renderer: add transformers

src/render/Transformer.hpp

@@ -0,0 +1,13 @@
+#pragma once
+
+#include "Framebuffer.hpp"
+
+// A window transformer can be attached to a window.
+// If any is attached, Hyprland will render the window to a separate fb, then call the transform() func with it,
+// and finally render it back to the main fb after all transformers pass.
+class IWindowTransformer {
+  public:
+    // called by Hyprland. For more data about what is being rendered, inspect render data.
+    // returns the out fb.
+    virtual CFramebuffer* transform(CFramebuffer* in) = 0;
+};