wlr_scene: Introduce xcursor helper

include/wlr/types/wlr_scene.h

@@ -33,6 +33,7 @@ struct wlr_xdg_surface;
 struct wlr_layer_surface_v1;
 struct wlr_drag_icon;
 struct wlr_surface;
+struct wlr_xcursor_manager;
 
 struct wlr_scene_node;
 struct wlr_scene_buffer;
@@ -506,4 +507,10 @@ void wlr_scene_layer_surface_v1_configure(
 struct wlr_scene_tree *wlr_scene_drag_icon_create(
 	struct wlr_scene_tree *parent, struct wlr_drag_icon *drag_icon);
 
+/**
+ * Add a node displaying an xcursor to the scene-graph.
+ */
+struct wlr_scene_tree *wlr_scene_xcursor_create(struct wlr_scene_tree *parent,
+	struct wlr_xcursor_manager *manager, const char *name);
+
 #endif

types/meson.build

@@ -14,6 +14,7 @@ wlr_files += files(
 	'scene/surface.c',
 	'scene/wlr_scene.c',
 	'scene/output_layout.c',
+	'scene/xcursor.c',
 	'scene/xdg_shell.c',
 	'scene/layer_shell_v1.c',
 	'seat/wlr_seat_keyboard.c',

types/scene/xcursor.c

@@ -0,0 +1,204 @@
+#define _POSIX_C_SOURCE 200809L
+#include <drm_fourcc.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wlr/types/wlr_scene.h>
+#include <wlr/types/wlr_xcursor_manager.h>
+#include <wlr/interfaces/wlr_buffer.h>
+
+struct xcursor_buffer {
+	struct wlr_buffer base;
+	struct wlr_xcursor_image image;
+};
+
+static void xcursor_buffer_handle_destroy(struct wlr_buffer *wlr_buffer) {
+	struct xcursor_buffer *buffer = wl_container_of(wlr_buffer, buffer, base);
+	free(buffer);
+}
+
+static bool xcursor_buffer_handle_begin_data_ptr_access(struct wlr_buffer *wlr_buffer,
+		uint32_t flags, void **data, uint32_t *format, size_t *stride) {
+	struct xcursor_buffer *buffer = wl_container_of(wlr_buffer, buffer, base);
+	*data = buffer->image.buffer;
+	*stride = buffer->image.width * 4;
+	*format = DRM_FORMAT_ARGB8888;
+	return true;
+}
+
+static void xcursor_buffer_handle_end_data_ptr_access(struct wlr_buffer *wlr_buffer) {
+	// This space is intentionally left blank
+}
+
+static const struct wlr_buffer_impl xcursor_buffer_impl = {
+	.destroy = xcursor_buffer_handle_destroy,
+	.begin_data_ptr_access = xcursor_buffer_handle_begin_data_ptr_access,
+	.end_data_ptr_access = xcursor_buffer_handle_end_data_ptr_access,
+};
+
+struct wlr_scene_xcursor {
+	struct wlr_scene_tree *tree;
+	struct wlr_scene_buffer *buffer;
+	struct wlr_xcursor_manager *manager;
+	char *name;
+	float scale;
+
+	struct wl_list outputs; // struct wlr_scene_xcursor_output.link
+
+	struct wl_listener output_enter;
+	struct wl_listener output_leave;
+	struct wl_listener tree_destroy;
+};
+
+struct wlr_scene_xcursor_output {
+	struct wlr_scene_xcursor *xcursor;
+	struct wlr_output *output;
+	struct wl_list link;
+	struct wl_listener commit;
+};
+
+static void scene_xcursor_update_cursor(struct wlr_scene_xcursor *cursor) {
+	float scale = 1;
+	struct wlr_scene_xcursor_output *output;
+	wl_list_for_each(output, &cursor->outputs, link) {
+		if (output->output->scale > scale) {
+			output->output->scale = scale;
+		}
+	}
+
+	if (scale == cursor->scale) {
+		return;
+	}
+
+	cursor->scale = scale;
+
+	if (!wlr_xcursor_manager_load(cursor->manager, scale)) {
+		return;
+	}
+
+	struct wlr_xcursor *xcursor =
+		wlr_xcursor_manager_get_xcursor(cursor->manager, cursor->name, scale);
+	if (!xcursor) {
+		return;
+	}
+
+	struct wlr_xcursor_image *image = xcursor->images[0];
+
+	struct xcursor_buffer *xcursor_buffer = calloc(1, sizeof(*xcursor_buffer));
+	if (!xcursor_buffer) {
+		return;
+	}
+
+	wlr_buffer_init(&xcursor_buffer->base, &xcursor_buffer_impl, image->width, image->height);
+	xcursor_buffer->image = *image;
