MFC实现CListBox的继承实现自定义效果

目标 - 实现有背景颜色项的列表

思路

• 需要知道CListBox的每个item的绘制方法
• 需要知道CListBox的item的测量方法
  查看源码找到关键的量重写的方法：

virtual void DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct);
virtual void MeasureItem(LPMEASUREITEMSTRUCT lpMeasureItemStruct);

开始实现

• 自定义控件的操作步骤
  参考https://www.jianshu.com/p/e2fe069cfe35这边MFC的定义控件步骤
  再创建控件类的时候，父类要选择CListBox
  有个不一样的是在界面上的控件，可以是CListBox，也可以是Custom Control，只需要在控件属性的class
  写成我们自定义的类名。

代码

控件的头文件

class CColorListBox : public CListBox
{
    DECLARE_DYNAMIC(CColorListBox)

public:
    CColorListBox();
    virtual ~CColorListBox();

    BOOL InitControl(CWnd* pWnd);   //用来做初始化控件的方法

public:
    virtual BOOL PreCreateWindow(CREATESTRUCT &cs);
    virtual void DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct);   //一定要复写的方法
    virtual void MeasureItem(LPMEASUREITEMSTRUCT lpMeasureItemStruct);  //一定要复写的方法
    BOOL RegisterWindowClass(HINSTANCE hInstance = NULL);

protected:
    DECLARE_MESSAGE_MAP()
};

控件的源文件

// ColorListBox.cpp : 实现文件
#include "stdafx.h"
#include "ColorListBox.h"
#include "CustomUIApp.h"


// CColorListBox

IMPLEMENT_DYNAMIC(CColorListBox, CListBox)

CColorListBox::CColorListBox()
{
    RegisterWindowClass();   //控件注册类
}

CColorListBox::~CColorListBox()
{
}


BEGIN_MESSAGE_MAP(CColorListBox, CListBox)
END_MESSAGE_MAP()

BOOL CColorListBox::RegisterWindowClass(HINSTANCE hInstance)
{
    LPCWSTR className = L"CColorListBox"; // 控件类名，必须和属性的class一致
    WNDCLASS windowclass;

    if (hInstance)
        hInstance = AfxGetInstanceHandle();

    if (!(::GetClassInfo(hInstance, className, &windowclass)))
    {
        windowclass.style = CS_DBLCLKS;
        windowclass.lpfnWndProc = ::DefWindowProc;
        windowclass.cbClsExtra = windowclass.cbWndExtra = 0;
        windowclass.hInstance = hInstance;
        windowclass.hIcon = NULL;
        windowclass.hCursor = AfxGetApp()->LoadStandardCursor(IDC_ARROW);
        windowclass.hbrBackground = ::GetSysColorBrush(COLOR_WINDOW);
        windowclass.lpszMenuName = NULL;
        windowclass.lpszClassName = className;
    }
    return AfxRegisterClass(&windowclass);
}

//初始化控件，设置对应的控件属性, 列表控件才能显示数据，该方法必须调用，才可以正常显示数据
BOOL CColorListBox::InitControl(CWnd* pWnd)
{
    if (pWnd == NULL) return false;

    CRect rect;
    GetWindowRect(&rect);
    pWnd->ScreenToClient(&rect);

    UINT id = GetDlgCtrlID();
    BOOL ret = DestroyWindow();
    if (ret == FALSE) return false;
        //设置控件的属性  
    ret = Create(WS_CHILD | WS_VISIBLE | WS_TABSTOP | LBS_OWNERDRAWVARIABLE | LBS_HASSTRINGS | LBS_NOTIFY, rect, pWnd, id);
    return ret;
}

BOOL CColorListBox::PreCreateWindow(CREATESTRUCT &cs)
{
    if (!CListBox::PreCreateWindow(cs))
        return FALSE;
    cs.style &= ~(LBS_SORT | LBS_OWNERDRAWVARIABLE);
    cs.style |= LBS_OWNERDRAWFIXED;
    return TRUE;
}

void CColorListBox::DrawItem(LPDRAWITEMSTRUCT lpDIS)
{
    ASSERT(lpDIS->CtlType == ODT_LISTBOX);
    LPCTSTR lpszText = (LPCTSTR)lpDIS->itemData;

    CDC dc;

    dc.Attach(lpDIS->hDC);

    COLORREF crOldTextColor = dc.GetTextColor();
    COLORREF crOldBkColor = dc.GetBkColor();

    // If this item is selected, set the background color   
    // and the text color to appropriate values. Also, erase  
    // rect by filling it with the background color.  
    if ((lpDIS->itemAction | ODA_SELECT) &&
        (lpDIS->itemState & ODS_SELECTED))
    {
        dc.SetTextColor(::GetSysColor(COLOR_HIGHLIGHTTEXT));
        dc.SetBkColor(::GetSysColor(COLOR_HIGHLIGHT));
        dc.FillSolidRect(&lpDIS->rcItem,
            ::GetSysColor(COLOR_HIGHLIGHT));
    }
    else
    {
        if (lpDIS->itemID % 2)
            dc.FillSolidRect(&lpDIS->rcItem, RGB(128, 128, 128));
        else
            dc.FillSolidRect(&lpDIS->rcItem, RGB(255, 128, 255));
    }

    // If this item has the focus, draw a red frame around the  
    // item's rect.  
    if ((lpDIS->itemAction | ODA_FOCUS) &&
        (lpDIS->itemState & ODS_FOCUS))
    {
        CBrush br(RGB(0, 0, 128));
        dc.FrameRect(&lpDIS->rcItem, &br);
    }
    lpDIS->rcItem.left += 5;
    // Draw the text.  
    CString sText;
    GetText(lpDIS->itemID, sText);
    CRect rect = lpDIS->rcItem;

    // Setup the text format.
    UINT nFormat = DT_LEFT | DT_SINGLELINE | DT_VCENTER;
    if (GetStyle() & LBS_USETABSTOPS)
        nFormat |= DT_EXPANDTABS;
    dc.DrawText(
        sText, -1, &rect, nFormat | DT_CALCRECT);  //这边是计算
    dc.DrawText(
        sText, -1, &rect, nFormat);   //这边是绘制文字
    //设置字体颜色和背景颜色
    dc.SetTextColor(crOldTextColor);
    dc.SetBkColor(crOldBkColor);

    dc.Detach();
}

void CColorListBox::MeasureItem(LPMEASUREITEMSTRUCT lpMIS)
{
    lpMIS->itemHeight = ::GetSystemMetrics(SM_CYMENUCHECK);
}

在对话框的调用：

BOOL CSecondDlg::OnInitDialog()
{
    CDialogEx::OnInitDialog();
    BOOL ret = m_colorlb.InitControl(this);
    // TODO:  在此添加额外的初始化

    return TRUE;  // return TRUE unless you set the focus to a control
                  // 异常: OCX 属性页应返回 FALSE
}

void CSecondDlg::OnBnClickedAddData()
{
    m_colorlb.AddString(L"11111111");
    m_colorlb.AddString(L"22222222");
}