Text Rendering Overview

Abstract

This page aims to give an explanation of how all the parts in rendering a TextSymbolizer play together. (For textplacement branch)

TextSymbolizer

As it's only property contains a pointer to a text_placements object.

text_placements

This object handles the management of all TextSymbolizer properties. It can be used as a base class for own objects which implement new processing semantics.

Functions

• get_all_expressions: Get a list of all expressions used in any placement. This function is used to collect attributes.
• get_placement_info: (Abstract function) Get a text_ placement_info object to use in rendering. The returned object creates a list of settings which is used to try to find a placement and stores all information that is generated by the placement finder.

This function usually is implemented as

{
     return text_placement_info_ptr(new text_placement_info_XXX(this));
}

Properties

All properties are grouped into a class text_symbolizer_properties accessible via public member properties. They are used by subclasses as their defaults.