## VipsArgument

VipsArgument

## Synopsis

    #define             VIPS_UNREF                          (X)
    enum                VipsArgumentFlags;
    #define             VIPS_ARGUMENT_REQUIRED_INPUT
    #define             VIPS_ARGUMENT_OPTIONAL_INPUT
    #define             VIPS_ARGUMENT_REQUIRED_OUTPUT
                        VipsArgument;
                        VipsArgumentClass;
                        VipsArgumentInstance;
    typedef             VipsArgumentTable;
    VipsArgumentInstance * vips__argument_get_instance      (VipsArgumentClass *Param1,
                                                             VipsObject *Param2);
    VipsArgument *      vips__argument_table_lookup         (VipsArgumentTable *Param1,
                                                             GParamSpec *Param2);
    void                vips__object_set_member             (VipsObject *object,
                                                             GParamSpec *pspec,
                                                             GObject **member,
                                                             GObject *argument);
    void *              (*VipsArgumentMapFn)                (VipsObject *Param1,
                                                             GParamSpec *Param2,
                                                             VipsArgumentClass *Param3,
                                                             VipsArgumentInstance *Param4,
                                                             void *a,
                                                             void *b);
    void *              vips_argument_map                   (VipsObject *object,
                                                             VipsArgumentMapFn fn,
                                                             void *a,
                                                             void *b);
    void                vips_argument_dispose_all           (VipsObject *object);
    #define             VIPS_ARGUMENT_FOR_ALL               (OBJECT,
                                                             PSPEC,
                                                             ARG_CLASS,
                                                             ARG_INSTANCE)
    #define             VIPS_ARGUMENT_FOR_ALL_END
    struct              VipsObject;
    struct              VipsObjectClass;
    gboolean            vips_pspec_value_is_null            (GParamSpec *pspec,
                                                             const GValue *value);
    void                vips_object_set_property            (GObject *gobject,
                                                             guint property_id,
                                                             const GValue *value,
                                                             GParamSpec *pspec);
    void                vips_object_get_property            (GObject *gobject,
                                                             guint property_id,
                                                             GValue *value,
                                                             GParamSpec *pspec);
    void                vips_object_preclose                (VipsObject *object);
    int                 vips_object_build                   (VipsObject *object);
    void                vips_object_print_class             (VipsObjectClass *klass);
    void                vips_object_print                   (VipsObject *object);
    void                vips_object_print_name              (VipsObject *object);
    gboolean            vips_object_sanity                  (VipsObject *object);
    void                vips_object_class_install_argument  (VipsObjectClass *Param1,
                                                             GParamSpec *pspec,
                                                             VipsArgumentFlags flags,
                                                             guint offset);
    int                 vips_object_set_argument_from_string
                                                            (VipsObject *object,
                                                             const char *name,
                                                             const char *value);
    gboolean            vips_object_get_argument_needs_string
                                                            (VipsObject *object,
                                                             const char *name);
    int                 vips_object_get_argument_to_string  (VipsObject *object,
                                                             const char *name,
                                                             const char *arg);
    int                 vips_object_set_required            (VipsObject *object,
                                                             const char *value);
    void *              (*VipsObjectSetArguments)           (VipsObject *Param1,
                                                             void *Param2,
                                                             void *Param3);
    VipsObject *        vips_object_new                     (GType type,
                                                             VipsObjectSetArguments set,
                                                             void *a,
                                                             void *b);
    VipsObject *        vips_object_new_from_string         (VipsObjectClass *object_class,
                                                             const char *p);
    void                vips_object_to_string               (VipsObject *object,
                                                             VipsBuf *buf);
    void *              vips_object_map                     (VipsSListMap2Fn fn,
                                                             void *a,
                                                             void *b);
    void *              (*VipsTypeMap)                      (GType Param1,
                                                             void *Param2);
    void *              (*VipsTypeMap2)                     (GType Param1,
                                                             void *Param2,
                                                             void *Param3);
    void *              (*VipsClassMap)                     (VipsObjectClass *Param1,
                                                             void *Param2);
    void *              vips_type_map                       (GType base,
                                                             VipsTypeMap2 fn,
                                                             void *a,
                                                             void *b);
    void *              vips_type_map_all                   (GType base,
                                                             VipsTypeMap fn,
                                                             void *a);
    void *              vips_class_map_all                  (GType base,
                                                             VipsClassMap fn,
                                                             void *a);
    int                 vips_class_depth                    (VipsObjectClass *klass);
    VipsObjectClass *   vips_class_find                     (const char *basename,
                                                             const char *nickname);
    GType               vips_type_find                      (const char *basename,
                                                             const char *nickname);
    void                vips_object_local_cb                (VipsObject *vobject,
                                                             GObject *gobject);
    #define             vips_object_local                   (V,
                                                             G)
    void                vips_object_print_all               (void);
    void                vips_object_sanity_all              (void);
    void                vips_object_rewind                  (VipsObject *object);

