Question

Description

I’m writing application what use listView. listView that I use is a simple list view, only I switch on doubleBufer by inheriting listView and in constructor I have write:

this->DoubleBuffer = true;

So I have some columns in my listView and when I click column I need to sort column items. Everything goes okay when I have 500 items, but when items count in listView become more then 50.000 and I press column in order to sort items in it, my list froze for 1 minute and application stop response. Below I present code of sorting.

Sorting Code

ref class DomainSorter : public System::Collections::IComparer {
        public:
            virtual int Compare( System::Object^ x, System::Object^ y) {
                System::Windows::Forms::ListViewItem^ lvi1 = static_cast<System::Windows::Forms::ListViewItem^>(o1);
                System::String^ str1 = lvi1->SubItems[COLUMN_DOMAIN]->Text;
                System::Windows::Forms::ListViewItem^ lvi2 = static_cast<System::Windows::Forms::ListViewItem^>(o2);
                System::String^ str2 = lvi2->SubItems[COLUMN_DOMAIN]->Text;

                int result = 0;

                if( lvi1->ListView->Sorting == System::Windows::Forms::SortOrder::Ascending)
                     result = System::String::Compare( str1, str2 );
                else result = System::String::Compare( str2, str1 );

                return result;
            }

        };

void OnColumnClick( )
{
    listViewDomainsInfo->BeginUpdate( );
    listViewDomainsInfo->ListViewItemSorter = gcnew DomainSorter( );
    if (listViewDomainsInfo->Sorting == SortOrder::Ascending)
    listViewDomainsInfo->Sorting = SortOrder::Descending;
    else listViewDomainsInfo->Sorting = SortOrder::Ascending;
    listViewDomainsInfo->EndUpdate( ); 
}

Question

How I can increase speed of listView sorting. (I knew that I can use virtual list but I didn’t want) can you help me to make this code works faster ?

Answer 1

If you want the faster sorting you should not to use integrated sorting behavior.
For example:

1. Rewrite your sorting provider to work with ListViewItem instead Object
2. Sort items by yourself
3. Then call listViewDomainsInfo->Items->Clear() and listViewDomainsInfo->Items->AddrRange()

That’s should work faster. Also note that you should restore visible items range manually in this case.