在Delphi 11 Alexandria中Windows 10中的32位VCL应用程序中,我向用户显示了一个输入对话框:
var aNewFolderName: string := 'New Project Folder';
if Vcl.Dialogs.InputQuery('New Project Folder', 'Enter the name of the new Project Folder:', aNewFolderName) then
begin
// Todo: Create the folder if everything went OK, ELSE REPEAT the input action :-(
end;
在用户单击OK按钮之前,是否有一种方法来验证用户的输入?(例如,检查不允许的字符、现有文件夹等)。在用户单击OK之后,只在无效输入的情况下重复整个输入操作并不是非常明智和有效的:
var aNewFolderName: string := 'New Project Folder';
var InputIsValid: Boolean;
repeat
if Vcl.Dialogs.InputQuery('New Project Folder', 'Enter the name of the new Project Folder:', aNewFolderName) then
begin
InputIsValid := CheckInput(aNewFolderName);
if InputIsValid then CreateTheFolder(aNewFolderName);
end
else
BREAK;
until InputIsValid;
此外,使用这种方法,用户没有关于任何无效输入的特定原因的反馈。
发布于 2022-02-06 14:27:21
虽然可以使用重复的对话框来解决这个问题,但从UX的角度来看,我并不认为这是一个特别优雅的解决方案。
我宁愿做我自己的对话,做这样的事情:
procedure TForm1.btnSetPasswordClick(Sender: TObject);
begin
var psw := '';
if SuperInput(
Self,
'Frog Simulator',
'Please enter the new frog password:',
psw,
function(const Text: string; out AErrorMessage: string): Boolean
begin
if Text.Length < 8 then
begin
AErrorMessage := 'The password''s length must be at least 8 characters.';
Exit(False);
end;
if not StrHasChrOfType(Text, TCharacter.IsLetter) then
begin
AErrorMessage := 'The password must contain at least one letter.';
Exit(False);
end;
if not StrHasChrOfType(Text, TCharacter.IsDigit) then
begin
AErrorMessage := 'The password must contain at least one digit.';
Exit(False);
end;
if not StrHasChrOfType(Text, TCharacter.IsPunctuation) then
begin
AErrorMessage := 'The password must contain at least one punctuation character.';
Exit(False);
end;
Result := True;
end)
then
lblNewPassword.Caption := psw;
end;
下面是代码:
unit SuperInputDlg;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ExtCtrls;
type
TValidator = reference to function(const Text: string;
out AErrorMessage: string): Boolean;
TSuperInputForm = class(TForm)
lblCaption: TLabel;
shClient: TShape;
Edit: TEdit;
pbErrorIcon: TPaintBox;
lblError: TLabel;
Validator: TTimer;
btnOK: TButton;
btnCancel: TButton;
procedure FormCreate(Sender: TObject);
procedure pbErrorIconPaint(Sender: TObject);
procedure EditChange(Sender: TObject);
procedure ValidatorTimer(Sender: TObject);
procedure btnOKClick(Sender: TObject);
procedure FormDestroy(Sender: TObject);
private
FErrorIcon: HICON;
FLIWSD: Boolean;
FValidator: TValidator;
function DoValidate: Boolean;
public
end;
function SuperInput(AOwnerForm: TCustomForm; const ACaption, AMainInstruction: string;
var AText: string; AValidator: TValidator = nil): Boolean;
implementation
{$R *.dfm}
function Scale(X: Integer): Integer;
begin
Result := MulDiv(X, Screen.PixelsPerInch, 96);
end;
procedure TSuperInputForm.btnOKClick(Sender: TObject);
begin
if DoValidate then
ModalResult := mrOK;
end;
function TSuperInputForm.DoValidate: Boolean;
begin
var LErrMsg: string;
var LIsValid := not Assigned(FValidator) or FValidator(Edit.Text, LErrMsg);
btnOK.Enabled := LIsValid;
if not LIsValid then
lblError.Caption := LErrMsg;
pbErrorIcon.Visible := not LIsValid;
lblError.Visible := not LIsValid;
Result := LIsValid;
end;
procedure TSuperInputForm.EditChange(Sender: TObject);
begin
Validator.Enabled := False;
Validator.Enabled := True;
end;
procedure TSuperInputForm.FormCreate(Sender: TObject);
var
ComCtl: HMODULE;
LoadIconWithScaleDown: function(hinst: HINST; pszName: LPCWSTR; cx: Integer;
cy: Integer; var phico: HICON): HResult; stdcall;
begin
ComCtl := LoadLibrary('ComCtl32.dll');
if ComCtl <> 0 then
begin
try
LoadIconWithScaleDown := GetProcAddress(ComCtl, 'LoadIconWithScaleDown');
if Assigned(LoadIconWithScaleDown) then
LoadIconWithScaleDown(0, IDI_ERROR, Scale(16), Scale(16), FErrorIcon);
finally
FreeLibrary(ComCtl);
end;
end;
FLIWSD := FErrorIcon <> 0;
if FErrorIcon = 0 then
FErrorIcon := LoadIcon(0, IDI_ERROR);
end;
procedure TSuperInputForm.FormDestroy(Sender: TObject);
begin
if FLIWSD then
DestroyIcon(FErrorIcon);
end;
procedure TSuperInputForm.pbErrorIconPaint(Sender: TObject);
begin
if FErrorIcon <> 0 then
DrawIconEx(pbErrorIcon.Canvas.Handle, 0, 0, FErrorIcon,
Scale(16), Scale(16), 0, 0, DI_NORMAL);
end;
procedure TSuperInputForm.ValidatorTimer(Sender: TObject);
begin
DoValidate;
end;
function SuperInput(AOwnerForm: TCustomForm; const ACaption, AMainInstruction: string;
var AText: string; AValidator: TValidator = nil): Boolean;
begin
var LFrm := TSuperInputForm.Create(AOwnerForm);
try
LFrm.Caption := ACaption;
LFrm.lblCaption.Caption := AMainInstruction;
LFrm.Edit.Text := AText;
LFrm.FValidator := AValidator;
LFrm.DoValidate;
Result := LFrm.ShowModal = mrOk;
if Result then
AText := LFrm.Edit.Text;
finally
LFrm.Free;
end;
end;
end.
