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/*
* tkQTreePriv.h --
*
* Private implementation for Q-Tree.
*
* Copyright (c) 2015-2017 Gregor Cramer
*
* See the file "license.terms" for information on usage and redistribution of
* this file, and for a DISCLAIMER OF ALL WARRANTIES.
*/
#ifndef _TKQTREE
# error "do not include this private header file"
#endif
#ifdef _TK_NEED_IMPLEMENTATION
#include <assert.h>
#ifdef _MSC_VER
# if _MSC_VER >= 1900
# define inline __inline
# else
# define inline
# endif
#elif __STDC_VERSION__ < 199901L
# define inline /* we are not C99 conform */
#endif
inline
bool
TkQTreeRectIsEmpty(
const TkQTreeRect *rect)
{
assert(rect);
/*
* Normally this natural statement will be used here:
*
* return rect->xmin >= rect->xmax || rect->ymin >= rect->ymax;
*
* GCC gives the following warning when optimization is enabled:
*
* assuming signed overflow does not occur when assuming that (X + c) < X
* is always false [-Wstrict-overflow]
*
* I guess that GCC is converting (optimizing) this statement into:
*
* return rect->xmin - rect->xmax >= 0 || rect->ymin - rect->ymax >= 0;
*
* So I will use the latter statement to avoid this warning. Unfortunately
* this has the drawback that on machines with different architectures
* the transformed statement can be a bit slower than the natural statement,
* but I will assume that on such architectures GCC will transform it (back)
* to the natural one (when optimization is enabled), without giving a warning,
* because the natural statement doesn't use arithmetic.
*
* Note that this problem only happen with signed values.
*/
return rect->xmin - rect->xmax >= 0 || rect->ymin - rect->ymax >= 0;
}
inline
bool
TkQTreeRectIsEqual(
const TkQTreeRect *rect1,
const TkQTreeRect *rect2)
{
assert(rect1);
assert(rect2);
return rect1->xmin == rect2->xmin
&& rect1->xmax == rect2->xmax
&& rect1->ymin == rect2->ymin
&& rect1->ymax == rect2->ymax;
}
inline
bool
TkQTreeRectContainsPoint(
const TkQTreeRect *rect,
TkQTreeCoord x,
TkQTreeCoord y)
{
assert(rect);
return y < rect->ymax && rect->ymin <= y && x < rect->xmax && rect->xmin <= x;
}
inline
bool
TkQTreeRectContainsRect(
const TkQTreeRect *rect1,
const TkQTreeRect *rect2)
{
assert(rect1);
assert(rect2);
return rect1->xmin <= rect2->xmin
&& rect2->xmax <= rect1->xmax
&& rect1->ymin <= rect2->ymin
&& rect2->ymax <= rect1->ymax;
}
inline
bool
TkQTreeRectIntersects(
const TkQTreeRect *rect1,
const TkQTreeRect *rect2)
{
assert(rect1);
assert(rect2);
return rect1->xmin < rect2->xmax
&& rect2->xmin < rect1->xmax
&& rect1->ymin < rect2->ymax
&& rect2->ymin < rect1->ymax;
}
inline
TkQTreeRect *
TkQTreeRectSet(
TkQTreeRect *rect,
TkQTreeCoord xmin,
TkQTreeCoord ymin,
TkQTreeCoord xmax,
TkQTreeCoord ymax)
{
assert(rect);
assert(xmin <= xmax);
assert(ymin <= ymax);
rect->xmin = xmin;
rect->ymin = ymin;
rect->xmax = xmax;
rect->ymax = ymax;
return rect;
}
inline
TkQTreeRect *
TkQTreeRectTranslate(
TkQTreeRect *rect,
TkQTreeCoord dx,
TkQTreeCoord dy)
{
assert(rect);
rect->xmin += dx;
rect->xmax += dx;
rect->ymin += dy;
rect->ymax += dy;
return rect;
}
#undef _TK_NEED_IMPLEMENTATION
#endif /* _TK_NEED_IMPLEMENTATION */
/* vi:set ts=8 sw=4: */
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