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Thumbnails Viewer using ListCtrl

By , 27 Jan 2006
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Sample Image - ThumbViewer.jpg

Introduction

There are several image libraries and sources currently available. So I made my mind up to make a free Image Viewer using a free image library, and I got many free demo programs. I think a good image viewer must be able to show thumbnail images in a selected directory. I found some sources showing thumbnails, but they didn't support several formats, only BMP files. This thumbnail viewer is based on CxImage, so if there is an image format supported by CxImage, this viewer also supports that format.

Implementation

I want to show you the core part in this article. How to make a CListCtrl, CImageList, and then how to load images and attach that image to an ImageList.

1. Creating CListCtrl and CImageList

I used a CListView instead of CListCtrl, but you know that CListView uses CListCtrl internally. So overriding Create(...) will make your icon view CListCtrl initially. And then on OnInitialUpdate(), make ImageList which can support 24 bit color images and attach to CListCtrl.

return CListView::Create(lpszClassName, _T("ListView"),
  dwStyle|LVS_SHOWSELALWAYS|LVS_ALIGNTOP|LVS_ICON|LVS_SINGLESEL|
  LVS_AUTOARRANGE, rect, pParentWnd, nID, pContext);

....
m_ImageListThumb.Create(THUMBNAIL_WIDTH, THUMBNAIL_HEIGHT, ILC_COLOR24, 0, 1);
 ListCtrl.SetImageList(&m_ImageListThumb, LVSIL_NORMAL);

2. Load Images and Insert Items

Create a Compatible DC and a Bitmap Handle. Stretch a loaded image to the Bitmap Handle and then attach it to CBitmap. Finally, replace CBitmap with an image in the ImageList.

unsigned __stdcall CThumbViewerView::LoadThumbNail(LPVOID lpParam)
{
 CThumbViewerView* pView=(CThumbViewerView*)lpParam;
 CThumbViewerDoc* pDoc=pView->GetDocument();

 CListCtrl& ListCtrl=pView->GetListCtrl();
 CImageList* pImgList=&pView->m_ImageListThumb;

 // reset our image list
 for(int i=0; i<pImgList->GetImageCount(); i++)
  pImgList->Remove(i); 

 // remove all items from list view
 ListCtrl.DeleteAllItems();

 pImgList->SetImageCount(pDoc->m_vFileName.size());

 char path[MAX_PATH];
 vector<CString>::iterator iter;
 
 // Set redraw to FALSE to avoid flickering during adding new items
 ListCtrl.SetRedraw(FALSE);
 int nIndex=0;
 for(iter=pDoc->m_vFileName.begin(); 
     iter!=pDoc->m_vFileName.end() && pView->m_bTerminate!=true; 
     iter++, nIndex++)
 {
          ListCtrl.InsertItem(nIndex, *iter, nIndex);
 }

 ListCtrl.SetRedraw(TRUE);
 ListCtrl.Invalidate();

 // 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=THUMBNAIL_WIDTH;
 rcBorder.bottom=THUMBNAIL_HEIGHT;

 const float fRatio=(float)THUMBNAIL_HEIGHT/THUMBNAIL_WIDTH;

 int XDest, YDest, nDestWidth, nDestHeight;
 nIndex=0;
 for(iter=pDoc->m_vFileName.begin(); 
     iter!=pDoc->m_vFileName.end() && pView->m_bTerminate!=true; 
     iter++, nIndex++)
 {
  // Load Image File
  sprintf(path, "%s\\%s", pDoc->m_strCurrentDirectory, *iter);

  int nImageType=pDoc->GetTypeFromFileName(path);
  if(nImageType==CXIMAGE_FORMAT_UNKNOWN)
   continue;

  CxImage image(path, nImageType);

  if(image.IsValid()==false)
   continue;

  // Calculate Rect to fit to canvas
  const float fImgRatio=(float)image.GetHeight()/image.GetWidth();
  if(fImgRatio > fRatio)
  {
   nDestWidth=THUMBNAIL_HEIGHT/fImgRatio;
   XDest=(THUMBNAIL_WIDTH-nDestWidth)/2;
   YDest=0;
   nDestHeight=THUMBNAIL_HEIGHT;
  }
  else
  {
   XDest=0;
   nDestWidth=THUMBNAIL_WIDTH;
   nDestHeight=THUMBNAIL_WIDTH*fImgRatio;
   YDest=(THUMBNAIL_HEIGHT-nDestHeight)/2;
  }

  CClientDC cdc(pView);
  HDC hDC=::CreateCompatibleDC(cdc.m_hDC);
  HBITMAP bm = CreateCompatibleBitmap(cdc.m_hDC, THUMBNAIL_WIDTH, 
                                      THUMBNAIL_HEIGHT);
  HBITMAP pOldBitmapImage = (HBITMAP)SelectObject(hDC,bm);
  // Draw Background
  ::FillRect(hDC, &rcBorder, hBrushBk);

