如何在ShowMessage中显示一个表格？

Question

我正在尝试使用ShowMessage显示一个表格，它应该长这样：

short            | Description for "short"
verylongtext     | Description for "verylongtext"

如何在简单的消息对话框中获得两个正确对齐的列？

我尝试使用空格对齐列，但ShowMessage的字体是可变的。然后我尝试使用制表符对齐它们，但我不知道如何计算每行的正确制表符数量。

有一种可靠的方法来计算制表符数量吗？

PS：我想避免为此编写自定义对话框。

- Jens Mühlenhoff

Answer 1

您可以在自定义对话框中使用列表视图。

我的类支持标准的Windows图标（和声音）：信息、警告、错误、确认、无。这是没有图标的版本：

使用起来很容易：

TTableDialog.ShowTable
  (
    Self,
    'Audio Properties',
    ['Duration', 'Samples per channel', 'Total data size', 'Channels', 'Bits per sample', 'Sample rate', 'Bitrate'],
    ['1 h 15 min 0 s', '216 000 000', '824 MB', '1', '32', '48 kHz', '1 536 kbit/sec'],
    mtInformation
  )

它支持DPI缩放（高DPI）和所有Windows版本，从Windows XP（也可能适用于Windows 2000，但我还没有测试过）到Windows 10：

表格是一个列表视图，您可以获得它的所有优点，例如滚动条、截断省略号和工具提示：

您还可以指定对话框的大小，使其适合内容：

TTableDialog.ShowTable
  (
    Self,
    'Audio Properties',
    ['Duration', 'Samples per channel', 'Total data size', 'Channels', 'Bits per sample', 'Sample rate', 'Bitrate', 'Maximum fractional sample value'],
    ['1 h 15 min 0 s', '216 000 000', '824 MB', '1', '32', '48 kHz', '1 536 kbit/sec', '0.1'],
    mtInformation,
    360,
    240
  )

当然，“确定”按钮既是默认值，也是取消，所以您可以使用“Enter”或“Escape”来关闭对话框。

最后，按下“Ctrl”+“C”将把表格复制到剪贴板。

完整源代码：

uses
  ComCtrls, Math, Clipbrd;

type
  TTableDialog = class
  strict private
    type TFormData = class(TComponent)
    public
      ListView: TListView;
      IconKind: PWideChar;
      Icon: HICON;
      LIWSD: Boolean;
    end;
    class function Scale(X: Integer): Integer;
    class procedure FormShow(Sender: TObject);
    class procedure FormDestroy(Sender: TObject);
    class procedure FormPaint(Sender: TObject);
    class procedure FormKeyPress(Sender: TObject; var Key: Char);
    class procedure LVToClipboard(AListView: TListView);
  public
    class procedure ShowTable(AOwner: TCustomForm; const ACaption: string;
      const ANames, AValues: array of string;
      ADialogType: TMsgDlgType = mtInformation;
      const AWidth: Integer = 360; const AHeight: Integer = 200);
  end;

class procedure TTableDialog.FormShow(Sender: TObject);
var
  FormData: TFormData;
  ComCtl: HMODULE;
  LoadIconWithScaleDown: function(hinst: HINST; pszName: LPCWSTR; cx: Integer;
    cy: Integer; var phico: HICON): HResult; stdcall;
begin
  if not (Sender is TForm) then
    Exit;
  if not (TObject(TForm(Sender).Tag) is TFormData) then
    Exit;
  TForm(Sender).OnShow := nil;
  FormData := TFormData(TForm(Sender).Tag);
  if FormData.IconKind = nil then
    Exit;
  ComCtl := LoadLibrary('ComCtl32.dll');
  if ComCtl <> 0 then
  begin
    try
      LoadIconWithScaleDown := GetProcAddress(ComCtl, 'LoadIconWithScaleDown');
      if Assigned(LoadIconWithScaleDown) then
        FormData.LIWSD := Succeeded(LoadIconWithScaleDown(0, FormData.IconKind,
          Scale(32), Scale(32), FormData.Icon));
    finally
      FreeLibrary(ComCtl);
    end;
  end;
  if not FormData.LIWSD then
    FormData.Icon := LoadIcon(0, FormData.IconKind);
end;

class procedure TTableDialog.FormDestroy(Sender: TObject);
var
  FormData: TFormData;
begin
  if not (Sender is TForm) then
    Exit;
  if not (TObject(TForm(Sender).Tag) is TFormData) then
    Exit;
  FormData := TFormData(TForm(Sender).Tag);
  if (FormData.Icon <> 0) and FormData.LIWSD then
    DestroyIcon(FormData.Icon);
end;

class procedure TTableDialog.FormKeyPress(Sender: TObject; var Key: Char);
var
  FormData: TFormData;
begin
  if not (Sender is TForm) then
    Exit;
  if not (TObject(TForm(Sender).Tag) is TFormData) then
    Exit;
  FormData := TFormData(TForm(Sender).Tag);
  case Key of
    ^C:
      LVToClipboard(FormData.ListView);
  end;
end;

class procedure TTableDialog.FormPaint(Sender: TObject);
var
  FormData: TFormData;
  Frm: TForm;
  Y: Integer;
begin

  if not (Sender is TForm) then
    Exit;

  if not (TObject(TForm(Sender).Tag) is TFormData) then
    Exit;

