建立拖動image

//建立拖動image
cimagelist *cmylist::makedragimage(int item)
{
   cimagelist *ilist = new cimagelist;          //    create a new image-list

   crect rc;
   getitemrect(item, &rc, lvir_bounds);         //       get the complete row
   rc.offsetrect(-rc.left, -rc.top);            //     make it (0, 0)-aligned
   rc.right = getcolumnwidth(0);                //  just want the 1st columne

   ilist->create(rc.width(), rc.height(), ilc_color24 | ilc_mask, 1, 1);

   cdc *pdc = getdc();                          //         get device-context

   if(pdc) {

      // create a memory-dc for the image and attach a bitmap to it

      cdc drawdc;
      drawdc.createcompatibledc(pdc);
      cbitmap drawmap;
      drawmap.createcompatiblebitmap(pdc, rc.width(), rc.height());
      cbitmap *old = drawdc.selectobject(&drawmap);

      // erase the background../di2001.jpgd draw the item into the device context

      drawdc.fillsolidrect(rc, getsyscolor(color_window));

      drawitemstruct dis;
      dis.hdc       = drawdc.m_hdc;             // device-context to draw in
      dis.rcitem    = rc;                       //        the item rectangle
      dis.itemid    = item;                     //             the item's id
      dis.itemstate = ods_default;              //           or ods_selected
      drawitem(&dis);                           //     draw item into the dc

      drawdc.selectobject(old);                 // switch back to old bitmap

      // create a memory-dc for the mask and attach a bitmap to it. to  make
      // the bitmap just one bit depth, we make it compatible to the memory-
      // dc instead of the screen-dc as above

      cdc maskdc;
      maskdc.createcompatibledc(pdc);
      cbitmap maskmap;
      maskmap.createcompatiblebitmap(&maskdc, rc.width(), rc.height());
      old = maskdc.selectobject(&maskmap);

      // erase the background../di2001.jpgd draw the item into the device context

      maskdc.fillsolidrect(rc, getsyscolor(color_window));

      dis.hdc       = maskdc.m_hdc;             // device-context to draw in
      dis.rcitem    = rc;                       //        the item rectangle
      dis.itemid    = item;                     //             the item's id
      dis.itemstate = ods_default;              //           or ods_selected
      drawitem(&dis);                           //          draw into the dc

      maskdc.selectobject(old);                 // switch back to old bitmap

     // add the image (and mask) to the image-list

     ilist->add(&drawmap, &maskmap);
     releasedc(pdc);
   }

   return ilist;
}