1 files changed, 96 insertions, 0 deletions
diff --git a/src/screenshot.h b/src/screenshot.h
new file mode 100644
index 0000000..96cee42
--- /dev/null
+++ b/src/screenshot.h
@@ -0,0 +1,96 @@
+#ifndef SCREENSHOT_H
+#define SCREENSHOT_H
+
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+
+#ifdef USE_XSHM
+#include <X11/extensions/XShm.h>
+#endif
+
+typedef struct {
+    XImage          *image;
+#ifdef USE_XSHM
+    XShmSegmentInfo *shminfo;
+#endif
+} Screenshot;
+
+Screenshot *new_screenshot(Display *display, Window window);
+void       destroy_screenshot(Display *display, Screenshot *screenshot);
+
+// TODO(20260315T135543): maybe add error checking
+
+#ifdef SCREENSHOT_IMPL
+
+#include <stdlib.h>
+
+#ifdef USE_XSHM
+#include <sys/shm.h>
+#endif
+
+#define UNUSED(x) (void)(x)
+
+Screenshot *new_screenshot(Display *d, Window w) {
+    Screenshot *result = malloc(sizeof(Screenshot));
+
+    XWindowAttributes attributes;
+    XGetWindowAttributes(d, w, &attributes);
+
+#ifdef USE_XSHM
+    result->shminfo = malloc(sizeof(XShmSegmentInfo));
+
+    int screen = DefaultScreen(d);
+
+    result->image = XShmCreateImage(
+        d,
+        DefaultVisual(d, screen),
+        DefaultDepthOfScreen(ScreenOfDisplay(d, screen)),
+        ZPixmap,
+        NULL,
+        result->shminfo,
+        attributes.width,
+        attributes.height
+    );
+
+    result->shminfo->shmid = shmget(
+        IPC_PRIVATE,
+        result->image->bytes_per_line * result->image->height,
+        IPC_CREAT | 0777
+    );
+
+    result->shminfo->shmaddr  = (char*)shmat(result->shminfo->shmid, 0, 0);
+    result->image->data       = result->shminfo->shmaddr;
+    result->shminfo->readOnly = False;
+
+    XShmAttach(d, result->shminfo);
+
+    XShmGetImage(d, w, result->image, 0, 0, AllPlanes);
+#else // USE_XSHM
+    result->image = XGetImage(d, w, 0, 0,
+                              attributes.width, attributes.height,
+                              AllPlanes, ZPixmap);
+#endif // USE_XSHM
+
+    return result;
+}
+
+void destroy_screenshot(Display *d, Screenshot *s) {
+    if (!s) return;
+
+#ifdef USE_XSHM
+    XSync(d, False);
+    XShmDetach(d, s->shminfo);
+    XDestroyImage(s->image);
+    shmdt(s->shminfo->shmaddr);
+    shmctl(s->shminfo->shmid, IPC_RMID, 0);
+    free(s->shminfo);
+#else
+    UNUSED(d);
+    XDestroyImage(s->image);
+#endif
+    free(s);
+}
+
+#endif // SCREENSHOT_IMPL
+
+#endif // SCREENSHOT_H