用 GDI 操作 EMF 文件[6]: GetEnhMetaFileHeader - 获取 EMF 的头文件

//增强图元文件的头文件结构 TEnhMetaHeader:

tagENHMETAHEADER = packed record

  iType: DWORD;          {记录类型}

  nSize: DWORD;          {结构大小}

  rclBounds: TRect;      {外接矩形(单位是像素)}

  rclFrame: TRect;       {图片矩形(单位是 0.1 毫米)}

  dSignature: DWORD;     {文件签名}

  nVersion: DWORD;       {文件版本}

  nBytes: DWORD;         {文件尺寸}

  nRecords: DWORD;       {记录数}

  nHandles: Word;        {句柄数}

  sReserved: Word;       {保留}

  nDescription: DWORD;   {说明文本的长度}

  offDescription: DWORD; {说明文本的偏移量}

  nPalEntries: DWORD;    {调色板的元素数}

  szlDevice: TSize;      {分辨率(像素)}

  szlMillimeters: TSize; {分辨率(毫米)}

  cbPixelFormat: DWORD;  {}

  offPixelFormat: DWORD; {}

  bOpenGL: DWORD;        {}

end;


 
   

本例效果图:

---

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 文件头}

procedure TForm1.Button1Click(Sender: TObject);

const

  n = #13#10;

var

  MetaHeaderSize: Integer;    {文件头大小}

  MetaHeader: PEnhMetaHeader; {文件头结构的指针}

  str: string;

  buf: array[Word] of Char;

begin

  MetaHeaderSize := GetEnhMetaFileHeader(HMetaFile, 0, nil);

  GetMem(MetaHeader, MetaHeaderSize);

  GetEnhMetaFileHeader(HMetaFile, MetaHeaderSize, MetaHeader);



  str := 'iType:          %d' + n +

         'nSize:          %d' + n +

         'rclBounds:      %d,%d,%d,%d' + n +

         'rclFrame:       %d,%d,%d,%d' + n +

         'dSignature:     %d' + n +

         'nVersion:       %d' + n +

         'nBytes:         %d' + n +

         'nRecords:       %d' + n +

         'nHandles:       %d' + n +

         //'sReserved:      %d' + n +

         'nDescription:   %d' + n +

         'offDescription: %d' + n +

         'nPalEntries:    %d' + n +

         'szlDevice:      %d,%d' + n +

         'szlMillimeters: %d,%d' + n +

         'cbPixelFormat:  %d' + n +

         'offPixelFormat: %d' + n +

         'bOpenGL:        %d';



  wvsprintf(buf, PChar(str), PChar(MetaHeader));

  ShowMessage(buf);

  FreeMem(MetaHeader);

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.