From b6c1760de5952584cb868f491a12addfb9d9c114 Mon Sep 17 00:00:00 2001
From: emersion <contact@emersion.fr>
Date: Tue, 27 Mar 2018 12:04:37 -0400
Subject: xwayland: create DND window, add DND atom helpers

---
 include/xwayland/xwm.h | 18 ++++++++++++++++
 xwayland/selection.c   | 58 ++++++++++++++++++++++++++++++++++++++++++++++++--
 xwayland/xwm.c         | 16 ++++++++++++--
 3 files changed, 88 insertions(+), 4 deletions(-)

diff --git a/include/xwayland/xwm.h b/include/xwayland/xwm.h
index 9e21ea3a..81a4df0b 100644
--- a/include/xwayland/xwm.h
+++ b/include/xwayland/xwm.h
@@ -53,6 +53,20 @@ enum atom_name {
 	NET_WM_WINDOW_TYPE_DROPDOWN_MENU,
 	NET_WM_WINDOW_TYPE_POPUP_MENU,
 	NET_WM_WINDOW_TYPE_COMBO,
+	DND_SELECTION,
+	DND_AWARE,
+	DND_STATUS,
+	DND_POSITION,
+	DND_ENTER,
+	DND_LEAVE,
+	DND_DROP,
+	DND_FINISHED,
+	DND_PROXY,
+	DND_TYPE_LIST,
+	DND_ACTION_MOVE,
+	DND_ACTION_COPY,
+	DND_ACTION_ASK,
+	DND_ACTION_PRIVATE,
 	ATOM_LAST,
 };
 
@@ -64,6 +78,8 @@ enum net_wm_state_action {
 	NET_WM_STATE_TOGGLE = 2,
 };
 
+#define XDND_VERSION 5
+
 struct wlr_xwm_selection {
 	struct wlr_xwm *xwm;
 	xcb_atom_t atom;
@@ -100,6 +116,8 @@ struct wlr_xwm {
 	struct wlr_xwm_selection clipboard_selection;
 	struct wlr_xwm_selection primary_selection;
 
+	xcb_window_t dnd_window;
+
 	struct wlr_xwayland_surface *focus_surface;
 
 	struct wl_list surfaces; // wlr_xwayland_surface::link
diff --git a/xwayland/selection.c b/xwayland/selection.c
index 72f3de3e..a7ed2cf0 100644
--- a/xwayland/selection.c
+++ b/xwayland/selection.c
@@ -12,6 +12,32 @@
 
 static const size_t incr_chunk_size = 64 * 1024;
 
+static xcb_atom_t data_device_manager_dnd_action_to_atom(
+		struct wlr_xwm *xwm, enum wl_data_device_manager_dnd_action action) {
+	if (action & WL_DATA_DEVICE_MANAGER_DND_ACTION_COPY) {
+		return xwm->atoms[DND_ACTION_COPY];
+	} else if (action & WL_DATA_DEVICE_MANAGER_DND_ACTION_MOVE) {
+		return xwm->atoms[DND_ACTION_MOVE];
+	} else if (action & WL_DATA_DEVICE_MANAGER_DND_ACTION_ASK) {
+		return xwm->atoms[DND_ACTION_ASK];
+	}
+	return XCB_ATOM_NONE;
+}
+
+static enum wl_data_device_manager_dnd_action
+		data_device_manager_dnd_action_from_atom(struct wlr_xwm *xwm,
+		enum atom_name atom) {
+	if (atom == xwm->atoms[DND_ACTION_COPY] ||
+			atom == xwm->atoms[DND_ACTION_PRIVATE]) {
+		return WL_DATA_DEVICE_MANAGER_DND_ACTION_COPY;
+	} else if (atom == xwm->atoms[DND_ACTION_MOVE]) {
+		return WL_DATA_DEVICE_MANAGER_DND_ACTION_MOVE;
+	} else if (atom == xwm->atoms[DND_ACTION_ASK]) {
+		return WL_DATA_DEVICE_MANAGER_DND_ACTION_ASK;
+	}
+	return WL_DATA_DEVICE_MANAGER_DND_ACTION_NONE;
+}
+
 static void xwm_selection_send_notify(struct wlr_xwm_selection *selection,
 		xcb_atom_t property) {
 	xcb_selection_notify_event_t selection_notify = {
@@ -807,7 +833,8 @@ static void selection_init(struct wlr_xwm *xwm,
 }
 
