Update SaveGuard

and add a test in tests/test-context.cc. Fixes #9

3 files changed, 47 insertions, 30 deletions

diff --git a/cairomm/context.cc b/cairomm/context.cc
index ce1a838..aa217ba 100644
--- a/cairomm/context.cc
+++ b/cairomm/context.cc
@@ -886,16 +886,17 @@ RefPtr<const Surface> Context::get_group_target() const
   return get_surface_wrapper(surface);
 }
 
-SaveGuard::SaveGuard(RefPtr<Context> context) : ctx_{context}
+SaveGuard::SaveGuard(const RefPtr<Context>& context)
+: ctx_{context}
 {
-  ctx_->save();
+  if (ctx_)
+    ctx_->save();
 }
 
 SaveGuard::~SaveGuard()
 {
-  ctx_->restore();
+  if (ctx_)
+    ctx_->restore();
 }
 
 } //namespace Cairo
-
-// vim: ts=2 sw=2 et
diff --git a/cairomm/context.h b/cairomm/context.h
index 1a77c78..20f1e7b 100644
--- a/cairomm/context.h
+++ b/cairomm/context.h
@@ -250,14 +250,14 @@ public:
    * It isn't necessary to clear all saved states before a cairo_t is freed.
    * Any saved states will be freed when the Context is destroyed.
    *
-   * @sa restore()
+   * @sa restore(), SaveGuard
    */
   void save();
 
   /** Restores cr to the state saved by a preceding call to save() and removes
    * that state from the stack of saved states.
    *
-   * @sa save()
+   * @sa save(), SaveGuard
    */
   void restore();
 
@@ -1703,33 +1703,43 @@ protected:
   cobject* m_cobject;
 };
 
-
-/** RAII-style context save/restore class.  context->save() is called
- * automatically when the object is created, and context->restore() is called
- * when the object is destroyed.  This allows you to write code such as:
+/** RAII-style context save/restore class.
+ * Cairo::Context::save() is called automatically when the object is created,
+ * and Cairo::Context::restore() is called when the object is destroyed.
+ * This allows you to write code such as:
+ * @code
+ * // context initial state
+ * {
+ *   Cairo::SaveGuard saver(context);
+ *   ... // manipulate context
+ * }
+ * // context is restored to initial state
+ * @endcode
  *
- *     // context initial state
- *     {
- *         Cairo::SaveGuard saver(context);
- *         ... // manipulate context
- *     }
- *     // context is restored to initial state
+ * @newin{1,18}
  */
-class SaveGuard final {
-  public:
-    /// Constructor: the context is saved
-    explicit SaveGuard(RefPtr<Context> context);
-    /// Copy constructor deleted
-    SaveGuard(const SaveGuard &) = delete;
-    /// Destructor; the context is restored
-    ~SaveGuard();
-  private:
-    RefPtr<Context> ctx_;
-};
+class SaveGuard final
+{
+public:
+  /// Constructor, the context is saved.
+  CAIROMM_API explicit SaveGuard(const RefPtr<Context>& context);
+
+#ifndef DOXYGEN_IGNORE_THIS
+  // noncopyable
+  SaveGuard(const SaveGuard&) = delete;
+  SaveGuard& operator=(const SaveGuard&) = delete;
+  // nonmovable
+  SaveGuard(SaveGuard&&) = delete;
+  SaveGuard& operator=(SaveGuard&&) = delete;
+#endif //DOXYGEN_IGNORE_THIS
 
+  /// Destructor, the context is restored.
+  CAIROMM_API ~SaveGuard();
+
+private:
+  RefPtr<Context> ctx_;
+};
 
 } // namespace Cairo
 
 #endif //__CAIROMM_CONTEXT_H
-
-// vim: ts=2 sw=2 et
diff --git a/tests/test-context.cc b/tests/test-context.cc
index 830a099..b249489 100644
--- a/tests/test-context.cc
+++ b/tests/test-context.cc
@@ -70,6 +70,12 @@ BOOST_AUTO_TEST_CASE(test_save_restore)
   BOOST_CHECK_EQUAL (4.0, cr->get_line_width ());
   cr->restore ();
   BOOST_CHECK_EQUAL (2.3, cr->get_line_width ());
+  {
+    Cairo::SaveGuard guard(cr);
+    cr->set_line_width(3.0);
+    BOOST_CHECK_EQUAL(3.0, cr->get_line_width());
+  }
+  BOOST_CHECK_EQUAL(2.3, cr->get_line_width());
 }
 
 BOOST_AUTO_TEST_CASE(test_operator)