scbutil.c File Reference

#include <math.h>
#include <glib.h>
#include "scblog.h"
#include "scbutil.h"

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Defines
#define	_GNU_SOURCE
Functions
static int	CCW (const ScbPointPtr p0, const ScbPointPtr p1, const ScbPointPtr p2)
gboolean	erscribble_is_rect_intersect (const ScbRectPtr r1, const ScbRectPtr r2)
gboolean	erscribble_is_lines_intersect (const ScbPointPtr p1, const ScbPointPtr p2, const ScbPointPtr p3, const ScbPointPtr p4)

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Define Documentation

#define _GNU_SOURCE

Copyright (C) 2008 iRex Technologies B.V. All rights reserved.

Definition at line 28 of file scbutil.c.

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Function Documentation

static int CCW	(	const ScbPointPtr	p0,
		const ScbPointPtr	p1,
		const ScbPointPtr	p2
	)			[static]

Definition at line 108 of file scbutil.c.

References _ScbPoint::x, and _ScbPoint::y.

Referenced by erscribble_is_lines_intersect().

{
    long dx1, dx2 ;
    long dy1, dy2 ;

    dx1 = p1->x - p0->x ; dx2 = p2->x - p0->x ;
    dy1 = p1->y - p0->y ; dy2 = p2->y - p0->y ;
    /* This is basically a slope comparison: we don't do divisions because
    * of divide by zero possibilities with pure horizontal and pure
    * vertical lines.
    */ 
    return ((dx1 * dy2 > dy1 * dx2) ? 1 : -1) ;
}

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gboolean erscribble_is_lines_intersect	(	const ScbPointPtr	p1,
		const ScbPointPtr	p2,
		const ScbPointPtr	p3,
		const ScbPointPtr	p4
	)

Definition at line 84 of file scbutil.c.

References CCW().

Referenced by erscribble_stroke_line_hit_test().

{
    gboolean bRet = ((( CCW(p1, p2, p3) * CCW(p1, p2, p4)) <= 0)
        && (( CCW(p3, p4, p1) * CCW(p3, p4, p2)  <= 0) )) ;

   
    return bRet;
}

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gboolean erscribble_is_rect_intersect	(	const ScbRectPtr	rect1,
		const ScbRectPtr	rect2
	)

Copyright (C) 2008 iRex Technologies B.V. All rights reserved.

Definition at line 71 of file scbutil.c.

References _ScbRect::bottom, _ScbRect::left, _ScbRect::right, and _ScbRect::top.

Referenced by erscribble_stroke_line_hit_test(), and erscribble_stroke_point_hit_test().

{
    // check two rectangles is intersect or not, 
    // these two rectangles should be normalized.
    return ! ( r2->left > r1->right 
        || r2->right < r1->left 
        || r2->top > r1->bottom 
        || r2->bottom < r1->top 
        );
}

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