mirror of
https://github.com/libsdl-org/SDL.git
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111 lines
3.1 KiB
C
111 lines
3.1 KiB
C
/*
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Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org>
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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.
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*/
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#include <SDL3/SDL.h>
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#include <SDL3/SDL_main.h>
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#define SQUARE_SIZE 100.0f
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/* Draw opaque red squares at the four corners of the form, and draw a red square with an alpha value of 180 in the center of the form */
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static void draw(SDL_Renderer *renderer)
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{
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SDL_FRect rect = { 0.0f, 0.0f, SQUARE_SIZE, SQUARE_SIZE };
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int w, h;
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SDL_GetCurrentRenderOutputSize(renderer, &w, &h);
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SDL_SetRenderDrawColor(renderer, 0, 0, 0, 0);
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SDL_RenderClear(renderer);
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if (w >= 3 * SQUARE_SIZE && h >= 3 * SQUARE_SIZE) {
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SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255);
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rect.x = 0.0f;
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rect.y = 0.0f;
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SDL_RenderFillRect(renderer, &rect);
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rect.y = h - SQUARE_SIZE;
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SDL_RenderFillRect(renderer, &rect);
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rect.x = w - SQUARE_SIZE;
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SDL_RenderFillRect(renderer, &rect);
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rect.y = 0.0f;
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SDL_RenderFillRect(renderer, &rect);
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}
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SDL_SetRenderDrawColor(renderer, 255, 0, 0, 180);
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rect.x = (w - SQUARE_SIZE) / 2;
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rect.y = (h - SQUARE_SIZE) / 2;
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SDL_RenderFillRect(renderer, &rect);
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}
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int main(int argc, char *argv[])
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{
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SDL_Window *window = NULL;
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SDL_Renderer *renderer = NULL;
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bool done = false;
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SDL_Event event;
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int return_code = 1;
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window = SDL_CreateWindow("SDL Software Renderer Transparent Test", 800, 600, SDL_WINDOW_TRANSPARENT | SDL_WINDOW_RESIZABLE);
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if (!window) {
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SDL_Log("Couldn't create transparent window: %s", SDL_GetError());
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goto quit;
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}
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/* Create a software renderer */
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renderer = SDL_CreateRenderer(window, SDL_SOFTWARE_RENDERER);
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if (!renderer) {
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SDL_Log("Couldn't create renderer: %s", SDL_GetError());
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goto quit;
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}
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/* Make sure we're setting the alpha channel while drawing */
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SDL_SetRenderDrawBlendMode(renderer, SDL_BLENDMODE_NONE);
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/* We're ready to go! */
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while (!done) {
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while (SDL_PollEvent(&event)) {
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switch (event.type) {
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case SDL_EVENT_KEY_DOWN:
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if (event.key.key == SDLK_ESCAPE) {
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done = true;
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}
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break;
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case SDL_EVENT_WINDOW_EXPOSED:
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/* The software renderer is persistent, so only redraw as-needed */
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draw(renderer);
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break;
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case SDL_EVENT_QUIT:
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done = true;
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break;
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default:
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break;
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}
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}
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/* Show everything on the screen and wait a bit */
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SDL_RenderPresent(renderer);
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SDL_Delay(100);
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}
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/* Success! */
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return_code = 0;
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quit:
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SDL_DestroyRenderer(renderer);
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SDL_DestroyWindow(window);
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SDL_Quit();
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return return_code;
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}
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