Marble/GeoData/GeoDataUse: Difference between revisions

Revision as of 21:51, 14 September 2011

Using GeoData

This page tries to summarise the use of GeoData classes in marble so that its implementation details can match the use cases, and understand if any what issues might arise from manipulating them otherwise.

Use Cases

The use cases identified so far are:

use any GeoData class as a convenient data holder in APIs.
It is expected in that regard that classes have shared data.

Let's call this usecase the "ToolClass" usecase.
use GeoDataDocument as the root document of a "data file" in-memory representation, or even another grouping of information.
In this use case, there would exist a "tree" of data matching a logical grouping of information.

Let's call this usecase the "DataTree" usecase.

Actual Implemented Use Details

GeoData classes have shared data, in the sense that e.g. copying a GeoDataFeature is a shallow copy, with deep copy happening when one of the instances need to modify a value. This is all for the "ToolClass", and not much useful for the "DataTree". Pure parameter passing benefits from shallow copy.

FileManager uses FileLoader which build a GeoDataDocument from files it opens. It internally uses the GeoParser classes and framework for xml files. Those files then provided through the GeoDataTreeModel model.

PositionTracker keeps a document with past positions retrieved from PositionProviderPlugin plugins.

RoutingManager handles routing data in a document with instructions retrieved from Marble Runners Plugins which derive from MarbleAbstractRunner.

TODO others??

Common Issues and Pitfalls

In the past or present, some issues have appeared and need to be remembered/adressed:

memory ownership is an issue to be determined depending on use case.
Compliance with KML spec is a priority, limiting differing needs.

@@ Line 15: / Line 15: @@
 === Actual Implemented Use Details ===
-* GeoData classes have shared data, in the sense that e.g. copying a GeoDataFeature is a shallow copy, with deep copy happening when one of the instances need to modify a value. This is all for the "ToolClass", and not much useful for the "DataTree".
+* GeoData classes have shared data, in the sense that e.g. copying a GeoDataFeature is a shallow copy, with deep copy happening when one of the instances need to modify a value. This is all for the "ToolClass", and not much useful for the "DataTree". Pure parameter passing benefits from shallow copy.
 * {{class|FileManager|kdeedu|4.x}} uses {{class|FileLoader|kdeedu|4.x}} which build a {{class|GeoDataDocument|kdeedu|4.x}} from files it opens. It internally uses the {{class|GeoParser|kdeedu|4.x}} classes and framework for xml files. Those files then provided through the {{class|GeoDataTreeModel|kdeedu|4.x}} model.
-* {{class|PlacemarkManager|kdeedu|4.x}} uses placemarks retrieved from the FileManager, and provides a {{class|PlacemarkModel|kdeedu|4.x}} model which contains them.
 * {{class|PositionTracker|kdeedu|4.x}} keeps a document with past positions retrieved from {{class|PositionProviderPlugin|kdeedu|4.x}} plugins.