4 files changed, 77 insertions, 2 deletions

diff --git a/rootston/cursor.c b/rootston/cursor.c
index 65109534..6b509640 100644
--- a/rootston/cursor.c
+++ b/rootston/cursor.c
@@ -1,8 +1,10 @@
 #define _XOPEN_SOURCE 700
+#include <stdlib.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <string.h>
 #include <math.h>
+#include <assert.h>
 #ifdef __linux__
 #include <linux/input-event-codes.h>
 #elif __FreeBSD__
@@ -11,6 +13,7 @@
 #include <wayland-server.h>
 #include <wlr/types/wlr_cursor.h>
 #include <wlr/util/log.h>
+#include <wlr/types/wlr_data_device.h>
 #include "rootston/config.h"
 #include "rootston/input.h"
 #include "rootston/desktop.h"
@@ -295,6 +298,60 @@ static void handle_tool_tip(struct wl_listener *listener, void *data) {
 			(uint32_t)(event->time_usec / 1000), BTN_LEFT, event->state);
 }
 
+static void handle_drag_icon_destroy(struct wl_listener *listener, void *data) {
+	struct roots_drag_icon *drag_icon =
+		wl_container_of(listener, drag_icon, surface_destroy);
+	wl_list_remove(&drag_icon->link);
+	wl_list_remove(&drag_icon->surface_destroy.link);
+	wl_list_remove(&drag_icon->surface_commit.link);
+	free(drag_icon);
+}
+
+static void handle_drag_icon_commit(struct wl_listener *listener, void *data) {
+	struct roots_drag_icon *drag_icon =
+		wl_container_of(listener, drag_icon, surface_commit);
+	// TODO the spec hints at rules that can determine whether the drag icon is
+	// mapped here, but it is not completely clear so we need to test more
+	// toolkits to see how we should interpret the surface state here.
+	drag_icon->sx += drag_icon->surface->current->sx;
+	drag_icon->sy += drag_icon->surface->current->sy;
+
+	drag_icon->mapped = drag_icon->surface->texture->valid;
+}
+
+static void handle_pointer_grab_begin(struct wl_listener *listener,
+		void *data) {
+	struct roots_input *input =
+		wl_container_of(listener, input, pointer_grab_begin);
+	struct wlr_seat_pointer_grab *grab = data;
+
+	if (grab->interface == &wlr_data_device_pointer_drag_interface) {
+		struct wlr_drag *drag = grab->data;
+		if (drag->icon) {
+			struct roots_drag_icon *iter_icon;
+			wl_list_for_each(iter_icon, &input->drag_icons, link) {
+				if (iter_icon->surface == drag->icon) {
+					// already in the list
+					return;
+				}
+			}
+
+			struct roots_drag_icon *drag_icon =
+				calloc(1, sizeof(struct roots_drag_icon));
+			drag_icon->surface = drag->icon;
+			wl_list_insert(&input->drag_icons, &drag_icon->link);
+
+			wl_signal_add(&drag->icon->events.destroy,
+				&drag_icon->surface_destroy);
+			drag_icon->surface_destroy.notify = handle_drag_icon_destroy;
+
+			wl_signal_add(&drag->icon->events.commit,
+				&drag_icon->surface_commit);
+			drag_icon->surface_commit.notify = handle_drag_icon_commit;
+		}
+	}
+}
+
 static void handle_pointer_grab_end(struct wl_listener *listener, void *data) {
 	struct roots_input *input =
 		wl_container_of(listener, input, pointer_grab_end);
@@ -362,6 +419,9 @@ void cursor_initialize(struct roots_input *input) {
 	wl_signal_add(&input->wl_seat->events.pointer_grab_end, &input->pointer_grab_end);
 	input->pointer_grab_end.notify = handle_pointer_grab_end;
 
+	wl_signal_add(&input->wl_seat->events.pointer_grab_begin, &input->pointer_grab_begin);
+	input->pointer_grab_begin.notify = handle_pointer_grab_begin;
+
 	wl_list_init(&input->request_set_cursor.link);
 	wl_signal_add(&input->wl_seat->events.request_set_cursor,
 		&input->request_set_cursor);
diff --git a/rootston/input.c b/rootston/input.c
index 86a87e24..f08b735a 100644
--- a/rootston/input.c
+++ b/rootston/input.c
@@ -110,6 +110,8 @@ struct roots_input *input_create(struct roots_server *server,
 	cursor_load_config(config, input->cursor,
 		input, server->desktop);
 
+	wl_list_init(&input->drag_icons);
+
 	return input;
 }
 
diff --git a/rootston/main.c b/rootston/main.c
index 5a60000c..f262a30f 100644
--- a/rootston/main.c
+++ b/rootston/main.c
@@ -19,11 +19,11 @@ int main(int argc, char **argv) {
 	assert(server.backend = wlr_backend_autocreate(server.wl_display));
 
 	assert(server.renderer = wlr_gles2_renderer_create(server.backend));
+	server.data_device_manager =
+		wlr_data_device_manager_create(server.wl_display);
 	wl_display_init_shm(server.wl_display);
 	server.desktop = desktop_create(&server, server.config);
 	server.input = input_create(&server, server.config);
-	server.data_device_manager = wlr_data_device_manager_create(
-			server.wl_display);
 
 	const char *socket = wl_display_add_socket_auto(server.wl_display);
 	if (!socket) {
diff --git a/rootston/output.c b/rootston/output.c
index 39a90fe3..f50306a3 100644
--- a/rootston/output.c
+++ b/rootston/output.c
@@ -150,6 +150,19 @@ static void output_frame_notify(struct wl_listener *listener, void *data) {
 		render_view(view, desktop, wlr_output, &now);
 	}
 
+	struct roots_drag_icon *drag_icon = NULL;
+	wl_list_for_each(drag_icon, &server->input->drag_icons, link) {
+		if (!drag_icon->mapped) {
+			continue;
+		}
+
+		struct wlr_surface *icon = drag_icon->surface;
+		struct wlr_cursor *cursor = server->input->cursor;
+		double icon_x = cursor->x + drag_icon->sx;
+		double icon_y = cursor->y + drag_icon->sy;
+		render_surface(icon, desktop, wlr_output, &now, icon_x, icon_y, 0);
+	}
+
 	wlr_renderer_end(server->renderer);
 	wlr_output_swap_buffers(wlr_output);