VIPS Reference Manual: VipsObject

VipsObject

VipsObject — the VIPS base object class

Stability Level

Stable, unless otherwise indicated

Functions

#define	VIPS_UNREF()
#define	VIPS_ARG_IMAGE()
#define	VIPS_ARG_INTERPOLATE()
#define	VIPS_ARG_BOOL()
#define	VIPS_ARG_DOUBLE()
#define	VIPS_ARG_BOXED()
#define	VIPS_ARG_INT()
#define	VIPS_ARG_UINT64()
#define	VIPS_ARG_ENUM()
#define	VIPS_ARG_FLAGS()
#define	VIPS_ARG_STRING()
#define	VIPS_ARG_POINTER()
VipsArgumentInstance *	vips__argument_get_instance ()
VipsArgument *	vips__argument_table_lookup ()
void	vips__object_set_member ()
void *	(*VipsArgumentMapFn) ()
void *	vips_argument_map ()
void *	(*VipsArgumentClassMapFn) ()
void *	vips_argument_class_map ()
gboolean	vips_argument_class_needsstring ()
int	vips_object_get_argument ()
gboolean	vips_object_argument_isset ()
VipsArgumentFlags	vips_object_get_argument_flags ()
int	vips_object_get_argument_priority ()
#define	VIPS_ARGUMENT_FOR_ALL()
#define	VIPS_ARGUMENT_COLLECT_SET()
#define	VIPS_ARGUMENT_COLLECT_GET()
gboolean	vips_value_is_null ()
void	vips_object_set_property ()
void	vips_object_get_property ()
void	vips_object_preclose ()
int	vips_object_build ()
void	vips_object_summary_class ()
void	vips_object_summary ()
void	vips_object_dump ()
void	vips_object_print_summary_class ()
void	vips_object_print_summary ()
void	vips_object_print_dump ()
void	vips_object_print_name ()
gboolean	vips_object_sanity ()
void	vips_object_class_install_argument ()
int	vips_object_set_argument_from_string ()
gboolean	vips_object_argument_needsstring ()
int	vips_object_get_argument_to_string ()
int	vips_object_set_required ()
void *	(*VipsObjectSetArguments) ()
VipsObject *	vips_object_new ()
int	vips_object_set_valist ()
int	vips_object_set ()
int	vips_object_set_from_string ()
VipsObject *	vips_object_new_from_string ()
void	vips_object_to_string ()
void *	vips_object_map ()
void *	(*VipsTypeMapFn) ()
void *	(*VipsTypeMap2Fn) ()
void *	(*VipsClassMapFn) ()
void *	vips_type_map ()
void *	vips_type_map_all ()
int	vips_type_depth ()
GType	vips_type_find ()
const char *	vips_nickname_find ()
void *	vips_class_map_all ()
VipsObjectClass *	vips_class_find ()
VipsObject **	vips_object_local_array ()
void	vips_object_local_cb ()
#define	vips_object_local()
void	vips_object_set_static ()
void	vips_object_print_all ()
void	vips_object_sanity_all ()
void	vips_object_rewind ()
void	vips_object_unref_outputs ()
const char *	vips_object_get_description ()

Properties

gchar *	description	Read / Write
gchar *	nickname	Read / Write

Signals

void	close	Run Last
gint	postbuild	Run Last
void	postclose	Run Last
void	preclose	Run Last

Types and Values

enum	VipsArgumentFlags
#define	VIPS_ARGUMENT_REQUIRED_INPUT
#define	VIPS_ARGUMENT_OPTIONAL_INPUT
#define	VIPS_ARGUMENT_REQUIRED_OUTPUT
#define	VIPS_ARGUMENT_OPTIONAL_OUTPUT
	VipsArgument
	VipsArgumentClass
	VipsArgumentInstance
typedef	VipsArgumentTable
#define	VIPS_ARGUMENT_COLLECT_END

Object Hierarchy

    GObject
    ╰── VipsObject
        ├── VipsOperation
        ├── VipsImage
        ├── VipsInterpolate
        ├── VipsRegion
        ╰── VipsThreadState

Includes

#include <vips/vips.h>

Description

The VipsObject class and associated types and macros.

VipsObject is the base class for all objects in libvips. It has the following major features:

Functional class creation Vips objects have a very regular lifecycle: initialise, build, use, destroy. They behave rather like function calls and are free of side-effects.