## Object Hierarchy

      GEnum
       +----VipsArgumentFlags

      GObject
       +----VipsObject
             +----VipsOperation
             +----VipsFormat
             +----VipsImage
             +----VipsInterpolate
             +----VipsPool
             +----VipsRegion
             +----VipsThreadState

## Properties

      "description"              gchar*                : Read / Write
      "nickname"                 gchar*                : Read / Write

## Signals

      "close"                                          : Run Last
      "postclose"                                      : Run Last
      "preclose"                                       : Run Last

## Description

## Details

### VIPS_UNREF()

    #define VIPS_UNREF( X ) VIPS_FREEF( g_object_unref, (X) )

### enum VipsArgumentFlags

    typedef enum {
    	VIPS_ARGUMENT_NONE = 0,
    	VIPS_ARGUMENT_REQUIRED = 1,
    	VIPS_ARGUMENT_CONSTRUCT = 2,
    	VIPS_ARGUMENT_SET_ONCE = 4,
    	VIPS_ARGUMENT_INPUT = 8,
    	VIPS_ARGUMENT_OUTPUT = 16
    } VipsArgumentFlags;

Flags we associate with each object argument.

Have separate input & output flags. Both set is an error; neither set is OK.

Input gobjects are automatically reffed, output gobjects automatically ref us. We also automatically watch for "destroy" and unlink.

`VIPS_ARGUMENT_NONE` | no flags
`VIPS_ARGUMENT_REQUIRED` | must be set in the constructor
`VIPS_ARGUMENT_CONSTRUCT` | can only be set in the constructor
`VIPS_ARGUMENT_SET_ONCE` | can only be set once
`VIPS_ARGUMENT_INPUT` | is an input argument (one we depend on)
`VIPS_ARGUMENT_OUTPUT` | is an output argument (depends on us)

### VIPS_ARGUMENT_REQUIRED_INPUT

    #define             VIPS_ARGUMENT_REQUIRED_INPUT

### VIPS_ARGUMENT_OPTIONAL_INPUT

    #define             VIPS_ARGUMENT_OPTIONAL_INPUT

### VIPS_ARGUMENT_REQUIRED_OUTPUT

    #define             VIPS_ARGUMENT_REQUIRED_OUTPUT

### VipsArgument

    typedef struct {
    	GParamSpec *pspec; /* pspec for this argument */

    	/* More stuff, see below */
    } VipsArgument;

### VipsArgumentClass

    typedef struct {
    	VipsArgument parent;

    	/* The class of the object we are an arg for.
    	 */
    	VipsObjectClass *object_class;

    	VipsArgumentFlags flags;
    	guint offset;		/* G_STRUCT_OFFSET of member in object */
    } VipsArgumentClass;

### VipsArgumentInstance

    typedef struct {
    	VipsArgument parent;

    	/* The object we are attached to.
    	 */
    	VipsObject *object;

    	/* Has been set.
    	 */
    	gboolean assigned;

    	/* If this is an output argument, keep the id of our "close" handler
    	 * here.
    	 */
    	gulong close_id;
    } VipsArgumentInstance;

### VipsArgumentTable

    typedef GHashTable VipsArgumentTable;

### vips__argument_get_instance ()

    VipsArgumentInstance * vips__argument_get_instance      (VipsArgumentClass *Param1,
                                                             VipsObject *Param2);

### vips__argument_table_lookup ()

    VipsArgument *      vips__argument_table_lookup         (VipsArgumentTable *Param1,
                                                             GParamSpec *Param2);

### vips__object_set_member ()

    void                vips__object_set_member             (VipsObject *object,
                                                             GParamSpec *pspec,
                                                             GObject **member,
                                                             GObject *argument);

