How preferences work

This document contains information about how user preferences are stored and manipulated in the Second Life Viewer Client.

The gSavedSettings Control Group

The values for user preferences are stored in gSavedSettings, a global variable of the class LLControlGroup (see "indra/llxml/llcontrol.cpp" for the definition of that class). At the end of the session (i.e. when the viewer client is quit), persistent settings are saved to "settings.xml". They will be loaded from that file at the beginning of the next session.

Declaring a New Preference

As of 1.20, this section is outdated. From the release notes, "The settings system has been significantly revamped. llcontroldef.cpp has been replaced with an XML file controlling all settings values: app_settings/settings.xml"

Old description follows:

All preferences must be declared in "indra/newview/llcontroldef.cpp" to be used. The declaration informs the client of details about the preference:

• its data type (e.g. color, string, float);
• its name (e.g. "EffectColor");
• its initial (default) value;
• its documentation string, which is displayed in the "Debug Settings" floater (in the Client menu);
• (optional) its persistence, i.e. whether it will be saved between sessions.

The following example (taken from "indra/newview/llcontroldef.cpp") declares a preference which stores a 4-channel (RGBA) color, called "EffectColor", with a default value of totally-opaque white (1, 1, 1, 1), and a documentation string, "Particle effects color":

gSavedSettings.declareColor4("EffectColor", LLColor4(1.f, 1.f, 1.f, 1.f), "Particle effects color");

This next example shows how you can specify that the preference should NOT persist between sessions, by giving NO_PERSIST as a fourth argument to the declaration:

gSavedSettings.declareBOOL("ShowTools", FALSE, "", NO_PERSIST);

The full list of data types, their declaration function names, and data type descriptions follows. Note that for data types which start with "LL" (e.g. LLString), the declare function name does not contain the leading "LL" (thus it becomes "declareString", not "declareLLString")

Data Type	Declare Function	Description
U32	declareU32	Unsigned 32-bit Integer
S32	declareS32	Signed 32-bit Integer
F32	declareF32	32-bit Float
BOOL	declareBOOL	Boolean (True/False)
LLString	declareString	Character String (Text)
LLVector3	declareVec3	3D Vector
LLVector3d	declareVec3d	3D Vector (double data size)
LLRect	declareRect	Rectangle (left, bottom, width, height)
LLColor4U	declareColor4U	Unsigned 4-Channel Color (RGBA)
LLColor4	declareColor4	4-Channel Color (RGBA)
LLColor3	declareColor3	3-Channel Color (RGB)

Accessing Preference Data

The LLControlGroup class (of which gSavedSettings is an instance) defines "get" and "set" functions for each of the data types. The functions follow this format, where "DataType" is replaced with the proper data type, e.g. BOOL, F32, LLColor4. (As with the declare functions, the get and set function names to not contain the leading "LL" for data types like LLString and LLColor4.)

LLControlGroup::getDataType( LLString name );
LLControlGroup::setDataType( LLString name, DataType new_value );

A contrived example of retrieving and then setting an LLColor4-typed preference:

LLColor4 my_color;
my_color = gSavedSettings.getColor4( "EffectColor" );
gSavedSettings.setColor4( "EffectColor", my_color );

There are three additional "get" functions for certain special cases:

Function Name	Return Type	Description
getWString	LLWString	Wide-Data Strings (multiple bytes per char)
getText	LLString	Special handler for strings from a file?
getColor	LLColor4	Handles both LLColor4 and LLColor4u types.