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This commit is contained in:
John Cupitt 2007-11-09 14:26:41 +00:00
parent 74c0ee0ba8
commit 19c9cccbfc
7 changed files with 69 additions and 90 deletions
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6
TODO
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@ -16,12 +16,6 @@
is there a problem
- update docs, add pages for new cbs
part of im_malloc.3
update nip2 for the new system ... seems to just be imageinfo_progress_add()
- test ppm writer
- missing libstdc++ in link? what if we configure with no openexr?

16
doc/src/iosys.tex
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@ -120,7 +120,7 @@ typedef struct {
/* Derived fields that may be read by the user.
*/
char *filename; /* File name */
struct time_info *time;/* Timing for eval callback */
im_time_t *time; /* Timing for eval callback */
int kill; /* Set to non-zero to block eval */
... and lots of other private fields used by VIPS for
@ -592,13 +592,12 @@ descriptor. The base memory allocation function is \verb+im_malloc()+. It
has type:
\begin{verbatim}
void *im_malloc( IMAGE *im,
size_t size )
void *im_malloc( IMAGE *, size_t )
\end{verbatim}
It operates exactly as the standard \verb+malloc()+ C library function,
except that the area of memory it allocates is local to image descriptor
\verb+im+. If \verb+im_malloc()+ is unable to allocate memory, it returns
except that the area of memory it allocates is local to an image.
If \verb+im_malloc()+ is unable to allocate memory, it returns
\verb+NULL+. If you pass \verb+NULL+ instead of a valid image descriptor,
then \verb+im_malloc()+ allocates memory globally and you must free it
yourself at some stage.
@ -606,7 +605,7 @@ yourself at some stage.
To free memory explicitly, use \verb+im_free()+:
\begin{verbatim}
int im_free( void *mem )
int im_free( void * )
\end{verbatim}
\noindent
@ -618,7 +617,7 @@ a new object. You give it a descriptor and a type, and it returns a pointer
to enough space to hold an object of that type. It has type:
\begin{verbatim}
type-name *IM_NEW( IMAGE *im, type-name )
type-name *IM_NEW( IMAGE *, type-name )
\end{verbatim}
The second macro, \verb+IM_ARRAY()+, is very similar, but allocates
@ -626,8 +625,7 @@ space for an array of objects. Note that, unlike the usual \verb+calloc()+
C library function, it does not initialise the array to zero. It has type:
\begin{verbatim}
type-name *IM_ARRAY( IMAGE *im,
int n, type-name )
type-name *IM_ARRAY( IMAGE *, int, type-name )
\end{verbatim}
Finally, \verb+IM_NUMBER()+ returns the number of elements in an array of

50
doc/src/pio.tex
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@ -797,8 +797,7 @@ full details.
\label{sec:callback}
VIPS lets you attach callbacks to image descriptors. These are functions
you provide that VIPS will call when certain events occur. This release
of VIPS supports three callbacks:
you provide that VIPS will call when certain events occur.
\subsubsection{Close callbacks}
@ -806,44 +805,35 @@ These callbacks are invoked just before an image is closed. They are useful
for freeing objects which are associated with the image. All callbacks are
triggered in the reverse order to the order in which they were attached. This
is sometimes important when freeing objects which contain pointers to
other objects.
other objects. Close callbacks are guaranteed to be called, and to be called
exactly once.
Use \verb+im_add_close_callback()+ to add a close callback:
\begin{verbatim}
int
im_add_close_callback( IMAGE *im,
int (*callback)(),
void *a, void *b )
typedef int (*im_callback)( void *, void * )
int im_add_close_callback( IMAGE *,
im_callback_fn,
void *, void * )
\end{verbatim}
\noindent
where \verb+callback()+ is a function supplied by you which has type:
\begin{verbatim}
int callback( void *a, void *b )
\end{verbatim}
\noindent
and which returns 0 on success, and -1 on error, setting
\verb+im_error()+. As with \verb+im_generate()+, the values \verb+a+
and \verb+b+ are carried around for you by VIPS, and may be used as your
As with \verb+im_generate()+, the two \verb+void *+ pointers
are carried around for you by VIPS and may be used as your
function sees fit.
\subsubsection{Preclose callbacks}
Preclose callbacks are called before any shutdown has occured. Everything is
still alive and your callback can do anything to the image. Preclose callbacks
are guaranteed to be called, and to be called exactly once. See the manual
page for \verb+im_add_preclose_callback()+ for full details.
\subsubsection{Eval callbacks}
These are callbacks which are invoked by VIPS during evaluation. They
are called each time a region is filled with data (for PIO functions), or
each time \verb+im_writeline()+ is called (for WIO functions). The callback
has access to a large struct containing information about the progress of
evaluation, useful for user-interfaces built on top of VIPS. See the manual
page for \verb+im_add_eval_callback()+ for full details.
\subsubsection{Evalend callbacks}
These are triggered after completion of evaluation of an image, just after all
stop functions have been called. Evalend callbacks are useful for summarising
the results of a computation, see the example in the section below.
These are callbacks which are invoked periodically by VIPS during evaluation.
The callback has access to a struct containing information about the progress
of evaluation, useful for user-interfaces built on top of VIPS. See the
manual page for \verb+im_add_eval_callback()+ for full details.
\subsection{Memory allocation revisited}

