libvips

vips_format_sizeof ()

guint64
vips_format_sizeof (VipsBandFormat format);

vips_format_sizeof_unsafe ()

guint64
vips_format_sizeof_unsafe (VipsBandFormat format);

A fast but dangerous version of vips_format_sizeof(). You must have previously range-checked format or you'll crash.

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vips_image_get_width ()

int
vips_image_get_width (const VipsImage *image);

[method]

vips_image_get_height ()

int
vips_image_get_height (const VipsImage *image);

[method]

vips_image_get_bands ()

int
vips_image_get_bands (const VipsImage *image);

[method]

vips_image_get_format ()

VipsBandFormat
vips_image_get_format (const VipsImage *image);

[method]

vips_image_guess_format ()

VipsBandFormat
vips_image_guess_format (const VipsImage *image);

Return the VipsBandFormat for an image, guessing a sane value if the set value looks crazy.

For example, for a float image tagged as rgb16, we'd return ushort.

[method]

vips_image_get_coding ()

VipsCoding
vips_image_get_coding (const VipsImage *image);

[method]

vips_image_get_interpretation ()

VipsInterpretation
vips_image_get_interpretation (const VipsImage *image);

Return the VipsInterpretation set in the image header. Use vips_image_guess_interpretation() if you want a sanity-checked value.

[method]

vips_image_guess_interpretation ()

VipsInterpretation
vips_image_guess_interpretation (const VipsImage *image);

Return the VipsInterpretation for an image, guessing a sane value if the set value looks crazy.

[method]

vips_image_get_xres ()

double
vips_image_get_xres (const VipsImage *image);

[method]

vips_image_get_yres ()

double
vips_image_get_yres (const VipsImage *image);

[method]

vips_image_get_xoffset ()

int
vips_image_get_xoffset (const VipsImage *image);

[method]

vips_image_get_yoffset ()

int
vips_image_get_yoffset (const VipsImage *image);

[method]

vips_image_get_filename ()

const char *
vips_image_get_filename (const VipsImage *image);

[method]

vips_image_get_mode ()

const char *
vips_image_get_mode (const VipsImage *image);

Image modes are things like "t", meaning a memory buffer, and "p" meaning a delayed computation.

[method]

vips_image_get_scale ()

double
vips_image_get_scale (const VipsImage *image);

Matrix images can have an optional scale field for use by integer convolution.

[method]

vips_image_get_offset ()

double
vips_image_get_offset (const VipsImage *image);

Matrix images can have an optional offset field for use by integer convolution.

[method]

vips_image_get_data ()

const void *
vips_image_get_data (VipsImage *image);

Return a pointer to the image's pixel data, if possible. This can involve allocating large amounts of memory and performing a long computation. Image pixels are laid out in band-packed rows.

Since this function modifies image , it is not threadsafe. Only call it on images which you are sure have not been shared with another thread.

See also: vips_image_wio_input(), vips_image_copy_memory().

[method]

vips_image_init_fields ()

void
vips_image_init_fields (VipsImage *image,
                        int xsize,
                        int ysize,
                        int bands,
                        VipsBandFormat format,
                        VipsCoding coding,
                        VipsInterpretation interpretation,
                        double xres,
                        double yres);

A convenience function to set the header fields after creating an image. Normally you copy the fields from your input images with vips_image_pipelinev() and then make any adjustments you need, but if you are creating an image from scratch, for example vips_black() or vips_jpegload(), you do need to set all the fields yourself.

See also: vips_image_pipelinev().

[method]

vips_image_set ()

void
vips_image_set (VipsImage *image,
                const char *name,
                GValue *value);

Set a piece of metadata on image . Any old metadata with that name is destroyed. The GValue is copied into the image, so you need to unset the value when you're done with it.

For example, to set an integer on an image (though you would use the convenience function vips_image_set_int() in practice), you would do:

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GValue value = { 0 };

g_value_init (&value, G_TYPE_INT);
g_value_set_int (&value, 42);
vips_image_set (image, name, &value);
g_value_unset (&value);

See also: vips_image_get().

[method]

vips_image_get ()

int
vips_image_get (const VipsImage *image,
                const char *name,
                GValue *value_copy);

Fill value_copy with a copy of the header field. value_copy must be zeroed but uninitialised.

This will return -1 and add a message to the error buffer if the field does not exist. Use vips_image_get_typeof() to test for the existence of a field first if you are not certain it will be there.

