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SDL_rect.c
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SDL_rect.c
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/*
SDL - Simple DirectMedia Layer
Copyright (C) 1997-2006 Sam Lantinga
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Sam Lantinga
slouken@libsdl.org
*/
#include "SDL_config.h"
#include "SDL_video.h"
#include "SDL_rect_c.h"
SDL_bool
SDL_HasIntersection(const SDL_Rect * A, const SDL_Rect * B)
{
int Amin, Amax, Bmin, Bmax;
/* Horizontal intersection */
Amin = A->x;
Amax = Amin + A->w;
Bmin = B->x;
Bmax = Bmin + B->w;
if (Bmin > Amin)
Amin = Bmin;
if (Bmax < Amax)
Amax = Bmax;
if (Amax <= Amin)
return SDL_FALSE;
/* Vertical intersection */
Amin = A->y;
Amax = Amin + A->h;
Bmin = B->y;
Bmax = Bmin + B->h;
if (Bmin > Amin)
Amin = Bmin;
if (Bmax < Amax)
Amax = Bmax;
if (Amax <= Amin)
return SDL_FALSE;
return SDL_TRUE;
}
SDL_bool
SDL_IntersectRect(const SDL_Rect * A, const SDL_Rect * B, SDL_Rect * result)
{
int Amin, Amax, Bmin, Bmax;
/* Horizontal intersection */
Amin = A->x;
Amax = Amin + A->w;
Bmin = B->x;
Bmax = Bmin + B->w;
if (Bmin > Amin)
Amin = Bmin;
result->x = Amin;
if (Bmax < Amax)
Amax = Bmax;
result->w = Amax - Amin;
/* Vertical intersection */
Amin = A->y;
Amax = Amin + A->h;
Bmin = B->y;
Bmax = Bmin + B->h;
if (Bmin > Amin)
Amin = Bmin;
result->y = Amin;
if (Bmax < Amax)
Amax = Bmax;
result->h = Amax - Amin;
return !SDL_RectEmpty(result);
}
void
SDL_UnionRect(const SDL_Rect * A, const SDL_Rect * B, SDL_Rect * result)
{
int Amin, Amax, Bmin, Bmax;
/* Horizontal union */
Amin = A->x;
Amax = Amin + A->w;
Bmin = B->x;
Bmax = Bmin + B->w;
if (Bmin < Amin)
Amin = Bmin;
result->x = Amin;
if (Bmax > Amax)
Amax = Bmax;
result->w = Amax - Amin;
/* Vertical intersection */
Amin = A->y;
Amax = Amin + A->h;
Bmin = B->y;
Bmax = Bmin + B->h;
if (Bmin < Amin)
Amin = Bmin;
result->y = Amin;
if (Bmax > Amax)
Amax = Bmax;
result->h = Amax - Amin;
}
void
SDL_AddDirtyRect(SDL_DirtyRectList * list, const SDL_Rect * rect)
{
SDL_DirtyRect *dirty;
/* FIXME: At what point is this optimization too expensive? */
for (dirty = list->list; dirty; dirty = dirty->next) {
if (SDL_HasIntersection(&dirty->rect, rect)) {
SDL_UnionRect(&dirty->rect, rect, &dirty->rect);
return;
}
}
if (list->free) {
dirty = list->free;
list->free = dirty->next;
} else {
dirty = (SDL_DirtyRect *) SDL_malloc(sizeof(*dirty));
if (!dirty) {
return;
}
}
dirty->rect = *rect;
dirty->next = list->list;
list->list = dirty;
++list->count;
}
void
SDL_ClearDirtyRects(SDL_DirtyRectList * list)
{
list->free = list->list;
list->list = NULL;
list->count = 0;
}
void
SDL_FreeDirtyRects(SDL_DirtyRectList * list)
{
while (list->list) {
SDL_DirtyRect *elem = list->list;
list->list = elem->next;
SDL_free(elem);
}
while (list->free) {
SDL_DirtyRect *elem = list->free;
list->free = elem->next;
SDL_free(elem);
}
}
/* vi: set ts=4 sw=4 expandtab: */