[rrd-developers] [patch] improvements to and experiments with dashing

[Peter Speck]

Hi,

I've improved the handling of dashes in the SVG code and added it to 
EPS. Then I have made graphs having dashed gridlines, and my observation 
from that is:

We might have to let rrd_graph specify the orgin of the dash so we can 
fine tune where the gridlines start. I have extended the major vertical 
lines one pixel down (so it is 3 below) as pixel 2 is an off-pixel in my 
graphs, and thus it starts at pixel 1 just like the grey line.

In the svg/eps code I currently have the orgin at 0,0 so that two dashed 
lines (with same on/off values) have their pattern aligned no matter 
where they start. It looked weird having the major and minor grid lines 
being slightly out of sync due to different starting positions.


2 patches for current cvs:

1) Orgin for dashes in svg code. Support for dash in eps.
Patches only svg/eps code in src/rrd_gfx.c
http://www.vitality.dk/rrdtool/patches/2002-04-07-better-dash.diff

2) Modification of rrd_graph so it uses dashes for gridlines much like 
rrdtool 1.0
Avoids drawing minor vertical gridlines where a major gridline is to 
avoid artifacts from having the grey line beneath the red one.
Patches src/rrd_graph.c and src/rrd_graph.h
http://www.vitality.dk/rrdtool/patches/2002-04-07-grid-dash.diff

Example
http://www.vitality.dk/rrdtool/dashes1.svg
http://www.vitality.dk/rrdtool/dashes1.eps
Partial screendump of svg, zoomed to 800%:
http://www.vitality.dk/rrdtool/dashes1.png


---
    - Peter Speck

                       If PacMan had affected us as kids
                       we'd be running around in dark rooms,
                       munching pills and listening to electronic music


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