Attachment 15833 Details for Bug 15348 – Fix printer crash

[patch] Fix printer crash

0001-PS-Fix-inefficient-implementation-of-Tm-Td-operator.patch (text/plain), 2.99 KB, created by Adrian Johnson on 2008-04-11 05:16:39 UTC

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Creator: Adrian Johnson

Created: 2008-04-11 05:16:39 UTC

Size: 2.99 KB

patch

obsolete

>From c5814d2aa3cb68a13bc9cc8b6a47f660febcad71 Mon Sep 17 00:00:00 2001
>From: Adrian Johnson <ajohnson@redneon.com>
>Date: Fri, 11 Apr 2008 21:42:19 +0930
>Subject: [PATCH] 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.
>---
> src/cairo-ps-surface.c |    9 +++++----
> 1 files changed, 5 insertions(+), 4 deletions(-)
>
>diff --git a/src/cairo-ps-surface.c b/src/cairo-ps-surface.c
>index 54f5afe..f6940bf 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");
> 
>-- 
>1.5.2.4
>

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