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VIPS maintains an error buffer (a log of localised text messages), a set of functions for adding messages, and a way to access and clear the buffer.
The error buffer is global, that is, it is shared between all threads. You can add to the buffer from any thread (there is a lock to prevent corruption), but it's sensible to only read and clear the buffer from the main thread of execution.
The general principle is: if you detect an error, log a message for the user. If a function you call detects an error, just propogate it and don't add another message.
IMAGE *im; if( !(im = vips_image_new_from_file( filename, NULL )) ) // vips_image_new_from_file() will set a message, we don't need to return( -1 ); if( vips_image_get_width( im ) < 100 ) { // we have detected an error, we must set a message vips_error( "myprogram", "%s", _( "width too small" ) ); return( -1 ); }
The domain argument most of these functions take is not localised and is supposed to indicate the component which failed.
const char *
vips_error_buffer (void
);
Get a pointer to the start of the error buffer as a C string. The string is owned by the error system and must not be freed.
See also: vips_error_clear()
.
void
vips_error_clear (void
);
Clear and reset the error buffer. This is typically called after presenting an error to the user.
See also: vips_error_buffer()
.
void
vips_error_freeze (void
);
Stop errors being logged. Use vips_error_thaw()
to unfreeze. You can
nest freeze/thaw pairs.
void vips_error (const char *domain
,const char *fmt
,...
);
Format the string in the style of printf()
and append to the error buffer.
See also: vips_error_system()
, vips_verror()
.
void vips_verror (const char *domain
,const char *fmt
,va_list ap
);
Append a message to the error buffer.
See also: vips_error()
.
void vips_error_system (int err
,const char *domain
,const char *fmt
,...
);
Format the string in the style of printf()
and append to the error buffer.
Then create and append a localised message based on the system error code,
usually the value of errno.
See also: vips_verror_system()
.
void vips_verror_system (int err
,const char *domain
,const char *fmt
,va_list ap
);
Format the string in the style of printf()
and append to the error buffer.
Then create and append a localised message based on the system error code,
usually the value of errno.
See also: vips_error_system()
.
void
vips_error_g (GError **error
);
This function sets the glib error pointer from the vips error buffer and clears it. It's handy for returning errors to glib functions from vips.
See vips_g_error()
for the inverse operation.
See also: g_set_error()
, vips_g_error()
.
void
vips_g_error (GError **error
);
This function adds the GError
to the vips error buffer and clears it. It's
the opposite of vips_error_g()
.
See also: vips_error_g()
.
void vips_warn (const char *domain
,const char *fmt
,...
);
Sends a formatted warning message to stderr. If you define the environment variable IM_WARNING, these message are surpressed.
Warning messages are used to report things like overflow counts.
See also: vips_info()
, vips_vwarn()
.
void vips_vwarn (const char *domain
,const char *fmt
,va_list ap
);
Sends a formatted warning message to stderr. If you define the environment variable VIPS_WARNING, these message are surpressed.
Warning messages are used to report things like overflow counts.
See also: vips_info()
, vips_warn()
.
void vips_info (const char *domain
,const char *fmt
,...
);
Sends a formatted informational message to stderr if the --vips-info flag has been given to the program or the environment variable IM_INFO has been defined.
Informational messages are used to report details about the operation of functions.
See also: vips_vinfo()
, vips_warn()
.
void vips_vinfo (const char *domain
,const char *fmt
,va_list ap
);
Sends a formatted informational message to stderr if the --vips-info flag has been given to the program or the environment variable IM_INFO has been defined.
Informational messages are used to report details about the operation of functions.
See also: vips_info()
, vips_warn()
.
void vips_error_exit (const char *fmt
,...
);
Sends a formatted error message to stderr, then sends the contents of the error buffer, if any, then shuts down vips and terminates the program with an error code.
fmt
may be NULL
, in which case only the error buffer is printed before
exiting.
See also: vips_error()
.
int vips_check_uncoded (const char *domain
,VipsImage *im
);
Check that the image is not coded. If not, set an error message and return non-zero.
See also: vips_error()
.
int vips_check_coding (const char *domain
,VipsImage *im
,VipsCoding coding
);
Check that the image has the required coding
.
If not, set an error message
and return non-zero.
See also: vips_error()
.
int vips_check_coding_known (const char *domain
,VipsImage *im
);
Check that the image is uncoded, LABQ coded or RAD coded. If not, set an error message and return non-zero.
See also: vips_error()
.
int vips_check_coding_noneorlabq (const char *domain
,VipsImage *im
);
Check that the image is uncoded or LABQ coded. If not, set an error message and return non-zero.
See also: vips_error()
.
int vips_check_coding_same (const char *domain
,VipsImage *im1
,VipsImage *im2
);
Check that the images have the same coding. If not, set an error message and return non-zero.
See also: vips_error()
.
int vips_check_mono (const char *domain
,VipsImage *im
);
Check that the image has exactly one band. Otherwise set an error message and return non-zero.
See also: vips_error()
.
int vips_check_bands (const char *domain
,VipsImage *im
,int bands
);
Check that the image has bands
bands.
