[cairo-bugs] [Bug 23364] Useless digits for float numbers in Cairo output

[bugzilla-daemon at freedesktop.org]

http://bugs.freedesktop.org/show_bug.cgi?id=23364





--- Comment #12 from clark <wzhu at microstrategy.com>  2009-08-23 23:30:17 PST ---
(In reply to comment #11)
> If you really want to control the output precision now you can edit the
> "#define SIGNIFICANT_DIGITS_AFTER_DECIMAL" at the top of
> src/cairo-output-stream.c.
> I don't think overloading the meaning of cairo_set_tolerance() to control
> floating point precision in vector backends as well as the tolerance of curve
> flattening in image backends and is good API design.
> Using a tolerance in device units does not make sense for all the floating
> point values emitted by the PDF backend. For example in PDF floats are used
> for:
>  - coordinates
>  - colors
>  - Td operator for text
>  - pattern matrices
>  - function domains
> Coordinates are already limited to 3 decimal places due to the use of
> 24.8 fixed point.
> Controlling the precision of colors is not possible with a parameter in device
> units. Users may wish to control the precision of color independently of
> coordinates.
> Neither does it make sense to use a value in device units to control the
> precision of values in pattern matrices. These should be set using number of
> significant figures.
> The mesh gradient patches on my 'mesh' branch adds an additional complication
> when making precision adjustable. The number of bits per coordinate and bits
> per color component of coordinates and colors in the shading stream is
> selectable.
> There really isn't any way to control the output precision of all these
> different floats with one paramater. Maybe the proposed debug environment
> variable would be a good way to set the precision particularly as many
> applications are unlikely to make available a user configurable setting for
> output precision.

Thanks for your constant explanations.


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