Run-time introspection Vips objects can be fully introspected at run-time. There is not need for separate source-code analysis.

Command-line interface Any vips object can be run from the command-line with the vips driver program.

The VipsObject lifecycle

VipsObject s have a strictly defined lifecycle, split broadly as construct and then use. In detail, the stages are:

g_object_new(). The VipsObject is created with g_object_new(). Objects in this state are blank slates and need to have their various parameters set.
g_object_set(). You loop over the VipsArgument that the object has defined with vips_argument_map(). Arguments have a set of flags attached to them for required, optional, input, output, type, and so on. You must set all required arguments.
vips_object_build(). Call this to construct the object and get it ready for use. Building an object happens in four stages, see below.
g_object_get(). The object has now been built. You can read out any computed values.
g_object_unref(). When you are done with an object, you can unref it. See the section on reference counting for an explanation of the convention that VipsObject uses. When the last ref to an object is released, the object is closed. Objects close in three stages, see below.

The stages inside vips_object_build() are:

Chain up through the object's build class methods. At each stage, each class does any initial setup and checking, then chains up to its superclass.
The innermost build method inside VipsObject itself checks that all input arguments have been set and then returns.
All object build methods now finish executing, from innermost to outermost. They know all input arguments have been checked and supplied, so now they set all output arguments.
vips_object_build() finishes the process by checking that all output objects have been set, and then triggering the “postbuild” signal. “postbuild” only runs if the object has constructed successfuly.

VipsOperation has a cache of recent operation objects, see that class for an explanation of vips_cache_operation_build().

Finally the stages inside close are:

“preclose”. This is emitted at the start of the VipsObject dispose. The object is still functioning.
“close”. This runs just after all VipsArgument held by the object have been released.
“postclose”. This runs right at the end. The object pointer is still valid, but nothing else is.

VipsArgument

libvips has a simple mechanism for automating at least some aspects of GObject properties. You add a set of macros to your _class_init() which describe the arguments, and set the get and set functions to the vips ones.

See extending for a complete example.

The VipsObject reference counting convention

VipsObject has a set of conventions to simplify reference counting.

All input GObject have a ref added to them, owned by the object. When a VipsObject is unreffed, all of these refs to input objects are automatically dropped.
All output GObject hold a ref to the object. When a GObject which is an output of a VipsObject is disposed, it must drop this reference. VipsObject which are outputs of other VipsObject will do this automatically.

See VipsOperation for an example of VipsObject reference counting.

Functions

VIPS_UNREF()

#define             VIPS_UNREF( X )

VIPS_ARG_IMAGE()

#define             VIPS_ARG_IMAGE( CLASS, NAME, PRIORITY, LONG, DESC, FLAGS, OFFSET )

VIPS_ARG_INTERPOLATE()

#define             VIPS_ARG_INTERPOLATE( CLASS, NAME, PRIORITY, LONG, DESC, FLAGS, OFFSET )

VIPS_ARG_BOOL()

#define             VIPS_ARG_BOOL( CLASS, NAME, PRIORITY, LONG, DESC, \
            	FLAGS, OFFSET, VALUE )

VIPS_ARG_DOUBLE()

#define             VIPS_ARG_DOUBLE( CLASS, NAME, PRIORITY, LONG, DESC, \
            	FLAGS, OFFSET, MIN, MAX, VALUE )

VIPS_ARG_BOXED()

#define             VIPS_ARG_BOXED( CLASS, NAME, PRIORITY, LONG, DESC, \
            	FLAGS, OFFSET, TYPE )

VIPS_ARG_INT()

#define             VIPS_ARG_INT( CLASS, NAME, PRIORITY, LONG, DESC, \
            	FLAGS, OFFSET, MIN, MAX, VALUE )

VIPS_ARG_UINT64()

#define             VIPS_ARG_UINT64( CLASS, NAME, PRIORITY, LONG, DESC, \
            	FLAGS, OFFSET, MIN, MAX, VALUE )

VIPS_ARG_ENUM()

#define             VIPS_ARG_ENUM( CLASS, NAME, PRIORITY, LONG, DESC, \
            	FLAGS, OFFSET, TYPE, VALUE )

VIPS_ARG_FLAGS()

#define             VIPS_ARG_FLAGS( CLASS, NAME, PRIORITY, LONG, DESC, \
            	FLAGS, OFFSET, TYPE, VALUE )

VIPS_ARG_STRING()

