Friday, August 13, 2010

Lines Styles and staring over again

Well, it sometimes happens that you are almost there and you should just add those 2% and you find that little something that you think you will need or you should put in there. And even if your schedule tells you to leave it out, you can't sleep at night, awake staring at the white roof of your room.

Well, this is what happened to me, since I wanted to make the uDig style editor from the merging of SLD into the QGIS gui design. So I decided, as you probably saw in my latest posts, that there had to be something called rules which would represent a style property for a certain geometry.

In SLD there are things called FeatureTypeStyle and Rule. And later I will show you also what they can infuence.

For now let's start with a simple road-map.

Which in the editor looks like:

You might note that the rules list if now a tree viewer. Whan looking at the tree viewer think of the following mapping:

root elements = groups = FeatureTypeStyle
children elements = rule = Rule

For some that might sound strange, but I know some will understand :)

Alright, let's add a second rule that has a line a bit thicker then the first, in order to give the feeling of a line with black border.

We now have a group with two rules, which will result in:

And exactly here lies the problem. Do you see the ugly overlapping of the roads?

If we instead do the same with two groups and one rule per group:

we gain the wanted result:

if we then also take care a bit of the caps and joins of the lines it looks even better:

To end the thing with some more fun, let's play with the dashing of the lines.

We first set the dash of the red line to 40.0, 40.0:

and let's also add some ticks to make it nicer:

And here we go:

Well, we have again the overlapping problem... so we try to split in more groups:

which is better, but we still have problems on the line ends:

Well, at the end I also did a try with graphics stroke, but that one is not yet well supported in the geotools 2.6 series, which is on what uDig 1.2 bases on:

They say geotools 2.7 has better support for graphics strokes, so that will be available in uDig 1.3.

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