basic: libvips Reference Manual

basic

basic — a few typedefs used everywhere

Stability Level

Stable, unless otherwise indicated

Functions

int	(*VipsCallbackFn) ()
void *	(*VipsSListMap2Fn) ()
void *	(*VipsSListMap4Fn) ()
void *	(*VipsSListFold2Fn) ()
char *	vips_path_filename7 ()
char *	vips_path_mode7 ()

Properties

gint	bands	Read / Write
VipsCoding	coding	Read / Write
VipsDemandStyle	demand	Read / Write
gchar *	filename	Read / Write
gpointer	foreign-buffer	Read / Write
VipsBandFormat	format	Read / Write
gint	height	Read / Write
VipsInterpretation	interpretation	Read / Write
gboolean	kill	Read / Write
gchar *	mode	Read / Write
guint64	sizeof-header	Read / Write
gint	width	Read / Write
gint	xoffset	Read / Write
gdouble	xres	Read / Write
gint	yoffset	Read / Write
gdouble	yres	Read / Write

Signals

void	eval	Run Last
void	invalidate	Action
void	minimise	Action
void	posteval	Run Last
void	preeval	Run Last
void	written	Action

Types and Values

typedef	VipsPel
enum	VipsPrecision
	VipsImage
	VipsRegion

Object Hierarchy

    GObject
    ╰── VipsObject
        ├── VipsImage
        ╰── VipsRegion

Includes

#include <vips/vips.h>

Description

A few simple typedefs used by VIPS.

Functions

VipsCallbackFn ()

int
(*VipsCallbackFn) (void *a,
                   void *b);

VipsSListMap2Fn ()

void *
(*VipsSListMap2Fn) (void *item,
                    void *a,
                    void *b);

VipsSListMap4Fn ()

void *
(*VipsSListMap4Fn) (void *item,
                    void *a,
                    void *b,
                    void *c,
                    void *d);

VipsSListFold2Fn ()

void *
(*VipsSListFold2Fn) (void *item,
                     void *a,
                     void *b,
                     void *c);

vips_path_filename7 ()

char *
vips_path_filename7 (const char *path);

Return the filename part of a vips7 path. For testing only.

Parameters

path

path to split

vips_path_mode7 ()

char *
vips_path_mode7 (const char *path);

Return the mode part of a vips7 path. For testing only.

Parameters

path

path to split

Types and Values

VipsPel

typedef unsigned char VipsPel;

A picture element. Cast this to whatever the associated VipsBandFormat says to get the value.

enum VipsPrecision

How accurate an operation should be.

Members

VIPS_PRECISION_INTEGER	int everywhere
VIPS_PRECISION_FLOAT	float everywhere
VIPS_PRECISION_APPROXIMATE	approximate integer output
VIPS_PRECISION_LAST

VipsImage

typedef struct _VipsImage VipsImage;

An image. These can represent an image on disc, a memory buffer, an image in the process of being written to disc or a partially evaluated image in memory.

VipsRegion

typedef struct {
	/* Users may read these two fields.
	 */
	VipsImage *im;		/* Link back to parent image */
	VipsRect valid;		/* Area of parent we can see */

	/* The rest of VipsRegion is private.
	 */
} VipsRegion;

A small part of a VipsImage. valid holds the left/top/width/height of the area of pixels that are available from the region.

Members

VipsImage *`im`;	the VipsImage that this region is defined on
VipsRect `valid`;	the VipsRect of pixels that this region represents

Property Details

The `“bands”` property

  “bands”                    gint

Number of bands in image.

Owner: VipsImage

Flags: Read / Write

Allowed values: [1,10000000]

Default value: 1

The `“coding”` property

  “coding”                   VipsCoding

Pixel coding.

Owner: VipsImage

Flags: Read / Write

Default value: VIPS_CODING_NONE

The `“demand”` property

  “demand”                   VipsDemandStyle

Preferred demand style for this image.

Owner: VipsImage

Flags: Read / Write

Default value: VIPS_DEMAND_STYLE_SMALLTILE

The `“filename”` property

  “filename”                 gchar *

Image filename.

Owner: VipsImage

Flags: Read / Write

Default value: NULL

The `“foreign-buffer”` property

  “foreign-buffer”           gpointer

Pointer to foreign pixels.

Owner: VipsImage

Flags: Read / Write

The `“format”` property

  “format”                   VipsBandFormat

Pixel format in image.

Owner: VipsImage

Flags: Read / Write

Default value: VIPS_FORMAT_UCHAR

The `“height”` property

  “height”                   gint

Image height in pixels.

Owner: VipsImage

Flags: Read / Write

Allowed values: [1,10000000]

Default value: 1

The `“interpretation”` property

  “interpretation”           VipsInterpretation

Pixel interpretation.

Owner: VipsImage

Flags: Read / Write

Default value: VIPS_INTERPRETATION_MULTIBAND

The `“kill”` property

  “kill”                     gboolean

Block evaluation on this image.

Owner: VipsImage

Flags: Read / Write

Default value: FALSE

The `“mode”` property

  “mode”                     gchar *

Open mode.