#define             VIPS_ARG_STRING( CLASS, NAME, PRIORITY, LONG, DESC, FLAGS, OFFSET, \
            	VALUE )

VIPS_ARG_POINTER()

#define             VIPS_ARG_POINTER( CLASS, NAME, PRIORITY, LONG, DESC, FLAGS, OFFSET )

vips__argument_get_instance ()

VipsArgumentInstance *
vips__argument_get_instance (VipsArgumentClass *argument_class,
                             VipsObject *object);

Convenience ... given the VipsArgumentClass, get the VipsArgumentInstance.

vips__argument_table_lookup ()

VipsArgument *
vips__argument_table_lookup (VipsArgumentTable *argument_class,
                             GParamSpec *pspec);

vips__object_set_member ()

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

VipsArgumentMapFn ()

void *
(*VipsArgumentMapFn) (VipsObject *object,
                      GParamSpec *pspec,
                      VipsArgumentClass *argument_class,
                      VipsArgumentInstance *argument_instance,
                      void *a,
                      void *b);

vips_argument_map ()

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

Loop over the vips_arguments to an object. Stop when fn returns non-NULL and return that value.

Parameters

object	object whose args should be enumerated
fn	call this function for every argument
a	client data
b	client data

Returns

NULL if fn returns NULL for all arguments, otherwise the first non-NULL value from fn .

VipsArgumentClassMapFn ()

void *
(*VipsArgumentClassMapFn) (VipsObjectClass *object_class,
                           GParamSpec *pspec,
                           VipsArgumentClass *argument_class,
                           void *a,
                           void *b);

vips_argument_class_map ()

void *
vips_argument_class_map (VipsObjectClass *object_class,
                         VipsArgumentClassMapFn fn,
                         void *a,
                         void *b);

And loop over a class. Same as ^^, but with no VipsArgumentInstance.

vips_argument_class_needsstring ()

gboolean
vips_argument_class_needsstring (VipsArgumentClass *argument_class);

vips_object_get_argument ()

int
vips_object_get_argument (VipsObject *object,
                          const char *name,
                          GParamSpec **pspec,
                          VipsArgumentClass **argument_class,
                          VipsArgumentInstance **argument_instance);

Look up the three things you need to work with a vips argument.

Parameters

object	the object to fetch the args from
name	arg to fetch
pspec	the pspec for this arg.	[transfer none]
argument_class	the argument_class for this arg.	[transfer none]
argument_instance	the argument_instance for this arg.	[transfer none]

Returns

0 on success, or -1 on error.

vips_object_argument_isset ()

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

Convenience: has an argument been assigned. Useful for bindings.

Parameters

object	the object to fetch the args from
name	arg to fetch

Returns

TRUE if the argument has been assigned.

vips_object_get_argument_flags ()

VipsArgumentFlags
vips_object_get_argument_flags (VipsObject *object,
                                const char *name);

Convenience: get the flags for an argument. Useful for bindings.

Parameters

object	the object to fetch the args from
name	arg to fetch

Returns

The VipsArgumentFlags for this argument.

vips_object_get_argument_priority ()

int
vips_object_get_argument_priority (VipsObject *object,
                                   const char *name);

Convenience: get the priority for an argument. Useful for bindings.

Parameters

object	the object to fetch the args from
name	arg to fetch

Returns

The priority of this argument.

VIPS_ARGUMENT_FOR_ALL()

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

VIPS_ARGUMENT_COLLECT_SET()

#define             VIPS_ARGUMENT_COLLECT_SET( PSPEC, ARG_CLASS, AP )

VIPS_ARGUMENT_COLLECT_GET()

#define             VIPS_ARGUMENT_COLLECT_GET( PSPEC, ARG_CLASS, AP )

vips_value_is_null ()

gboolean
vips_value_is_null (GParamSpec *psoec,
                    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_summary_class ()

void
vips_object_summary_class (VipsObjectClass *klass,
                           VipsBuf *buf);

Generate a human-readable summary for a class.

Parameters

klass	class to summarise
buf	write summary here

vips_object_summary ()

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

Generate a human-readable summary for an object.

Parameters

object	object to summarise
buf	write summary here

vips_object_dump ()

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

Dump everything that vips knows about an object to a string.

