/*

    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;

}

void

SDL_ClearDirtyRects(SDL_DirtyRectList * list)

{

    SDL_DirtyRect *prev, *curr;

    /* Skip to the end of the free list */

    prev = NULL;

    for (curr = list->free; curr; curr = curr->next) {

        prev = curr;

    }

    /* Add the list entries to the end */

    if (prev) {

        prev->next = list->list;

    } else {

        list->free = list->list;

    }

    list->list = NULL;

}

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);

    }

}

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