tk4.2 C API - CanvPsY






NAME

     Tk_CanvasPsY,      Tk_CanvasPsBitmap,      Tk_CanvasPsColor,
     Tk_CanvasPsFont, Tk_CanvasPsPath, Tk_CanvasPsStipple - util-
     ity procedures for generating Postscript for canvases


SYNOPSIS

     #include <tk.h>

     double
     Tk_CanvasPsY(canvas, canvasY)

     int
     Tk_CanvasPsBitmap(interp, canvas, bitmap, x, y, width, height)

     int
     Tk_CanvasPsColor(interp, canvas, colorPtr)

     int
     Tk_CanvasPsFont(interp, canvas, fontStructPtr)

     Tk_CanvasPsPath(interp, canvas, coordPtr, numPoints)

     int
     Tk_CanvasPsStipple(interp, canvas, bitmap)


ARGUMENTS

     Tk_Canvas      canvas           (in)      A token that iden-
                                               tifies   a  canvas
                                               widget  for  which
                                               Postscript      is
                                               being generated.

     double         canvasY          (in)      Y-coordinate    in
                                               the  space  of the
                                               canvas.

     Tcl_Interp     *interp          (in/out)  A Tcl interpreter;
                                               Postscript      is
                                               appended  to   its
                                               result,   or   the
                                               result   may    be
                                               replaced  with  an
                                               error message.

     Pixmap         bitmap           (in)      Bitmap to use  for
                                               generating
                                               Postscript.

     int            x                (in)      X-coordinate
                                               within  bitmap  of
                                               left    edge    of
                                               region to output.

     int            y                (in)      Y-coordinate
                                               within  bitmap  of
                                               top edge of region
                                               to output.

     int            width            (in)      Width of region of
                                               bitmap  to output,
                                               in pixels.

     int            height           (in)      Height  of  region
                                               of  bitmap to out-
                                               put, in pixels.

     XColor         *colorPtr        (in)      Information  about
                                               color value to set
                                               in Postscript.

     XFontStruct    *fontStructPtr   (in)      Font   for   which
                                               Postscript  is  to
                                               be generated.

     double         *coordPtr        (in)      Pointer   to    an
                                               array  of  coordi-
                                               nates for  one  or
                                               more points speci-
                                               fied   in   canvas
                                               coordinates.   The
                                               order of values in
                                               coordPtr   is  x1,
                                               y1,  x2,  y2,  x3,
                                               y3, and so on.

     int            numPoints        (in)      Number  of  points
                                               at coordPtr.





DESCRIPTION

     These procedures are called by canvas type managers to carry
     out common functions related to generating Postscript.  Most
     of the procedures take a canvas argument, which refers to  a
     canvas widget for which Postscript is being generated.

     Tk_CanvasY takes as argument a y-coordinate in the space  of
     a  canvas and returns the value that should be used for that
     point in the Postscript currently being generated  for  can-
     vas.    Y   coordinates   require   transformation   because
     Postscript uses an origin at the lower-left corner whereas X
     uses   an   origin  at  the  upper-left  corner.   Canvas  x
     coordinates can  be  used  directly  in  Postscript  without
     transformation.

     Tk_CanvasPsBitmap generates Postscript to describe a  region
     of  a  bitmap.   The Postscript is generated in proper image
     data format for Postscript,  i.e.,  as  data  between  angle
     brackets,  one bit per pixel.  The Postscript is appended to
     interp->result  and  TCL_OK  is  returned  unless  an  error
     occurs,  in  which  case  TCL_ERROR  is returned and interp-
     >result is overwritten with an error message.

     Tk_CanvasPsColor generates Postscript  to  set  the  current
     color  to  correspond  to its colorPtr argument, taking into
     account any color map specified in the  postscript  command.
     It  appends  the  Postscript  to  interp->result and returns
     TCL_OK unless an error occurs, in which  case  TCL_ERROR  is
     returned  and  interp->result  is  overwritten with an error
     message.

     Tk_CanvasPsFont generates Postscript that sets  the  current
     font   to   match  fontStructPtr  as  closely  as  possible.
     Tk_CanvasPsFont takes into account any font map specified in
     the  postscript command, and it does the best it can at map-
     ping X fonts to Postscript fonts.  It appends the Postscript
     to interp->result and returns TCL_OK unless an error occurs,
     in which case TCL_ERROR is returned  and  interp->result  is
     overwritten with an error message.

     Tk_CanvasPsPath generates Postscript to set the current path
     to  the  set  of points given by coordPtr and numPoints.  It
     appends the resulting Postscript to interp->result.

     Tk_CanvasPsStipple generates Postscript that will  fill  the
     current  path  in  stippled  fashion.  It uses bitmap as the
     stipple pattern and the current Postscript color;   ones  in
     the  stipple  bitmap  are  drawn  in  the current color, and
     zeroes are not drawn at all.  The Postscript is appended  to
     interp->result  and  TCL_OK  is  returned,  unless  an error
     occurs, in which case  TCL_ERROR  is  returned  and  interp-
     >result is overwritten with an error message.



KEYWORDS

     bitmap, canvas, color, font, path, Postscript, stipple