wl_backend: implement client_snapshot via buffer read (XWayland: XGetImage, native: wlr_buffer)

ROADMAP.md

@@ -63,15 +63,13 @@ XWayland bridge auto-syncs. Needs verification.
 
 ### 1.4 Remaining Vtable Stubs
 
-These vtable slots are stubs or partial implementations:
-
-| Slot | Purpose | Needed For |
-|------|---------|------------|
-| `overlay_draw_*` | Pixman animation buffer | Iconify zoom animation |
-| `client_snapshot` | Window thumbnail capture | Switch panel thumbnails, icon preview |
-| `window_set_border` | Scene rect border nodes | Window borders |
-| `client_synth_configure` | XDG configure scheduling | Resize negotiation |
-| `pointer_change_grab` | Grab parameter update | Menu tracking |
+| Slot | Status |
+|------|--------|
+| `overlay_draw_*` | ✅ Done — real pixman overlay implementation |
+| `client_snapshot` | ❌ Stub — needs last-committed texture → RImage |
+| `window_set_border` | ✅ No-op (borders drawn into frame buffer) |
+| `client_synth_configure` | ✅ Done — XDG configure + XWayland configure |
+| `pointer_change_grab` | ⚠️ No-op — menu tracking may need this |
 
 ---
 

src/backend/wayland/wl_backend.c

@@ -7882,7 +7882,65 @@ static int wl_client_get_pid(WNativeWindow win)
 
 static RImage *
 wl_client_snapshot(WScreen *scr, WNativeWindow client_win, WNativeWindow frame_win)
-{ (void)scr; (void)client_win; (void)frame_win; return NULL; }
+{
+    (void)frame_win;
+    struct wl_toplevel_view *v = wl_find_view_by_id(client_win);
+    if (!v) return NULL;
+
+    /* XWayland: capture via XGetImage on the WM's X display */
+    if (v->xw_surface && wl_state.x_display) {
+        Window xid = (Window)v->xw_surface->window_id;
+        XWindowAttributes attr;
+        if (!XGetWindowAttributes(wl_state.x_display, xid, &attr))
+            return NULL;
+        XImage *img = XGetImage(wl_state.x_display, xid,
+                                 0, 0, attr.width, attr.height,
+                                 AllPlanes, ZPixmap);
+        if (!img) return NULL;
+        RImage *res = RCreateImageFromXImage(scr->rcontext, img, NULL);
+        XDestroyImage(img);
+        return res;
+    }
+
+    /* Native Wayland: read pixels from last committed surface buffer */
+    if (!v->xdg_surface || !v->xdg_surface->surface) return NULL;
+    struct wlr_surface *s = v->xdg_surface->surface;
+    if (!s->buffer) return NULL;
+    struct wlr_buffer *buf = &s->buffer->base;
+
+    uint32_t fmt;
+    void *data;
+    size_t stride;
+    if (!wlr_buffer_begin_data_ptr_access(buf, WLR_BUFFER_DATA_PTR_ACCESS_READ, &data, &fmt, &stride))
+        return NULL;
+
+    int w = s->current.width;
+    int h = s->current.height;
+    if (w <= 0 || h <= 0) {
+        wlr_buffer_end_data_ptr_access(buf);
+        return NULL;
+    }
+
+    /* Create RImage and copy pixels (ARGB32 → RGBA byte order swap) */
+    RImage *res = RCreateImage(w, h, True);
+    if (res) {
+        unsigned char *src = (unsigned char *)data;
+        unsigned char *dst = res->data;
+        for (int y = 0; y < h; y++) {
+            for (int x = 0; x < w; x++) {
+                int si = y * stride + x * 4;
+                int di = (y * w + x) * 4;
+                dst[di + 0] = src[si + 2]; /* B → R */
+                dst[di + 1] = src[si + 1]; /* G → G */
+                dst[di + 2] = src[si + 0]; /* R → B */
+                dst[di + 3] = src[si + 3]; /* A → A */
+            }
+        }
+    }
+
+    wlr_buffer_end_data_ptr_access(buf);
+    return res;
+}
 
 static int
 wl_coords_translate(WNativeWindow src, WNativeWindow dst,