Playing with xcb+cairo instead

mess/cairo-xcb.c

@@ -0,0 +1,121 @@
+// x-run: ~/scripts/runc.sh % -lX11 -lcairo -lxcb -lm
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <xcb/xcb.h>
+#include <xcb/xproto.h>
+#include <cairo/cairo.h>
+#include <cairo/cairo-xcb.h>
+#include <unistd.h>
+#include <math.h>
+
+#define EVENT(T, A, B) T *A = (T *)B
+
+void render(xcb_connection_t *connection, int wid, cairo_t *cr, int win_w, int win_h);
+
+int main(void) {
+  xcb_connection_t *connection = xcb_connect(getenv("DISPLAY"), NULL);
+  if (!connection) {
+    fprintf(stderr, "xcb_connect() failed\n");
+    return EXIT_FAILURE;
+  }
+
+  xcb_screen_t *screen = xcb_setup_roots_iterator(xcb_get_setup(connection)).data;
+  xcb_window_t wid = xcb_generate_id(connection);
+
+  xcb_visualtype_t *visual = NULL;
+  {
+    for (
+        xcb_depth_iterator_t iter_depth = xcb_screen_allowed_depths_iterator(screen);
+        iter_depth.rem;
+        xcb_depth_next(&iter_depth)) {
+      int visual_length = xcb_depth_visuals_length(iter_depth.data);
+      visual = xcb_depth_visuals(iter_depth.data);
+      for (int i = 0; i < visual_length; i++) {
+        if (visual->visual_id == screen->root_visual) {
+          goto found_visual;
+        }
+      }
+    }
+found_visual: {}
+  }
+
+  int win_w = 150, win_h = 150;
+  uint32_t mask = XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK,
+           values[2] = {
+             screen->white_pixel,
+             XCB_EVENT_MASK_EXPOSURE | XCB_EVENT_MASK_STRUCTURE_NOTIFY | XCB_EVENT_MASK_FOCUS_CHANGE
+           };
+  xcb_create_window(connection,
+      XCB_COPY_FROM_PARENT,
+      wid, screen->root,
+      0, 0, win_w, win_h, 0,
+      XCB_WINDOW_CLASS_INPUT_OUTPUT,
+      screen->root_visual, mask, values);
+
+  xcb_map_window(connection, wid);
+  xcb_flush(connection);
+
+  cairo_surface_t *surface = cairo_xcb_surface_create(connection, wid, visual, win_w, win_h);
+  cairo_t *cr = cairo_create(surface);
+
+  xcb_generic_event_t *event;
+  bool running = true;
+
+  while (running) {
+    while ((event = xcb_poll_for_event(connection))) {
+      switch (event->response_type & ~0x80) {
+        case XCB_CONFIGURE_NOTIFY:
+          {
+            EVENT(xcb_configure_notify_event_t, evt, event);
+            if (win_w != evt->width || win_h != evt->height) {
+              printf("resize %dx%d -> %dx%d\n", win_w, win_h, evt->width, evt->height);
+              cairo_destroy(cr);
+              surface = cairo_xcb_surface_create(connection, wid, visual, win_w, win_h);
+              cr = cairo_create(surface);
+              win_w = evt->width;
+              win_h = evt->height;
+            }
+          }
+          break;
+        case XCB_FOCUS_IN:
+          printf("focus in\n");
+          break;
+        case XCB_FOCUS_OUT:
+          printf("focus out\n");
+          break;
+        case XCB_EXPOSE:
+          printf("expose\n");
+          break;
+        case XCB_DESTROY_NOTIFY:
+          cairo_destroy(cr);
+          running = false;
+          break;
+        default:
+          printf("event: %d\n", event->response_type);
+          break;
+      }
+      free(event);
+    }
+
+    if (running) {
+      render(connection, wid, cr, win_w, win_h);
+      usleep(1000000 / 60);
+    }
+  }
+
+  xcb_destroy_window(connection, wid);
+  xcb_disconnect(connection);
+}
+
+void render(xcb_connection_t *connection, int wid, cairo_t *cr, int win_w, int win_h) {
+  static float t = 0.0;
+  xcb_clear_area(connection, 0, wid, 0, 0, 0, 0);
+  cairo_set_source_rgb(cr, sin(t) * 0.5 + 0.5, cos(t) * 0.5 + 0.5, 0);
+  cairo_rectangle(cr, win_w * 0.5, win_h * 0.5, sin(t) * 0.5 * win_w, cos(t) * 0.5 * win_h);
+  cairo_fill(cr);
+  xcb_flush(connection);
+  t += 1.0 / 60.0;
+}