util/transform: move over wl_output_transform helpers

These aren't really tied to wlr_output.

1 files changed, 28 insertions, 0 deletions

diff --git a/include/wlr/util/transform.h b/include/wlr/util/transform.h
new file mode 100644
index 00000000..d0ec5f53
--- /dev/null
+++ b/include/wlr/util/transform.h
@@ -0,0 +1,28 @@
+/*
+ * This an unstable interface of wlroots. No guarantees are made regarding the
+ * future consistency of this API.
+ */
+#ifndef WLR_USE_UNSTABLE
+#error "Add -DWLR_USE_UNSTABLE to enable unstable wlroots features"
+#endif
+
+#ifndef WLR_UTIL_TRANSFORM_H
+#define WLR_UTIL_TRANSFORM_H
+
+#include <wayland-server-protocol.h>
+
+/**
+ * Returns the transform that, when composed with `tr`, gives
+ * `WL_OUTPUT_TRANSFORM_NORMAL`.
+ */
+enum wl_output_transform wlr_output_transform_invert(
+	enum wl_output_transform tr);
+
+/**
+ * Returns a transform that, when applied, has the same effect as applying
+ * sequentially `tr_a` and `tr_b`.
+ */
+enum wl_output_transform wlr_output_transform_compose(
+	enum wl_output_transform tr_a, enum wl_output_transform tr_b);
+
+#endif