% This is a standard prolog for Postscript generated by Tk's canvas
% widget.
% RCS: @(#) $Id: tkCanvPs.c,v 1.4 1998/09/22 18:57:16 stanton Exp $
% The definitions below just define all of the variables used in
% any of the procedures here. This is needed for obscure reasons
% explained on p. 716 of the Postscript manual (Section H.2.7,
% "Initializing Variables," in the section on Encapsulated Postscript).
% Define the array ISOLatin1Encoding (which specifies how characters are
% encoded for ISO-8859-1 fonts), if it isn't already present (Postscript
% level 2 is supposed to define it, but level 1 doesn't).
% font ISOEncode font
% This procedure changes the encoding of a font from the default
% Postscript encoding to ISOLatin1. It's typically invoked just
% before invoking "setfont". The body of this procedure comes from
% Section 5.6.1 of the Postscript book.
/ISOEncode {
dup length dict begin
{1 index /FID ne {def} {pop pop} ifelse} forall
/Encoding ISOLatin1Encoding def
currentdict
end
% I'm not sure why it's necessary to use "definefont" on this new
% font, but it seems to be important; just use the name "Temporary"
% for the font.
/Temporary exch definefont
} bind def
% StrokeClip
%
% This procedure converts the current path into a clip area under
% the assumption of stroking. It's a bit tricky because some Postscript
% interpreters get errors during strokepath for dashed lines. If
% this happens then turn off dashes and try again.
% desiredSize EvenPixels closestSize
%
% The procedure below is used for stippling. Given the optimal size
% of a dot in a stipple pattern in the current user coordinate system,
% compute the closest size that is an exact multiple of the device's
% pixel size. This allows stipple patterns to be displayed without
% aliasing effects.
/EvenPixels {
% Compute exact number of device pixels per stipple dot.
dup 0 matrix currentmatrix dtransform
dup mul exch dup mul add sqrt
% Round to an integer, make sure the number is at least 1, and compute
% user coord distance corresponding to this.
dup round dup 1 lt {pop 1} if
exch div mul
} bind def
% width height string StippleFill --
%
% Given a path already set up and a clipping region generated from
% it, this procedure will fill the clipping region with a stipple
% pattern. "String" contains a proper image description of the
% stipple pattern and "width" and "height" give its dimensions. Each
% stipple dot is assumed to be about one unit across in the current
% user coordinate system. This procedure trashes the graphics state.
/StippleFill {
% The following code is needed to work around a NeWSprint bug.
/tmpstip 1 index def
% Change the scaling so that one user unit in user coordinates
% corresponds to the size of one stipple dot.
1 EvenPixels dup scale
% Compute the bounding box occupied by the path (which is now
% the clipping region), and round the lower coordinates down
% to the nearest starting point for the stipple pattern. Be
% careful about negative numbers, since the rounding works
% differently on them.
pathbbox
4 2 roll
5 index div dup 0 lt {1 sub} if cvi 5 index mul 4 1 roll
6 index div dup 0 lt {1 sub} if cvi 6 index mul 3 2 roll
% Stack now: width height string y1 y2 x1 x2
% Below is a doubly-nested for loop to iterate across this area
% in units of the stipple pattern size, going up columns then
% across rows, blasting out a stipple-pattern-sized rectangle at
% each position
6 index exch {
2 index 5 index 3 index {
% Stack now: width height string y1 y2 x y
gsave
1 index exch translate
5 index 5 index true matrix tmpstip imagemask
grestore
} for
pop
} for
pop pop pop pop pop
} bind def
% -- AdjustColor --
% Given a color value already set for output by the caller, adjusts
% that value to a grayscale or mono value if requested by the CL
% variable.
% x y strings spacing xoffset yoffset justify stipple DrawText --
% This procedure does all of the real work of drawing text. The
% color and font must already have been set by the caller, and the
% following arguments must be on the stack:
%
% x, y - Coordinates at which to draw text.
% strings - An array of strings, one for each line of the text item,
% in order from top to bottom.
% spacing - Spacing between lines.
% xoffset - Horizontal offset for text bbox relative to x and y: 0 for
% nw/w/sw anchor, -0.5 for n/center/s, and -1.0 for ne/e/se.
% yoffset - Vertical offset for text bbox relative to x and y: 0 for
% nw/n/ne anchor, +0.5 for w/center/e, and +1.0 for sw/s/se.
% justify - 0 for left justification, 0.5 for center, 1 for right justify.
% stipple - Boolean value indicating whether or not text is to be
% drawn in stippled fashion. If text is stippled,
% procedure StippleText must have been defined to call
% StippleFill in the right way.
%
% Also, when this procedure is invoked, the color and font must already
% have been set for the text.
% Compute the baseline offset and the actual font height.
0 0 moveto (TXygqPZ) false charpath
pathbbox dup /baseline exch def
exch pop exch sub /height exch def pop
newpath
% Translate coordinates first so that the origin is at the upper-left
% corner of the text's bounding box. Remember that x and y for
% positioning are still on the stack.
translate
lineLength xoffset mul
strings length 1 sub spacing mul height add yoffset mul translate
% Now use the baseline and justification information to translate so
% that the origin is at the baseline and positioning point for the
% first line of text.
justify lineLength mul baseline neg translate
% Iterate over each of the lines to output it. For each line,
% compute its width again so it can be properly justified, then
% display it.
strings {
dup stringwidth pop
justify neg mul 0 moveto
stipple {
% The text is stippled, so turn it into a path and print
% by calling StippledText, which in turn calls StippleFill.
% Unfortunately, many Postscript interpreters will get
% overflow errors if we try to do the whole string at
% once, so do it a character at a time.
