.\"
.\" Copyright (c) 2007 Hypertriton, Inc. <http://hypertriton.com/>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
.\" INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
.\" (INCLUDING BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
.\" IN ANY WAY OUT OF THE USE OF THIS SOFTWARE EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd October 21, 2007
.Dt RG_FEATURE 3
.Os
.ds vT FreeSG API Reference
.ds oS FreeSG 1.0
.Sh NAME
.Nm RG_Feature
.Nd FreeSG-RG feature framework
.Sh SYNOPSIS
.Bd -literal
#include <agar/core.h>
#include <agar/gui.h>
#include <freesg/rg.h>
.Ed
.Sh DESCRIPTION
The
.Nm
element performs some operation on the surface of a
.Xr RG_Tile 3 .
For example, a
.Sq Blur
filter may be implemented as a
.Nm .
The interface is defined by the
.Fa RG_FeatureOps
structure:
.Bd -literal
typedef struct rg_feature_ops {
	const char *type;       /* Feature name */
	size_t len;             /* Size of structure */
	const char *desc;       /* Feature description */
	int flags;
#define FEATURE_AUTOREDRAW 0x01 /* Automatic redraw on edit */

	void (*init)(void *self, RG_Tileset *set, int flags);
	int  (*load)(void *self, AG_DataSource *ds);
	void (*save)(void *self, AG_DataSource *ds);
	void (*destroy)(void *self);
	void (*apply)(void *self, RG_Tile *tile, int x, int y);
	void (*menu)(void *self, AG_MenuItem *menu);
	AG_Toolbar *(*toolbar)(void *self, RG_Tileview *view);
	AG_Window  *(*edit)(void *self, RG_Tileview *view);
}
.Ed
.Pp
The
.Fn init ,
.Fn load ,
.Fn save ,
.Fn destroy
and
.Fn edit
operations are analogous to the
.Xr AG_Object 3
operations of the same name.
.Fn init
must invoke
.Fn RG_FeatureInit .
.Pp
The
.Fn menu
and
.Fn toolbar
operations, where not NULL, generate and return
.Xr AG_Menu 3
items and an
.Xr AG_Toolbar 3 ,
respectively, for the GUI.
.Pp
The
.Fn apply
operation performs the actual modification on the tile.
The
.Fa x
and
.Fa y
arguments are specific to the instance of this feature and may be ignored.
.Sh INTERFACE
.nr nS 1
.Ft "void"
.Fn RG_FeatureInit "void *feature" "RG_Tileset *ts" "int flags" "const RG_FeatureOps *featureOps"
.Pp
.Ft "void"
.Fn RG_FeatureAddPixmap "RG_Feature *feature" "RG_Pixmap *pixmap"
.Pp
.Ft "void"
.Fn RG_FeatureAddSketch "RG_Feature *feature" "RG_Sketch *sketch"
.Pp
.Ft "void"
.Fn RG_FeatureDelPixmap "RG_Feature *feature" "RG_Pixmap *pixmap"
.Pp
.Ft "void"
.Fn RG_FeatureDelSketch "RG_Feature *feature" "RG_Sketch *sketch"
.Pp
.nr nS 0
The
.Fn RG_FeatureInit
function initializes a derivate of the
.Nm
structure, described by the
.Fa ops
structure (see
.Dq DESCRIPTION
section).
The following
.Fa flags
are defined:
.Bl -tag -width "FEATURE_AUTOREDRAW "
.It FEATURE_AUTOREDRAW
Periodically redraw target tile when feature is undergoing edition.
.El
.Pp
Features occasionally need to reference other resources in the current
.Ft RG_Tileset .
The
.Fn RG_FeatureAddPixmap
and
.Fn RG_FeatureAddSketch
functions add a reference to a pixmap or sketch, respectively.
.Fn RG_FeatureDelPixmap
and
.Fn RG_FeatureDelSketch
remove the given reference.
.Sh SEE ALSO
.Xr RG 3 ,
.Xr RG_Anim 3 ,
.Xr RG_Pixmap 3 ,
.Xr RG_Sketch 3 ,
.Xr RG_Texture 3 ,
.Xr RG_Tile 3 ,
.Xr RG_Tileview 3