init commit

src/main.c

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+/* textures.c ... */
+
+/*
+ * This example creates an SDL window and renderer, and then draws some
+ * textures to it every frame.
+ *
+ * This code is public domain. Feel free to use it for any purpose!
+ */
+
+#define SDL_MAIN_USE_CALLBACKS 1  /* use the callbacks instead of main() */
+
+#include <X11/Xlib.h>
+#include <X11/extensions/shape.h>
+#include <X11/extensions/Xfixes.h>
+
+#include <SDL3/SDL.h>
+#include <SDL3/SDL_main.h>
+#include <stdio.h>
+
+/* We will use this renderer to draw into this window every frame. */
+static SDL_Window *window = NULL;
+static SDL_Renderer *renderer = NULL;
+static SDL_Texture *texture = NULL;
+static int texture_width = 0;
+static int texture_height = 0;
+
+static int WINDOW_WIDTH;
+static int WINDOW_HEIGHT;
+
+void make_window_clickthrough() {
+    Display *dpy = (Display *)SDL_GetPointerProperty(SDL_GetWindowProperties(window), SDL_PROP_WINDOW_X11_DISPLAY_POINTER, NULL);
+    Window xwin = (Window)SDL_GetNumberProperty(SDL_GetWindowProperties(window), SDL_PROP_WINDOW_X11_WINDOW_NUMBER, 0);
+
+    // Make input shape empty → ignores mouse events
+    XRectangle rect;
+    XserverRegion region = XFixesCreateRegion(dpy, &rect, 0);
+    XFixesSetWindowShapeRegion(dpy, xwin, ShapeInput, 0, 0, region);
+    XFixesDestroyRegion(dpy, region);
+
+    XFlush(dpy);
+}
+
+/* This function runs once at startup. */
+SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
+{
+    SDL_Surface *surface = NULL;
+    char *bmp_path = NULL;
+
+    SDL_SetAppMetadata("systemd", "1.0", "org.kernel.systemd");
+
+    if (!SDL_Init(SDL_INIT_VIDEO)) {
+        SDL_Log("Couldn't initialize SDL: %s", SDL_GetError());
+        return SDL_APP_FAILURE;
+    }
+
+    // Init window size to fullscreen
+    int num_displays;
+    SDL_DisplayID *displays = SDL_GetDisplays(&num_displays);
+    SDL_Log("Found %d display(s)", num_displays);
+
+    const SDL_DisplayMode* DisplayMode =  SDL_GetCurrentDisplayMode(displays[0]);
+    SDL_free(displays);
+    if(DisplayMode==NULL){
+        printf("Error could not get display mode");
+        return 1;
+    }
+    WINDOW_WIDTH = DisplayMode->w;
+    WINDOW_HEIGHT = DisplayMode->h;
+
+
+    if (!SDL_CreateWindowAndRenderer("systemd", WINDOW_WIDTH, WINDOW_HEIGHT,
+        SDL_WINDOW_TRANSPARENT | SDL_WINDOW_ALWAYS_ON_TOP | SDL_WINDOW_BORDERLESS ,
+        &window, &renderer)) {
+        SDL_Log("Couldn't create window/renderer: %s", SDL_GetError());
+        return SDL_APP_FAILURE;
+    }
+
+    make_window_clickthrough();
+
+    /* Textures are pixel data that we upload to the video hardware for fast drawing. Lots of 2D
+       engines refer to these as "sprites." We'll do a static texture (upload once, draw many
+       times) with data from a bitmap file. */
+
+    /* SDL_Surface is pixel data the CPU can access. SDL_Texture is pixel data the GPU can access.
+       Load a .bmp into a surface, move it to a texture from there. */
+    SDL_asprintf(&bmp_path, "%ssample.bmp", SDL_GetBasePath());  /* allocate a string of the full file path */
+    surface = SDL_LoadBMP(bmp_path);
+    if (!surface) {
+        SDL_Log("Couldn't load bitmap: %s", SDL_GetError());
+        return SDL_APP_FAILURE;
+    }
+
+    SDL_free(bmp_path);  /* done with this, the file is loaded. */
+
+    texture_width = surface->w;
+    texture_height = surface->h;
+
+    texture = SDL_CreateTextureFromSurface(renderer, surface);
+    if (!texture) {
+        SDL_Log("Couldn't create static texture: %s", SDL_GetError());
+        return SDL_APP_FAILURE;
+    }
+
+    SDL_DestroySurface(surface);  /* done with this, the texture has a copy of the pixels now. */
+
+    return SDL_APP_CONTINUE;  /* carry on with the program! */
+}
+
+/* This function runs when a new event (mouse input, keypresses, etc) occurs. */
+SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event)
+{
+    if (event->type == SDL_EVENT_QUIT) {
+        return SDL_APP_SUCCESS;  /* end the program, reporting success to the OS. */
+    }
+    return SDL_APP_CONTINUE;  /* carry on with the program! */
+}
+
+/* This function runs once per frame, and is the heart of the program. */
+SDL_AppResult SDL_AppIterate(void *appstate)
+{
+    SDL_FRect dst_rect;
+    const Uint64 now = SDL_GetTicks();
+
+    /* we'll have some textures move around over a few seconds. */
+    const float direction = ((now % 2000) >= 1000) ? 1.0f : -1.0f;
+    const float scale = ((float) (((int) (now % 1000)) - 500) / 500.0f) * direction;
+
+    /* as you can see from this, rendering draws over whatever was drawn before it. */
+    SDL_SetRenderDrawColor(renderer, 0, 0, 0, SDL_ALPHA_TRANSPARENT);  /* black, full alpha */
+    SDL_RenderClear(renderer);  /* start with a blank canvas. */
+
+    /* Just draw the static texture a few times. You can think of it like a
+       stamp, there isn't a limit to the number of times you can draw with it. */
+
+    /* top left */
+    dst_rect.x = (100.0f * scale);
+    dst_rect.y = 0.0f;
+    dst_rect.w = (float) texture_width;
+    dst_rect.h = (float) texture_height;
+    SDL_RenderTexture(renderer, texture, NULL, &dst_rect);
+
+    /* center this one. */
+    dst_rect.x = ((float) (WINDOW_WIDTH - texture_width)) / 2.0f;
+    dst_rect.y = ((float) (WINDOW_HEIGHT - texture_height)) / 2.0f;
+    dst_rect.w = (float) texture_width;
+    dst_rect.h = (float) texture_height;
+    SDL_RenderTexture(renderer, texture, NULL, &dst_rect);
+
+    /* bottom right. */
+    dst_rect.x = ((float) (WINDOW_WIDTH - texture_width)) - (100.0f * scale);
+    dst_rect.y = (float) (WINDOW_HEIGHT - texture_height);
+    dst_rect.w = (float) texture_width;
+    dst_rect.h = (float) texture_height;
+    SDL_RenderTexture(renderer, texture, NULL, &dst_rect);
+
+    SDL_RenderPresent(renderer);  /* put it all on the screen! */
+
+    return SDL_APP_CONTINUE;  /* carry on with the program! */
+}
+
+/* This function runs once at shutdown. */
+void SDL_AppQuit(void *appstate, SDL_AppResult result)
+{
+    SDL_DestroyTexture(texture);
+    /* SDL will clean up the window/renderer for us. */
+}