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Media Player Classic - HC 原始碼分析系列文章列表：

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前幾篇文章分析了Media Player Classic - HC（mpc-hc）的核心類（CMainFrame）：

核心類分析完之後，分析了一下CAboutDlg：

發現CAboutDlg和普通的MFC對話方塊類其實沒有什麼區別。CAboutDlg功能相對比較簡單，本文將會分析一個功能相對比較複雜的類：MediaInfo選項卡。在播放視訊的時候，右鍵點選視訊->選擇“屬性”->MediaInfo就可以檢視該選項卡。一般情況下，該選項卡給出了正在播放的視訊檔案的詳細引數（確實是非常的詳細），包括：封裝格式，視訊編碼，音訊編碼等等。是獲取視訊詳細引數的最佳途徑。

該選項卡的功能實際上是呼叫了開源專案MediaInfo的庫。MediaInfo之前已經進行過詳細介紹：

在此不再重複。先看看該選項卡長什麼樣子。

先來看看MediaInfo選項卡類的定義是什麼樣的吧。該類的定義位於PPageFileMediaInfo.h檔案中。

/* 雷霄驊 
 * 中國傳媒大學/數字電視技術 
 * [email protected] 
 * 
 */  
/*
 * (C) 2009-2013 see Authors.txt
 *
 * This file is part of MPC-HC.
 *
 * MPC-HC is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * MPC-HC is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#pragma once

// CPPageFileMediaInfo dialog
// 【屬性】頁面裡面的【MediaInfo】
class CPPageFileMediaInfo : public CPropertyPage
{
    DECLARE_DYNAMIC(CPPageFileMediaInfo)

private:
    CComPtr<IFilterGraph> m_pFG;
public:
	//建構函式都是兩個引數
    CPPageFileMediaInfo(CString fn, IFilterGraph* pFG);
    virtual ~CPPageFileMediaInfo();

    // Dialog Data
    enum { IDD = IDD_FILEMEDIAINFO };
	//顯示資訊的控制元件
    CEdit m_mediainfo;
    CString m_fn;
    CFont* m_pCFont;
	//資訊
    CString MI_Text;

#if !USE_STATIC_MEDIAINFO
    static bool HasMediaInfo();
#endif
protected:
    virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support
	//初始化，載入MediaInfo庫，讀取檔案資訊
    virtual BOOL OnInitDialog();

    DECLARE_MESSAGE_MAP()

public:
	//顯示視窗，並不做其他事情
    afx_msg void OnShowWindow(BOOL bShow, UINT nStatus);
};
 

該類和普通的MFC對話方塊類差別也不大。需要注意的有以下幾點：

1.有一個變數：CComPtr<IFilterGraph> m_pFG，這個是mpc-hc中的變數，先不分析該變數的全部程式碼，在這裡僅說一下它的作用：獲取正在播放的視訊檔案的路徑。

2.有一個控制元件類：CEdit m_mediainfo，對應介面上那個大框框，用於顯示資訊。

3.有一個字串變數：CString MI_Text，用於儲存MediaInfo得到的媒體資訊。

下面來看看具體類的實現，該類的實現位於PPageFileMediaInfo.cpp檔案中。

/* 雷霄驊 
 * 中國傳媒大學/數字電視技術 
 * [email protected]
 
 
 * 
 */  
/*
 * (C) 2009-2013 see Authors.txt
 *
 * This file is part of MPC-HC.
 *
 * MPC-HC is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * MPC-HC is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

// PPageFileMediaInfo.cpp : implementation file


#include "stdafx.h"
#include "mplayerc.h"
#include "PPageFileMediaInfo.h"
#include "WinAPIUtils.h"

#if USE_STATIC_MEDIAINFO
#include "MediaInfo/MediaInfo.h"
using namespace MediaInfoLib;
#else
#include "MediaInfoDLL.h"
using namespace MediaInfoDLL;
#endif


// CPPageFileMediaInfo dialog

IMPLEMENT_DYNAMIC(CPPageFileMediaInfo, CPropertyPage)
CPPageFileMediaInfo::CPPageFileMediaInfo(CString fn, IFilterGraph* pFG)
    : CPropertyPage(CPPageFileMediaInfo::IDD, CPPageFileMediaInfo::IDD)
    , m_fn(fn)
    , m_pFG(pFG)
    , m_pCFont(nullptr)
{
}

CPPageFileMediaInfo::~CPPageFileMediaInfo()
{
    delete m_pCFont;
    m_pCFont = nullptr;
}

void CPPageFileMediaInfo::DoDataExchange(CDataExchange* pDX)
{
    __super::DoDataExchange(pDX);
    DDX_Control(pDX, IDC_MIEDIT, m_mediainfo);
}


BEGIN_MESSAGE_MAP(CPPageFileMediaInfo, CPropertyPage)
    ON_WM_SHOWWINDOW()
END_MESSAGE_MAP()