Parameters

object	object to dump
buf	write dump here

vips_object_print_summary_class ()

void
vips_object_print_summary_class (VipsObjectClass *klass);

vips_object_print_summary ()

void
vips_object_print_summary (VipsObject *object);

vips_object_print_dump ()

void
vips_object_print_dump (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 *cls,
                                    GParamSpec *pspec,
                                    VipsArgumentFlags flags,
                                    int priority,
                                    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_argument_needsstring ()

gboolean
vips_object_argument_needsstring (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 *object,
                           void *a,
                           void *b);

vips_object_new ()

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

g_object_new() the object, set any arguments with set , call vips_object_build() and return the complete object.

Parameters

type	object to create
set	set arguments with this
a	client data
b	client data

Returns

the new object

vips_object_set_valist ()

int
vips_object_set_valist (VipsObject *object,
                        va_list ap);

See vips_object_set().

Parameters

object	object to set arguments on
ap	`NULL`-terminated list of argument/value pairs

Returns

0 on success, -1 on error

vips_object_set ()

int
vips_object_set (VipsObject *object,
                 ...);

Set a list of vips object arguments. For example:

vips_object_set (operation,
  "input", in,
  "output", &out,
  NULL);

Input arguments are given in-line, output arguments are given as pointers to where the output value should be written.

Parameters

object	object to set arguments on
...	`NULL`-terminated list of argument/value pairs

Returns

0 on success, -1 on error

vips_object_set_from_string ()

int
vips_object_set_from_string (VipsObject *object,
                             const char *string);

Set object arguments from a string. The string can be something like "a=12", or "a = 12, b = 13", or "fred". The string can optionally be enclosed in brackets.

You'd typically use this between creating the object and building it.

Parameters

object	object to set arguments on
string	arguments as a string

Returns

0 on success, -1 on error

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);

The inverse of vips_object_new_from_string(): turn object into eg. "VipsInterpolateSnohalo1(blur=.333333)".

Parameters

object	object to stringify
buf	write string here

vips_object_map ()

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

Call a function for all alive objects. Stop when fn returns non-NULL and return that value.

Parameters

fn	function to call for all objects
a	client data
b	client data

Returns

NULL if fn returns NULL for all arguments, otherwise the first non-NULL value from fn .

VipsTypeMapFn ()

void *
(*VipsTypeMapFn) (GType type,
                  void *a);

VipsTypeMap2Fn ()

void *
(*VipsTypeMap2Fn) (GType type,
                   void *a,
                   void *b);

VipsClassMapFn ()

void *
(*VipsClassMapFn) (VipsObjectClass *cls,
                   void *a);

vips_type_map ()

void *
vips_type_map (GType base,
               VipsTypeMap2Fn fn,
               void *a,
               void *b);

Map over a type's children. Stop when fn returns non-NULL and return that value.

Parameters

base	base type
fn	call this function for every type
a	client data
b	client data

Returns

NULL if fn returns NULL for all arguments, otherwise the first non-NULL value from fn .

vips_type_map_all ()

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

Map over a type's children, direct and indirect. Stop when fn returns non-NULL and return that value.

Parameters

base	base type
fn	call this function for every type
a	client data

Returns

NULL if fn returns NULL for all arguments, otherwise the first non-NULL value from fn .

vips_type_depth ()

int
vips_type_depth (GType type);

vips_type_find ()

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

vips_nickname_find ()

const char *
vips_nickname_find (GType type);

Return the VIPS nickanme for a GType. Handy for language bindings.

Parameters

type

GType to search for

Returns

the class nickname.

[transfer none]

vips_class_map_all ()

void *
vips_class_map_all (GType type,
                    VipsClassMapFn fn,
                    void *a);

Loop over all the subclasses of type . Non-abstract classes only. Stop when fn returns non-NULL and return that value.

Parameters

type	base type
fn	call this function for every type
a	client data

Returns

NULL if fn returns NULL for all arguments, otherwise the first non-NULL value from fn .

vips_class_find ()

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

Search below basename, return the first class whose name or nickname matches.

Parameters

basename	name of base class
nickname	search for a class with this nickname

Returns

the found class.

vips_object_local_array ()

VipsObject **
vips_object_local_array (VipsObject *parent,
                         int n);

Make an array of NULL VipsObject pointers. When parent closes, every non-NULL pointer in the array will be unreffed and the array will be freed. Handy for creating a set of temporary images for a function.

The array is NULL-terminated, ie. contains an extra NULL element at the end.