  Frm := TForm(Sender);
  FormData := TFormData(TForm(Sender).Tag);

  Y := Frm.ClientHeight - Scale(25 + 8 + 8);

  Frm.Canvas.Brush.Color := clWhite;
  Frm.Canvas.FillRect(Rect(0, 0, Frm.ClientWidth, Y));

  Frm.Canvas.Pen.Color := $00DFDFDF;
  Frm.Canvas.MoveTo(0, Y);
  Frm.Canvas.LineTo(Frm.ClientWidth, Y);

  if FormData.Icon <> 0 then
    DrawIconEx(Frm.Canvas.Handle, Scale(8), Scale(8), FormData.Icon,
      Scale(32), Scale(32), 0, 0, DI_NORMAL);

end;

class procedure TTableDialog.LVToClipboard(AListView: TListView);

  function GetRow(AIndex: Integer): string;
  begin
    if InRange(AIndex, 0, AListView.Items.Count - 1) and (AListView.Items[AIndex].SubItems.Count = 1) then
      Result := AListView.Items[AIndex].Caption + #9 + AListView.Items[AIndex].SubItems[0]
    else
      Result := '';
  end;

var
  S: string;
  i: Integer;
begin
  if AListView = nil then
    Exit;
  S := GetRow(0);
  for i := 1 to AListView.Items.Count - 1 do
    S := S + sLineBreak + GetRow(i);
  Clipboard.AsText := S;
end;

class function TTableDialog.Scale(X: Integer): Integer;
begin
  Result := MulDiv(X, Screen.PixelsPerInch, 96);
end;

class procedure TTableDialog.ShowTable(AOwner: TCustomForm; const ACaption: string;
  const ANames, AValues: array of string;
  ADialogType: TMsgDlgType = mtInformation;
  const AWidth: Integer = 360; const AHeight: Integer = 200);
const
  Sounds: array[TMsgDlgType] of Integer =
    (MB_ICONWARNING, MB_ICONERROR, MB_ICONINFORMATION, MB_ICONQUESTION, 0);
  Icons: array[TMsgDlgType] of MakeIntResource =
    (IDI_WARNING, IDI_ERROR, IDI_INFORMATION, IDI_QUESTION, nil);
var
  dlg: TForm;
  lv: TListView;
  btn: TButton;
  i: Integer;
  snd: Integer;
begin

  if Length(ANames) <> Length(AValues) then
    raise Exception.Create('The lengths of the columns don''t match.');

  dlg := TForm.Create(AOwner);
  try

    dlg.BorderStyle := bsDialog;
    dlg.Caption := ACaption;
    dlg.Width := Scale(AWidth);
    dlg.Height := Scale(AHeight);
    dlg.Position := poOwnerFormCenter;
    dlg.Scaled := False;
    dlg.Font.Name := 'Segoe UI';
    dlg.Font.Size := 9;
    dlg.Tag := NativeInt(TFormData.Create(dlg));
    TFormData(dlg.Tag).IconKind := Icons[ADialogType];
    dlg.OnShow := FormShow;
    dlg.OnDestroy := FormDestroy;
    dlg.OnPaint := FormPaint;
    dlg.OnKeyPress := FormKeyPress;
    dlg.KeyPreview := True;

    btn := TButton.Create(dlg);
    btn.Parent := dlg;
    btn.Caption := 'OK';
    btn.Default := True;
    btn.Cancel := True;
    btn.ModalResult := mrOk;
    btn.Width:= Scale(75);
    btn.Height := Scale(25);
    btn.Left := dlg.ClientWidth - btn.Width - Scale(8);
    btn.Top := dlg.ClientHeight - btn.Height - Scale(8);

