CListCtrl 显示图片及大批量数据的加载速度与闪烁问题

一般在用CListCtrl显示大数据量时，都会直接加入到CListCtrl中，这样会导致界面刷新速度慢，如果有图片则会导致闪烁。

这是对计算机大数据量处理的思想没掌握好。

从用户的角度来考虑，计算机显示的数据超过一定量后，再增加数据量，用户不旦不会方便，相反会影响User对有用信息的定位。

所以，用户界面上始终不应该显示超大超多的数据。如果数据量很多，则考虑用Filter，Query或分页显示。

万不得一实在要用很多数据，也要将数据先放到内存中，通过GetDispInfo 来显示用户想要的数据。而不是将数据都InsertItem中。

代码来源于codeproject.

代码如下：

// BMPListDlg.cpp : implementation file
//

#include "stdafx.h"
#include "BMPList.h"
#include "BMPListDlg.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#endif

// CAboutDlg dialog used for App About
class CAboutDlg : public CDialog
{
public:
    CAboutDlg();

// Dialog Data
    enum { IDD = IDD_ABOUTBOX };

    protected:
    virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support

// Implementation
protected:
    DECLARE_MESSAGE_MAP()
};

CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD)
{
}

void CAboutDlg::DoDataExchange(CDataExchange* pDX)
{
    CDialog::DoDataExchange(pDX);
}

BEGIN_MESSAGE_MAP(CAboutDlg, CDialog)
END_MESSAGE_MAP()


// CBMPListDlg dialog


CBMPListDlg::CBMPListDlg(CWnd* pParent /*=NULL*/)
    : CDialog(CBMPListDlg::IDD, pParent)
{
    m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);
}

void CBMPListDlg::DoDataExchange(CDataExchange* pDX)
{
    CDialog::DoDataExchange(pDX);
    DDX_Control(pDX, IDC_LIST1, m_cList);
}

BEGIN_MESSAGE_MAP(CBMPListDlg, CDialog)
    ON_WM_SYSCOMMAND()
    ON_WM_PAINT()
    ON_WM_QUERYDRAGICON()
    ON_NOTIFY(LVN_GETDISPINFO, IDC_LIST1, GetDispInfo)
    //}}AFX_MSG_MAP
END_MESSAGE_MAP()


// CBMPListDlg message handlers

BOOL CBMPListDlg::OnInitDialog()
{
    CDialog::OnInitDialog();

    // Add "About..." menu item to system menu.

    // IDM_ABOUTBOX must be in the system command range.
    ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);
    ASSERT(IDM_ABOUTBOX < 0xF000);

    CMenu* pSysMenu = GetSystemMenu(FALSE);
    if (pSysMenu != NULL)
    {
        CString strAboutMenu;
        strAboutMenu.LoadString(IDS_ABOUTBOX);
        if (!strAboutMenu.IsEmpty())
        {
            pSysMenu->AppendMenu(MF_SEPARATOR);
            pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);
        }
    }

    // Set the icon for this dialog.  The framework does this automatically
    // when the application's main window is not a dialog
    SetIcon(m_hIcon, TRUE);            // Set big icon
    SetIcon(m_hIcon, FALSE);        // Set small icon

    // Create 256 color image lists
    // Need to create image list with a phantom bitmap.
    // This image list is only used to hold the place.  The images are loaded
    // dynamically as the list control is scrolled.
    if(m_imageList.GetSafeHandle() == NULL)
    {
        m_imageList.Create(210, 160, ILC_COLOR24 | ILC_MASK, 8, 1);
        m_cList.SetImageList(&m_imageList, LVSIL_SMALL);
        m_cList.SetImageList(&m_imageList, LVSIL_NORMAL);
        m_imageList.SetImageCount(1);
    }

