tor-browser

The Tor Browser
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scoped_gdi_object.h (2365B)

      1 /*
      2 *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
      3 *
      4 *  Use of this source code is governed by a BSD-style license
      5 *  that can be found in the LICENSE file in the root of the source
      6 *  tree. An additional intellectual property rights grant can be found
      7 *  in the file PATENTS.  All contributing project authors may
      8 *  be found in the AUTHORS file in the root of the source tree.
      9 */
     10 
     11 #ifndef MODULES_DESKTOP_CAPTURE_WIN_SCOPED_GDI_HANDLE_H_
     12 #define MODULES_DESKTOP_CAPTURE_WIN_SCOPED_GDI_HANDLE_H_
     13 
     14 #include <windows.h>
     15 
     16 #include <cstddef>
     17 
     18 namespace webrtc {
     19 namespace win {
     20 
     21 // Scoper for GDI objects.
     22 template <class T, class Traits>
     23 class ScopedGDIObject {
     24 public:
     25  ScopedGDIObject() : handle_(NULL) {}
     26  explicit ScopedGDIObject(T object) : handle_(object) {}
     27 
     28  ~ScopedGDIObject() { Traits::Close(handle_); }
     29 
     30  ScopedGDIObject(const ScopedGDIObject&) = delete;
     31  ScopedGDIObject& operator=(const ScopedGDIObject&) = delete;
     32 
     33  T Get() { return handle_; }
     34 
     35  void Set(T object) {
     36    if (handle_ && object != handle_)
     37      Traits::Close(handle_);
     38    handle_ = object;
     39  }
     40 
     41  ScopedGDIObject& operator=(T object) {
     42    Set(object);
     43    return *this;
     44  }
     45 
     46  T release() {
     47    T object = handle_;
     48    handle_ = NULL;
     49    return object;
     50  }
     51 
     52  operator T() { return handle_; }
     53 
     54 private:
     55  T handle_;
     56 };
     57 
     58 // The traits class that uses DeleteObject() to close a handle.
     59 template <typename T>
     60 class DeleteObjectTraits {
     61 public:
     62  DeleteObjectTraits() = delete;
     63  DeleteObjectTraits(const DeleteObjectTraits&) = delete;
     64  DeleteObjectTraits& operator=(const DeleteObjectTraits&) = delete;
     65 
     66  // Closes the handle.
     67  static void Close(T handle) {
     68    if (handle)
     69      DeleteObject(handle);
     70  }
     71 };
     72 
     73 // The traits class that uses DestroyCursor() to close a handle.
     74 class DestroyCursorTraits {
     75 public:
     76  DestroyCursorTraits() = delete;
     77  DestroyCursorTraits(const DestroyCursorTraits&) = delete;
     78  DestroyCursorTraits& operator=(const DestroyCursorTraits&) = delete;
     79 
     80  // Closes the handle.
     81  static void Close(HCURSOR handle) {
     82    if (handle)
     83      DestroyCursor(handle);
     84  }
     85 };
     86 
     87 typedef ScopedGDIObject<HBITMAP, DeleteObjectTraits<HBITMAP> > ScopedBitmap;
     88 typedef ScopedGDIObject<HCURSOR, DestroyCursorTraits> ScopedCursor;
     89 
     90 }  // namespace win
     91 }  // namespace webrtc
     92 
     93 #endif  // MODULES_DESKTOP_CAPTURE_WIN_SCOPED_GDI_HANDLE_H_