67 lines
1.6 KiB
Groff
67 lines
1.6 KiB
Groff
.TH MACROS 3 "11 April 1990"
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.SH NAME
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IM_IMAGE_ADDR, IM_IMAGE_SIZEOF_ELEMENT, IM_IMAGE_SIZEOF_PEL,
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IM_IMAGE_SIZEOF_LINE, IM_IMAGE_N_ELEMENTS \-
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macros for images
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.SH SYNOPSIS
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.B #include <vips/vips.h>
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int IM_IMAGE_SIZEOF_ELEMENT( im )
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.br
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IMAGE *im;
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int IM_IMAGE_SIZEOF_PEL( im )
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.br
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IMAGE *im;
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int IM_IMAGE_SIZEOF_LINE( im )
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.br
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IMAGE *im;
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int IM_IMAGE_N_ELEMENTS( im )
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.br
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IMAGE *im;
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char *IM_IMAGE_ADDR( im, x, y )
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.br
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IMAGE *im;
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.br
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int x;
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.br
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int y;
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.SH DESCRIPTION
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These macros help to simplify address arithmetic for images.
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IM_IMAGE_SIZEOF_ELEMENT(3) returns sizeof( one band element ).
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IM_IMAGE_SIZEOF_PEL(3) returns sizeof( one pel ).
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IM_IMAGE_SIZEOF_LINE(3) returns sizeof( one horizontal line of pels ).
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IM_IMAGE_N_ELEMENTS(3) returns the number of band elements across a horizontal line.
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IM_IMAGE_ADDR(3) returns a pointer to the pixel at position (x,y) in the
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image. The point (x,y) should lie within the image.
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If the macro DEBUG has been defined, then IM_IMAGE_ADDR(3) will also
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perform bounds checking. If you ask for the address of a pel outside the
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image,
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then IM_IMAGE_ADDR(3) will print an error message of the form:
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IM_IMAGE_ADDR: point out of bounds, file "test.c", line 18
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(point x=50, y=0
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should have been within Rect left=0, top=0, width=50, height=50)
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and call abort(3).
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DEBUG needs to be defined *before* vips.h is included. Either define DEBUG
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with -D in your Makefile, or have a #define DEBUG right at the top of your
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file.
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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_REGION_ADDR(3), 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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