    // Set up list control
    // Nothing special here.  Just some columns for the report view.
    m_cList.InsertColumn(0, _T("Column 1"), LVCFMT_LEFT, 200);
    m_cList.InsertColumn(1, _T("Column 2"), LVCFMT_LEFT, 100);
    m_cList.InsertColumn(3, _T("Column 3"), LVCFMT_LEFT, 100);
    m_cList.InsertColumn(4, _T("Column 4"), LVCFMT_LEFT, 100);
    m_cList.SetExtendedStyle(LVS_EX_FULLROWSELECT |LVS_EX_INFOTIP | LVS_EX_FLATSB |LVS_EX_GRIDLINES);

    // Add some data
    InsertItems();
    return TRUE;  // return TRUE  unless you set the focus to a control
}

void CBMPListDlg::GetDispInfo(NMHDR *pNMHDR, LRESULT *pResult)
{
    NMLVDISPINFO *pDispInfo = reinterpret_cast<NMLVDISPINFO*>(pNMHDR);

    //Create a pointer to the item
    LV_ITEM* pItem= &(pDispInfo)->item;

    //Which item number?
    int nItem = pItem->iItem;

    CMyDataInfo *pInfo = NULL;
    if(nItem > m_MyDataArray.GetSize()-1)
        return; // Just to be safe

    pInfo = (CMyDataInfo *)m_MyDataArray.GetAt(nItem);
    if(pInfo == NULL)
        return;
    
    //Do we need text information?
    if (pItem->mask & LVIF_TEXT) {
        CString csText;

        //Which column?
        if(pItem->iSubItem == 0)
            csText = pInfo->m_csColumn1;
        else if (pItem->iSubItem == 1) // Column 1
            csText = pInfo->m_csColumn2;
        else if (pItem->iSubItem == 2) // Column 2
            csText = pInfo->m_csColumn3;
        else if (pItem->iSubItem == 3) // Column 3
            csText = pInfo->m_csColumn4;

        //Copy the text to the LV_ITEM structure
        //Maximum number of characters is in pItem->cchTextMax
        lstrcpyn(pItem->pszText, csText, pItem->cchTextMax);
    }

    //Does the list need image information?
    if( pItem->mask & LVIF_IMAGE) {
        TRACE(_T("pItem|%d|%d\n"), pItem->iItem, pItem->iSubItem);
        // Need to reset first item of image list to the correct bitmap
        HBITMAP hBmp = (HBITMAP)::LoadImage(AfxGetInstanceHandle(),pInfo->m_csImage,
            IMAGE_BITMAP,0,0,LR_LOADFROMFILE);
        if(hBmp != NULL) {
            CBitmap *cBmp = CBitmap::FromHandle(hBmp);
            if(cBmp != NULL)
                m_imageList.Replace(0,cBmp,NULL);
        }
        // Note, there is no Navigator 0.bmp so that image will always display blank to 
        // illustrate what would happen when the file is not found.
        else {
            CBitmap *cBmp = new CBitmap();
            cBmp->LoadBitmap(IDB_BLANK);
            m_imageList.Replace(0,cBmp,NULL);
            delete cBmp;
        }
        pItem->iImage = 0; // Always use 0 since only one element
    }
    *pResult = 0;
}

void CBMPListDlg::InsertItems()
{
    m_MyDataArray.RemoveAll(); // Clear the array

    // Add some data (100000 records)
    // These items are stored in an array, not in the list control itself.
    // We're just putting in enough here to identify the row and column
    // This is the slowest operation in the prgram, but we need some data
    // to do the illustration.
    for(int i = 0; i < 100; ++i) {
        CMyDataInfo *pInfo = new CMyDataInfo();
        if(pInfo) {
            CString cs;
            cs.Format(_T("R%dColumn1"),i);
            pInfo->m_csColumn1 = cs;
            cs.Format(_T("R%dColumn2"),i);
            pInfo->m_csColumn2 = cs;
            cs.Format(_T("R%dColumn3"),i);
            pInfo->m_csColumn3 = cs;
            cs.Format(_T("R%dColumn4"),i);
            pInfo->m_csColumn4 = cs;

