output: add wlr_output_add_software_cursors_to_render_pass()

Same as wlr_output_render_software_cursors(), but takes a
struct wlr_render_pass.

include/wlr/types/wlr_output.h

@@ -112,6 +112,7 @@ struct wlr_output_state {
 };
 
 struct wlr_output_impl;
+struct wlr_render_pass;
 
 /**
  * A compositor output region. This typically corresponds to a monitor that
@@ -515,6 +516,13 @@ void wlr_output_lock_software_cursors(struct wlr_output *output, bool lock);
  */
 void wlr_output_render_software_cursors(struct wlr_output *output,
 	const pixman_region32_t *damage);
+/**
+ * Render software cursors.
+ *
+ * This is a utility function that can be called when compositors render.
+ */
+void wlr_output_add_software_cursors_to_render_pass(struct wlr_output *output,
+	struct wlr_render_pass *render_pass, const pixman_region32_t *damage);
 /**
  * Get the set of DRM formats suitable for the primary buffer, assuming a
  * buffer with the specified capabilities.

types/output/cursor.c

@@ -7,6 +7,7 @@
 #include <wlr/types/wlr_compositor.h>
 #include <wlr/types/wlr_matrix.h>
 #include <wlr/util/log.h>
+#include <wlr/util/region.h>
 #include "render/allocator/allocator.h"
 #include "types/wlr_buffer.h"
 #include "types/wlr_output.h"
@@ -156,6 +157,61 @@ void wlr_output_render_software_cursors(struct wlr_output *output,
 	pixman_region32_fini(&render_damage);
 }
 
+void wlr_output_add_software_cursors_to_render_pass(struct wlr_output *output,
+		struct wlr_render_pass *render_pass, const pixman_region32_t *damage) {
+	int width, height;
+	wlr_output_transformed_resolution(output, &width, &height);
+
+	pixman_region32_t render_damage;
+	pixman_region32_init_rect(&render_damage, 0, 0, width, height);
+	if (damage != NULL) {
+		pixman_region32_intersect(&render_damage, &render_damage, damage);
+	}
+
+	struct wlr_output_cursor *cursor;
+	wl_list_for_each(cursor, &output->cursors, link) {
+		if (!cursor->enabled || !cursor->visible ||
+				output->hardware_cursor == cursor) {
+			continue;
+		}
+
+		struct wlr_texture *texture = cursor->texture;
+		if (cursor->surface != NULL) {
+			texture = wlr_surface_get_texture(cursor->surface);
+		}
+		if (texture == NULL) {
+			continue;
+		}
+
+		struct wlr_box box;
+		output_cursor_get_box(cursor, &box);
+
+		pixman_region32_t cursor_damage;
+		pixman_region32_init_rect(&cursor_damage, box.x, box.y, box.width, box.height);
+		pixman_region32_intersect(&cursor_damage, &cursor_damage, &render_damage);
+		if (!pixman_region32_not_empty(&cursor_damage)) {
+			pixman_region32_fini(&cursor_damage);
+			continue;
+		}
+
+		enum wl_output_transform transform =
+			wlr_output_transform_invert(output->transform);
+		wlr_box_transform(&box, &box, transform, width, height);
+		wlr_region_transform(&cursor_damage, &cursor_damage, transform, width, height);
+
+		wlr_render_pass_add_texture(render_pass, &(struct wlr_render_texture_options) {
+			.texture = texture,
+			.dst_box = box,
+			.clip = &cursor_damage,
+			.transform = output->transform,
+		});
+
+		pixman_region32_fini(&cursor_damage);
+	}
+
+	pixman_region32_fini(&render_damage);
+}
+
 static void output_cursor_damage_whole(struct wlr_output_cursor *cursor) {
 	struct wlr_box box;
 	output_cursor_get_box(cursor, &box);