+
+	wlr_scene_node_set_position(&cursor->buffer->node,
+		-image->hotspot_x, -image->hotspot_y);
+	wlr_scene_buffer_set_dest_size(cursor->buffer,
+		image->width / scale, image->height / scale);
+	wlr_scene_buffer_set_buffer(cursor->buffer, &xcursor_buffer->base);
+
+	wlr_buffer_drop(&xcursor_buffer->base);
+}
+
+static void handle_output_commit(struct wl_listener *listener, void *data) {
+	struct wlr_scene_xcursor_output *output = wl_container_of(listener, output, commit);
+	struct wlr_output_event_commit *event = data;
+
+	if (event->committed & WLR_OUTPUT_STATE_SCALE) {
+		scene_xcursor_update_cursor(output->xcursor);
+	}
+}
+
+static void handle_output_enter(struct wl_listener *listener, void *data) {
+	struct wlr_scene_xcursor *cursor = wl_container_of(listener, cursor, output_enter);
+	struct wlr_scene_output *scene_output = data;
+
+	struct wlr_scene_xcursor_output *output = calloc(1, sizeof(*output));
+	if (!output) {
+		return;
+	}
+
+	output->output = scene_output->output;
+	output->xcursor = cursor;
+
+	output->commit.notify = handle_output_commit;
+	wl_signal_add(&output->output->events.commit, &output->commit);
+
+	wl_list_insert(&cursor->outputs, &output->link);
+	scene_xcursor_update_cursor(cursor);
+}
+
+static void output_destroy(struct wlr_scene_xcursor_output *output) {
+	wl_list_remove(&output->link);
+	wl_list_remove(&output->commit.link);
+	free(output);
+}
+
+static void handle_output_leave(struct wl_listener *listener, void *data) {
+	struct wlr_scene_xcursor *cursor = wl_container_of(listener, cursor, output_leave);
+	struct wlr_scene_output *scene_output = data;
+
+	struct wlr_scene_xcursor_output *output, *tmp_output;
+	wl_list_for_each_safe(output, tmp_output, &cursor->outputs, link) {
+		if (output->output == scene_output->output) {
+			output_destroy(output);
+			scene_xcursor_update_cursor(cursor);
+			return;
+		}
+	}
+}
+
+static void scene_xcursor_handle_tree_destroy(struct wl_listener *listener, void *data) {
+	struct wlr_scene_xcursor *cursor = wl_container_of(listener, cursor, tree_destroy);
+
+	struct wlr_scene_xcursor_output *output, *tmp_output;
+	wl_list_for_each_safe(output, tmp_output, &cursor->outputs, link) {
+		output_destroy(output);
+	}
+
+	wl_list_remove(&cursor->tree_destroy.link);
+	free(cursor->name);
+	free(cursor);
+}
+
+struct wlr_scene_tree *wlr_scene_xcursor_create(struct wlr_scene_tree *parent,
+		struct wlr_xcursor_manager *manager, const char *name) {
+	struct wlr_scene_xcursor *cursor = calloc(1, sizeof(*cursor));
+	if (!cursor) {
+		return NULL;
+	}
+
+	cursor->tree = wlr_scene_tree_create(parent);
+	if (!cursor->tree) {
+		free(cursor);
+		return NULL;
+	}
+
+	cursor->buffer = wlr_scene_buffer_create(cursor->tree, NULL);
+	if (!cursor->buffer) {
+		wlr_scene_node_destroy(&cursor->tree->node);
+		free(cursor);
+		return NULL;
+	}
+
+	cursor->name = strdup(name);
+	if (!cursor->name) {
+		wlr_scene_node_destroy(&cursor->tree->node);
+		free(cursor);
+		return NULL;
+	}
+
+	wl_list_init(&cursor->outputs);
+	cursor->manager = manager;
+
+	cursor->output_enter.notify = handle_output_enter;
+	wl_signal_add(&cursor->buffer->events.output_enter, &cursor->output_enter);
+	cursor->output_leave.notify = handle_output_leave;
+	wl_signal_add(&cursor->buffer->events.output_leave, &cursor->output_leave);
+	cursor->tree_destroy.notify = scene_xcursor_handle_tree_destroy;
+	wl_signal_add(&cursor->tree->node.events.destroy, &cursor->tree_destroy);
+
+	scene_xcursor_update_cursor(cursor);
+
+	return cursor->tree;
+}