generate

generate — calculate pixels and pixel buffers

Stability Level

Stable, unless otherwise indicated

Synopsis

#include <vips/vips.h>

void *              (*VipsStartFn)                      (VipsImage *out,
                                                         void *a,
                                                         void *b);
int                 (*VipsGenerateFn)                   (VipsRegion *out,
                                                         void *seq,
                                                         void *a,
                                                         void *b);
int                 (*VipsStopFn)                       (void *seq,
                                                         void *a,
                                                         void *b);
void *              vips_start_one                      (VipsImage *out,
                                                         void *a,
                                                         void *b);
int                 vips_stop_one                       (void *seq,
                                                         void *a,
                                                         void *b);
void *              vips_start_many                     (VipsImage *out,
                                                         void *a,
                                                         void *b);
int                 vips_stop_many                      (void *seq,
                                                         void *a,
                                                         void *b);
VipsImage **        vips_allocate_input_array           (VipsImage *out,
                                                         ...);
int                 vips_image_generate                 (VipsImage *im,
                                                         VipsStartFn start,
                                                         VipsGenerateFn generate,
                                                         VipsStopFn stop,
                                                         void *a,
                                                         void *b);
int                 vips_demand_hint_array              (VipsImage *image,
                                                         VipsDemandStyle hint,
                                                         VipsImage **in);
int                 vips_demand_hint                    (VipsImage *image,
                                                         VipsDemandStyle hint,
                                                         ...);

Description

These functions let you generate regions of pixels in an image processing operation, and ask for regions of image to be calculated.

Details

VipsStartFn ()

void *              (*VipsStartFn)                      (VipsImage *out,
                                                         void *a,
                                                         void *b);

Start a new processing sequence for this generate function. This allocates per-thread state, such as an input region.

See also: vips_start_one(), vips_start_many().

image :

image being calculated

a :

user data

b :

user data

Returns :

a new sequence value

VipsGenerateFn ()

int                 (*VipsGenerateFn)                   (VipsRegion *out,
                                                         void *seq,
                                                         void *a,
                                                         void *b);

Fill image->valid with pixels. seq contains per-thread state, such as the input regions.

See also: vips_image_generate(), vips_stop_many().

region :

VipsRegion to fill

seq :

sequence value

a :

user data

b :

user data

Returns :

0 on success, -1 on error.

VipsStopFn ()

int                 (*VipsStopFn)                       (void *seq,
                                                         void *a,
                                                         void *b);

Stop a processing sequence. This frees per-thread state, such as an input region.

See also: vips_stop_one(), vips_stop_many().

seq :

sequence value

a :

user data

b :

user data

Returns :

0 on success, -1 on error.

vips_start_one ()

void *              vips_start_one                      (VipsImage *out,
                                                         void *a,
                                                         void *b);

Start function for one image in. Input image is a.

See also: vips_image_generate().

out :

image to generate

a :

user data

b :

user data

vips_stop_one ()

int                 vips_stop_one                       (void *seq,
                                                         void *a,
                                                         void *b);

Stop function for one image in. Input image is a.

See also: vips_image_generate().

seq :

sequence value

a :

user data

b :

user data

vips_start_many ()

void *              vips_start_many                     (VipsImage *out,
                                                         void *a,
                                                         void *b);

Start function for many images in. a is a pointer to a NULL-terminated array of input images.

See also: vips_image_generate(), vips_allocate_input_array()

out :

image to generate

a :

user data

b :

user data

vips_stop_many ()

int                 vips_stop_many                      (void *seq,
                                                         void *a,
                                                         void *b);

Stop function for many images in. a is a pointer to a NULL-terminated array of input images.

See also: vips_image_generate().

seq :

sequence value

a :

user data

b :

user data

vips_allocate_input_array ()

VipsImage **        vips_allocate_input_array           (VipsImage *out,
                                                         ...);

Convenience function --- make a NULL-terminated array of input images. Use with vips_start_many().

See also: vips_image_generate(), vips_start_many().

image :

free array when this image closes

... :

NULL-terminated list of input images

Returns :

NULL-terminated array of images. Do not free the result.

vips_image_generate ()

int                 vips_image_generate                 (VipsImage *im,
                                                         VipsStartFn start,
                                                         VipsGenerateFn generate,
                                                         VipsStopFn stop,
                                                         void *a,
                                                         void *b);

Generates an image. The action depends on the image type.

For images opened with "p", vips_image_generate() just attaches the start/generate/stop callbacks and returns.

For "t" images, memory is allocated for the whole image and it is entirely generated using vips_sink().

For "w" images, memory for a few scanlines is allocated and vips_sink_disc() used to generate the image in small chunks. As each chunk is generated, it is written to disc.

See also: vips_sink(), vips_image_new(), vips_region_prepare().

image :

generate this image

start :

start sequences with this function

generate :

generate pixels with this function

stop :

stop sequences with this function

a :

user data

b :

user data

Returns :

0 on success, or -1 on error.

vips_demand_hint_array ()

int                 vips_demand_hint_array              (VipsImage *image,
                                                         VipsDemandStyle hint,
                                                         VipsImage **in);

Operations can set demand hints, that is, hints to the VIPS IO system about the type of region geometry this operation works best with. For example, operations which transform coordinates will usually work best with VIPS_DEMAND_STYLE_SMALLTILE, operations which work on local windows of pixels will like VIPS_DEMAND_STYLE_FATSTRIP.

VIPS uses the list of input images to build the tree of operations it needs for the cache invalidation system. You have to call this function, or its varargs friend vips_demand_hint().

See also: vips_demand_hint(), vips_image_generate().

image :

image to set hint for

hint :

hint for this image

in :

array of input images to this operation

Returns :

0 on success, or -1 on error.

vips_demand_hint ()

int                 vips_demand_hint                    (VipsImage *image,
                                                         VipsDemandStyle hint,
                                                         ...);

Build an array and call vips_demand_hint_array().

See also: vips_demand_hint(), vips_image_generate().

image :

image to set hint for

hint :

hint for this image

... :

NULL-terminated list of input images to this operation

Returns :

0 on success, or -1 on error.

See Also

image, region