Owner: VipsImage

Flags: Read / Write

Default value: "p"

The `“sizeof-header”` property

  “sizeof-header”            guint64

Offset in bytes from start of file.

Owner: VipsImage

Flags: Read / Write

Allowed values: <= 1000000000

Default value: 64

The `“width”` property

  “width”                    gint

Image width in pixels.

Owner: VipsImage

Flags: Read / Write

Allowed values: [1,10000000]

Default value: 1

The `“xoffset”` property

  “xoffset”                  gint

Horizontal offset of origin.

Owner: VipsImage

Flags: Read / Write

Allowed values: [-10000000,10000000]

Default value: 0

The `“xres”` property

  “xres”                     gdouble

Horizontal resolution in pixels/mm.

Owner: VipsImage

Flags: Read / Write

Allowed values: [-0,1e+06]

Default value: 0

The `“yoffset”` property

  “yoffset”                  gint

Vertical offset of origin.

Owner: VipsImage

Flags: Read / Write

Allowed values: [-10000000,10000000]

Default value: 0

The `“yres”` property

  “yres”                     gdouble

Vertical resolution in pixels/mm.

Owner: VipsImage

Flags: Read / Write

Allowed values: [-0,1e+06]

Default value: 0

Signal Details

The `“eval”` signal

void
user_function (VipsImage *image,
               gpointer   progress,
               gpointer   user_data)

The ::eval signal is emitted once per work unit (typically a 128 x 128 area of pixels) during image computation.

You can use this signal to update user-interfaces with progress feedback. Beware of updating too frequently: you will usually need some throttling mechanism.

Use vips_image_set_progress() to turn on progress reporting for an image.

Parameters

image	the image being calculated
progress	VipsProgress for this image
user_data	user data set when the signal handler was connected.

Flags: Run Last

The `“invalidate”` signal

void
user_function (VipsImage *image,
               gpointer   user_data)

The ::invalidate signal is emitted when an image or one of it's upstream data sources has been destructively modified. See vips_image_invalidate_all().

Parameters

image	the image that has changed
user_data	user data set when the signal handler was connected.

Flags: Action

The `“minimise”` signal

void
user_function (VipsImage *image,
               gpointer   user_data)

The ::minimise signal is emitted when an image has been asked to minimise memory usage. All non-essential caches are dropped. See vips_image_minimise_all().

Parameters

image	the image that is being minimised
user_data	user data set when the signal handler was connected.

Flags: Action

The `“posteval”` signal

void
user_function (VipsImage *image,
               gpointer   progress,
               gpointer   user_data)

The ::posteval signal is emitted once at the end of the computation of image . It's a good place to shut down evaluation feedback.

Use vips_image_set_progress() to turn on progress reporting for an image.

Parameters

image	the image that was calculated
progress	VipsProgress for this image
user_data	user data set when the signal handler was connected.

Flags: Run Last

The `“preeval”` signal

void
user_function (VipsImage *image,
               gpointer   progress,
               gpointer   user_data)

The ::preeval signal is emitted once before computation of image starts. It's a good place to set up evaluation feedback.

Use vips_image_set_progress() to turn on progress reporting for an image.

Parameters

image	the image to be calculated
progress	VipsProgress for this image
user_data	user data set when the signal handler was connected.

Flags: Run Last

The `“written”` signal

void
user_function (VipsImage *image,
               gpointer   result,
               gpointer   user_data)

The ::written signal is emitted just after an image has been written to. It is used by vips to implement things like write to foreign file formats.

Parameters

image	the image that was calculated
result	set to non-zero to indicate error
user_data	user data set when the signal handler was connected.

Flags: Action

basic

Stability Level

Functions

Properties

Signals

Types and Values

Object Hierarchy

Includes

Description

Functions

VipsCallbackFn ()

VipsSListMap2Fn ()

VipsSListMap4Fn ()

VipsSListFold2Fn ()

vips_path_filename7 ()

Parameters

vips_path_mode7 ()

Parameters

Types and Values

VipsPel

enum VipsPrecision

Members

VipsImage

VipsRegion

Members

Property Details

The “bands” property

The “coding” property

The “demand” property

The “filename” property

The “foreign-buffer” property

The “format” property

The “height” property

The “interpretation” property

The “kill” property

The “mode” property

The “sizeof-header” property

The “width” property

The “xoffset” property

The “xres” property

The “yoffset” property

The “yres” property

Signal Details

The “eval” signal

Parameters

The “invalidate” signal

Parameters

The “minimise” signal

Parameters

The “posteval” signal

Parameters

The “preeval” signal

Parameters

The “written” signal

Parameters

The `“bands”` property

The `“coding”` property

The `“demand”` property

The `“filename”` property

The `“foreign-buffer”` property

The `“format”` property

The `“height”` property

The `“interpretation”` property

The `“kill”` property

The `“mode”` property

The `“sizeof-header”` property

The `“width”` property

The `“xoffset”` property

The `“xres”` property

The `“yoffset”` property

The `“yres”` property

The `“eval”` signal

The `“invalidate”` signal

The `“minimise”` signal

The `“posteval”` signal

The `“preeval”` signal

The `“written”` signal