如何在OpenDialog界面上加上一点自己的东西？(20分)

在OpenDialog执行时，显示的界面上，除了本身的那些东西，
我还想放上一点自己的东西，就像Photoshop打开文件时一样，
可以预览图像。

怎样可以实现这一点？

可以参考Delphi中的TPictureOpenDialog和TPictureSaveDialog的源代码.
在$Delphi/source/vcl中.

自己做个对话框啦

继承TpenDialog，在create中做你想做的事

我参照TPictureOpenDialog写了一个类似的OpenDialog,结果却不如愿，
在procedure DoShow中，GetClientRect时返回的Rect总是 top=0,bottom=0,left=0
为什么，望高人指点，谢谢。

代码如下：

unit RepOpenDialog;

interface

Uses
Dialogs,graphics,extctrls,stdctrls,buttons,classes,Controls,
consts,Windows,Sysutils,forms;
Type
TRepOpenDialog = class(TOpenDialog)
private
FCheckPanel: TPanel;
FChkDrawHLine:TCheckBox;
FChkDrawVLine:TCheckBox;
protected
procedure DoClose; override;
procedure DoShow; override;
published
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
end;

procedure Register;
implementation

constructor TRepOpenDialog.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
FCheckPanel := TPanel.Create(Self);
with FCheckPanel do
begin
Name := 'CheckPanel';
Caption := '';
SetBounds(204, 5, 169, 200);
BevelOuter := bvNone;
BorderWidth := 6;
TabOrder := 1;
FChkDrawHLine := TCheckBox.Create(Self);
FChkDrawVLine := TCheckBox.Create(Self);
with FChkDrawHLine do
begin
Name := 'ChkDrawHLine';
Caption := '';
SetBounds(6, 6, 157, 23);
Align := alTop;
AutoSize := False;
Parent := FCheckPanel;
end;
with FChkDrawVLine do
begin
Name := 'ChkDrawVLine';
Caption := '';
SetBounds(6, 6, 157, 23);
Align := alTop;
AutoSize := False;
Parent := FCheckPanel;
end;
end;
end;

destructor TRepOpenDialog.Destroy;
begin
FChkDrawHLine.Free;
FChkDrawVLine.Free;
FCheckPanel.Free;
inherited Destroy;
end;
procedure TRepOpenDialog.DoClose;
begin
inherited DoClose;
{ Hide any hint windows left behind }
Application.HideHint;
end;

procedure TRepOpenDialog.DoShow;
var
PreviewRect, StaticRect: TRect;
begin
{ Set preview area to entire dialog }
GetClientRect(Handle, PreviewRect);
StaticRect := GetStaticRect;
{ Move preview area to right of static area }
PreviewRect.Left := StaticRect.Left + (StaticRect.Right - StaticRect.Left);
Inc(PreviewRect.Top, 4);
FCheckPanel.BoundsRect := PreviewRect;
FCheckPanel.ParentWindow := Handle;
inherited DoShow;
end;
procedure Register;
begin
RegisterComponents('Standard', [TRepOpenDialog]);
end;
end.

如果直接在FORM中画个对话框也不错啊！

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多人接受答案了。