### VipsArgumentMapFn ()

    void *              (*VipsArgumentMapFn)                (VipsObject *Param1,
                                                             GParamSpec *Param2,
                                                             VipsArgumentClass *Param3,
                                                             VipsArgumentInstance *Param4,
                                                             void *a,
                                                             void *b);

### vips_argument_map ()

    void *              vips_argument_map                   (VipsObject *object,
                                                             VipsArgumentMapFn fn,
                                                             void *a,
                                                             void *b);

### vips_argument_dispose_all ()

    void                vips_argument_dispose_all           (VipsObject *object);

### VIPS_ARGUMENT_FOR_ALL()

    #define             VIPS_ARGUMENT_FOR_ALL( OBJECT, PSPEC, ARG_CLASS, ARG_INSTANCE )

### VIPS_ARGUMENT_FOR_ALL_END

    #define VIPS_ARGUMENT_FOR_ALL_END } } }

### struct VipsObject

    struct VipsObject;

### struct VipsObjectClass

    struct VipsObjectClass {
    	GObjectClass parent_class;

    	/* Build the object ... all argument properties have been set,
    	 * now build the thing.
    	 */
    	int (*build)( VipsObject *object );

    	/* Try to print something about the class, handy for help displays.
    	 */
    	void (*print_class)( struct _VipsObjectClass *, VipsBuf * );

    	/* Try to print something about the object, handy for debugging.
    	 */
    	void (*print)( VipsObject *, VipsBuf * );

    	/* Sanity-check the object. Print messages and stuff.
    	 * Handy for debugging.
    	 */
    	void (*sanity)( VipsObject *, VipsBuf * );

    	/* Rewind. Save and restore any stuff that needs to survive a
    	 * dispose().
    	 */
    	void (*rewind)( VipsObject * );

    	/* Just before close, everything is still alive.
    	 */
    	void (*preclose)( VipsObject * );

    	/* Close, time to free stuff.
    	 */
    	void (*close)( VipsObject * );

    	/* Post-close, everything is dead, except the VipsObject pointer.
    	 * Useful for eg. deleting the file associated with a temp image.
    	 */
    	void (*postclose)( VipsObject * );

    	/* The CLI interface. Implement these four to get CLI input and output
    	 * for your object.
    	 */

    	/* Given a command-line arg (eg. a filename), make an instance of the
    	 * object. Just do the g_object_new(), don't call _build().
    	 *
    	 * Don't call this directly, see vips_object_new_from_string().
    	 */
    	VipsObject *(*new_from_string)( const char *string );

    	/* The inverse of ^^. Given an object, output what ->new_from_string()
    	 * would have been given to make that object.
    	 */
    	void (*to_string)( VipsObject *, VipsBuf * );

    	/* Does this output arg need an arg from the command line? Image
    	 * output, for example, needs a filename to write to.
    	 */
    	gboolean output_needs_arg;

    	/* Write the object to the string. Return 0 for success, or -1 on
    	 * error, setting vips_error(). string is NULL if output_needs_arg()
    	 * was FALSE.
    	 */
    	int (*output_to_arg)( VipsObject *object, const char *string );

    	/* Class nickname, eg. "VipsInterpolateBicubic" has "bicubic" as a
    	 * nickname. Not internationalised.
    	 */
    	const char *nickname;

    	/* Class description. Used for help messages, so internationalised.
    	 */
    	const char *description;

    	/* Table of arguments for this class and any derived classes. Order
    	 * is important, so keep a traverse list too. We can't rely on the
    	 * ordering given by g_object_class_list_properties() since it comes
    	 * from a hash :-(
    	 */
    	VipsArgumentTable *argument_table;
    	GSList *argument_table_traverse;
    };

### vips_pspec_value_is_null ()

    gboolean            vips_pspec_value_is_null            (GParamSpec *pspec,
                                                             const GValue *value);

### vips_object_set_property ()

    void                vips_object_set_property            (GObject *gobject,
                                                             guint property_id,
                                                             const GValue *value,
                                                             GParamSpec *pspec);

### vips_object_get_property ()

    void                vips_object_get_property            (GObject *gobject,
                                                             guint property_id,
                                                             GValue *value,
                                                             GParamSpec *pspec);

### vips_object_preclose ()

    void                vips_object_preclose                (VipsObject *object);

