michael@0: // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: #ifndef BASE_SCOPED_HANDLE_WIN_H_
michael@0: #define BASE_SCOPED_HANDLE_WIN_H_
michael@0: 
michael@0: #include <windows.h>
michael@0: 
michael@0: #include "base/basictypes.h"
michael@0: #include "base/logging.h"
michael@0: 
michael@0: // Used so we always remember to close the handle.
michael@0: // The class interface matches that of ScopedStdioHandle in  addition to an
michael@0: // IsValid() method since invalid handles on windows can be either NULL or
michael@0: // INVALID_HANDLE_VALUE (-1).
michael@0: //
michael@0: // Example:
michael@0: //   ScopedHandle hfile(CreateFile(...));
michael@0: //   if (!hfile.Get())
michael@0: //     ...process error
michael@0: //   ReadFile(hfile.Get(), ...);
michael@0: //
michael@0: // To sqirrel the handle away somewhere else:
michael@0: //   secret_handle_ = hfile.Take();
michael@0: //
michael@0: // To explicitly close the handle:
michael@0: //   hfile.Close();
michael@0: class ScopedHandle {
michael@0:  public:
michael@0:   ScopedHandle() : handle_(NULL) {
michael@0:   }
michael@0: 
michael@0:   explicit ScopedHandle(HANDLE h) : handle_(NULL) {
michael@0:     Set(h);
michael@0:   }
michael@0: 
michael@0:   ~ScopedHandle() {
michael@0:     Close();
michael@0:   }
michael@0: 
michael@0:   // Use this instead of comparing to INVALID_HANDLE_VALUE to pick up our NULL
michael@0:   // usage for errors.
michael@0:   bool IsValid() const {
michael@0:     return handle_ != NULL;
michael@0:   }
michael@0: 
michael@0:   void Set(HANDLE new_handle) {
michael@0:     Close();
michael@0: 
michael@0:     // Windows is inconsistent about invalid handles, so we always use NULL
michael@0:     if (new_handle != INVALID_HANDLE_VALUE)
michael@0:       handle_ = new_handle;
michael@0:   }
michael@0: 
michael@0:   HANDLE Get() {
michael@0:     return handle_;
michael@0:   }
michael@0: 
michael@0:   operator HANDLE() { return handle_; }
michael@0: 
michael@0:   HANDLE Take() {
michael@0:     // transfers ownership away from this object
michael@0:     HANDLE h = handle_;
michael@0:     handle_ = NULL;
michael@0:     return h;
michael@0:   }
michael@0: 
michael@0:   void Close() {
michael@0:     if (handle_) {
michael@0:       if (!::CloseHandle(handle_)) {
michael@0:         NOTREACHED();
michael@0:       }
michael@0:       handle_ = NULL;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:  private:
michael@0:   HANDLE handle_;
michael@0:   DISALLOW_EVIL_CONSTRUCTORS(ScopedHandle);
michael@0: };
michael@0: 
michael@0: // Like ScopedHandle, but for HANDLEs returned from FindFile().
michael@0: class ScopedFindFileHandle {
michael@0:  public:
michael@0:   explicit ScopedFindFileHandle(HANDLE handle) : handle_(handle) {
michael@0:     // Windows is inconsistent about invalid handles, so we always use NULL
michael@0:     if (handle_ == INVALID_HANDLE_VALUE)
michael@0:       handle_ = NULL;
michael@0:   }
michael@0: 
michael@0:   ~ScopedFindFileHandle() {
michael@0:     if (handle_)
michael@0:       FindClose(handle_);
michael@0:   }
michael@0: 
michael@0:   // Use this instead of comparing to INVALID_HANDLE_VALUE to pick up our NULL
michael@0:   // usage for errors.
michael@0:   bool IsValid() const { return handle_ != NULL; }
michael@0: 
michael@0:   operator HANDLE() { return handle_; }
michael@0: 
michael@0:  private:
michael@0:   HANDLE handle_;
michael@0: 
michael@0:   DISALLOW_EVIL_CONSTRUCTORS(ScopedFindFileHandle);
michael@0: };
michael@0: 
michael@0: // Like ScopedHandle but for HDC.  Only use this on HDCs returned from
michael@0: // CreateCompatibleDC.  For an HDC returned by GetDC, use ReleaseDC instead.
