PS: Fix inefficient implementation of Tm/Td operators that was crashing printers

The Td and Tm operator emulation were setting the font matrix like this:

  /some_font [xx yx xy yy x0 y0] selectfont

where [xx yx xy yy] is the font matrix and [x0 y0] is the position of
the first glyph to be drawn. This seemed to be the easiest way to
emulate the Tm operator since the six arguments to Tm required by PDF
are xx,yx,xy,yy,x0,y0.

Before the switch to pdf-operators the font matrix was set like this:

  /somefont [xx yx xy yy 0 0] selectfont x0 y0 moveto

The selectfont operator is equivalent to calling findfont, makefont,
and setfont. The makefont operator creates a new font dictionary for
specified font that contains the specified font matrix. The
description of the makefont operator in the PostScript Language
Reference Manual states:

  "The interpreter keeps track of font dictionaries recently created
   by makefont. Calling makefont multiple times with the same font and
   matrix will usually return the same font rather than create a new
   one."

So the emulation of Tm and Td was creating a new font dictionary every
time a text string was displayed due to the change in the translation
components of the font matrix. Previously the font dictionary was
re-used as with the translation components of the matrix set to zero,
the font matrix did not change frequently.

Some printers did not handle well the frequent creation a font
dictionary every time a few glyphs were displayed.

Fix this by ensuring the translation components of the font matrix
used in the emulation of Tm and Td operators is always set to
zero. Use moveto instead for the translation components.
(cherry picked from commit c5814d2aa3cb68a13bc9cc8b6a47f660febcad71)

1 files changed, 5 insertions, 4 deletions

diff --git a/src/cairo-ps-surface.c b/src/cairo-ps-surface.c
index 54f5afec3..f6940bfd6 100644
--- a/src/cairo-ps-surface.c
+++ b/src/cairo-ps-surface.c
@@ -183,10 +183,11 @@ _cairo_ps_surface_emit_header (cairo_ps_surface_t *surface)
 				 "    { show } { -0.001 mul 0 cairo_font_matrix dtransform rmoveto } ifelse\n"
 				 "  } forall\n"
 				 "} bind def\n"
-				 "/Td { matrix translate cairo_font_matrix matrix concatmatrix dup\n"
-				 "   /cairo_font_matrix exch def cairo_font exch selectfont 0 0 moveto } bind def\n"
-				 "/Tm { 6 array astore dup /cairo_font_matrix exch def\n"
-				 "      cairo_font exch selectfont 0 0 moveto } bind def\n"
+				 "/Td { matrix translate cairo_font_matrix matrix concatmatrix aload\n"
+				 "      /cairo_font_matrix exch def 6 2 roll 0 0 6 array astore\n"
+				 "      cairo_font exch selectfont moveto } bind def\n"
+				 "/Tm { 6 copy 6 array astore /cairo_font_matrix exch def 6 2 roll 0 0\n"
+				 "      6 array astore cairo_font exch selectfont moveto } bind def\n"
 				 "/g { setgray } bind def\n"
 				 "/rg { setrgbcolor } bind def\n");