 void xwm_selection_init(struct wlr_xwm *xwm) {
-	uint32_t values[] = { XCB_EVENT_MASK_PROPERTY_CHANGE };
+	// Clipboard and primary selection
+	uint32_t selection_values[] = { XCB_EVENT_MASK_PROPERTY_CHANGE };
 	xwm->selection_window = xcb_generate_id(xwm->xcb_conn);
 	xcb_create_window(xwm->xcb_conn,
 		XCB_COPY_FROM_PARENT,
@@ -818,7 +845,7 @@ void xwm_selection_init(struct wlr_xwm *xwm) {
 		0,
 		XCB_WINDOW_CLASS_INPUT_OUTPUT,
 		xwm->screen->root_visual,
-		XCB_CW_EVENT_MASK, values);
+		XCB_CW_EVENT_MASK, selection_values);
 
 	xcb_set_selection_owner(xwm->xcb_conn,
 		xwm->selection_window,
@@ -827,6 +854,30 @@ void xwm_selection_init(struct wlr_xwm *xwm) {
 
 	selection_init(xwm, &xwm->clipboard_selection, xwm->atoms[CLIPBOARD]);
 	selection_init(xwm, &xwm->primary_selection, xwm->atoms[PRIMARY]);
+
+	// Drag'n'drop
+	uint32_t dnd_values[] = { XCB_EVENT_MASK_PROPERTY_CHANGE };
+	xwm->dnd_window = xcb_generate_id(xwm->xcb_conn);
+	xcb_create_window(xwm->xcb_conn,
+		XCB_COPY_FROM_PARENT,
+		xwm->dnd_window,
+		xwm->screen->root,
+		0, 0,
+		10, 10,
+		0,
+		XCB_WINDOW_CLASS_INPUT_OUTPUT,
+		xwm->screen->root_visual,
+		XCB_CW_EVENT_MASK, dnd_values);
+
+	uint32_t version = XDND_VERSION;
+	xcb_change_property(xwm->xcb_conn,
+		XCB_PROP_MODE_REPLACE,
+		xwm->dnd_window,
+		xwm->atoms[DND_AWARE],
+		XCB_ATOM_ATOM,
+		32,
+		1,
+		&version);
 }
 
 void xwm_selection_finish(struct wlr_xwm *xwm) {
@@ -836,6 +887,9 @@ void xwm_selection_finish(struct wlr_xwm *xwm) {
 	if (xwm->selection_window) {
 		xcb_destroy_window(xwm->xcb_conn, xwm->selection_window);
 	}
+	if (xwm->dnd_window) {
+		xcb_destroy_window(xwm->xcb_conn, xwm->dnd_window);
+	}
 	if (xwm->seat) {
 		if (xwm->seat->selection_data_source &&
 				xwm->seat->selection_data_source->cancel == data_source_cancel) {
diff --git a/xwayland/xwm.c b/xwayland/xwm.c
index 8911c553..a1ac43d6 100644
--- a/xwayland/xwm.c
+++ b/xwayland/xwm.c
@@ -56,9 +56,22 @@ const char *atom_map[ATOM_LAST] = {
 	"_NET_WM_WINDOW_TYPE_DROPDOWN_MENU",
 	"_NET_WM_WINDOW_TYPE_POPUP_MENU",
 	"_NET_WM_WINDOW_TYPE_COMBO",
+	"XdndSelection",
+	"XdndAware",
+	"XdndStatus",
+	"XdndPosition",
+	"XdndEnter",
+	"XdndLeave",
+	"XdndDrop",
+	"XdndFinished",
+	"XdndProxy",
+	"XdndTypeList",
+	"XdndActionMove",
+	"XdndActionCopy",
+	"XdndActionAsk",
+	"XdndActionPrivate",
 };
 
-/* General helpers */
 // TODO: replace this with hash table?
 static struct wlr_xwayland_surface *lookup_surface(struct wlr_xwm *xwm,
 		xcb_window_t window_id) {
@@ -1531,4 +1544,3 @@ bool xwm_atoms_contains(struct wlr_xwm *xwm, xcb_atom_t *atoms,
 
 	return false;
 }
-
-- 
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