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Add new placement algorithm.

herm 2012-07-28 12:36:08 -07:00
parent 0a79f68e47
commit 84479ca1a6
1 changed files with 18 additions and 2 deletions
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TextSymbolizer.md

@ -84,8 +84,11 @@ The first parameter is the field name of a database field, or from a shape file,
You must load the needed fonts first, otherwise you'll get a run time error. But you can load as many true type fonts as you like. Mapnik is coming with a couple of fonts in "mapnik/fonts". I recommend to load all of this fonts, regardless if you need them or not.
## Placements
In Mapnik 2 the possibility to try different placements if the text can't be placed at the intended position is introduced. Currently only one algorithm ("simple") is implemented.
In Mapnik 2 the possibility to try different placements if the text can't be placed at the intended position is introduced.
Algorithms:
### Simple
(This is the only algorithm supported in Mapnik 2.0)
It expects a string to specify which positions and size should be used. The format is POSITIONS,[SIZES].
POSITIONS is any combination of N, E, S, W, NE, SE, NW, SW (direction) and X (exact position as give by "displacement") (separated by commas, may not be empty).
@ -115,8 +118,21 @@ An XML example might look like:
/>[label]</TextSymbolizer>
```
### List
Here a list of styles is defined and tried one by one till a valid position is found. Each style inherits from the previous one.
It is defined in XML by:
```xml
<TextSymbolizer face-name="DejaVu Sans Book" size="16" placement="point" dy="8" fill="blue" placement-type="list">[name]
<Placement size="10" dy="-8" fill="red"/><!-- Reduces text size and changes offset -->
<Placement fill="green">[abbreviated_name]</Placement> <!-- size="10", dy="-8", fill="green", shorter text -->
<Placement fill="orange" dy="8">[nr]</Placement> <!-- size="10", dy="8", fill="orange", shortest text -->
</TextSymbolizer>
```
(Note [abbreviated_name] and [nr] have to be supplied by the data source!)
## New syntax
Starting with r3354 Mapnik2 supports a new syntax:
Starting with Mapnik 2.0 a new syntax is used:
```xml
<TextSymbolizer name="[label]" />