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.

COPYRIGHT

National Gallery, 1992

AUTHOR

J. Cupitt