Question

Listview控件中是否有功能可以上下移动项目？

Answer 1

没有使用TListView（我主要使用数据库网格），我把你的问题作为学习的机会。以下代码是结果，大卫的答案更具视觉导向性。它有一些限制：它只会移动第一个选定的项目，当它移动项目时，vsicon和vsSmallIcon的显示在移动后很奇怪。

procedure TForm1.btnDownClick(Sender: TObject);
var
  Index: integer;
  temp : TListItem;
begin
  // use a button that cannot get focus, such as TSpeedButton
  if ListView1.Focused then
    if ListView1.SelCount>0 then
    begin
      Index := ListView1.Selected.Index;
      if Index<ListView1.Items.Count then
      begin
        temp := ListView1.Items.Insert(Index+2);
        temp.Assign(ListView1.Items.Item[Index]);
        ListView1.Items.Delete(Index);
        // fix display so moved item is selected/focused
        ListView1.Selected := temp;
        ListView1.ItemFocused := temp;
      end;
    end;
end;

procedure TForm1.btnUpClick(Sender: TObject);
var
  Index: integer;
  temp : TListItem;
begin
  // use a button that cannot get focus, such as TSpeedButton
  if ListView1.Focused then
    if ListView1.SelCount>0 then
    begin
      Index := ListView1.Selected.Index;
      if Index>0 then
      begin
        temp := ListView1.Items.Insert(Index-1);
        temp.Assign(ListView1.Items.Item[Index+1]);
        ListView1.Items.Delete(Index+1);
        // fix display so moved item is selected/focused
        ListView1.Selected := temp;
        ListView1.ItemFocused := temp;
      end;
    end;
end;

Answer 2

您有两种选择：

删除它们，然后将它们重新插入新位置。
使用虚拟列表视图并在数据结构中移动它们。

我做第一个选项的例程是这样的：

procedure TBatchTaskList.MoveTasks(const Source: array of TListItem; Target: TListItem);
var
  i, InsertIndex: Integer;
begin
  Assert(IsMainThread);
  BeginUpdate;
  Try
    //work out where to move them
    if Assigned(Target) then begin
      InsertIndex := FListItems.IndexOf(Target);
    end else begin
      InsertIndex := FListItems.Count;
    end;

    //create new items for each moved task
    for i := 0 to high(Source) do begin
      SetListItemValues(
        FListItems.Insert(InsertIndex+i),
        TBatchTask(Source[i].Data)
      );
      Source[i].Data := nil;//handover ownership to the new item
    end;

    //set selection and focus item to give feedback about the move
    for i := 0 to high(Source) do begin
      FListItems[InsertIndex+i].Selected := Source[i].Selected;
    end;
    FBatchList.ItemFocused := FListItems[InsertIndex];

    //delete the duplicate source tasks
    for i := 0 to high(Source) do begin
      Source[i].Delete;
    end;
  Finally
    EndUpdate;
  End;
end;

方法SetListItemValues用于填充列表视图的列。

这是虚拟控件如此出色的一个很好的例子。

Delphi：Listview中的Shift-Up和Shift-Down

2 个答案: