Taking screenshot of one window by ID

TODO: iterate over entire tree and take separate screenshots of each
window

img/scrall/.gitignore

@@ -0,0 +1 @@
+scrall

img/scrall/Makefile

@@ -0,0 +1,12 @@
+CFLAGS += -Wall -Wextra `exec pkg-config --cflags raylib xcb xcb-composite`
+LDFLAGS := -lm `pkg-config --libs raylib xcb xcb-composite`
+
+scrall: main.c
+	$(CC) $(CFLAGS) main.c $(LDFLAGS) -o scrall
+
+
+clean:
+	$(RM) scrall
+
+run: scrall
+	./scrall

img/scrall/main.c

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+// x-run: make run
+#include <assert.h>
+#include <raylib.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <xcb/xcb.h>
+#include <xcb/xproto.h>
+#include <xcb/composite.h>
+
+
+Image get_screenshot(xcb_connection_t *conn, xcb_window_t wid);
+
+int main(int argc, char **argv) {
+  xcb_connection_t *xcb = xcb_connect(NULL, NULL);
+
+  SetConfigFlags(FLAG_WINDOW_TRANSPARENT);
+  InitWindow(0, 0, "img/scrall");
+
+
+  Image screenshot = get_screenshot(xcb, 50331654);
+  assert(screenshot.width > 0);
+
+  Texture2D screenshot_tex = LoadTextureFromImage(screenshot);
+  SetWindowSize(screenshot.width, screenshot.height);
+
+  while (!WindowShouldClose()) {
+    BeginDrawing();
+    ClearBackground(BLANK);
+    DrawTexture(screenshot_tex, 0, 0, WHITE);
+    EndDrawing();
+  }
+}
+
+Image get_screenshot(xcb_connection_t *conn, xcb_window_t wid) {
+  xcb_generic_error_t *err = NULL;
+
+  xcb_composite_redirect_window(conn, wid, XCB_COMPOSITE_REDIRECT_AUTOMATIC);
+
+  xcb_get_geometry_cookie_t gg_cookie = xcb_get_geometry(conn, wid);
+  xcb_get_geometry_reply_t *gg_reply = xcb_get_geometry_reply(conn, gg_cookie, &err);
+
+  if (!gg_reply) {
+    fprintf(stderr, "xcb: error: geometry: %d\n", err->error_code);
+    return (Image){
+      .data = err, .width = 0, .height = 0, .format = 0, .mipmaps = 0
+    };
+  }
+
+  int win_w = gg_reply->width;
+  int win_h = gg_reply->height;
+  assert(gg_reply->depth == 32);
+  fprintf(stderr, "width: %d\nheight: %d\n", win_w, win_h);
+
+  free(gg_reply);
+
+  xcb_pixmap_t win_pixmap = xcb_generate_id(conn);
+  xcb_composite_name_window_pixmap(conn, wid, win_pixmap);
+
+  xcb_get_image_cookie_t gi_cookie = xcb_get_image(conn, XCB_IMAGE_FORMAT_Z_PIXMAP, win_pixmap, 0, 0, win_w, win_h, (uint32_t)(~0UL));
+  xcb_get_image_reply_t *gi_reply = xcb_get_image_reply(conn, gi_cookie, &err);
+  if (!gi_reply) {
+    fprintf(stderr, "xcb: error: get_image_reply: %d\n", err->error_code);
+    return (Image){
+      .data = err, .width = 0, .height = 0, .format = 0, .mipmaps = 0
+    };
+  }
+
+  int data_len = xcb_get_image_data_length(gi_reply);
+  fprintf(stderr, "data_len: %d\n", data_len);
+
+  uint8_t *data = xcb_get_image_data(gi_reply);
+
+  Image img = GenImageColor(win_w, win_h, BLANK);
+
+  for (int i = 0; i < data_len; i += 4) {
+    ((uint8_t *)img.data)[i + 0] = data[i + 2];
+    ((uint8_t *)img.data)[i + 1] = data[i + 1];
+    ((uint8_t *)img.data)[i + 2] = data[i + 0];
+    ((uint8_t *)img.data)[i + 3] = data[i + 3];
+  }
+
+  free(gi_reply);
+
+  return img;
+}