问题
I am trying to display a table using ShowMessage that looks like this:
short | Description for "short"
verylongtext | Description for "verylongtext"
How do I get two correctly aligned columns like that in a simple message dialog?
I tried to align the columns using spaces, but the font of ShowMessage is variable. Then I tried to align them using tab characters, but I do not know how to calculate the proper tab count for each row.
Is there a reliable way to calculate the tab count?
PS: I would like to avoid writing a custom dialog for this purpose.
回答1:
You could use a list view in a custom dialog box, as well.
My class supports the standard Windows icons (and sounds): information, warning, error, confirmation, none. Here is the icon-less version:
It is easy to use:
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
)
It supports DPI scaling (high DPI) and all Windows versions from Windows XP (it might work on Windows 2000 as well, I just haven't tested that) to Windows 10:
The table is a list view, so you get all its benefits, like a scrollbar, truncation ellipses, and tooltips:
You can also specify the dialog's size to make it fit the contents:
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
)
Of course, the OK button is both Default and Cancel, so you can dismiss the dialog with Enter or Escape.
Finally, pressing Ctrl+C will copy the table to clipboard.
Full source code:
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;
回答2:
If you're not writing a custom dialog for this, when will you? It's not that hard. Just create a form, drop a TMemo on it and make that memo readonly. You can set a monospaced font like Courier New, and your problem is solved. You got the advantage of scrollbars and selection too, and you can choose to make it non-modal.
I would even recommend showing this type of data in a grid (like TStringGrid) instead of a memo or label.
Calculating how to display this text in a messagebox will require much more effort than just creating a custom dialog.
回答3:
Just created something that shows a popup like this:
Just call the procedure below, and add a TStringList as a parameter. Of course you could pimp this by using a TListView, icons, scrollbars, etc.
Put it in a separate unit, and you'll always be able to easily show stuff like this.
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;
Example on how to use it:
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;
来源：https://stackoverflow.com/questions/4648758/how-to-display-a-table-in-showmessage