            // This will count from Navigator 0.bmp to Navigator 4.bmp.  There is no
            // file Navigator 0.bmp so those rows will use the blank bitmap from the build in
            // resources.
            cs.Format(_T("Navigator %d.bmp"),(i % 5));
            pInfo->m_csImage = cs; // Just repeat images every 4 
            m_MyDataArray.Add(pInfo);
        }
    }

    m_cList.DeleteAllItems();

    // This sets the count in the list without adding any items.  This is very fast.
    m_cList.SetItemCountEx((int)m_MyDataArray.GetCount(), LVSICF_NOSCROLL|LVSICF_NOINVALIDATEALL);
}

void CBMPListDlg::OnSysCommand(UINT nID, LPARAM lParam)
{
    if ((nID & 0xFFF0) == IDM_ABOUTBOX)
    {
        CAboutDlg dlgAbout;
        dlgAbout.DoModal();
    }
    else
    {
        CDialog::OnSysCommand(nID, lParam);
    }
}

// If you add a minimize button to your dialog, you will need the code below
//  to draw the icon.  For MFC applications using the document/view model,
//  this is automatically done for you by the framework.

void CBMPListDlg::OnPaint()
{
    if (IsIconic())
    {
        CPaintDC dc(this); // device context for painting

        SendMessage(WM_ICONERASEBKGND, reinterpret_cast<WPARAM>(dc.GetSafeHdc()), 0);

        // Center icon in client rectangle
        int cxIcon = GetSystemMetrics(SM_CXICON);
        int cyIcon = GetSystemMetrics(SM_CYICON);
        CRect rect;
        GetClientRect(&rect);
        int x = (rect.Width() - cxIcon + 1) / 2;
        int y = (rect.Height() - cyIcon + 1) / 2;

        // Draw the icon
        dc.DrawIcon(x, y, m_hIcon);
    }
    else
    {
        CDialog::OnPaint();
    }
}

// The system calls this function to obtain the cursor to display while the user drags
//  the minimized window.
HCURSOR CBMPListDlg::OnQueryDragIcon()
{
    return static_cast<HCURSOR>(m_hIcon);
}





// BMPListDlg.h : header file
//

#pragma once
#include "afxcmn.h"

// Data object handling class
class CMyDataInfo : public CObject
{
// Construction/Destruction
public:
    CMyDataInfo() {};
    ~CMyDataInfo() {};
// Attributes
public:
    CString m_csColumn1;
    CString m_csColumn2;
    CString m_csColumn3;
    CString m_csColumn4;
    CString m_csImage; // BMP to show

// Implementation
};

class CMyDataArray : public CObArray
{
// Construction/Destruction
public:
    CMyDataArray() {};
    ~CMyDataArray() {
        for(int i = 0; i < GetSize(); ++ i)
            delete GetAt(i);
        RemoveAll();
    };

// Attributes
public:
};

// CBMPListDlg dialog
class CBMPListDlg : public CDialog
{
// Construction
public:
    CBMPListDlg(CWnd* pParent = NULL);    // standard constructor
    ~CBMPListDlg(){m_imageList.DeleteImageList();};
    
// Dialog Data
    enum { IDD = IDD_BMPLIST_DIALOG };

    protected:
    virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support


// Implementation
protected:
    HICON m_hIcon;
    CImageList    m_imageList;
    void InsertItems();
    int m_nItems;
    CMyDataArray m_MyDataArray;
    
    // Generated message map functions
    virtual BOOL OnInitDialog();
    afx_msg void OnSysCommand(UINT nID, LPARAM lParam);
    afx_msg void OnPaint();
    afx_msg HCURSOR OnQueryDragIcon();
    afx_msg void GetDispInfo(NMHDR *pNMHDR, LRESULT *pResult);
    DECLARE_MESSAGE_MAP()
public:
    CListCtrl m_cList;
};

注意，本人的观点如下：

CListCtrl默认第一列的mask时有LVIF_IMAGE属性。

此例子数据量超过10万时，仍然速度很快，没有闪烁现象。