3

我最近获得了基于列数据类型对 TListView 的列进行排序的帮助。

这是代码：

procedure TfrmFind.lvwTagsColumnClick(Sender: TObject; Column: TListColumn);
begin
 ColumnToSort := Column.Index;
 (Sender as TCustomListView).AlphaSort;
end;

procedure TfrmFind.lvwTagsCompare(Sender: TObject; Item1, Item2: TListItem;
  Data: Integer; var Compare: Integer);
var
 ix: Integer;
 begin
 if ColumnToSort = 0 then
  Compare := CompareText(Item1.Caption,Item2.Caption)
 else
 if ColumnToSort = 1 then
  Compare := CompareTextAsInteger(Item1.subitems[0],Item2.subitems[0])
 else
if ColumnToSort = 2 then
  Compare := CompareTextAsDateTime(Item1.subitems[1],Item2.subitems[1])
 else
 begin
 ix := ColumnToSort - 1;
 Compare := CompareText(Item1.SubItems[ix],Item2.SubItems[ix]);
 end;
end;

如果可能的话，我想添加升序和降序排序的功能吗？

用户单击一次以升序排序，然后单击第二次以降序排序

我可以从我目前拥有的代码中做到这一点吗？

如何在左列添加字形以显示排序类型（升序与降序）？

******************************************************************************

根据专家回答修改：2013 年 3 月 25 日

procedure TfrmFind.lvwTagsColumnClick(Sender: TObject; Column: TListColumn);
begin
 ColumnToSort := Column.Index;
 Column.Tag:= Column.Tag * -1;
 if Column.Tag = 0 then Column.Tag:=1;
 (Sender as TCustomListView).AlphaSort;
end;

procedure TfrmFind.lvwTagsCompare(Sender: TObject; Item1, Item2: TListItem;
  Data: Integer; var Compare: Integer);
begin
Case ColumnToSort of
    0:  Compare := TRzListView(Sender).Tag * CompareText(Item1.Caption, Item2.Caption);
    1:  Compare := TRzListView(Sender).Tag * CompareTextAsInteger(Item1.subitems[0],Item2.subitems[0]);
    2:  Compare := TRzListView(Sender).Tag * CompareTextAsDateTime(Item1.subitems[1],Item2.subitems[1]);
    else
    Compare := TRzListView(Sender).Tag * CompareText(Item1.Caption, Item2.Caption);
  End;
end;
4

3 回答 3

8

您现在尝试做的事情相当复杂。为了能够掌握这一点，我建议您构建一组精心设计的低级帮助程序。然后，您可以用简洁明了的方法编写高级 UI 代码。

首先，让我们有一些获取和设置列表标题排序状态的例程。这是列表视图的标题控件中的向上/向下排序图标。

function ListViewFromColumn(Column: TListColumn): TListView;
begin
  Result := (Column.Collection as TListColumns).Owner as TListView;
end;

type
  THeaderSortState = (hssNone, hssAscending, hssDescending);

function GetListHeaderSortState(Column: TListColumn): THeaderSortState;
var
  Header: HWND;
  Item: THDItem;
begin
  Header := ListView_GetHeader(ListViewFromColumn(Column).Handle);
  ZeroMemory(@Item, SizeOf(Item));
  Item.Mask := HDI_FORMAT;
  Header_GetItem(Header, Column.Index, Item);
  if Item.fmt and HDF_SORTUP<>0 then
    Result := hssAscending
  else if Item.fmt and HDF_SORTDOWN<>0 then
    Result := hssDescending
  else
    Result := hssNone;
end;

procedure SetListHeaderSortState(Column: TListColumn; Value: THeaderSortState);
var
  Header: HWND;
  Item: THDItem;
begin
  Header := ListView_GetHeader(ListViewFromColumn(Column).Handle);
  ZeroMemory(@Item, SizeOf(Item));
  Item.Mask := HDI_FORMAT;
  Header_GetItem(Header, Column.Index, Item);
  Item.fmt := Item.fmt and not (HDF_SORTUP or HDF_SORTDOWN);//remove both flags
  case Value of
  hssAscending:
    Item.fmt := Item.fmt or HDF_SORTUP;
  hssDescending:
    Item.fmt := Item.fmt or HDF_SORTDOWN;
  end;
  Header_SetItem(Header, Column.Index, Item);
end;

我从这个答案中获取了这段代码：如何在 TListView 列上显示排序箭头？

接下来我会做一个记录来保存排序规范。理想情况下，这将到达其Data参数中的排序比较函数。但遗憾的是，VCL 框架错过了将该参数用于其预期目的的机会。因此，我们需要将活动排序的规范存储在拥有列表视图的表单中。

type
  TSortSpecification = record
    Column: TListColumn;
    Ascending: Boolean;
    CompareItems: function(const s1, s2: string): Integer;
  end;

