path: root/library/prolog.ps

%%BeginProlog
50 dict begin

% This is a standard prolog for Postscript generated by Tk's canvas
% widget.
% RCS: @(#) $Id: prolog.ps,v 1.4 2008/11/22 18:08:51 dkf 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).

/baseline 0 def
/stipimage 0 def
/height 0 def
/justify 0 def
/lineLength 0 def
/spacing 0 def
/stipple 0 def
/strings 0 def
/xoffset 0 def
/yoffset 0 def
/tmpstip null def

% 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).

systemdict /ISOLatin1Encoding known not {
    /ISOLatin1Encoding [
	/space /space /space /space /space /space /space /space
	/space /space /space /space /space /space /space /space
	/space /space /space /space /space /space /space /space
	/space /space /space /space /space /space /space /space
	/space /exclam /quotedbl /numbersign /dollar /percent /ampersand
	    /quoteright
	/parenleft /parenright /asterisk /plus /comma /minus /period /slash
	/zero /one /two /three /four /five /six /seven
	/eight /nine /colon /semicolon /less /equal /greater /question
	/at /A /B /C /D /E /F /G
	/H /I /J /K /L /M /N /O
	/P /Q /R /S /T /U /V /W
	/X /Y /Z /bracketleft /backslash /bracketright /asciicircum /underscore
	/quoteleft /a /b /c /d /e /f /g
	/h /i /j /k /l /m /n /o
	/p /q /r /s /t /u /v /w
	/x /y /z /braceleft /bar /braceright /asciitilde /space
	/space /space /space /space /space /space /space /space
	/space /space /space /space /space /space /space /space
	/dotlessi /grave /acute /circumflex /tilde /macron /breve /dotaccent
	/dieresis /space /ring /cedilla /space /hungarumlaut /ogonek /caron
	/space /exclamdown /cent /sterling /currency /yen /brokenbar /section
	/dieresis /copyright /ordfeminine /guillemotleft /logicalnot /hyphen
	    /registered /macron
	/degree /plusminus /twosuperior /threesuperior /acute /mu /paragraph
	    /periodcentered
	/cedillar /onesuperior /ordmasculine /guillemotright /onequarter
	    /onehalf /threequarters /questiondown
	/Agrave /Aacute /Acircumflex /Atilde /Adieresis /Aring /AE /Ccedilla
	/Egrave /Eacute /Ecircumflex /Edieresis /Igrave /Iacute /Icircumflex
	    /Idieresis
	/Eth /Ntilde /Ograve /Oacute /Ocircumflex /Otilde /Odieresis /multiply
	/Oslash /Ugrave /Uacute /Ucircumflex /Udieresis /Yacute /Thorn
	    /germandbls
	/agrave /aacute /acircumflex /atilde /adieresis /aring /ae /ccedilla
	/egrave /eacute /ecircumflex /edieresis /igrave /iacute /icircumflex
	    /idieresis
	/eth /ntilde /ograve /oacute /ocircumflex /otilde /odieresis /divide
	/oslash /ugrave /uacute /ucircumflex /udieresis /yacute /thorn
	    /ydieresis
    ] def
} if

% 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.

/StrokeClip {
    {strokepath} stopped {
	(This Postscript printer gets limitcheck overflows when) =
	(stippling dashed lines;  lines will be printed solid instead.) =
	[] 0 setdash strokepath} if
    clip
} bind def

% 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.

/AdjustColor {
    CL 2 lt {
	currentgray
	CL 0 eq {
	    .5 lt {0} {1} ifelse
	} if
	setgray
    } if
} bind def

% angle 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:
%
% angle -	Angle through which to rotate text, in degrees.
% 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.

/DrawText {
    /stipple exch def
    /justify exch def
    /yoffset exch def
    /xoffset exch def
    /spacing exch def
    /strings exch def

    % First scan through all of the text to find the widest line.

    /lineLength 0 def
    strings {
	stringwidth pop
	dup lineLength gt {/lineLength exch def} {pop} ifelse
	newpath
    } forall

    % Compute the baseline offset and the actual font height.

    0 0 moveto (TXygqPZÄ) false charpath
    pathbbox dup /baseline exch def
    exch pop exch sub /height exch def pop
    newpath

    % Translate and rotatecoordinates first so that the origin is at the
    % upper-left corner of the text's bounding box. Remember that angle, x and
    % y for positioning are still on the stack.

    translate
    rotate
    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.

	    gsave
	    /char (X) def
	    {
		char 0 3 -1 roll put
		currentpoint
		gsave
		char true charpath clip StippleText
		grestore
		char stringwidth translate
		moveto
	    } forall
	    grestore
	} {show} ifelse
	0 spacing neg translate
    } forall
} bind def

%%EndProlog