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| author | Ken Sharp <ken.sharp@artifex.com> | 2022-08-31 15:03:43 +0100 |
|---|---|---|
| committer | Chris Liddell <chris.liddell@artifex.com> | 2022-09-02 15:59:07 +0100 |
| commit | 7f2719bff1d50e151918cf505fa695edc65e936f (patch) | |
| tree | 05213b658ab869dff742a099b001df90d449fe36 | |
| parent | 6d896bacd03c5be09685a5ae5fca94b3347165d2 (diff) | |
| download | ghostpdl-7f2719bff1d50e151918cf505fa695edc65e936f.tar.gz | |
Documentation - Add a note about precision of the bbox device
Bug #705830 "imprecise bbox of PDF"
| -rw-r--r-- | doc/Devices.htm | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/doc/Devices.htm b/doc/Devices.htm index da3c6d480..035f02744 100644 --- a/doc/Devices.htm +++ b/doc/Devices.htm @@ -1978,6 +1978,14 @@ pixels, e.g.,</p> gs -dNOPAUSE -dBATCH -sDEVICE=bbox -r100 -g500000x500000 </code></blockquote> +<p> +The box returned by the bbox device is just sufficient to contain the pixels which would be rendered by +Ghostscript at the selected resolution. The language rendering rules can mean this differs by up to two pixels from +the 'theoretical' area covered, and the precise area covered by curves and line joins is also, to some +extent, related to the resolution. Finally the actual pixel position needs to be converted back to +PostScript points, and that can be affected by mathematical precision, which can cause rounding errors. +As a result the bounding box returned may differ very slightly from that which was expected. +</p> <h3><a name="Ink_coverage_output"></a>Ink coverage output</h3> <p> |