For example, to read a double from an image (though of course you would use vips_image_get_double() in practice):

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GValue value = { 0 };
double d;

if (vips_image_get (image, name, &value))
  return -1;

if (G_VALUE_TYPE (&value) != G_TYPE_DOUBLE) {
  vips_error( "mydomain", 
    _("field \"%s\" is of type %s, not double"),
    name, 
    g_type_name (G_VALUE_TYPE (&value)));
  g_value_unset (&value);
  return -1;
}

d = g_value_get_double (&value);
g_value_unset (&value);

See also: vips_image_get_typeof(), vips_image_get_double().

[method]

vips_image_get_as_string ()

int
vips_image_get_as_string (const VipsImage *image,
                          const char *name,
                          char **out);

Returns name from image in out . This function will read any field, returning it as a printable string. You need to free the string with g_free() when you are done with it.

This will base64-encode BLOBs, for example. Use vips_buf_appendgv() to make a string that's for humans.

See also: vips_image_get(), vips_image_get_typeof(), vips_buf_appendgv().

[method]

vips_image_get_typeof ()

GType
vips_image_get_typeof (const VipsImage *image,
                       const char *name);

Read the GType for a header field. Returns zero if there is no field of that name.

See also: vips_image_get().

[method]

vips_image_remove ()

gboolean
vips_image_remove (VipsImage *image,
                   const char *name);

Find and remove an item of metadata. Return FALSE if no metadata of that name was found.

See also: vips_image_set(), vips_image_get_typeof().

[method]

VipsImageMapFn ()

void *
(*VipsImageMapFn) (VipsImage *image,
                   const char *name,
                   GValue *value,
                   void *a);

vips_image_map ()

void *
vips_image_map (VipsImage *image,
                VipsImageMapFn fn,
                void *a);

This function calls fn for every header field, including every item of metadata.

Like all _map functions, the user function should return NULL to continue iteration, or a non-NULL pointer to indicate early termination.

See also: vips_image_get_typeof(), vips_image_get().

[method]

vips_image_get_fields ()

gchar **
vips_image_get_fields (VipsImage *image);

Get a NULL-terminated array listing all the metadata field names on image . Free the return result with g_strfreev().

This is handy for language bindings. From C, it's usually more convenient to use vips_image_map().

[method]

vips_image_set_area ()

void
vips_image_set_area (VipsImage *image,
                     const char *name,
                     VipsCallbackFn free_fn,
                     void *data);

Attaches data as a metadata item on image under the name name . When VIPS no longer needs the metadata, it will be freed with free_fn .

See also: vips_image_get_double(), vips_image_set()

[method]

vips_image_get_area ()

int
vips_image_get_area (const VipsImage *image,
                     const char *name,
                     void **data);

Gets data from image under the name name . A convenience function over vips_image_get(). Use vips_image_get_typeof() to test for the existance of a piece of metadata.

See also: vips_image_set_area(), vips_image_get(), vips_image_get_typeof()

[method]

vips_image_set_blob ()

void
vips_image_set_blob (VipsImage *image,
                     const char *name,
                     VipsCallbackFn free_fn,
                     void *data,
                     size_t length);

Attaches blob as a metadata item on image under the name name . A convenience function over vips_image_set() using a vips_blob.

See also: vips_image_get_blob(), vips_image_set().

[method]

vips_image_get_blob ()

int
vips_image_get_blob (const VipsImage *image,
                     const char *name,
                     void **data,
                     size_t *length);

Gets blob from image under the name name , optionally returns its length in length . A convenience function over vips_image_get(). Use vips_image_get_typeof() to test for the existance of a piece of metadata.

See also: vips_image_get(), vips_image_get_typeof(), vips_blob_get(),

[method]

vips_image_get_int ()

int
vips_image_get_int (const VipsImage *image,
                    const char *name,
                    int *out);

Gets out from im under the name name . The value will be transformed into an int, if possible.

See also: vips_image_get(), vips_image_get_typeof()

[method]

vips_image_set_int ()

void
vips_image_set_int (VipsImage *image,
                    const char *name,
                    int i);

Attaches i as a metadata item on image under the name name . A convenience function over vips_image_set().

See also: vips_image_get_int(), vips_image_set()

[method]

vips_image_get_double ()

int
vips_image_get_double (const VipsImage *image,
                       const char *name,
                       double *out);

Gets out from im under the name name . The value will be transformed into a double, if possible.

See also: vips_image_get(), vips_image_get_typeof()

[method]

vips_image_set_double ()

void
vips_image_set_double (VipsImage *image,
                       const char *name,
                       double d);

Attaches d as a metadata item on image as name . A convenience function over vips_image_set().

