HWndDC.h

/*
 * Copyright (C) 2012 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef HWndDC_h
#define HWndDC_h

#include <windows.h>
#include <wtf/NonCopyable.h>

namespace WebCore {

class HWndDC {
    WTF_MAKE_NONCOPYABLE(HWndDC);
public:
    HWndDC()
        : m_hwnd(0)
        , m_hdc(0)
    {
    }

    explicit HWndDC(HWND hwnd)
        : m_hwnd(hwnd)
        , m_hdc(::GetDC(hwnd))
    {
    }

    HWndDC(HWND hwnd, HRGN hrgnClip, DWORD flags)
        : m_hwnd(hwnd)
        , m_hdc(::GetDCEx(hwnd, hrgnClip, flags))
    {
    }

    ~HWndDC()
    {
        clear();
    }

    HDC setHWnd(HWND hwnd)
    {
        clear();
        m_hwnd = hwnd;
        m_hdc = ::GetDC(hwnd);
        return m_hdc;
    }

    void clear()
    {
        if (!m_hdc)
            return;
        ::ReleaseDC(m_hwnd, m_hdc);
        m_hwnd = 0;
        m_hdc = 0;
    }

    operator HDC()
    {
        return m_hdc;
    }

private:
    HWND m_hwnd;
    HDC m_hdc;
};

} // namespace WebCore

#endif // HWndDC_h