用 GDI 操作 EMF 文件[4]: 重绘 EMF

本例效果图:

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代码文件:

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unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
    procedure FormMouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure Button1Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

var
  HMetaFile: HENHMETAFILE;
  f: Boolean;
  x1,y1: Integer;
  R: TRect;

procedure TForm1.FormCreate(Sender: TObject);
const
  Path = 'C:\Temp\MyMetaFile.emf';
begin
  HMetaFile := GetEnhMetaFile(PChar(Path));
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  DeleteEnhMetaFile(HMetaFile);
end;

procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  f := True;
  x1 := X;
  y1 := Y;
  R := Rect(x1,y1,X,Y);
end;

procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
  if not f then Exit;
  DrawFocusRect(Canvas.Handle, R);
  R := Rect(x1,y1,X,Y);
  DrawFocusRect(Canvas.Handle, R);
  R := Rect(x1,y1,X,Y);
end;

procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  f := False;
  PlayEnhMetaFile(Canvas.Handle, HMetaFile, R);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  Refresh;
end;

end.

窗体文件:

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object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 206
  ClientWidth = 339
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  Position = poDesktopCenter
  OnCreate = FormCreate
  OnDestroy = FormDestroy
  OnMouseDown = FormMouseDown
  OnMouseMove = FormMouseMove
  OnMouseUp = FormMouseUp
  PixelsPerInch = 96
  TextHeight = 13
  object Button1: TButton
    Left = 256
    Top = 173
    Width = 75
    Height = 25
    Caption = 'Button1'
    TabOrder = 0
    OnClick = Button1Click
  end
end