Bug 2729

Summary:	Negative dash offsets
Product:	cairo	Reporter:	Owen Taylor <otaylor>
Component:	general	Assignee:	Carl Worth <cworth>
Status:	RESOLVED FIXED	QA Contact:	cairo-bugs mailing list <cairo-bugs>
Severity:	normal
Priority:	high	CC:	jwatt
Version:	0.9.3
Hardware:	x86 (IA32)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:
Attachments:	Test case Current output Test case and fix, ready for CVS.

Description Owen Taylor 2005-03-14 14:33:57 UTC

Negative dash offsets work strangely ... instead of treating the 
dash pattern as infinitely repeating in both directions, patterns
of the pattern less than 0 are consider to be all on.

E.g. a 1,1 dash with an offset of 5 gives [6,1,1,1,1,1]

The test case attached also reveals something else that suprised me ..
a 1,1 dash offset by 50% gives a noticeably striated result. But
thinking about it, that's a consequence of the subsampling algorithm
The values are 120 and 135 out of 255 ... e.g, +/- a sample column.

Comment 1 Owen Taylor 2005-03-14 14:35:06 UTC

Created attachment 2106 [details]
Test case

Test case for test/

Comment 2 Owen Taylor 2005-03-14 14:35:39 UTC

Created attachment 2107 [details]
Current output

Comment 3 Carl Worth 2005-08-19 10:53:17 UTC

Created attachment 2930 [details] [review]
Test case and fix, ready for CVS.

Comment 4 Carl Worth 2005-08-19 12:02:19 UTC

2005-08-19  Carl Worth  <cworth@cworth.org>

        Fix for bug #2729:

        * src/cairo-gstate.c: (_cairo_gstate_set_dash): Adjust negative
        offsets up to their equivalent positive value. Add error checking
        for dash values, (must each be non-negative and must not be all
        zero).

        * src/cairo.c (cairo_set_dash): Add documentation.

        * src/cairo.h:
        * src/cairo.c: (cairo_status_to_string): Add new
        CAIRO_STATUS_INVALID_DASH.

        * test/.cvsignore:
        * test/Makefile.am: Add dash-offfset-negative test from Owen.

        * doc/public/tmpl/cairo.sgml: churn

Comment 5 Carl Worth 2005-08-22 17:14:35 UTC

Move bugs against "cvs" version to "0.9.3" so we can remove the "cvs" version.

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