Start to permeate more ownership.

dw/platform.hh

@@ -1,6 +1,8 @@
 #ifndef __DW_PLATFORM_HH__
 #define __DW_PLATFORM_HH__
 
+#include <memory>
+
 #ifndef __INCLUDED_FROM_DW_CORE_HH__
 #   error Do not include this file directly, use "core.hh" instead.
 #endif
@@ -152,8 +154,8 @@ public:
     *
     * "gamma" is the value by which the image data is gamma-encoded.
     */
-   virtual Imgbuf *createImgbuf (Imgbuf::Type type, int width, int height,
-                                 double gamma) = 0;
+   virtual std::unique_ptr< Imgbuf > createImgbuf( Imgbuf::Type type, int width, int height,
+                                 double gamma )= 0;
 
    /**
     * \brief Copy selected text (0-terminated).