render: add render pass helpers

include/wlr/render/interface.h

@@ -79,4 +79,10 @@ struct wlr_render_pass_impl {
 		const struct wlr_render_rect_options *options);
 };
 
+void wlr_render_texture_options_get_src_box(const struct wlr_render_texture_options *options,
+	struct wlr_fbox *box);
+void wlr_render_texture_options_get_dst_box(const struct wlr_render_texture_options *options,
+	struct wlr_box *box);
+float wlr_render_texture_options_get_alpha(const struct wlr_render_texture_options *options);
+
 #endif

render/pass.c

@@ -23,3 +23,30 @@ void wlr_render_pass_add_rect(struct wlr_render_pass *render_pass,
 		const struct wlr_render_rect_options *options) {
 	render_pass->impl->add_rect(render_pass, options);
 }
+
+void wlr_render_texture_options_get_src_box(const struct wlr_render_texture_options *options,
+		struct wlr_fbox *box) {
+	*box = options->src_box;
+	if (wlr_fbox_empty(box)) {
+		*box = (struct wlr_fbox){
+			.width = options->texture->width,
+			.height = options->texture->height,
+		};
+	}
+}
+
+void wlr_render_texture_options_get_dst_box(const struct wlr_render_texture_options *options,
+		struct wlr_box *box) {
+	*box = options->dst_box;
+	if (wlr_box_empty(box)) {
+		box->width = options->texture->width;
+		box->height = options->texture->height;
+	}
+}
+
+float wlr_render_texture_options_get_alpha(const struct wlr_render_texture_options *options) {
+	if (options->alpha == NULL) {
+		return 1;
+	}
+	return *options->alpha;
+}