求ShowMessage()使用方法

[sunnysab]

VC6
rt
求ShowMessage()使用方法,很好奇，因为今天网上有个源码用到了这个函数。我找了baidu，没有什么有价值的资料

[hyz_cs]

VC不是有AfxMessageBox吗

[sololie]

ShowMessage没有重载，只有一种形式 ShowMessage("hello heck"); vcl中的ShowMessag内部调用了vcl的ShowMessagePos,ShowMessagePos调用了MessageDlgPos，MessageDlgPos调用了MessageDlgPosHelp，MessageDlgPosHelp调用了CreateMessageDialog， CreateMessageDialog。 CreateMessageDialog 实现如下：

function CreateMessageDialog(const Msg: string; DlgType: TMsgDlgType;
  Buttons: TMsgDlgButtons): TForm;
const
  mcHorzMargin = 8;
  mcVertMargin = 8;
  mcHorzSpacing = 10;
  mcVertSpacing = 10;
  mcButtonWidth = 50;
  mcButtonHeight = 14;
  mcButtonSpacing = 4;
var
  DialogUnits: TPoint;
  HorzMargin, VertMargin, HorzSpacing, VertSpacing, ButtonWidth,
  ButtonHeight, ButtonSpacing, ButtonCount, ButtonGroupWidth,
  IconTextWidth, IconTextHeight, X, ALeft: Integer;
  B, DefaultButton, CancelButton: TMsgDlgBtn;
  IconID: PChar;
  TextRect: TRect;
begin
  Result := TMessageForm.CreateNew(Application);
  with Result do
  begin
    BiDiMode := Application.BiDiMode;
    BorderStyle := bsDialog;
    Canvas.Font := Font;
    KeyPreview := True;
    OnKeyDown := TMessageForm(Result).CustomKeyDown;
    DialogUnits := GetAveCharSize(Canvas);
    HorzMargin := MulDiv(mcHorzMargin, DialogUnits.X, 4);
    VertMargin := MulDiv(mcVertMargin, DialogUnits.Y, 8);
    HorzSpacing := MulDiv(mcHorzSpacing, DialogUnits.X, 4);
    VertSpacing := MulDiv(mcVertSpacing, DialogUnits.Y, 8);
    ButtonWidth := MulDiv(mcButtonWidth, DialogUnits.X, 4);
    for B := Low(TMsgDlgBtn) to High(TMsgDlgBtn) do
    begin
      if B in Buttons then
      begin
        if ButtonWidths[B] = 0 then
        begin
          TextRect := Rect(0,0,0,0);
          Windows.DrawText( canvas.handle,
            PChar(LoadResString(ButtonCaptions[B])), -1,
            TextRect, DT_CALCRECT or DT_LEFT or DT_SINGLELINE or
            DrawTextBiDiModeFlagsReadingOnly);
          with TextRect do ButtonWidths[B] := Right - Left + 8;
        end;
        if ButtonWidths[B] > ButtonWidth then
          ButtonWidth := ButtonWidths[B];
      end;
    end;
    ButtonHeight := MulDiv(mcButtonHeight, DialogUnits.Y, 8);
    ButtonSpacing := MulDiv(mcButtonSpacing, DialogUnits.X, 4);
    SetRect(TextRect, 0, 0, Screen.Width div 2, 0);
    DrawText(Canvas.Handle, PChar(Msg), Length(Msg)+1, TextRect,
      DT_EXPANDTABS or DT_CALCRECT or DT_WORDBREAK or
      DrawTextBiDiModeFlagsReadingOnly);
    IconID := IconIDs[DlgType];
    IconTextWidth := TextRect.Right;
    IconTextHeight := TextRect.Bottom;
    if IconID <> nil then
    begin
      Inc(IconTextWidth, 32 + HorzSpacing);
      if IconTextHeight < 32 then IconTextHeight := 32;
    end;
    ButtonCount := 0;
    for B := Low(TMsgDlgBtn) to High(TMsgDlgBtn) do
      if B in Buttons then Inc(ButtonCount);
    ButtonGroupWidth := 0;
    if ButtonCount <> 0 then
      ButtonGroupWidth := ButtonWidth * ButtonCount +
        ButtonSpacing * (ButtonCount - 1);
    ClientWidth := Max(IconTextWidth, ButtonGroupWidth) + HorzMargin * 2;
    ClientHeight := IconTextHeight + ButtonHeight + VertSpacing +
      VertMargin * 2;
    Left := (Screen.Width div 2) - (Width div 2);
    Top := (Screen.Height div 2) - (Height div 2);
    if DlgType <> mtCustom then
      Caption := LoadResString(Captions[DlgType]) else
      Caption := Application.Title;
    if IconID <> nil then
      with TImage.Create(Result) do
      begin
        Name := 'Image';
        Parent := Result;
        Picture.Icon.Handle := LoadIcon(0, IconID);
        SetBounds(HorzMargin, VertMargin, 32, 32);
      end;
    TMessageForm(Result).Message := TLabel.Create(Result);
    with TMessageForm(Result).Message do
    begin
      Name := 'Message';
      Parent := Result;
      WordWrap := True;
      Caption := Msg;
      BoundsRect := TextRect;
      BiDiMode := Result.BiDiMode;
      ALeft := IconTextWidth - TextRect.Right + HorzMargin;
      if UseRightToLeftAlignment then
        ALeft := Result.ClientWidth - ALeft - Width;
      SetBounds(ALeft, VertMargin,
        TextRect.Right, TextRect.Bottom);
    end;
    if mbOk in Buttons then DefaultButton := mbOk else
      if mbYes in Buttons then DefaultButton := mbYes else
        DefaultButton := mbRetry;
    if mbCancel in Buttons then CancelButton := mbCancel else
      if mbNo in Buttons then CancelButton := mbNo else
        CancelButton := mbOk;
    X := (ClientWidth - ButtonGroupWidth) div 2;
    for B := Low(TMsgDlgBtn) to High(TMsgDlgBtn) do
      if B in Buttons then
        with TButton.Create(Result) do
        begin
          Name := ButtonNames[B];
          Parent := Result;
          Caption := LoadResString(ButtonCaptions[B]);
          ModalResult := ModalResults[B];
          if B = DefaultButton then Default := True;
          if B = CancelButton then Cancel := True;
          SetBounds(X, IconTextHeight + VertMargin + VertSpacing,
            ButtonWidth, ButtonHeight);
          Inc(X, ButtonWidth + ButtonSpacing);
          if B = mbHelp then
            OnClick := TMessageForm(Result).HelpButtonClick;
        end;
  end;
end;

[sunnysab]

只是昨天的时候，我在网上看到有人源码里加了这个函数，不知道怎么用。因为我调用的时候找了windows.h没用、

[vc8fans]

是API函数中的，是windows系统的函数，只是调用关系而已，