Add wxListCtrl::IsVisible()

Allow checking if the given item is (at least partially) visible on
screen.

Closes https://github.com/wxWidgets/wxWidgets/pull/1444

Closes #9949.

src/msw/listctrl.cpp

@@ -67,6 +67,10 @@
     #define NO_ITEM (-1)
 #endif
 
+#ifndef LVM_ISITEMVISIBLE
+    #define LVM_ISITEMVISIBLE (LVM_FIRST + 182)
+#endif
+
 // ----------------------------------------------------------------------------
 // private functions
 // ----------------------------------------------------------------------------
@@ -880,6 +884,25 @@ bool wxListCtrl::GetItem(wxListItem& info) const
     return success;
 }
 
+// Check if the item is visible
+bool wxListCtrl::IsVisible(long item) const
+{
+    bool result = ::SendMessage( GetHwnd(), LVM_ISITEMVISIBLE, (WPARAM) item, 0 ) != 0;
+    if ( result )
+    {
+        HWND hwndHdr = ListView_GetHeader(GetHwnd());
+        wxRect itemRect;
+        RECT headerRect;
+        if ( Header_GetItemRect( hwndHdr, 0, &headerRect ) )
+        {
+            GetItemRect( item, itemRect );
+            wxRect rectHeader = wxRectFromRECT( headerRect );
+            result = itemRect.GetBottom() > rectHeader.GetBottom();
+        }
+    }
+    return result;
+}
+
 // Sets information about the item
 bool wxListCtrl::SetItem(wxListItem& info)
 {