    lv := TListView.Create(dlg);
    TFormData(dlg.Tag).ListView := lv;
    lv.Parent := dlg;
    lv.DoubleBuffered := True;
    lv.ReadOnly := True;
    lv.BorderStyle := bsNone;
    lv.Left := Scale(8) + IfThen(Icons[ADialogType] <> nil, Scale(32 + 8));
    lv.Top := Scale(8);
    lv.Width := dlg.ClientWidth - Scale(16) - IfThen(Icons[ADialogType] <> nil, Scale(32 + 8));
    lv.Height := dlg.ClientHeight - Scale(16 + 8 + 4) - btn.Height;
    lv.ViewStyle := vsReport;
    lv.RowSelect := True;
    lv.ShowColumnHeaders := False;

    with lv.Columns.Add do
    begin
      Caption := 'Name';
      Width := Scale(150);
    end;
    with lv.Columns.Add do
    begin
      Caption := 'Value';
      Width := lv.ClientWidth - lv.Columns[0].Width -
        GetSystemMetricsForWindow(SM_CXVSCROLL, dlg.Handle) - scale(2);
    end;

    for i := 0 to High(ANames) do
      with lv.Items.Add do
      begin
        Caption := ANames[i];
        SubItems.Add(AValues[i]);
      end;

    snd := Sounds[ADialogType];
    if snd <> 0 then
      MessageBeep(snd);

    dlg.ShowModal;

  finally
    dlg.Free;
  end;

end;

- Andreas Rejbrand

---

太好了，它甚至支持CTRL+C，就像默认的MsgBox一样（尽管它缺少原始窗口标题和按钮标题）。 - AmigoJack

太好了。你的源代码缺少了这个部分：interface uses ComCtrls, Math, Clipbrd, System.Classes, Winapi.Windows, Vcl.Forms, Vcl.Dialogs; 和 implementationuses ppTypes, Vcl.StdCtrls, System.SysUtils, Vcl.Controls; - undefined

Answer 2

如果您不想为此编写自定义对话框，那么什么时候会呢？其实并不难。只需创建一个表单，在上面放置一个TMemo并将其设置为只读即可。您可以设置等宽字体，如Courier New，问题就解决了。您还可以获得滚动条和选择的优势，并选择使其非模态。

我甚至建议使用网格（如TStringGrid）而不是备忘录或标签来显示此类型数据。

计算如何在消息框中显示此文本将需要比创建自定义对话框更多的工作量。

- GolezTrol

---

等宽字体看起来很糟糕，但自定义对话框仍然是解决方案。 - David Heffernan

好的，你说服我了，我会采用Andreas的解决方案。 - Jens Mühlenhoff

Answer 3

刚刚创建了一个类似于这样的弹出窗口的东西：

只需调用下面的过程，并添加一个TStringList作为参数。 当然，您可以通过使用TListView、图标、滚动条等来改进它。

将其放在单独的单元中，您将始终能够轻松地显示此类内容。

uses ..., StdCtrls, ExtCtrls;


procedure ShowTablePopup(SL:TStringList);
var
  LButtonOK: TButton;
  LMemo: TMemo;
  LPanel: TPanel;
  LForm: TForm;
begin
  LForm := TForm.Create(Application);
  LMemo := TMemo.Create(LForm);
  LPanel := TPanel.Create(LForm);
  LButtonOK := TButton.Create(LForm);

  LForm.Left := 0;
  LForm.Top := 0;
  LForm.Caption := 'Values';
  LForm.ClientHeight := 250;
  LForm.ClientWidth := 400;

  LMemo.Parent := LForm;
  LMemo.AlignWithMargins := True;
  LMemo.Left := 3;
  LMemo.Top := 3;
  LMemo.Width := 295;
  LMemo.Height := 226;
  LMemo.Align := alClient;
  LMemo.Font.Name := 'Courier New';
  LMemo.Lines.Assign(SL);

  LPanel.Parent := LForm;
  LPanel.Caption := '';
  LPanel.Left := 0;
  LPanel.Top := 232;
  LPanel.Width := 301;
  LPanel.Height := 37;
  LPanel.Align := alBottom;
  LPanel.BevelOuter := bvNone;

  LButtonOK.Parent := LPanel;
  LButtonOK.AlignWithMargins := True;
  LButtonOK.Left := 223;
  LButtonOK.Top := 3;
  LButtonOK.Width := 75;
  LButtonOK.Height := 31;
  LButtonOK.Align := alRight;
  LButtonOK.Caption := '&OK';
  LButtonOK.ModalResult := mrOk;
  LButtonOK.Default := True;

  LForm.ShowModal;
end;

使用它的示例：

var
  SL:TStringList;
begin
  SL := TStringList.Create;
  try
    SL.Add('short            | Description for "short"');
    SL.Add('verylongtext     | Description for "verylongtext"');
    ShowTablePopup(SL);
  finally
    SL.Free;
  end;
end;

- Wouter van Nifterick