Showing the Image file thumbnail view in ListView control using VC++ 6.0

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Download source files - 15.1 Kb

Introduction
CListImageCtrl is MFC control derived from the CListCtrl class. The control has an extended feature for loading thumbnail view to the List control. It has a drag and drop functionality to get the image files from the window explorer and draw the thumbnail view for that image file. Here I have simply added a function for drawing that thing.

Step by Step procedure for creating the thumbnail
To develop the thumbnail ListView control, see the below section for step by step operations.

Create the ListImage Project
Create a New Project using the VC++ - MFC AppWizard (.exe).
Select the Dialog based option in the wizard - Step 1.
Finish the wizard.
Now the new project classes added to the workspace (You can see the class files from the fileView tab in Project Workspace tree.

Create the ListImage class for the thumbnail image
Go to the ClassView tab, select the project name and add a new MFC class by clicking the right mouse button on it.
Select CListCtrl as a base class for that.
Now the new class will be created in the project workspace.
How to bind the class to the listcontrol?
Select the Dialog form from the ResourceView.
Click the right mouse button from the form dialog and select the ClassWizard from the popup menu.
Now go to Member variable section select ListControl from the control list.
Press the Add variable button to add a variable for the ListControl. Select the variable type as the new created class name(ClistImageCtrl or ur added class name) in the Add member variable form.
Enable the Drop file for List Control…
Select the Dialog form from the ResourceView.
Open the Property window for List Control.
In that check the “Accept Files” check box from the Extended Styles.
Get the dropped files from the Explorer
Select the ListImage class from the classview.
Open the class wizard for that.
Add WM_DROPFILES Message function.
OnDropFiles() function will be automatically added to the class.
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void CListImageCtrl::OnDropFiles(HDROP hDropInfo)
{
    WORD wNumFilesDropped = DragQueryFile(hDropInfo, -1, NULL, 0);

    CString firstFile="";
    CFile Cf;
    DWORD TmpVal;
    char szText[MAX_PATH];
    int kk=0;
    int tTot=(int)wNumFilesDropped;
    int m_TotCount;

    for (WORD x = 0 ; x < wNumFilesDropped; x++)
    {
        kk++;
        // Get the number of bytes required by the file's full pathname
        WORD wPathnameSize = DragQueryFile(hDropInfo, x, NULL, 0);

        // Allocate memory to contain full pathname & zero byte
        char * npszFile = (char *) LocalAlloc(LPTR, wPathnameSize += 1);

        // If not enough memory, skip this one
        if (npszFile == NULL) continue;
        DragQueryFile(hDropInfo, x, npszFile, wPathnameSize);

        if (firstFile=="")
            firstFile=npszFile;

        CString nFileText;
        CString nPath;
        CString pItemText=npszFile;
        CFile Cf;

        int i=pItemText.ReverseFind('//');

        nFileText=pItemText.Mid(i+1);
        nPath=pItemText.Left(i+1);
        i=nFileText.Find("%");
        if (i==-1)
        {
            i=pItemText.Find(_T(".jpg"),0);
            if (i==-1)
                i=pItemText.Find(_T(".jpeg"),0);
            if (i==-1)
                i=pItemText.Find(_T(".JPG"),0);
            if (i==-1)
                i=pItemText.Find(_T(".JPEG"),0);

            if (i!=-1)
            {
                m_TotCount=GetItemCount();
                InsertItem(m_TotCount,nFileText,0);
                SetItemText(m_TotCount, 1, nPath);
                //Get File size
                DoEvents();
                if (Cf.Open(pItemText,0,0)==TRUE)
                {
                    TmpVal = Cf.GetLength();
                    wsprintf(szText, "%lu", TmpVal);
                    if (TmpVal>1024)
                    {
                        double kTmpVal=TmpVal;
                        double kdvTmp=kTmpVal/1024;
                        TmpVal=TmpVal/1024;
                        if (TmpVal>1024)
                        {
                            double dTmpVal=TmpVal;
                            double dvTmp=dTmpVal/1024;
                            CString szT=
                              ConvertDoubleToString(dvTmp) + _T(" MB");
                            wsprintf(szText, "%s", szT);
                        }
                        else
                        {
                            CString kszT=
                              ConvertDoubleToString(kdvTmp) + _T(" KB");
                            wsprintf(szText, "%s", kszT);
                        }
                    }
                    else
                        wsprintf(szText, "%lu BYTES", TmpVal);
 
                    SetItemText(m_TotCount, 2, szText);
                }
                Cf.Close();
                HBITMAP bitm=LoadPicture(pItemText);
                if (bitm!=NULL)
                {
                    CBitmap*    pImage = NULL;   
                    pImage = new CBitmap();                   
                    pImage->Attach(bitm);
                    int imgP=m_imageList.Add(pImage,RGB(0,0,0));
                    SetItem(m_TotCount, 0, LVIF_IMAGE, NULL, imgP,0, 0, 0);
                }
            }
        }