// CPPageFileMediaInfo message handlers
static WNDPROC OldControlProc;

static LRESULT CALLBACK ControlProc(HWND control, UINT message, WPARAM wParam, LPARAM lParam)
{
    if (message == WM_KEYDOWN) {
        if ((LOWORD(wParam) == 'A' || LOWORD(wParam) == 'a')
                && (GetKeyState(VK_CONTROL) < 0)) {
            CEdit* pEdit = (CEdit*)CWnd::FromHandle(control);
            pEdit->SetSel(0, pEdit->GetWindowTextLength(), TRUE);
            return 0;
        }
    }

    return CallWindowProc(OldControlProc, control, message, wParam, lParam); // call edit control's own windowproc
}
//初始化，載入MediaInfo庫，讀取檔案資訊
BOOL CPPageFileMediaInfo::OnInitDialog()
{
    __super::OnInitDialog();

    if (!m_pCFont) {
        m_pCFont = DEBUG_NEW CFont;
    }
    if (!m_pCFont) {
        return TRUE;
    }

    if (m_fn.IsEmpty()) {
        BeginEnumFilters(m_pFG, pEF, pBF) {
            CComQIPtr<IFileSourceFilter> pFSF = pBF;
            if (pFSF) {
				//當前檔案路徑
                LPOLESTR pFN = nullptr;
				//媒體型別
                AM_MEDIA_TYPE mt;
				//獲取當前檔案的路徑和媒體型別
                if (SUCCEEDED(pFSF->GetCurFile(&pFN, &mt)) && pFN && *pFN) {
                    m_fn = CStringW(pFN);
                    CoTaskMemFree(pFN);
                }
                break;
            }
        }
        EndEnumFilters;
    }

#if USE_STATIC_MEDIAINFO
	//使用靜態庫MediaInfo
	//檔案路徑
    MediaInfoLib::String f_name = m_fn;
    MediaInfoLib::MediaInfo MI;
#else
    MediaInfoDLL::String f_name = m_fn;
    MediaInfo MI;
#endif
	//設定
    MI.Option(_T("ParseSpeed"), _T("0"));
    MI.Open(f_name);
    MI.Option(_T("Complete"));
    MI.Option(_T("Language"), _T("  Config_Text_ColumnSize;30"));
	//資訊字串
    MI_Text = MI.Inform().c_str();
    MI.Close();
    if (!MI_Text.Find(_T("Unable to load"))) {
        MI_Text = _T("");
    }

    LOGFONT lf;
    ZeroMemory(&lf, sizeof(lf));
    lf.lfPitchAndFamily = DEFAULT_PITCH | FF_MODERN;
    // The empty string will fallback to the first font that matches the other specified attributes.
    LPCTSTR fonts[] = { _T("Lucida Console"), _T("Courier New"), _T("") };
    // Use a negative value to match the character height instead of the cell height.
    int fonts_size[] = { -10, -11, -11 };
    UINT i = 0;
    BOOL success;
    do {
        _tcscpy_s(lf.lfFaceName, fonts[i]);
        lf.lfHeight = fonts_size[i];
        success = IsFontInstalled(fonts[i]) && m_pCFont->CreateFontIndirect(&lf);
        i++;
    } while (!success && i < _countof(fonts));
	//控制元件設定字型和內容
    m_mediainfo.SetFont(m_pCFont);
    m_mediainfo.SetWindowText(MI_Text);

    // subclass the edit control
    OldControlProc = (WNDPROC)SetWindowLongPtr(m_mediainfo.m_hWnd, GWLP_WNDPROC, (LONG_PTR)ControlProc);

    return TRUE;  // return TRUE unless you set the focus to a control
    // EXCEPTION: OCX Property Pages should return FALSE
}
//顯示or不顯示？
void CPPageFileMediaInfo::OnShowWindow(BOOL bShow, UINT nStatus)
{
    __super::OnShowWindow(bShow, nStatus);
    if (bShow) {
        GetParent()->GetDlgItem(IDC_BUTTON_MI)->ShowWindow(SW_SHOW);
    } else {
        GetParent()->GetDlgItem(IDC_BUTTON_MI)->ShowWindow(SW_HIDE);
    }
}

#if !USE_STATIC_MEDIAINFO
bool CPPageFileMediaInfo::HasMediaInfo()
{
    MediaInfo MI;
    return MI.IsReady();
}
#endif

可以看出，主要的工作都是在OnInitDialog()函式中實現的。大體的步驟如下：

1.通過呼叫pFSF->GetCurFile(&pFN, &mt)，獲得當前檔案的路徑，存入pFN中。

2.因為字串型別不同，幾經轉換把pFN轉換為MediaInfo可以識別的字串f_name

3.根據該路徑，呼叫MediaInfo庫，獲得視訊的詳細資訊存入字串變數MI_Text。

4.將MI_Text顯示到控制元件上。

總體說來，過程並不複雜，理解起來還是比較簡單的。