canvpsy(3Tk)

NAME
     Tk_CanvasPsY, Tk_CanvasPsBitmap, Tk_CanvasPsColor, Tk_CanvasPsFont,
     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, fontStructPtr)

     Tk_CanvasPsPath(interp, canvas, coordPtr, numPoints)

     int
     Tk_CanvasPsStipple(interp, canvas, bitmap)

ARGUMENTS
     Tk_Canvas      canvas           (in)      A token that identifies 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
                                               output, 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
                                               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 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 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 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 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