DescendantsLines is an in-development addon for Gramps which generates a graphical descendants tree using orthogonal edges and routing ("square edges").
- 1 History
- 2 Limitations
- 3 Usage
- 4 Development
- 5 Command Line Interface
2010: this script needs some updates for avoiding minor issues.
A modified script is available on the addons repository. 
- No option for name display format
- Partial quoting of xml-syntax-like data. Data which resembles xml syntax (tags, etc) may cause error.
- Script ignores role on event (was added in 2007)
- Script ignores localized date handlers (using ISO date format, date quality in english)
- Memory limitation with a large database (DOM parsing)
- The last pixel column of each secondary line of each entry is wrong coloured (red instead black)
- The addon DescendantsLines does not use the Gramps document interface. (perhaps the Gramps document interface options should be hidden)
- DestinationOption does not have the usual error handling and user checking (e.g. for overwriting files)
- Create the directory $GRAMPSHOME/gramps/gramps34/plugins/DescendantsLines/ .
- Copy the files DescendantsLines.py and DescendantsLines.gpr.py from svn to the directory $GRAMPSHOME/gramps/gramps34/plugins/DescendantsLines/ .
- Open Gramps and generate the report -- Reports -> Graphical Reports -> Descendants Lines. Choose the output path on "Destination" (default $GRAMPSHOME/DescendantsLines.png). The "Filename" option will contain an empty file after the report is run.
- The script currently runs in "debug mode" so it generates copious terminal output such as "Unknown event type: ..." or "Unknown spouse: ...". These warnings are harmless.
The options for the addon DescendantsLines are:
- S_DOWN - The length of the vertical edges from descendant to spouse-bar
- S_UP - The length of the vertical edges from spouse-bar to spouse
- S_VPAD - Length of vertical padding spacing between spouse and spouse-bar (?)
- FL_PAD - Length of padding spacing between S_UP edges (vertical edges from spouse-bar to spouse) and O_DOWN edges (vertical edges from spouse-bar to child-bar)
- O_DOWN - The length of the vertical edges from spouse-bar to child-bar
- C_PAD - Length of padding spacing between children
- F_PAD - Length of padding spacing between families (?)
- C_UP - The length of the vertical edges from child to child-bar
- SP_PAD - Length of padding spacing between spouses
- max_gen - Maximum number of generations to include.
- inc_places - Whether to include event places in the output
- inc_marriages - Whether to include marriage information in the output
- Image:Charlemagne-DescendantsLines.png -- A family tree of Charlemagne starting from Chloderic King of Cologne. (No preview, click on "Full resolution")
There is an experimental try for migrating this Gtk/cairo code to a draw plugin working into Gramps (font, style, path, canvas, output formats).
The idea will be to keep the Gramps XML parsing, but with a copy of the active database and use of current report environment (output formats, style, path).
- Using the library get_event_or_fallback() methods from gen.utils. (done in Gramps-addons)
- Add a generation limit. (done in Gramps-addons)
- Make the XML export smaller. Use filter. (done in Gramps-addons)
- Think of tree compression algorithms.
Pass 1: generate a tmp XML with only data needed for the report, to load it as input
- Enable Person selection (Gramps ID) - done
- Generate a temp Gramps XML database matching 'IsDescendantFamilyOf' filter rule - done
- Input path - done (need to set @prefix@: path_to_SVN/src on const.py)
- Clean-up - done
- simple Gramps XML template with events, persons, families objects (only export primary event role reference).
- 'localized' dates (does not follow last DTD, which uses english and ISO format).
FINISHED - it works fine!
Pass 2: use draw report environment
- Generate a plugins/docgen/PNGDrawDoc.py file 
- Move Gtk code to draw report (if possible)
- Move cairo code to draw report (if possible)
- Output path
- Clean-up, pylint, etc ...
Pass 2 (Alternate): use of user-defined (mega)-widgets
- Have a look at mega-widget request and implementation 
- Output path through mega-widget
- Clean-up, pylint, etc ...
Pass 2 (Alternate): use a DestinationOption
- Use a DestinationOption
- Ignore standard Filename option
Command Line Interface
Gramps provides a cli support for running reports and tools .
- use stdin and stdout for command line import/export 
Feel free to contribute or improve it.