From 4ea8be24492f58564ff1b1efe9f7c4673078bcbc Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Tue, 2 Apr 2019 21:01:16 +0800
Subject: ...

---
 include/cru/platform/painter_util.hpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

(limited to 'include/cru/platform/painter_util.hpp')

diff --git a/include/cru/platform/painter_util.hpp b/include/cru/platform/painter_util.hpp
index fed0c487..5711d099 100644
--- a/include/cru/platform/painter_util.hpp
+++ b/include/cru/platform/painter_util.hpp
@@ -2,13 +2,17 @@
 #include "painter.hpp"
 
 #include <functional>
+#include <type_traits>
 
 namespace cru::platform::util {
+template <typename Fn>
 inline void WithTransform(Painter* painter, const Matrix& matrix,
-                   const std::function<void(Painter*)>& action) {
+                          const Fn& action) {
+  static_assert(std::is_invocable_v<decltype(action), Painter*>,
+                "Action must can be be invoked with painter.");
   const auto old = painter->GetTransform();
   painter->SetTransform(old * matrix);
   action(painter);
   painter->SetTransform(old);
 }
-}
+}  // namespace cru::platform::util
-- 
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