Example:

VipsObject **t;

t = vips_object_local_array( a, 5 );
if( 
  vips_add( a, b, &t[0], NULL ) ||
  vips_invert( t[0], &t[1], NULL ) ||
  vips_add( t[1], t[0], &t[2], NULL ) ||
  vips_costra( t[2], out, NULL ) )
  return( -1 );

Parameters

parent	objects unref when this object unrefs
n	array size

Returns

an array of NULL pointers of length n

vips_object_local_cb ()

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

vips_object_local()

#define             vips_object_local( V, G )

vips_object_set_static ()

void
vips_object_set_static (VipsObject *object,
                        gboolean static_object);

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);

vips_object_unref_outputs ()

void
vips_object_unref_outputs (VipsObject *object);

Unref all assigned output objects. Useful for language bindings.

After an object is built, all output args are owned by the caller. If something goes wrong before then, we have to unref the outputs that have been made so far. This function can also be useful for callers when they've finished processing outputs themselves.

Parameters

object

object to drop output refs from

vips_object_get_description ()

const char *
vips_object_get_description (VipsObject *object);

Fetch the object description. Useful for language bindings.

object.description is only avaliable after _build(), which can be too late. This function fetches from the instance, if possible, but falls back to the class description if we are too early.

Parameters

object

object to fetch description from

Returns

the object description

Types and Values

enum VipsArgumentFlags

VipsArgumentFlags is deprecated and should not be used in newly-written code.

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_SET_ALWAYS is handy for arguments which are set from C. For example, VipsImage::width is a property that gives access to the Xsize member of struct _VipsImage. We default its 'assigned' to TRUE since the field is always set directly by C.

VIPS_ARGUMENT_DEPRECATED arguments are not shown in help text, are not looked for if required, are not checked for "have-been-set". You can deprecate a required argument, but you must obviously add a new required argument if you do.

Input args with VIPS_ARGUMENT_MODIFY will be modified by the operation. This is used for things like the in-place drawing operations.

Members

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_SET_ALWAYS	don't do use-before-set checks
VIPS_ARGUMENT_INPUT	is an input argument (one we depend on)
VIPS_ARGUMENT_OUTPUT	is an output argument (depends on us)
VIPS_ARGUMENT_DEPRECATED	just there for back-compat, hide
VIPS_ARGUMENT_MODIFY	the input argument will be modified

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

VIPS_ARGUMENT_OPTIONAL_OUTPUT

#define             VIPS_ARGUMENT_OPTIONAL_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;
	int priority;		/* Order args by this */
	guint offset;		/* G_STRUCT_OFFSET of member in object */
} VipsArgumentClass;

VipsArgumentInstance

typedef struct {
	VipsArgument parent;

	/* The class we are part of.
	 */
	VipsArgumentClass *argument_class;

	/* 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;	

	/* We need to listen for "invalidate" on input images and send our own
	 * "invalidate" out. If we go, we need to disconnect.
	 */
	gulong invalidate_id;
} VipsArgumentInstance;

VipsArgumentTable

typedef GHashTable VipsArgumentTable;

VIPS_ARGUMENT_COLLECT_END

#define             VIPS_ARGUMENT_COLLECT_END

Property Details

The `“description”` property

  “description”              gchar *

Class description.

Flags: Read / Write

Default value: ""

The `“nickname”` property

  “nickname”                 gchar *

Class nickname.

Flags: Read / Write

Default value: ""

Signal Details

The `“close”` signal

void
user_function (VipsObject *object,
               gpointer    user_data)

The ::close signal is emitted once during object close. The object is dying and may not work.

Parameters

object	the object that is closing
user_data	user data set when the signal handler was connected.

Flags: Run Last

The `“postbuild”` signal

gint
user_function (VipsObject *object,
               gpointer    user_data)

The ::postbuild signal is emitted once just after successful object construction. Return non-zero to cause object construction to fail.

Parameters

object	the object that has been built
user_data	user data set when the signal handler was connected.

Flags: Run Last

The `“postclose”` signal

void
user_function (VipsObject *object,
               gpointer    user_data)

The ::postclose signal is emitted once after object close. The object pointer is still valid, but nothing else.

Parameters

object	the object that has closed
user_data	user data set when the signal handler was connected.

Flags: Run Last

The `“preclose”` signal

void
user_function (VipsObject *object,
               gpointer    user_data)

The ::preclose signal is emitted once just before object close starts. The oject is still alive.

Parameters

object	the object that is to close
user_data	user data set when the signal handler was connected.

Flags: Run Last