Otherwise set an error message
and return non-zero.
See also: vips_error()
.
int vips_check_bands_1or3 (const char *domain
,VipsImage *im
);
Check that the image has either one or three bands. Otherwise set an error message and return non-zero.
See also: vips_error()
.
int vips_check_bands_atleast (const char *domain
,VipsImage *im
,int bands
);
Check that the image has at least bands
bands.
Otherwise set an error message
and return non-zero.
See also: vips_error()
.
int vips_check_bands_1orn (const char *domain
,VipsImage *im1
,VipsImage *im2
);
Check that the images have the same number of bands, or that one of the images has just 1 band. If not, set an error message and return non-zero.
See also: vips_error()
.
int vips_check_bands_1orn_unary (const char *domain
,VipsImage *im
,int n
);
Check that an image has 1 or n
bands. Handy for unary operations, cf.
vips_check_bands_1orn()
.
If not, set an error message
and return non-zero.
See also: vips_check_bands_1orn()
.
int vips_check_bands_same (const char *domain
,VipsImage *im1
,VipsImage *im2
);
Check that the images have the same number of bands. If not, set an error message and return non-zero.
See also: vips_error()
.
int vips_check_bandno (const char *domain
,VipsImage *im
,int bandno
);
bandno
should be a valid band number (ie. 0 to im->Bands - 1), or can be
-1, meaning all bands.
If not, set an error message
and return non-zero.
See also: vips_error()
.
int vips_check_int (const char *domain
,VipsImage *im
);
Check that the image is in one of the integer formats. Otherwise set an error message and return non-zero.
See also: vips_error()
.
int vips_check_uint (const char *domain
,VipsImage *im
);
Check that the image is in one of the unsigned integer formats. Otherwise set an error message and return non-zero.
See also: vips_error()
.
int vips_check_uintorf (const char *domain
,VipsImage *im
);
Check that the image is unsigned int or float. Otherwise set an error message and return non-zero.
See also: vips_error()
.
int vips_check_noncomplex (const char *domain
,VipsImage *im
);
Check that the image is not complex. Otherwise set an error message and return non-zero.
See also: vips_error()
.
int vips_check_complex (const char *domain
,VipsImage *im
);
Check that the image is complex. Otherwise set an error message and return non-zero.
See also: vips_error()
.
int vips_check_format (const char *domain
,VipsImage *im
,VipsBandFormat fmt
);
Check that the image has the specified format. Otherwise set an error message and return non-zero.
See also: vips_error()
.
int vips_check_u8or16 (const char *domain
,VipsImage *im
);
Check that the image is 8 or 16-bit unsigned integer. Otherwise set an error message and return non-zero.
See also: vips_error()
.
int vips_check_8or16 (const char *domain
,VipsImage *im
);
Check that the image is 8 or 16-bit integer, signed or unsigned. Otherwise set an error message and return non-zero.
See also: vips_error()
.
int vips_check_u8or16orf (const char *domain
,VipsImage *im
);
Check that the image is 8 or 16-bit unsigned integer, or float. Otherwise set an error message and return non-zero.
See also: vips_error()
.
int vips_check_format_same (const char *domain
,VipsImage *im1
,VipsImage *im2
);
Check that the images have the same format. If not, set an error message and return non-zero.
See also: vips_error()
.
int vips_check_size_same (const char *domain
,VipsImage *im1
,VipsImage *im2
);
Check that the images have the same size. If not, set an error message and return non-zero.
See also: vips_error()
.
int vips_check_oddsquare (const char *domain
,VipsImage *im
);
Check that the image is square and that the sides are odd. If not, set an error message and return non-zero.
See also: vips_error()
.
int vips_check_vector_length (const char *domain
,int n
,int len
);
Check that n
== len
.
See also: vips_error()
.
int vips_check_vector (const char *domain
,int n
,VipsImage *im
);
Operations with a vector constant need a 1-element vector, or a vector with the same number of elements as there are bands in the image.
See also: vips_error()
.
int vips_check_hist (const char *domain
,VipsImage *im
);
Histogram images must have width or height 1, and must not have more than 65536 elements. Return 0 if the image will pass as a histogram, or -1 and set an error message otherwise.
See also: vips_error()
.
int vips_check_matrix (const char *domain
,VipsImage *im
,VipsImage **out
);
Matrix images must have width and height less than 100000 and have 1 band.
Return 0 if the image will pass as a matrix, or -1 and set an error message otherwise.
out
is set to be im
cast to double and stored in memory. Use
VIPS_MATRIX()
to address values in out
.
You must unref out
when you are done with it.
See also: VIPS_MATRIX()
, vips_object_local()
int vips_check_separable (const char *domain
,VipsImage *im
);
Separable matrix images must have width or height 1. Return 0 if the image will pass, or -1 and set an error message otherwise.
See also: vips_error()
.
int vips_check_precision_intfloat (const char *domain
,VipsPrecision precision
);
Check that prec
image is either float or int.
If not, set an error message
and return non-zero.
See also: vips_error()
.