和DFM:
object SuperInputForm: TSuperInputForm
Left = 0
Top = 0
Caption = 'Input Box'
ClientHeight = 166
ClientWidth = 469
Color = clBtnFace
Constraints.MaxHeight = 204
Constraints.MinHeight = 204
Constraints.MinWidth = 400
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -12
Font.Name = 'Segoe UI'
Font.Style = []
OldCreateOrder = False
Position = poOwnerFormCenter
OnCreate = FormCreate
OnDestroy = FormDestroy
DesignSize = (
469
166)
PixelsPerInch = 96
TextHeight = 15
object shClient: TShape
Left = 0
Top = 0
Width = 468
Height = 127
Anchors = [akLeft, akTop, akRight, akBottom]
Pen.Style = psClear
ExplicitWidth = 499
ExplicitHeight = 175
end
object lblCaption: TLabel
Left = 24
Top = 24
Width = 65
Height = 21
Caption = 'Input Box'
Font.Charset = DEFAULT_CHARSET
Font.Color = 10040064
Font.Height = -16
Font.Name = 'Segoe UI'
Font.Style = []
ParentFont = False
end
object pbErrorIcon: TPaintBox
Left = 24
Top = 88
Width = 16
Height = 16
OnPaint = pbErrorIconPaint
end
object lblError: TLabel
Left = 50
Top = 88
Width = 3
Height = 15
end
object Edit: TEdit
Left = 24
Top = 51
Width = 418
Height = 23
Anchors = [akLeft, akTop, akRight]
TabOrder = 0
OnChange = EditChange
ExplicitWidth = 449
end
object btnOK: TButton
Left = 286
Top = 133
Width = 75
Height = 25
Anchors = [akRight, akBottom]
Caption = 'OK'
Default = True
TabOrder = 1
OnClick = btnOKClick
ExplicitLeft = 317
ExplicitTop = 181
end
object btnCancel: TButton
Left = 367
Top = 133
Width = 75
Height = 25
Anchors = [akRight, akBottom]
Cancel = True
Caption = 'Cancel'
ModalResult = 2
TabOrder = 2
ExplicitLeft = 398
ExplicitTop = 181
end
object Validator: TTimer
OnTimer = ValidatorTimer
Left = 136
Top = 120
end
end
请注意,这只是我在十分钟内完成的一个草图--在一个真正的应用程序中,您会在这个程序上花费更多的时间。
附录1
type
TChrTestFcn = function(C: Char): Boolean;
function StrHasChrOfType(const AText: string; ATestFcn: TChrTestFcn): Boolean;
begin
for var S in AText do
if ATestFcn(S) then
Exit(True);
Result := False;
end;
发布于 2022-02-06 10:22:19
最简单和最通用的选项是编写自己的输入对话框,或者在对话框中包含验证代码,或者传递一个执行验证的回调方法。
但要回答你提出的问题:
“在用户单击OK按钮之前,是否有一种方法来验证用户的输入?”
不,据我所知,不可能。
发布于 2022-02-06 12:01:23
不,不可能。但也有其他选择:
InputQuery
的代码,编写类似的代码,然后在需要的地方进行修改(例如为TEdit
设置OnChange
处理程序)。InputQuery
那样)动态创建一个:- You can either use your own logic for getting the user's choice and input when the form is closed, or
- you set the form's `ModalResult` property (via code) anytime, and you can assign a `ModalResult` to each button (e.g. `mrCancel`), so it automatically sets the form's `ModalResult` property. Call your own form just as if it's [`MessageBox()`](https://docwiki.embarcadero.com/Libraries/Sydney/en/Vcl.Forms.TApplication.MessageBox): case MyForm.ShowModal() of IDOK: begin // User wants to proceed AND no error was found end; IDCANCEL: begin // User gave up end; else // Unexpected result end;
var aNewFolderName,sErrorMsg: String;开始重复aNewFolderName:=‘新建项目文件夹’;//用户已取消:如果没有Vcl.Dialogs.InputQuery,则留下循环(‘新建项目文件夹’),‘输入新项目文件夹的名称:’,aNewFolderName )然后中断;//在尝试之前已经出错?sErrorMsg:= CheckInput( aNewFolderName );//实际尝试,如果sErrorMsg= '‘那么sErrorMsg:= CreateTheFolder( aNewFolderName );//有什么要报告的吗?如果sErrorMsg<> '‘然后开始sErrorMsg:= sErrorMsg+ #13#10 +’sErrorMsg:=sErrorMsg+ #13#10 +‘Retry’以尝试另一个新项目名。‘+#13#10+’单击"Cancel“以不创建任何新项目。‘;如果MessageBox( sErrorMsg,'Error',MB_RETRYCANCEL )= IDCANCEL,则中断;end Otherwise开始中断;/否则我们完成(CreateTheFolder成功)结束;直到FALSE;end;
https://stackoverflow.com/questions/71005853
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