base/win/scoped_gdi_object.h

   1 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_WIN_SCOPED_GDI_OBJECT_H_
   6 #define BASE_WIN_SCOPED_GDI_OBJECT_H_
   7
   8 #include <windows.h>
   9
  10 #include "base/basictypes.h"
  11 #include "base/logging.h"
  12
  13 namespace base {
  14 namespace win {
  15
  16 // Like ScopedHandle but for GDI objects.
  17 template<class T>
  18 class ScopedGDIObject {
  19  public:
  20   ScopedGDIObject() : object_(NULL) {}
  21   explicit ScopedGDIObject(T object) : object_(object) {}
  22
  23   ~ScopedGDIObject() {
  24     Close();
  25   }
  26
  27   T Get() {
  28     return object_;
  29   }
  30
  31   void Set(T object) {
  32     if (object_ && object != object_)
  33       Close();
  34     object_ = object;
  35   }
  36
  37   ScopedGDIObject& operator=(T object) {
  38     Set(object);
  39     return *this;
  40   }
  41
  42   T release() {
  43     T object = object_;
  44     object_ = NULL;
  45     return object;
  46   }
  47
  48   operator T() { return object_; }
  49
  50  private:
  51   void Close() {
  52     if (object_)
  53       DeleteObject(object_);
  54   }
  55
  56   T object_;
  57   DISALLOW_COPY_AND_ASSIGN(ScopedGDIObject);
  58 };
  59
  60 // An explicit specialization for HICON because we have to call DestroyIcon()
  61 // instead of DeleteObject() for HICON.
  62 template<>
  63 void inline ScopedGDIObject<HICON>::Close() {
  64   if (object_)
  65     DestroyIcon(object_);
  66 }
  67
  68 // Typedefs for some common use cases.
  69 typedef ScopedGDIObject<HBITMAP> ScopedBitmap;
  70 typedef ScopedGDIObject<HRGN> ScopedRegion;
  71 typedef ScopedGDIObject<HFONT> ScopedHFONT;
  72 typedef ScopedGDIObject<HICON> ScopedHICON;
  73
  74 }  // namespace win
  75 }  // namespace base
  76
  77 #endif  // BASE_WIN_SCOPED_GDI_OBJECT_H_