然后在表单本身中，您将声明一个字段来保存其中之一：

type
  TfrmFind = class(...)
  private
    ....
    FSortSpecification: TSortSpecification;
    ....
  end;

比较函数使用规范。这很简单：

procedure TfrmFind.ListViewCompare(Sender: TObject; Item1, Item2: TListItem;
  Data: Integer; var Compare: Integer);
var
  Index: Integer;
  s1, s2: string;
begin
  Index := FSortSpecification.Column.Index;
  if Index=0 then
  begin
    s1 := Item1.Caption;
    s2 := Item2.Caption;
  end else
  begin
    s1 := Item1.SubItems[Index-1];
    s2 := Item2.SubItems[Index-1];
  end;
  Compare := FSortSpecification.CompareItems(s1, s2);
  if not FSortSpecification.Ascending then
    Compare := -Compare;
end;

接下来我们将实现一个排序功能。

procedure TfrmFind.Sort(Column: TListColumn; Ascending: Boolean);
var
  ListView: TListView;
begin
  FSortSpecification.Column := Column;
  FSortSpecification.Ascending := Ascending;
  case Column.Index of
  1:
    FSortSpecification.CompareItems := CompareTextAsInteger;
  2:
    FSortSpecification.CompareItems := CompareTextAsDateTime;
  else 
    FSortSpecification.CompareItems := CompareText;
  end;

  ListView := ListViewFromColumn(Column);
  ListView.OnCompare := ListViewCompare;
  ListView.AlphaSort;
end;

此Sort功能与OnClick处理程序分离。这将允许您独立于用户的 UI 操作对列进行排序。例如，您可能希望在首次显示表单时对特定列上的控件进行排序。

最后，OnClick处理程序可以调用排序函数：

procedure TfrmFind.lvwTagsColumnClick(Sender: TObject; Column: TListColumn);
var
  i: Integer;
  Ascending: Boolean;
  State: THeaderSortState;
begin
  Ascending := GetListHeaderSortState(Column)<>hssAscending;
  Sort(Column, Ascending);
  for i := 0 to ListView.Columns.Count-1 do
  begin
    if ListView.Column[i]=Column then
      if Ascending then
        State := hssAscending
      else
        State := hssDescending
    else
      State := hssNone;
    SetListHeaderSortState(ListView.Column[i], State);
  end;
end;

为了完整起见，这里有一个实现这些想法的完整单元：

unit uFind;

interface

uses
  Windows, Messages, SysUtils, Classes, Math, DateUtils, Controls, Forms, Dialogs, ComCtrls, CommCtrl;

type
  TSortSpecification = record
    Column: TListColumn;
    Ascending: Boolean;
    CompareItems: function(const s1, s2: string): Integer;
  end;

  TfrmFind = class(TForm)
    ListView: TListView;
    procedure lvwTagsColumnClick(Sender: TObject; Column: TListColumn);
  private
    FSortSpecification: TSortSpecification;
    procedure ListViewCompare(Sender: TObject; Item1, Item2: TListItem;
      Data: Integer; var Compare: Integer);
    procedure Sort(Column: TListColumn; Ascending: Boolean);
  end;

var
  frmFind: TfrmFind;

implementation

{$R *.dfm}

function CompareTextAsInteger(const s1, s2: string): Integer;
begin
  Result := CompareValue(StrToInt(s1), StrToInt(s2));
end;

function CompareTextAsDateTime(const s1, s2: string): Integer;
begin
  Result := CompareDateTime(StrToDateTime(s1), StrToDateTime(s2));
end;

function ListViewFromColumn(Column: TListColumn): TListView;
begin
  Result := (Column.Collection as TListColumns).Owner as TListView;
end;

type
  THeaderSortState = (hssNone, hssAscending, hssDescending);

function GetListHeaderSortState(Column: TListColumn): THeaderSortState;
var
  Header: HWND;
  Item: THDItem;
begin
  Header := ListView_GetHeader(ListViewFromColumn(Column).Handle);
  ZeroMemory(@Item, SizeOf(Item));
  Item.Mask := HDI_FORMAT;
  Header_GetItem(Header, Column.Index, Item);
  if Item.fmt and HDF_SORTUP<>0 then
    Result := hssAscending
  else if Item.fmt and HDF_SORTDOWN<>0 then
    Result := hssDescending
  else
    Result := hssNone;
end;

