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// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_WIN_MESSAGE_WINDOW_H_
#define BASE_WIN_MESSAGE_WINDOW_H_
#include <string>
#include "base/base_export.h"
#include "base/compiler_specific.h"
#include "base/functional/callback.h"
#include "base/threading/thread_checker.h"
#include "base/win/windows_types.h"
// Protect against windows.h being included before this header.
#undef FindWindow
namespace base {
namespace win {
// Implements a message-only window.
class BASE_EXPORT MessageWindow {
public:
// Used to register a process-wide message window class.
class WindowClass;
// Implement this callback to handle messages received by the message window.
// If the callback returns |false|, the first four parameters are passed to
// DefWindowProc(). Otherwise, |*result| is returned by the window procedure.
using MessageCallback =
base::RepeatingCallback<bool(UINT message,
WPARAM wparam,
LPARAM lparam,
LRESULT* result)>; // NOLINT
MessageWindow();
MessageWindow(const MessageWindow&) = delete;
MessageWindow& operator=(const MessageWindow&) = delete;
~MessageWindow();
// Creates a message-only window. The incoming messages will be passed by
// |message_callback|. |message_callback| must outlive |this|.
bool Create(MessageCallback message_callback);
// Same as Create() but assigns the name to the created window.
bool CreateNamed(MessageCallback message_callback,
const std::wstring& window_name);
HWND hwnd() const { return window_; }
// Retrieves a handle of the first message-only window with matching
// |window_name|.
static HWND FindWindow(const std::wstring& window_name);
private:
// Give |WindowClass| access to WindowProc().
friend class WindowClass;
// Contains the actual window creation code.
bool DoCreate(MessageCallback message_callback, const wchar_t* window_name);
// Invoked by the OS to process incoming window messages.
static LRESULT CALLBACK WindowProc(HWND hwnd,
UINT message,
WPARAM wparam,
LPARAM lparam);
// Invoked to handle messages received by the window.
MessageCallback message_callback_;
// Handle of the input window.
HWND window_ = nullptr;
THREAD_CHECKER(thread_checker_);
};
} // namespace win
} // namespace base
#endif // BASE_WIN_MESSAGE_WINDOW_H_
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