src/video/SDL_rect.c

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#include "../SDL_internal.h"

#include "SDL_rect.h"
#include "SDL_rect_c.h"

/* There's no float version of this at the moment, because it's not a public API
   and internally we only need the int version. */
SDL_bool
SDL_GetSpanEnclosingRect(int width, int height,
                         int numrects, const SDL_Rect * rects, SDL_Rect *span)
{
    int i;
    int span_y1, span_y2;
    int rect_y1, rect_y2;

    if (width < 1) {
        SDL_InvalidParamError("width");
        return SDL_FALSE;
    } else if (height < 1) {
        SDL_InvalidParamError("height");
        return SDL_FALSE;
    } else if (!rects) {
        SDL_InvalidParamError("rects");
        return SDL_FALSE;
    } else if (!span) {
        SDL_InvalidParamError("span");
        return SDL_FALSE;
    } else if (numrects < 1) {
        SDL_InvalidParamError("numrects");
        return SDL_FALSE;
    }

    /* Initialize to empty rect */
    span_y1 = height;
    span_y2 = 0;

    for (i = 0; i < numrects; ++i) {
        rect_y1 = rects[i].y;
        rect_y2 = rect_y1 + rects[i].h;

        /* Clip out of bounds rectangles, and expand span rect */
        if (rect_y1 < 0) {
            span_y1 = 0;
        } else if (rect_y1 < span_y1) {
            span_y1 = rect_y1;
        }
        if (rect_y2 > height) {
            span_y2 = height;
        } else if (rect_y2 > span_y2) {
            span_y2 = rect_y2;
        }
    }
    if (span_y2 > span_y1) {
        span->x = 0;
        span->y = span_y1;
        span->w = width;
        span->h = (span_y2 - span_y1);
        return SDL_TRUE;
    }
    return SDL_FALSE;
}


/* For use with the Cohen-Sutherland algorithm for line clipping, in SDL_rect_impl.h */
#define CODE_BOTTOM 1
#define CODE_TOP    2
#define CODE_LEFT   4
#define CODE_RIGHT  8

/* Same code twice, for float and int versions... */
#define RECTTYPE SDL_Rect
#define POINTTYPE SDL_Point
#define SCALARTYPE int
#define COMPUTEOUTCODE ComputeOutCode
#define SDL_HASINTERSECTION SDL_HasIntersection
#define SDL_INTERSECTRECT SDL_IntersectRect
#define SDL_RECTEMPTY SDL_RectEmpty
#define SDL_UNIONRECT SDL_UnionRect
#define SDL_ENCLOSEPOINTS SDL_EnclosePoints
#define SDL_INTERSECTRECTANDLINE SDL_IntersectRectAndLine
#include "SDL_rect_impl.h"

#define RECTTYPE SDL_FRect
#define POINTTYPE SDL_FPoint
#define SCALARTYPE float
#define COMPUTEOUTCODE ComputeOutCodeF
#define SDL_HASINTERSECTION SDL_HasIntersectionF
#define SDL_INTERSECTRECT SDL_IntersectFRect
#define SDL_RECTEMPTY SDL_FRectEmpty
#define SDL_UNIONRECT SDL_UnionFRect
#define SDL_ENCLOSEPOINTS SDL_EncloseFPoints
#define SDL_INTERSECTRECTANDLINE SDL_IntersectFRectAndLine
#include "SDL_rect_impl.h"

/* vi: set ts=4 sw=4 expandtab: */