procedure SetListHeaderSortState(Column: TListColumn; Value: THeaderSortState);
var
  Header: HWND;
  Item: THDItem;
begin
  Header := ListView_GetHeader(ListViewFromColumn(Column).Handle);
  ZeroMemory(@Item, SizeOf(Item));
  Item.Mask := HDI_FORMAT;
  Header_GetItem(Header, Column.Index, Item);
  Item.fmt := Item.fmt and not (HDF_SORTUP or HDF_SORTDOWN);//remove both flags
  case Value of
  hssAscending:
    Item.fmt := Item.fmt or HDF_SORTUP;
  hssDescending:
    Item.fmt := Item.fmt or HDF_SORTDOWN;
  end;
  Header_SetItem(Header, Column.Index, Item);
end;

procedure TfrmFind.ListViewCompare(Sender: TObject; Item1, Item2: TListItem;
  Data: Integer; var Compare: Integer);
var
  Index: Integer;
  s1, s2: string;
begin
  Index := FSortSpecification.Column.Index;
  if Index=0 then
  begin
    s1 := Item1.Caption;
    s2 := Item2.Caption;
  end else
  begin
    s1 := Item1.SubItems[Index-1];
    s2 := Item2.SubItems[Index-1];
  end;
  Compare := FSortSpecification.CompareItems(s1, s2);
  if not FSortSpecification.Ascending then
    Compare := -Compare;
end;

procedure TfrmFind.Sort(Column: TListColumn; Ascending: Boolean);
var
  ListView: TListView;
begin
  FSortSpecification.Column := Column;
  FSortSpecification.Ascending := Ascending;
  case Column.Index of
  1:
    FSortSpecification.CompareItems := CompareTextAsInteger;
  2:
    FSortSpecification.CompareItems := CompareTextAsDateTime;
  else
    FSortSpecification.CompareItems := CompareText;
  end;

  ListView := ListViewFromColumn(Column);
  ListView.OnCompare := ListViewCompare;
  ListView.AlphaSort;
end;

procedure TfrmFind.lvwTagsColumnClick(Sender: TObject; Column: TListColumn);
var
  i: Integer;
  Ascending: Boolean;
  State: THeaderSortState;
begin
  Ascending := GetListHeaderSortState(Column)<>hssAscending;
  Sort(Column, Ascending);
  for i := 0 to ListView.Columns.Count-1 do
  begin
    if ListView.Column[i]=Column then
      if Ascending then
        State := hssAscending
      else
        State := hssDescending
    else
      State := hssNone;
    SetListHeaderSortState(ListView.Column[i], State);
  end;
end;

end.
于 2013-03-25T08:09:21.637 回答
5

您可以使用您的代码。只需带标签即可切换排序

procedure TfrmFind.lvwTagsColumnClick(Sender: TObject; Column: TListColumn);
begin
 ColumnToSort := Column.Index;
 if Column.Tag = 0 then Column.Tag := 1 else Column.Tag := 0; 
 (Sender as TCustomListView).AlphaSort;
end;

在你的比较中

  Case ColumnToSort of
    0:begin
        if TListView(Sender).Column[ColumnToSort].Tag = 0 then
          Compare := CompareText(Item1.Caption, Item2.Caption)
        else
          Compare := CompareText(Item2.Caption, Item1.Caption);
      end;
    1:begin
      ........................
    end;
  End;

或建议的赌注是 TLama

procedure TfrmFind.lvwTagsColumnClick(Sender: TObject; Column: TListColumn);
begin
 ColumnToSort := Column.Index;
 Column.Tag := Column.Tag * -1;
 if Column.Tag = 0 then Column.Tag := 1; 
 (Sender as TCustomListView).AlphaSort;
end;

与比较

  Case ColumnToSort of
    0:  Compare := TListView(Sender).Column[ColumnToSort].Tag * CompareText(Item1.Caption, Item2.Caption);
    1: ........................

  End;
于 2013-03-25T00:10:35.290 回答
0

我认为有一个简单的方法。我已经在 C++Builder 中对其进行了测试，它工作正常。

注意：初始化 FColSorted = -1。

1.创建以下辅助方法。

void 
TFormFind::SetSortCol(int ASortCol)
{
  FColToSort = ASortCol;
  //If new column: ascending sort. Else: toggle sort order.
  FSortToggle = (FColSorted != FColToSort) ? +1 : -1*FSortToggle;
  ListView->AlphaSort();
  FColSorted = FColToSort;
}

2.使用带有 OnColumnClick 事件的辅助方法。

void __fastcall
TFormFind::ListViewColumnClick(TObject* Sender, TListColumn* Column)
{
  SetSortCol(Column->Index);
}

3.将 FSortToggle 与您的比较逻辑一起使用。

void __fastcall
TFormFind::ListViewCompare(TObject* Sender, 
  TListItem* Item1, TListItem* Item2, int Data, int& Compare)
{
  //Your Compare logic here.
  //...
  Compare = FSortToggle * Compare; 
}

最好的，

马塞洛。

于 2016-07-16T16:20:53.130 回答