  // Draw Image
  image.Stretch(hDC, XDest, YDest, nDestWidth, nDestHeight);

  // Draw Border
  ::FrameRect(hDC, &rcBorder, hBrushBorder);

  SelectObject(hDC, pOldBitmapImage);

  // Attach to Bitmap and Replace image in CImageList
  CBitmap bitmap;
  bitmap.Attach(bm);
  pImgList->Replace(nIndex, &bitmap, NULL);

  // Redraw only a current item for removing flickering and fast speed.
  ListCtrl.RedrawItems(nIndex, nIndex);

  // Release used DC and Object
  DeleteDC(hDC);
  DeleteObject(bm);
 }
 DeleteObject(hBrushBorder);
 DeleteObject(hBrushBk);

 ListCtrl.Invalidate();
 pView->m_bRunning=false;
 pView->m_bTerminate=false;

 _endthreadex( 0 );

 return 0;
}

Acknowledgment

You can download CxImage freely from here.

History

  • Ver. 1.0  15, Sep. 2003
    • First release.
  • Ver. 1.1  24, Mar. 2005
    • Fixed crashing when changing a directory fast.
    • Supports Unicode option using preprocessor _UNICODE.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

moah
Web Developer
Korea (Republic Of) Korea (Republic Of)
Youngjin Kim lives in South Korea. I'm interested in every part of Computer Science, cause it has not been long time since graduate a University.
But now I'm working and researching on Pattern Recognition. Using that trying to recognize a Handwriting Prints. Korean and Chinese are my interesting Research Part.

Comments and Discussions

 
GeneralMy vote of 5 Pinmember43noodles2-Jul-10 22:46 
Generalhello, I came across one question. I need your help... Pinmembercciill5-Sep-09 6:42 
QuestionWhy can't I hide the VScroll in listctrl??? PinmemberSophia2925-Nov-08 21:30 
GeneralDatagrid thumbnail images Pinmemberskyair29-Jun-08 15:49 
GeneralHai PinmemberSivan Manimala2-Jun-08 23:09 
QuestionPossible to only highlight name and not picture? Pinmemberalan9329-May-08 10:09 
AnswerRe: Possible to only highlight name and not picture? PinmemberDevoraNur24-Oct-09 20:51 
GeneralRe: Possible to only highlight name and not picture? Pinmemberalan9328-Oct-09 2:44 
General안녕하세요~ [modified] Pinmemberrider7617-Mar-08 15:22 
hi~
 
last 2~3 years ago had met a Korean in the face here is..(perfectly conglish..understand do ju sam(hae joo sam~^^)
 
wow~
realy how no long time see korean here.
 
leave traces because very very glad.
 
bye~^^
 
modified on Monday, March 17, 2008 9:28 PM

Questionhow can do it Pinmemberthrudoor27-Nov-07 23:27 
GeneralMore smooth Picture! PinmemberOpenGL_VC5-Apr-07 20:40 
GeneralRe: More smooth Picture! Pinmembermoah14-May-07 20:58 
GeneralLINK : fatal error LNK1181: cannot open input file "./lib/cximagecrtu.lib" PinmemberSKhokalay6-Dec-06 23:46 
GeneralLINK : fatal error LNK1181: cannot open input file "./lib/cximagecrtu.lib" PinmemberSKhokalay6-Dec-06 23:51 
GeneralRe: LINK : fatal error LNK1181: cannot open input file "./lib/cximagecrtu.lib" Pinmembercristitomi4-Apr-07 23:32 
GeneralRe: LINK : fatal error LNK1181: cannot open input file "./lib/cximagecrtu.lib" PinmemberSon Ji Seon26-May-09 3:28 
QuestionProblems in adding a new bar. Pinmemberperhapszy2-Aug-06 22:18 
AnswerRe: Problems in adding a new bar. Pinmembermoah4-Aug-06 19:20 
GeneralRe: Problems in adding a new bar. Pinmemberperhapszy7-Aug-06 22:40 
Questionlill more help plz Pinmembertahinn6-Jul-06 19:16 
AnswerRe: lill more help plz Pinmembermoah8-Jul-06 7:07 
GeneralRe: lill more help plz Pinmembertahinn12-Jul-06 2:50 
QuestionI can't build with Visual C++ 8 (2005) PinmemberAnderson Luís5-Jul-06 17:34 
AnswerRe: I can't build with Visual C++ 8 (2005) Pinmembermoah8-Jul-06 6:53 
GeneralRe: I can't build with Visual C++ 8 (2005) Pinmembertdjdyq23-Jul-08 19:26 

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