoly + 4
              ipfx = 0
              
              ' Walk POINTFX structs
              WHILE ipfx < @PolyCurve.cpfx
                szOut = "apfx[" + FORMAT$(ipfx) + "]" + $TAB + "= " + _
                                  FORMAT$(@PtFx[ipfx].x.value) + "." + FORMAT$(@PtFx[ipfx].x.fract * 100 \ 65536) + "," + _
                                  FORMAT$(@PtFx[ipfx].y.value) + "." + FORMAT$(@PtFx[ipfx].y.fract * 100 \ 65536) 
                PRINT #1, szOut
                INCR ipfx
              WEND
              
              PRINT #1, $CRLF
              
            CASE %TT_PRIM_QSPLINE : PRINT #1, $CRLF
            CASE %TT_PRIM_CSPLINE : PRINT #1, $CRLF
          END SELECT

          INCR ipoly
          curPoly = curPoly + 4 + @PolyCurve.cpfx * SIZEOF(@PtFx)
        WEND

        INCR ihdr
        curPointer = curPointer + @PolygonHeader.cb
      WEND
      
      CLOSE #1
    END IF
    HeapFree GetProcessHeap(), 0, bufferPointer
  END IF

  DeleteObject(SelectObject(hDC, hOldFont))
  ReleaseDC(hWndParent,hDC)

END FUNCTION