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Rect(3)                                                                Rect(3)




NAME

       im_rect_marginadjust,    im_rect_includespoint,   im_rect_includesrect,
       im_rect_intersectrect, im_rect_isempty, im_rect_unionrect, im_rect_nor-
       malise, im_rect_equalsrect, im_rect_dup, IM_RECT_RIGHT, IM_RECT_BOTTOM,
       IM_RECT_HCENTRE, IM_RECT_VCENTRE - rectangle algebra functions


SYNOPSIS

       #include <vips/vips.h>

       typedef struct {
            int left, top, width, height;
       } Rect;

       #define IM_RECT_RIGHT(R) ((R)->left + (R)->width)
       #define IM_RECT_BOTTOM(R) ((R)->top + (R)->height)
       #define IM_RECT_HCENTRE(R) ((R)->left + (R)->width / 2)
       #define IM_RECT_VCENTRE(R) ((R)->top + (R)->height / 2)

       void im_rect_marginadjust( Rect *r, int n );
       int im_rect_includespoint( Rect *r, int x, int y );
       int im_rect_includesrect( Rect *r1, Rect *r2 );
       void im_rect_intersectrect( Rect *r1, Rect *r2, Rect *r3 );
       int im_rect_isempty( Rect *r );
       void im_rect_unionrect( Rect *r1, Rect *r2, Rect *r3 );
       int im_rect_equalsrect( Rect *r1, Rect *r2 );
       Rect *im_rect_dup( Rect *r );
       void im_rect_normalise( Rect *r );


DESCRIPTION

       These functions perform simple algebra on Rect  structs.  There  should
       also be a set of functions to do rectlist algebra.

       im_rect_marginadjust(3)  expands  a  Rect by n units up, down, left and
       right.  Negative expansions shrink the Rect.

       im_rect_includespoint(3) returns non-zero if point  (x,y)  lies  within
       Rect r.

       im_rect_includesrect(3)  returns  non-zero  if  Rect r2 lies completely
       within Rect r1.

       im_rect_intersectrect(3) fills Rect r3 with the intersection  of  Rects
       r1 and r2.

       im_rect_isempty(3)  returns  non-zero  if  Rect r has either width less
       than or equal to 0 or height less than or equal to 0.

       im_rect_unionrect(3) fills Rect r3 with the bounding box of Rect r1 and
       Rect  r2. A proper union operation requires lists of rectangles, sadly.

       im_rect_equalsrect(3) returns non-zero if r1 and r2 are identical.

       im_rect_dup(3) allocates memory for a new Rect structure and copies the
       elements  of r into it. It returns a pointer to the new struct, or NULL
       on error.

       im_rect_normalise(3) flips r so that the same pixels are enclosed,  but
       width and height are guaranteed >=0.



SEE ALSO

       im_prepare(3), im_region_create(3)


COPYRIGHT

       National Gallery, 1992


AUTHOR

       J. Cupitt



                                  2 May 1991                           Rect(3)

im_rect_marginadjust 7.14.5 - Generated Mon Sep 8 19:32:11 CDT 2008
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