winewayland.drv: Handle Wayland data device selection event.

Handle the Wayland event which informs us of the new current clipboard
selection. We use the provided event information to update the available
formats in the Windows clipboard, without populating them with any
actual data. We populate the clipboard data on demand through the
handling of the WM_RENDERFORMAT message.

Signed-off-by: Alexandros Frantzis <alexandros.frantzis@collabora.com>

dlls/winewayland.drv/wayland_data_device.c

@@ -325,11 +325,78 @@ static void data_device_selection(void *data,
                                   struct wl_data_offer *wl_data_offer)
 {
     struct wayland_data_device *data_device = data;
+    struct wayland *wayland = thread_wayland();
+    struct wayland_data_offer *data_offer;
+    char **p;
+
+    TRACE("wl_data_offer=%u\n",
+          wl_data_offer ? wl_proxy_get_id((struct wl_proxy*)wl_data_offer) : 0);
+
+    /* We may get a selection event before we have had a chance to create the
+     * clipboard window after thread init (see wayland_init_thread_data), so
+     * we need to ensure we have a valid window here. */
+    wayland_data_device_ensure_clipboard_window(wayland);
 
     /* Destroy any previous data offer. */
     wayland_data_device_destroy_clipboard_data_offer(data_device);
 
+    /* If we didn't get an offer and we are the clipboard owner, empty the
+     * clipboard. Otherwise ignore the empty offer completely. */
+    if (!wl_data_offer)
+    {
+        if (NtUserGetClipboardOwner() == wayland->clipboard_hwnd)
+        {
+            NtUserOpenClipboard(NULL, 0);
+            NtUserEmptyClipboard();
+            NtUserCloseClipboard();
+        }
+        return;
+    }
+
+    data_offer = wl_data_offer_get_user_data(wl_data_offer);
+
+    /* If this offer contains the special winewayland tag mime-type, it was sent
+     * from us to notify external wayland clients about a wine clipboard update.
+     * The clipboard already contains all the required data, plus we need to ignore
+     * this in order to avoid an endless notification loop. */
+    wl_array_for_each(p, &data_offer->types)
+    {
+        if (!strcmp(*p, WINEWAYLAND_TAG_MIME_TYPE))
+        {
+            TRACE("ignoring offer produced by winewayland\n");
+            goto ignore_selection;
+        }
+    }
+
+    if (!NtUserOpenClipboard(data_offer->wayland->clipboard_hwnd, 0))
+    {
+        WARN("failed to open clipboard for selection\n");
+        goto ignore_selection;
+    }
+
+    NtUserEmptyClipboard();
+
+    /* For each mime type, mark that we have available clipboard data. */
+    wl_array_for_each(p, &data_offer->types)
+    {
+        struct wayland_data_device_format *format =
+            wayland_data_device_format_for_mime_type(*p);
+        if (format)
+        {
+            struct set_clipboard_params params = { .data = NULL };
+            TRACE("Avalaible clipboard format for %s => %u\n", *p, format->clipboard_format);
+            NtUserSetClipboardData(format->clipboard_format, 0, &params);
+        }
+    }
+
+    NtUserCloseClipboard();
+
     data_device->clipboard_wl_data_offer = wl_data_offer;
+
+    return;
+
+ignore_selection:
+    wayland_data_offer_destroy(data_offer);
 }
 
 static const struct wl_data_device_listener data_device_listener = {