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78 lines
1.9 KiB
C
78 lines
1.9 KiB
C
#include <SDL3/SDL.h>
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#include <SDL3/SDL_main.h>
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#ifdef SDL_PLATFORM_WINDOWS
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#define PNG_SHARED_LIBRARY "libpng16-16.dll"
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#elif defined(SDL_PLATFORM_APPLE)
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#define PNG_SHARED_LIBRARY "libpng16.16.dylib"
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#else
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#define PNG_SHARED_LIBRARY "libpng16.so.16"
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#endif
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SDL_ELF_NOTE_DLOPEN(
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"png",
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"Support for loading PNG images using libpng",
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SDL_ELF_NOTE_DLOPEN_PRIORITY_RECOMMENDED,
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PNG_SHARED_LIBRARY
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);
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typedef int png_sig_cmp_fn(const unsigned char *sig, size_t start, size_t num_to_check);
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static struct {
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SDL_SharedObject *library;
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png_sig_cmp_fn *png_sig_cmp;
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} libpng16;
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static bool libpng_init(void)
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{
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libpng16.library = SDL_LoadObject(PNG_SHARED_LIBRARY);
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if (!libpng16.library) {
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SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to load libpng library \"" PNG_SHARED_LIBRARY "\"");
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return false;
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}
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libpng16.png_sig_cmp = (png_sig_cmp_fn *)SDL_LoadFunction(libpng16.library, "png_sig_cmp");
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return libpng16.png_sig_cmp != NULL;
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}
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static void libpng_quit(void)
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{
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SDL_UnloadObject(libpng16.library);
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SDL_zero(libpng16);
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}
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static bool is_png(const char *path)
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{
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unsigned char header[8];
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size_t count;
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bool result;
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SDL_IOStream *io = SDL_IOFromFile(path, "rb");
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if (io == NULL) {
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return false;
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}
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count = SDL_ReadIO(io, header, sizeof(header));
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result = libpng16.png_sig_cmp(header, 0, count) == 0;
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SDL_CloseIO(io);
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return result;
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}
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int main(int argc, char *argv[])
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{
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int i;
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/* Enable standard application logging */
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SDL_SetLogPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);
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if (argc < 2) {
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SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Usage: %s IMAGE [IMAGE [IMAGE ... ]]", argv[0]);
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return 1;
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}
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if (!libpng_init()) {
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return 1;
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}
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for (i = 1; i < argc; i++) {
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SDL_Log("\"%s\" is a png: %s", argv[i], is_png(argv[i]) ? "YES" : "NO");
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}
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libpng_quit();
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return 0;
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}
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