See also: vips_image_get_double(), vips_image_set()

[method]

vips_image_get_string ()

int
vips_image_get_string (const VipsImage *image,
                       const char *name,
                       const char **out);

Gets out from im under the name name . The field must be of type VIPS_TYPE_REFSTRING.

Do not free out .

Use vips_image_get_as_string() to fetch any field as a string.

See also: vips_image_get(), vips_image_get_typeof()

[method]

vips_image_set_string ()

void
vips_image_set_string (VipsImage *image,
                       const char *name,
                       const char *str);

Attaches str as a metadata item on image as name . A convenience function over vips_image_set() using an vips_ref_string.

See also: vips_image_get_double(), vips_image_set(), vips_ref_string

[method]

vips_image_print_field ()

void
vips_image_print_field (const VipsImage *image,
                        const char *field);

Prints field name to stdout as ASCII. Handy for debugging.

[method]

vips_image_history_printf ()

int
vips_image_history_printf (VipsImage *image,
                           const char *format,
                           ...);

Add a line to the image history. The format and arguments are expanded, the date and time is appended prefixed with a hash character, and the whole string is appended to the image history and terminated with a newline.

For example:

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vips_image_history_printf (image, "vips invert %s %s", 
  in->filename, out->filename);

Might add the string

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"vips invert /home/john/fred.v /home/john/jim.v # Fri Apr 3 23:30:35 2009\n"

VIPS operations don't add history lines for you because a single action at the application level might involve many VIPS operations. History must be recorded by the application.

[method]

vips_image_history_args ()

int
vips_image_history_args (VipsImage *image,
                         const char *name,
                         int argc,
                         char *argv[]);

Formats the name/argv as a single string and calls vips_image_history_printf(). A convenience function for command-line prorams.

See also: vips_image_get_history().

[method]

vips_image_get_history ()

const char *
vips_image_get_history (VipsImage *image);

This function reads the image history as a C string. The string is owned by VIPS and must not be freed.

VIPS tracks the history of each image, that is, the sequence of operations that generated that image. Applications built on VIPS need to call vips_image_history_printf() for each action they perform, setting the command-line equivalent for the action.

See also: vips_image_history_printf().

[method]

VIPS_META_EXIF_NAME

#define VIPS_META_EXIF_NAME "exif-data"

The name that JPEG read and write operations use for the image's EXIF data.

VIPS_META_XMP_NAME

#define VIPS_META_XMP_NAME "xmp-data"

The name that read and write operations use for the image's XMP data.

VIPS_META_IPTC_NAME

#define VIPS_META_IPTC_NAME "iptc-data"

The name that read and write operations use for the image's IPTC data.

VIPS_META_PHOTOSHOP_NAME

#define VIPS_META_PHOTOSHOP_NAME "photoshop-data"

The name that TIFF read and write operations use for the image's TIFFTAG_PHOTOSHOP data.

VIPS_META_ICC_NAME

#define VIPS_META_ICC_NAME "icc-profile-data"

The name we use to attach an ICC profile. The file read and write operations for TIFF, JPEG, PNG and others use this item of metadata to attach and save ICC profiles. The profile is updated by the vips_icc_transform() operations.

VIPS_META_IMAGEDESCRIPTION

#define VIPS_META_IMAGEDESCRIPTION "image-description"

The IMAGEDESCRIPTION tag. Often has useful metadata.

VIPS_META_RESOLUTION_UNIT

#define VIPS_META_RESOLUTION_UNIT "resolution-unit"

The JPEG and TIFF read and write operations use this to record the file's preferred unit for resolution.

VIPS_META_LOADER

#define VIPS_META_LOADER "vips-loader"

Record the name of the original loader here. Handy for hinting file formats and for debugging.

VIPS_META_SEQUENTIAL

#define VIPS_META_SEQUENTIAL "vips-sequential"

Images loaded via vips_sequential() have this int field defined. Some operations (eg. vips_shrinkv()) add extra caches if they see it on their input.

VIPS_META_ORIENTATION

#define VIPS_META_ORIENTATION "orientation"

The orientation tag for this image. An int from 1 - 8 using the standard exif/tiff meanings.

VIPS_META_PAGE_HEIGHT

#define VIPS_META_PAGE_HEIGHT "page-height"

If set, the height of each page when this image was loaded. If you save an image with "page-height" set to a format that supports multiple pages, such as tiff, the image will be saved as a series of pages.