Thank you very much for your advice. I added a message macro,ON_UPDATE_COMMAND_UI(ID_GALLERY_THUMBNAILS,OnEnableButton),then it works.

 

Guess problem that this control is disabled. Add some update handler for control and enable it.

 

CGalleryItemThumbnail::CGalleryItemThumbnail()
{
 m_strPictureFile=_T("E:\\pic\\lack.bmp");
}
void CGalleryItemThumbnail::Draw(CDC *pDC, CXTPControlGallery *pGallery, CRect rcItem, BOOL bEnabled, BOOL bSelected, BOOL bPressed, BOOL bChecked)
{
 CXTPPaintManager* pPaintManager = pGallery->GetPaintManager();

 pPaintManager->DrawRectangle(pDC, rcItem, bSelected, FALSE, bEnabled, bChecked, FALSE, xtpBarTypePopup, xtpBarPopup);
 CWinImage img;
 img.load(m_strPictureFile.GetString());
 RECT rc={rcItem.left,rcItem.top,rcItem.right,rcItem.bottom};
img.draw(pDC->m_hDC,rc);
}

BOOL CMainFrame::CreateRibbonBar()
{

     --- ---

    CXTPRibbonTab* pTabGallery = pRibbonBar->AddTab(ID_TAB_GALLERIES);

 

//m_pItemsPictures is defined as CXTPControlGalleryItems* m_pItemsPictures  in MainFrame.h;

m_pItemsPictures=CXTPControlGalleryItems::CreateItems(GetCommandBars(),10000);
  m_pItemsPictures->SetItemSize(CSize(60,50));
  for (int nCount=0;nCount<10;++nCount)
  {
   m_pItemsPictures->AddItem(new CGalleryItemThumbnail());
  }

 

CXTPRibbonGroup* pGroup = pTabGallery->AddGroup(ID_GROUP_INLINE);
  pGroup->SetControlsCentering(TRUE);
  

  
  CXTPControlGallery* pPictureGallery=new CXTPControlGallery();
  pPictureGallery->SetControlSize(CSize(200, 60));
  pPictureGallery->SetResizable();
  pPictureGallery->SetItemsMargin(0, 1, 0, 1);
  pPictureGallery->ShowLabels(FALSE);
  pPictureGallery->ShowScrollBar(TRUE);
  pPictureGallery->ShowBorders(TRUE);
  pPictureGallery->SetItems(m_pItemsPictures);
  pGroup->Add(pPictureGallery,10000);
  ---

Show some code.

I added a gallery which includes dozens of  picture items  into a Ribbon group ,but the scrollbar on the gallery was unable to use. How to enable it, please help me out.

the left one gallery is what I added. The right two are in the samples.