2
man/Makefile.am
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@ -20,7 +20,9 @@ man_MANS = \
im_abs.3 \
im_acostra.3 \
im_add.3 \
im_add_preclose_callback.3 \
im_add_close_callback.3 \
im_add_evalstart_callback.3 \
im_add_eval_callback.3 \
im_add_evalend_callback.3 \
im_addgnoise.3 \

1
man/im_add_evalstart_callback.3 Normal file
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@ -0,0 +1 @@
.so man3/im_malloc.3

1
man/im_add_preclose_callback.3 Normal file
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@ -0,0 +1 @@
.so man3/im_malloc.3

83
man/im_malloc.3
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@ -1,51 +1,25 @@
.TH IM_AND 3 "30 October 1992"
.SH NAME
im_add_close_callback, im_add_eval_callback, im_malloc, im_free,
im_add_evalend_callback \- add image callbacks
im_add_evalend_callback, im_add_evalstart_callback, im_add_preclose_callback \- add image callbacks
.SH SYNOPSIS
.B #include <vips/vips.h>
int im_add_close_callback( im, fn, a, b )
.br
IMAGE *im;
.br
int (*fn)();
.br
void *a, *b;
typedef int (*im_callback_fn)( void *, void * );
int im_add_evalend_callback( im, fn, a, b )
.br
IMAGE *im;
.br
int (*fn)();
.br
void *a, *b;
int im_add_close_callback( IMAGE *, im_callback_fn, void *, void * );
where
int im_add_preclose_callback( IMAGE *, im_callback_fn, void *, void * );
int fn( a, b )
.br
void *a, *b;
int im_add_evalstart_callback( IMAGE *, im_callback_fn, void *, void * );
char *im_malloc( IMAGE *im, int size );
int im_add_eval_callback( IMAGE *, im_callback_fn, void *, void * );
int im_free( void *s );
int im_add_evalend_callback( IMAGE *, im_callback_fn, void *, void * );
.B #include <vips/vips.h>
void *im_malloc( IMAGE *, size_t );
int im_add_eval_callback( im, fn, a, b )
.br
IMAGE *im;
.br
int (*fn)();
.br
void *a, *b;
where
int fn( a, b )
.br
void *a, *b;
int im_free( void * );
.SH DESCRIPTION
These functions attach callbacks to images. Callbacks are functions, with
@ -62,7 +36,8 @@ is closed by
The callback is expected to return 0 for success and
non-zero for failure. If the function fails, then the whole
.B im_close(3)
fails.
fails. Close callbacks are guaranteed to be called exactly once, so they are a
good place to release resources.
This function is used by VIPS to implement
.B im_malloc(3).
@ -93,16 +68,27 @@ may even be circularity in your
.B im_close(3)
lists.
.B im_add_evalend_callback(3)
adds a callback which will be triggered when VIPS
has finished writing to the descriptor. If you want to output some diagnostics
from your function (an overflow count, for example), this is the callback to
use.
.B im_add_preclose_callback(3)
adds a callback which will be triggered when the image is closed, but before
any closing has started. Everything is still alive and you can do anything
with the image. Preclose callbacks are guaranteed to be called exactly once.
.B im_add_evalstart_callback(3)
adds a callback which will be triggered just before image evaluation starts.
It can be called many times. It's a good place to initalize data structures.
Don't allocate resources here.
Eval callbacks are inherited. That is, any images which use your image as
input will inherit your eval callbacks. As a result, if you add an eval
callback to an image, you will be notified if any later image uses your image
for computation.
If a later image adds eval callbacks, then the inheritance is broken, and that
image will recieve notification instead.
.B im_add_eval_callback(3)
adds a callback which will be triggered repeatedly as
the image is written to. This works for both PIO and WIO images,
although it is rather more successful with PIO image output.
the image is evaluated.
When the callback is triggered, the time field of the descriptor will point to
a
@ -111,12 +97,13 @@ structure, see vips.h
typedef struct {
IMAGE *im; /* Image we are part of */
GTimer *start; /* Start time */
time_t unused; /* For compatibility */
int run; /* Time we have been running (secs) */
int eta; /* Estimated seconds of computation left */
gint64 tpels; /* Number of pels we expect to calculate */
gint64 npels; /* Number of pels calculated so far */
int percent; /* Percent complete */
GTimer *start; /* Start time */
} im_time_t;
These fields are not exact! They should only be used to give approximate
@ -140,9 +127,15 @@ be used to provide a `cancel' feature in your user-interface.
if( im_add_eval_callback( out, eval_cb, out, NULL ) )
return( -1 );
... now as we write to out, we will get %complete
... now as out is evaluated, we will get %complete
... messages on stdout.
.B im_add_evalend_callback(3)
adds a callback which will be triggered when VIPS
has finished evaluating the image. If you want to output some diagnostics
from your function (an overflow count, for example), this is the callback to
use. Again, this can be called many times.
.SH RETURN VALUE
All functions return 0 on success and non-zero on error.
.SH SEE ALSO