78 lines
2.0 KiB
Groff
78 lines
2.0 KiB
Groff
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.TH IM_ARRAY 3 "11 April 1993"
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.SH NAME
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IM_ARRAY, IM_NEW, IM_NUMBER \- memory allocation macros
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.SH SYNOPSIS
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#include <vips/vips.h>
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type-name *IM_NEW( IMAGE *im, type-name )
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.br
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type-name *IM_ARRAY( IMAGE *im, int number, type-name )
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.br
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int IM_NUMBER( array )
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.SH DESCRIPTION
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NEW, NUMBER and ARRAY are macros built on im_malloc(3) which make memory
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allocation slightly easier. Given a type name, NEW returns a pointer to a
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piece of memory large enough to hold an object of that type. ARRAY works as
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NEW, but allocates space for a number of objects. Given an array, NUMBER
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returns the number of elements in that array.
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#define IM_NEW(IM,A) ((A *)im_malloc((IM),sizeof(A)))
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#define IM_NUMBER(R) (sizeof(R)/sizeof(R[0]))
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#define IM_ARRAY(IM,N,T) ((T *)im_malloc((IM),(N) * sizeof(T)))
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Both IM_ARRAY and IM_NEW take an image descriptor as their first
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parameter. Memory is allocated local to this descriptor, that is, when the
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descriptor is closed, the memory is automatically freed for you. If you
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pass NULL instead of an image descriptor, memory is allocated globally and
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is not automatically freed.
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(NOTE: in versions of VIPS before 7.3, NEW(3) and ARRAY(3) did not have the
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initial IMAGE parameter. If you are converting an old VIPS7.2 program, you
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will need to add a NULL parameter to the start of all NEW(3) and ARRAY(3)
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parameter lists.)
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Both functions return NULL on error, setting im_errorstring.
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Example:
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#include <vips/vips.h>
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/* A structure we want to carry about.
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*/
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typedef struct {
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...
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} Wombat;
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/* A static array of them.
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*/
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static Wombat swarm[] = {
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{ ... },
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{ ... },
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{ ... }
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};
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static int swarm_size = IM_NUMBER( swarm );
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int
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transform_wombat( IMAGE *in, IMAGE *out )
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{
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/* Allocate space for a Wombat.
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*/
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Wombat *mar = IM_NEW( out, Wombat );
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/* Allocate space for a copy of swarm.
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*/
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Wombat *mar = IM_ARRAY( out, swarm_size, Wombat );
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....
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}
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.SH COPYRIGHT
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National Gallery, 1993
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.SH SEE ALSO
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im_malloc(3), im_open_local(3).
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.SH AUTHOR
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J. Cupitt \- 23/7/93
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