当owner是MDI时，如何定位TForm poOwnerFormCenter？
当owner是MDI时，如何定位TForm poOwnerFormCenter？
提问于 2018-06-07 23:21:33
我想将TCustomForm的后代显示为对话框，以便将它们定位为poOwnerFormCenter。但是，当FormStyle为fsNormal时，正确定位窗体的代码不会在FormStyle为fsMDIChild时设置正确的位置。
当辅助表单具有FormStyle = fsNormal时，Button1将打开模式对话框，如下所示：
但是，当辅助窗体具有FormStyle = fsMDIChild时，定位似乎是相对于MDI子窗体相对于MDI父窗体的位置，而不是相对于MDI子窗体的绝对位置：
我不确定我是否犯了任何错误，这可能是一个bug或正常行为。
下面的代码用于显示对话框：
procedure TForm3.Button1Click(Sender: TObject);
var
AModalForm: TForm;
begin
AModalForm := TForm.Create(Self);
try
AModalForm.Position := poOwnerFormCenter;
AModalForm.ShowModal;
finally
AModalForm.Free;
end;
end;要复制的项目：
dpr
program Project2;
uses
Vcl.Forms,
Unit2 in 'Unit2.pas' {Form2},
Unit3 in 'Unit3.pas' {Form3};
{$R *.res}
var
AMainForm: TForm2;
A: TApplication;
begin
A := Application;
A.Initialize;
A.MainFormOnTaskbar := True;
A.CreateForm(TForm2, AMainForm);
A.Run;
end.Unit2
pas
unit Unit2;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ExtCtrls, Vcl.Menus;
type
TForm2 = class(TForm)
Button1: TButton;
Panel1: TPanel;
Button2: TButton;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
implementation
{$R *.dfm}
uses
Unit3;
procedure TForm2.Button1Click(Sender: TObject);
var
AForm: TForm3;
begin
AForm := TForm3.Create(Self);
AForm.FormStyle := fsMDIChild;
end;
procedure TForm2.Button2Click(Sender: TObject);
var
AForm: TForm3;
begin
AForm := TForm3.Create(Self);
AForm.FormStyle := fsNormal;
end;
end.dfm
object Form2: TForm2
Left = 0
Top = 0
Caption = 'Form2'
ClientHeight = 356
ClientWidth = 635
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'Tahoma'
Font.Style = []
FormStyle = fsMDIForm
OldCreateOrder = False
Visible = True
PixelsPerInch = 96
TextHeight = 13
object Panel1: TPanel
Left = 0
Top = 0
Width = 97
Height = 356
Align = alLeft
TabOrder = 0
object Button1: TButton
Left = 8
Top = 39
Width = 75
Height = 25
Caption = 'fsMDIChild'
TabOrder = 0
OnClick = Button1Click
end
object Button2: TButton
Left = 8
Top = 8
Width = 75
Height = 25
Caption = 'fsNormal'
TabOrder = 1
OnClick = Button2Click
end
end
endUnit3
pas
unit Unit3;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;
type
TForm3 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
implementation
{$R *.dfm}
procedure TForm3.Button1Click(Sender: TObject);
var
AModalForm: TForm;
begin
AModalForm := TForm.Create(Self);
try
AModalForm.Position := poOwnerFormCenter;
AModalForm.ShowModal;
finally
AModalForm.Free;
end;
end;
end.dfm
object Form3: TForm3
Left = 0
Top = 0
Caption = 'Form3'
ClientHeight = 336
ClientWidth = 635
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'Tahoma'
Font.Style = []
OldCreateOrder = False
Visible = True
PixelsPerInch = 96
TextHeight = 13
object Button1: TButton
Left = 8
Top = 8
Width = 75
Height = 25
Caption = 'Button1'
TabOrder = 0
OnClick = Button1Click
end
end回答 1
Stack Overflow用户
回答已采纳
发布于 2018-06-08 06:11:49
在尝试了在这里和其他地方找到的几个想法之后，我所有的尝试都失败了，我想最安全的解决方案如下所示。
Unit1 - Form1:TForm1 - fsMDIForm
Unit2 - Form2:TForm2 - fsMDIChild
Unit3 - AModalForm:TFom3 - ordinary form, shown modally, centered on the Form2最重要的部分仅仅是手动计算和设置AModalForm的Left和Top属性，使其居中。它还需要将Position属性设置为poDesigned
// Showing the modal form centered by a fsMDIChild form
procedure TForm2.Button1Click(Sender: TObject);
var
AModalForm: TForm3;
begin
AModalForm := TForm3.Create(self);
try
AModalForm.Left := Self.ClientOrigin.X + (Self.ClientWidth-AModalForm.Width) div 2;
AModalForm.Top := Self.ClientOrigin.Y + (Self.ClientHeight-AModalForm.Height) div 2;
AModalForm.Position := poDesigned;
AModalForm.ShowModal;
// use modalresult as needed
finally
AModalForm.Free;
end;
end;页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/50744920
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