NAME

       Tk_CanvasPsY, Tk_CanvasPsBitmap, Tk_CanvasPsColor, Tk_Can­
       vasPsFont, Tk_CanvasPsPath, Tk_CanvasPsStipple  -  utility
       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, tkFont)

       Tk_CanvasPsPath(interp, canvas, coordPtr, numPoints)

       int
       Tk_CanvasPsStipple(interp, canvas, bitmap)


ARGUMENTS

       Tk_Canvas      canvas      (in)      A  token that identi­
                                            fies 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.

                                            bitmap  to output, in
                                            pixels.

       int            height      (in)      Height of  region  of
                                            bitmap  to output, in
                                            pixels.

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

       Tk_Font        tkFont      (in)      Font    for     which
                                            Postscript  is  to be
                                            generated.

       double         *coordPtr   (in)      Pointer to  an  array
                                            of   coordinates  for
                                            one  or  more  points
                                            specified  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 argu­
       ment, which refers to a canvas widget for which Postscript
       is being generated.

       Tk_CanvasPsY 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
       canvas.   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 coor­
       dinates  can be used directly in Postscript without trans­
       formation.

       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.

       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 tkFont as closely as possible.  Tk_CanvasPs­
       Font takes into account any  font  map  specified  in  the
       postscript command, and it does the best it can at mapping
       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


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