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81 lines
2.5 KiB
C
81 lines
2.5 KiB
C
/*
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Copyright 1997-2023 Sam Lantinga <slouken@libsdl.org>
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Copyright 2023 Collabora Ltd.
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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#include "SDL3/SDL.h"
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/* Internal implementation of SDL_ReadSurfacePixel, shared between SDL_shape
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* and SDLTest */
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static int SDL_ReadSurfacePixel_impl(SDL_Surface *surface, int x, int y, Uint8 *r, Uint8 *g, Uint8 *b, Uint8 *a)
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{
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Uint32 pixel = 0;
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size_t bytes_per_pixel;
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void *p;
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if (surface == NULL || surface->format == NULL || surface->pixels == NULL) {
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return SDL_InvalidParamError("surface");
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}
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if (x < 0 || x >= surface->w) {
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return SDL_InvalidParamError("x");
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}
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if (y < 0 || y >= surface->h) {
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return SDL_InvalidParamError("y");
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}
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if (r == NULL) {
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return SDL_InvalidParamError("r");
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}
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if (g == NULL) {
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return SDL_InvalidParamError("g");
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}
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if (b == NULL) {
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return SDL_InvalidParamError("b");
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}
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if (a == NULL) {
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return SDL_InvalidParamError("a");
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}
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bytes_per_pixel = surface->format->BytesPerPixel;
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if (bytes_per_pixel > sizeof(pixel)) {
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return SDL_InvalidParamError("surface->format->BytesPerPixel");
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}
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SDL_LockSurface(surface);
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p = (Uint8 *)surface->pixels + y * surface->pitch + x * bytes_per_pixel;
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/* Fill the appropriate number of least-significant bytes of pixel,
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* leaving the most-significant bytes set to zero */
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#if SDL_BYTEORDER == SDL_BIG_ENDIAN
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SDL_memcpy(((Uint8 *) &pixel) + (sizeof(pixel) - bytes_per_pixel), p, bytes_per_pixel);
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#else
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SDL_memcpy(&pixel, p, bytes_per_pixel);
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#endif
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SDL_GetRGBA(pixel, surface->format, r, g, b, a);
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SDL_UnlockSurface(surface);
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return 0;
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}
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