        // clean up
        LocalFree(npszFile);
    }

    // Free the memory block containing the dropped-file information
    DragFinish(hDropInfo);

    // if this was a shortcut, we need to expand it to the target path
    int result=GetItemCount();
    SetItemState(result, LVIS_SELECTED |
        LVIS_FOCUSED | LVIS_ACTIVATING,
        LVIS_SELECTED | LVIS_FOCUSED | LVIS_ACTIVATING);
    //m_ProgList.SetActiveItem(k);
    //m_ProgList.SetFocus();
    result--;
    EnsureVisible(result, TRUE);
    SetFocus();
    SetRedraw(TRUE);
    RedrawWindow(NULL,NULL);

    CListCtrl::OnDropFiles(hDropInfo);
}
Creating Thumbnail image for the Picture file
Add the LoadPicture function to the ListImage class.
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HBITMAP CListImageCtrl::LoadPicture(CString mFile)
{
    CString pFSize;
    WCHAR wpath[MAX_PATH];
    MultiByteToWideChar(CP_ACP, 0, mFile, -1, wpath, MAX_PATH);
    IPicture* pPic;
    OleLoadPicturePath(wpath, NULL, NULL, NULL, IID_IPicture,(LPVOID*)&pPic);
    if (pPic==NULL) return NULL;

    HBITMAP hPic = NULL;
    pPic->get_Handle((UINT*)&hPic);
    long nWidth=THUMWIDTH;
    long nHeight=THUMHEIGHT;
    long mWid,mHei;
    pPic->get_Height(&mHei);
    pPic->get_Width(&mWid);
    HBITMAP hPicRet = (HBITMAP)CopyImage(hPic, IMAGE_BITMAP,
                        nWidth, nHeight , LR_COPYDELETEORG);  
    // Create Brushes for Border and BackGround
    HBRUSH hBrushBorder=::CreateSolidBrush(RGB(192, 192, 192));
    HBRUSH hBrushBk=::CreateSolidBrush(RGB(255, 255, 255));
    // Border Size
    RECT rcBorder;
    rcBorder.left=rcBorder.top=0;
    rcBorder.right=THUMWIDTH;
    rcBorder.bottom=THUMHEIGHT;
    const float fRatio=(float)THUMHEIGHT/THUMWIDTH;
    int XDest, YDest, nDestWidth, nDestHeight;
    // Calculate Rect to fit to canvas
    const float fImgRatio=(float)mHei/mWid;
    if(fImgRatio > fRatio)
    {
        nDestWidth=(THUMHEIGHT/fImgRatio);
        XDest=(THUMWIDTH-nDestWidth)/2;
        YDest=0;
        nDestHeight=THUMHEIGHT;
    }
    else
    {
        XDest=0;
        nDestWidth=THUMWIDTH;
        nDestHeight=(THUMWIDTH*fImgRatio);
        YDest=(THUMHEIGHT-nDestHeight)/2;
    }

    CClientDC cdc(this);
    HDC hDC=::CreateCompatibleDC(cdc.m_hDC);
    HBITMAP bm = CreateCompatibleBitmap(cdc.m_hDC, THUMWIDTH, THUMHEIGHT);
    HBITMAP pOldBitmapImage = (HBITMAP)SelectObject(hDC,bm);
    // Draw Background
    ::FillRect(hDC, &rcBorder, hBrushBk);
    // Draw Border
    ::FrameRect(hDC, &rcBorder, hBrushBorder);
    HBITMAP hBmReturn= (HBITMAP)::SelectObject(hDC, pOldBitmapImage);
    CDC hdcSrc, hdcDst;
    hdcSrc.CreateCompatibleDC(NULL);
    hdcDst.CreateCompatibleDC(NULL);
    // Load the bitmaps into memory DC
    CBitmap* hbmSrcT = (CBitmap*) hdcSrc.SelectObject(hPicRet);
    CBitmap* hbmDstT = (CBitmap*) hdcDst.SelectObject(hBmReturn);
    // This call sets up the mask bitmap.
    hdcDst.BitBlt(XDest,YDest,nDestWidth, nDestHeight, &hdcSrc,0,0,SRCCOPY);
    //hdcDst.StretchBlt(XDest,YDest,nDestWidth, nDestHeight,
    //                             &hdcSrc,0,0,48,48,SRCCOPY);
    pOldBitmapImage = (HBITMAP)SelectObject(hdcDst.m_hDC,bm);
    // Release used DC and Object
    DeleteDC(hDC);
    DeleteObject(hBrushBorder);
    DeleteObject(hBrushBk);
    return pOldBitmapImage;
}

About Karpaga Rajan

 Around 7 years of experience in software development, system design, prototyping, testing, implementation, maintenance and documentation.

Experience in System oriented programming (developed Anti – Virus Kit, Network security system, etc) and Embedded systems.

Capable of developing Device Drivers and building Custom ActiveX Controls in VC++ 6.0

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