### vips_object_build ()

    int                 vips_object_build                   (VipsObject *object);

### vips_object_print_class ()

    void                vips_object_print_class             (VipsObjectClass *klass);

### vips_object_print ()

    void                vips_object_print                   (VipsObject *object);

### vips_object_print_name ()

    void                vips_object_print_name              (VipsObject *object);

### vips_object_sanity ()

    gboolean            vips_object_sanity                  (VipsObject *object);

### vips_object_class_install_argument ()

    void                vips_object_class_install_argument  (VipsObjectClass *Param1,
                                                             GParamSpec *pspec,
                                                             VipsArgumentFlags flags,
                                                             guint offset);

### vips_object_set_argument_from_string ()

    int                 vips_object_set_argument_from_string
                                                            (VipsObject *object,
                                                             const char *name,
                                                             const char *value);

### vips_object_get_argument_needs_string ()

    gboolean            vips_object_get_argument_needs_string
                                                            (VipsObject *object,
                                                             const char *name);

### vips_object_get_argument_to_string ()

    int                 vips_object_get_argument_to_string  (VipsObject *object,
                                                             const char *name,
                                                             const char *arg);

### vips_object_set_required ()

    int                 vips_object_set_required            (VipsObject *object,
                                                             const char *value);

### VipsObjectSetArguments ()

    void *              (*VipsObjectSetArguments)           (VipsObject *Param1,
                                                             void *Param2,
                                                             void *Param3);

### vips_object_new ()

    VipsObject *        vips_object_new                     (GType type,
                                                             VipsObjectSetArguments set,
                                                             void *a,
                                                             void *b);

### vips_object_new_from_string ()

    VipsObject *        vips_object_new_from_string         (VipsObjectClass *object_class,
                                                             const char *p);

### vips_object_to_string ()

    void                vips_object_to_string               (VipsObject *object,
                                                             VipsBuf *buf);

### vips_object_map ()

    void *              vips_object_map                     (VipsSListMap2Fn fn,
                                                             void *a,
                                                             void *b);

### VipsTypeMap ()

    void *              (*VipsTypeMap)                      (GType Param1,
                                                             void *Param2);

### VipsTypeMap2 ()

    void *              (*VipsTypeMap2)                     (GType Param1,
                                                             void *Param2,
                                                             void *Param3);

### VipsClassMap ()

    void *              (*VipsClassMap)                     (VipsObjectClass *Param1,
                                                             void *Param2);

### vips_type_map ()

    void *              vips_type_map                       (GType base,
                                                             VipsTypeMap2 fn,
                                                             void *a,
                                                             void *b);

### vips_type_map_all ()

    void *              vips_type_map_all                   (GType base,
                                                             VipsTypeMap fn,
                                                             void *a);

### vips_class_map_all ()

    void *              vips_class_map_all                  (GType base,
                                                             VipsClassMap fn,
                                                             void *a);

### vips_class_depth ()

    int                 vips_class_depth                    (VipsObjectClass *klass);

### vips_class_find ()

    VipsObjectClass *   vips_class_find                     (const char *basename,
                                                             const char *nickname);

### vips_type_find ()

    GType               vips_type_find                      (const char *basename,
                                                             const char *nickname);

### vips_object_local_cb ()

    void                vips_object_local_cb                (VipsObject *vobject,
                                                             GObject *gobject);

### vips_object_local()

    #define             vips_object_local( V, G )

### vips_object_print_all ()

    void                vips_object_print_all               (void);

### vips_object_sanity_all ()

    void                vips_object_sanity_all              (void);

### vips_object_rewind ()

    void                vips_object_rewind                  (VipsObject *object);

## Property Details

### The `"description"` property

      "description"              gchar*                : Read / Write

Class description.

Default value: ""

### The `"nickname"` property

      "nickname"                 gchar*                : Read / Write

Class nickname.

Default value: ""

## Signal Details

### The `"close"` signal

    void                user_function                      (VipsObject *vipsobject,
                                                            gpointer    user_data)       : Run Last

### The `"postclose"` signal

    void                user_function                      (VipsObject *vipsobject,
                                                            gpointer    user_data)       : Run Last

### The `"preclose"` signal

    void                user_function                      (VipsObject *vipsobject,
                                                            gpointer    user_data)       : Run Last