michael@0: class ScopedHDC {
michael@0:  public:
michael@0:   ScopedHDC() : hdc_(NULL) { }
michael@0:   explicit ScopedHDC(HDC h) : hdc_(h) { }
michael@0: 
michael@0:   ~ScopedHDC() {
michael@0:     Close();
michael@0:   }
michael@0: 
michael@0:   HDC Get() {
michael@0:     return hdc_;
michael@0:   }
michael@0: 
michael@0:   void Set(HDC h) {
michael@0:     Close();
michael@0:     hdc_ = h;
michael@0:   }
michael@0: 
michael@0:   operator HDC() { return hdc_; }
michael@0: 
michael@0:  private:
michael@0:   void Close() {
michael@0: #ifdef NOGDI
michael@0:     assert(false);
michael@0: #else
michael@0:     if (hdc_)
michael@0:       DeleteDC(hdc_);
michael@0: #endif  // NOGDI
michael@0:   }
michael@0: 
michael@0:   HDC hdc_;
michael@0:   DISALLOW_EVIL_CONSTRUCTORS(ScopedHDC);
michael@0: };
michael@0: 
michael@0: // Like ScopedHandle but for GDI objects.
michael@0: template<class T>
michael@0: class ScopedGDIObject {
michael@0:  public:
michael@0:   ScopedGDIObject() : object_(NULL) {}
michael@0:   explicit ScopedGDIObject(T object) : object_(object) {}
michael@0: 
michael@0:   ~ScopedGDIObject() {
michael@0:     Close();
michael@0:   }
michael@0: 
michael@0:   T Get() {
michael@0:     return object_;
michael@0:   }
michael@0: 
michael@0:   void Set(T object) {
michael@0:     if (object_ && object != object_)
michael@0:       Close();
michael@0:     object_ = object;
michael@0:   }
michael@0: 
michael@0:   ScopedGDIObject& operator=(T object) {
michael@0:     Set(object);
michael@0:     return *this;
michael@0:   }
michael@0: 
michael@0:   operator T() { return object_; }
michael@0: 
michael@0:  private:
michael@0:   void Close() {
michael@0:     if (object_)
michael@0:       DeleteObject(object_);
michael@0:   }
michael@0: 
michael@0:   T object_;
michael@0:   DISALLOW_COPY_AND_ASSIGN(ScopedGDIObject);
michael@0: };
michael@0: 
michael@0: // Typedefs for some common use cases.
michael@0: typedef ScopedGDIObject<HBITMAP> ScopedBitmap;
michael@0: typedef ScopedGDIObject<HRGN> ScopedHRGN;
michael@0: typedef ScopedGDIObject<HFONT> ScopedHFONT;
michael@0: 
michael@0: 
michael@0: // Like ScopedHandle except for HGLOBAL.
michael@0: template<class T>
michael@0: class ScopedHGlobal {
michael@0:  public:
michael@0:   explicit ScopedHGlobal(HGLOBAL glob) : glob_(glob) {
michael@0:     data_ = static_cast<T*>(GlobalLock(glob_));
michael@0:   }
michael@0:   ~ScopedHGlobal() {
michael@0:     GlobalUnlock(glob_);
michael@0:   }
michael@0: 
michael@0:   T* get() { return data_; }
michael@0: 
michael@0:   size_t Size() const { return GlobalSize(glob_); }
michael@0: 
michael@0:   T* operator->() const  {
michael@0:     assert(data_ != 0);
michael@0:     return data_;
michael@0:   }
michael@0: 
michael@0:  private:
michael@0:   HGLOBAL glob_;
michael@0: 
michael@0:   T* data_;
michael@0: 
michael@0:   DISALLOW_EVIL_CONSTRUCTORS(ScopedHGlobal);
michael@0: };
michael@0: 
michael@0: #endif // BASE_SCOPED_HANDLE_WIN_H_