用 GDI 操作 EMF 文件[5]: GetEnhMetaFileDescription - 获取 EMF 文件的说明文本

再用 CreateEnhMetaFile 函数建立 EMF 文件时可以同时写入描述性说明;

用 GetEnhMetaFileDescription 函数可以读出 EMF 文件的说明文本.

本例给的说明文本非常简单, 不过标准的说明文本的格式应该是: 程序名#0文件标题#0#0

---

unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls;



type

  TForm1 = class(TForm)

    Button1: TButton;

    Button2: TButton;

    procedure FormCreate(Sender: TObject);

    procedure FormDestroy(Sender: TObject);

    procedure Button1Click(Sender: TObject);

    procedure Button2Click(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



var

  HMetaFile: HENHMETAFILE; {EMF 文件句柄}



{建立带说明的 EMF 文件}

procedure TForm1.FormCreate(Sender: TObject);

const

  Path = 'C:\Temp\MyMeateFile.emf';

  Description = 'ABCDE'; {当作 EMF 文件的说明}

var

  MetaFileDC: HDC;

begin

  {建立并写入说明}

  MetaFileDC := CreateEnhMetaFile(0, PChar(Path), nil, PChar(Description));

  {绘图}

  Rectangle(MetaFileDC, 11, 11, 111, 111);

  {结束编辑、保存文件, 并返回文件句柄}

  HMetaFile := CloseEnhMetaFile(MetaFileDC);

  {删除 DC}

  DeleteObject(MetaFileDC);

end;



{读取 EMF 文件的说明}

procedure TForm1.Button1Click(Sender: TObject);

var

  DescriptionSize: Integer; {说明段的大小}

  DescriptionBuf: PChar;    {接受说明的内存指针}

begin

  {获取大小}

  DescriptionSize := GetEnhMetaFileDescription(HMetaFile, 0, nil);

  {分配内存}

  GetMem(DescriptionBuf, DescriptionSize);

  {获取说明}

  GetEnhMetaFileDescription(HMetaFile, DescriptionSize, DescriptionBuf);

  {显示说明}

  ShowMessage(DescriptionBuf); {ABCDE}

  {释放内存}

  FreeMem(DescriptionBuf);

end;



{绘制在窗体}

procedure TForm1.Button2Click(Sender: TObject);

begin

  PlayEnhMetaFile(Canvas.Handle, HMetaFile, Rect(11,11,111,111));

end;



{删除 EMF 文件句柄}

procedure TForm1.FormDestroy(Sender: TObject);

begin

  DeleteEnhMetaFile(HMetaFile);

end;



end.