Number: 1445
Title: Node outline incorrect width with semitransparent colors (alpha)
Submitter: Ryan Schmidt
Date: Sat Sep 20 00:33:06 2008
Subsys: Dot
Version: 2.21.20080918.0445
System: x86-OSX-10.4.11
Severity: minor
Problem:
When I set penwidth larger (e.g. to 10 pixels) and use fill and stroke colors with an alpha component I see a problem: the stroke is not 10 px wide, it's maybe 5 px, and outside the outline the fill color continues for another 5 px.

The attached image was made using dot's cairo PNG renderer.
Input:

digraph G {
	penwidth [shape=rect style=filled color="#00000033" penwidth=10]
}
Output file: b1445.png
Comments:
[ellson] This is a weird one. It doesn't seem to happen with solid colors.

I think it must be something cairo is doing. I'm going to have to write a test.c with direct cairo calls...

I'm also wondering why your label's y positition is so low. Can you run this same test case with "-v" for me please?

[ryan] = This is a weird one. It doesn't seem to happen with solid colors.

Right! It seemed weird to me.

= I think it must be something cairo is doing. I'm going to have to write a test.c with direct cairo calls... = = = I'm also wondering why your label's y positition is so low.

Probably the font issue I mentioned earlier, that we didn't fully explore.

https://mailman.research.att.com/pipermail/graphviz-interest/2008q3/005484.html

You suspected the Graphviz Quartz code of being the problem, but I was seeing the problem on both Tiger and Leopard, so at least on Tiger the Quartz code is not being used (since the Quartz code in Graphviz still requires 10.5 or greater, last I heard).

I believe you asked me for more info and I failed to respond -- so sorry! Where should we pick up on that?

= Can you run this same test case with "-v" for me please?


dot - Graphviz version 2.21.20080918.0445 (Fri Sep 19 22:07:29 GMT 2008)
Activated plugin library: libgvplugin_pango.5.dylib
Using textlayout: textlayout:cairo
Activated plugin library: libgvplugin_dot_layout.5.dylib
Using layout: dot:dot_layout
Using render: cairo:cairo
Using device: png:cairo:cairo
The plugin configuration file:
    /opt/local/lib/graphviz/config5
        was successfully loaded.
    render    :  cairo dot fig gd map ps svg tk vml vrml xdot
    layout    :  circo dot fdp neato nop nop1 nop2 patchwork twopi
    textlayout    :  textlayout
    device    :  canon cmap cmapx cmapx_np dia dot eps fig gd gd2 gif gtk gv hpgl imap imap_np ismap jpe jpeg jpg mif mp pcl pdf pic plain plain-ext png ps ps2 svg svgz tk vml vmlz vrml vtx wbmp xdot xlib
    loadimage    :  (lib) gd gd2 gif jpe jpeg jpg png ps svg
fontname: "Times-Roman" resolved to: (ps) (PangoCairoATSUIFont) "Times New Roman 14"
network simplex:  1 nodes 0 edges maxiter=2147483647 balance=1
network simplex: 1 nodes 0 edges 0 iter 0.00 sec
mincross: pass 0 iter 0 trying 0 cur_cross 0 best_cross 0
mincross G: 0 crossings, 0.00 secs.
network simplex:  1 nodes 0 edges maxiter=2147483647 balance=2
network simplex: 1 nodes 0 edges 0 iter 0.00 sec
routesplines: 0 edges, 0 boxes 0.00 sec
Using render: cairo:cairo
Using device: png:cairo:cairo
dot: allocating a 19K cairo image surface (83 x 59 pixels)

Owner: ellson
Status: *