Delphi Modal窗体（ModalResult、ShowModal）的介绍、使用方法和注意事项

淡定从容凤英 發表於 2021-8-31 11:42:00

Delphi Modal窗体（ModalResult、ShowModal）的介绍、使用方法和注意事项

Delphi Modal窗体（ModalResult）的介绍、使用方法和注意事项
1、ModalResult 介绍
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<pre class="brush:delphi;gutter:true;">//usescontrols
const
mrNone = 0;
mrOk = idOk;
mrCancel = idCancel;
mrAbort = idAbort;
mrRetry = idRetry;
mrIgnore = idIgnore;
mrYes = idYes;
mrNo = idNo;
mrAll = mrNo + 1;
mrNoToAll= mrAll + 1;
mrYesToAll = mrNoToAll + 1;

type
TModalResult = Low(Integer)..High(Integer);

//useswindows
const
IDOK = 1; ID_OK = IDOK;
IDCANCEL = 2; ID_CANCEL = IDCANCEL;
IDABORT = 3; ID_ABORT = IDABORT;
IDRETRY = 4; ID_RETRY = IDRETRY;
IDIGNORE = 5; ID_IGNORE = IDIGNORE;
IDYES = 6; ID_YES = IDYES;
IDNO = 7; ID_NO = IDNO;
IDCLOSE = 8; ID_CLOSE = IDCLOSE;
</pre>
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ModalResult 表示模式对话框的返回值。应用程序可以使用任何整数值作为模式结果值。尽管TModalResult可以采用任何整数值，但为常用的TModalResult值定义了以下常量：
<ul>
<li>mrNone  //无。在用户退出之前用作默认值。</li>
<li>mrOk   //idOK   用户使用OK按钮退出。</li>
<li>mrCancel  //idCancel  用户使用“取消”按钮退出。</li>
<li>mrAbort   //idAbort用户使用中止按钮退出。</li>
<li>mrRetry   //idRetry用户使用重试按钮退出。</li>
<li>mrIgnore  //idIgnore用户使用IGNORE按钮退出。</li>
<li>mrYes  //IdYes 用户使用“是”按钮退出。</li>
<li>mrNo   //idNo 用户使用“否”按钮退出。</li>
<li>mrAll   //mrNo+1用户使用ALL按钮退出。</li>
<li>mrNoToAll  //mrAll+1用户使用“全部拒绝”按钮退出。</li>
<li>mrYesToAll   //mrNoToAll+1  用户使用“全部是”按钮退出。</li>
</ul>
2、ModalResult 注意事项：
<ul>
<li>ModalResult属性返回值执行之后，该按钮所在的窗体会自动关闭，请勿再次使用Close关闭窗体。</li>
<li>基本上窗体和按钮的都有ModalResult的属性值</li>
<li>窗体的ModalResult属性会自动传递给ShowModal，作为方法的返回值。</li>
</ul>
3、ShowModal 介绍
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<pre class="brush:delphi;gutter:true;">function ShowModal: Integer; virtual;

function TCustomForm.ShowModal: Integer;
var
WindowList: Pointer;
SaveFocusCount: Integer;
SaveCursor: TCursor;
SaveCount: Integer;
ActiveWindow: HWnd;
begin
CancelDrag;
if Visible or not Enabled or (fsModal in FFormState) or
(FormStyle = fsMDIChild) then
raise EInvalidOperation.Create(SCannotShowModal);
if GetCapture <> 0 then SendMessage(GetCapture, WM_CANCELMODE, 0, 0);
ReleaseCapture;
Application.ModalStarted;
try
Include(FFormState, fsModal);
ActiveWindow := GetActiveWindow;
SaveFocusCount := FocusCount;
Screen.FSaveFocusedList.Insert(0, Screen.FFocusedForm);
Screen.FFocusedForm := Self;
SaveCursor := Screen.Cursor;
Screen.Cursor := crDefault;
SaveCount := Screen.FCursorCount;
WindowList := DisableTaskWindows(0);
try
Show;
try
 SendMessage(Handle, CM_ACTIVATE, 0, 0);
 ModalResult := 0;
 repeat
 Application.HandleMessage;
 if Application.FTerminate then ModalResult := mrCancel else
 if ModalResult <> 0 then CloseModal;
 until ModalResult <> 0;
 Result := ModalResult;
 SendMessage(Handle, CM_DEACTIVATE, 0, 0);
 if GetActiveWindow <> Handle then ActiveWindow := 0;
finally
 Hide;
end;
finally
if Screen.FCursorCount = SaveCount then
 Screen.Cursor := SaveCursor
else Screen.Cursor := crDefault;
EnableTaskWindows(WindowList);
if Screen.FSaveFocusedList.Count > 0 then
begin
 Screen.FFocusedForm := Screen.FSaveFocusedList.First;
 Screen.FSaveFocusedList.Remove(Screen.FFocusedForm);
end else Screen.FFocusedForm := nil;
if ActiveWindow <> 0 then SetActiveWindow(ActiveWindow);
FocusCount := SaveFocusCount;
Exclude(FFormState, fsModal);
end;
finally
Application.ModalFinished;
end;
end;</pre>
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<ul>
<li>使用ShowModal将窗体显示为模态窗体。模式窗体是指在关闭窗体之前应用程序无法继续运行的窗体。因此，ShowModal在表单关闭之前不会返回。当窗体关闭时，它返回ModalResult属性的值。</li>
<li>要关闭模态窗体，请将其ModalResult属性设置为非零值。</li>
<li>注意：如果表单包含ModalResult属性设置为mrNone以外的值的按钮，则当用户单击其中一个按钮并将ModalResult值作为ShowModal的返回值返回时，表单将自动关闭。</li>
<li>您可以使用全局IsAbortResult、IsAllResult、IsNegativeResult或IsPositiveResult函数对照常见返回值检查返回值。　　</li>
</ul>
4、使用示例：
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<pre class="brush:delphi;gutter:true;">//Form1中:
if Form2.ShowModal = mrok then ShowMessage('TaoRoy OK！');

//Form2中
procedure TForm2.button1Click(Sender: TObject);
begin
self.ModalResult := mrok;
end;
</pre>
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创建时间：2021.08.31　　更新时间：

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来源：https://www.cnblogs.com/guorongtao/p/15209614.html

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Delphi Modal窗体（ModalResult、ShowModal）的介绍、使用方法和注意事项