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.Dd NOVEMBER 26, 2001
.Dt AG_CORE 3
.Os
.ds vT Agar API Reference
.ds oS Agar 1.0
.Sh NAME
.Nm AG_Core
.Nd agar core initialization and globals
.Sh SYNOPSIS
.Bd -literal
#include <agar/core.h>
.Ed
.Sh DESCRIPTION
These functions are responsible for the initialization of Agar's internals
and subsystems.
.Pp
.nr nS 1
.Ft "void"
.Fn AG_GetVersion "AG_AgarVersion *ver"
.Pp
.Ft "int"
.Fn AG_InitCore "const char *progname" "Uint flags"
.Pp
.Ft "int"
.Fn AG_InitVideo "int w" "int h" "int depth" "Uint flags"
.Pp
.Ft "int"
.Fn AG_InitVideoSDL "SDL_Surface *display" "Uint flags"
.Pp
.Ft "int"
.Fn AG_InitGUI "Uint flags"
.Pp
.Ft "void"
.Fn AG_AtExitFunc "void (*fn)(void)"
.Pp
.Ft "void"
.Fn AG_Quit "void"
.Pp
.Ft "void"
.Fn AG_QuitGUI "void"
.Pp
.Ft "void"
.Fn AG_Destroy "void"
.Pp
.Ft "void"
.Fn AG_DestroyGUI "void"
.Pp
.nr nS 0
The
.Fn AG_InitCore
function initializes the internal data structures of the Agar-Core library.
It must be invoked before any other
.Sq AG_
routine.
The
.Fa progname
argument is an arbitrary name for the application.
Available
.Fa flags
options include:
.Bl -tag -width "AG_NO_CFG_AUTOLOAD "
.It AG_VERBOSE
Allow errors and warning output on console.
.It AG_CREATE_DATADIR
If it does not exist, automatically create a
.Pa ~/.<progname>
data directory on startup.
.It AG_NO_CFG_AUTOLOAD
Skip loading of
.Xr AG_Config 3
configuration data on startup.
.El
.Pp
The
.Fn AG_InitVideo
function sets the video mode, initializes the font engine and GUI system.
The graphics backend is auto-selected.
.Pp
Assuming Agar was compiled with support for SDL,
.Fn AG_InitVideoSDL
initializes the GUI system to use an existing SDL display surface.
If the specified surface has the
.Dv SDL_OPENGL
flag set, it is assumed that Agar should render itself using OpenGL
primitives, otherwise plain framebuffer mode is used.
.Pp
The
.Fn AG_InitGUI
function initializes the Agar GUI system.
This involves registering the widget classes, initializing the global tables
(e.g., colors, primitives, cursors, icons), the themes, as well as the font
engine and the input devices.
.Fn AG_InitVideo
and
.Fn AG_InitVideoSDL
invoke
.Fn AG_InitGUI ,
so it is rarely used directly.
.Pp
The
.Fn AG_AtExitFunc
registers a function that will be invoked automatically by
.Fn AG_Destroy .
.Pp
.Fn AG_Quit
immediately terminates the application by releasing resources allocated by
Agar-Core and invoking
.Xr exit 2 .
.Pp
If Agar-GUI is in use, the
.Fn AG_QuitGUI
function should be used instead as it requests the termination of the
application through the event system, leaving an opportunity for the
termination to be interrupted or aborted (e.g., by confirmation dialogs).
.Pp
The
.Fn AG_Destroy
function immediately frees all resources allocated by Agar.
.Pp
.Fn AG_DestroyGUI
frees all resources allocated by the Agar GUI system.
Being implicitely invoked from
.Fn AG_Destroy ,
it is rarely used directly.
.Pp
.Sh AGAR VERSION INFORMATION
.nr nS 1
.Ft void
.Fn AG_GetVersion "AG_AgarVersion *ver"
.Pp
.Ft bool
.Fn AG_VERSION_ATLEAST "int major" "int minor" "int patchlevel"
.Pp
.nr nS 0
The
.Fn AG_GetVersion
function fills an
.Ft AG_AgarVersion
structure with version information:
.Bd -literal
typedef struct ag_agar_version {
	int major;
	int minor;
	int patch;
	const char *release;
} AG_AgarVersion;
.Ed
.Pp
Agar does not need to have been previously initialized for
.Fn AG_GetVersion
to work.
.Pp
The
.Fn AG_VERSION_ATLEAST
macro evaluates to true if the current Agar version is equal to, or exceeds
the given version number.
.Sh SEE ALSO
.Xr AG_Object 3 ,
.Xr AG_View 3 ,
.Xr AG_Widget 3 ,
.Xr AG_Window 3
.Pp
.Bd -literal
http://www.libsdl.org/
http://www.opengl.org/
.Ed
.Sh BUGS
Routines related to Agar-GUI should be documented in a separate manual page.