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  • JPEG和Variant的转换

    unit Unit1;

    interface

    uses 
      Windows, Messages, SysUtils, Classes, Graphics, Controls,     
      Forms, Dialogs,jpeg, ExtCtrls, StdCtrls,ActiveX, AxCtrls; 
    type 
      TForm1 = class(TForm) 
        Image1: TImage; 
        Button2: TButton; 
        Image2: TImage; 
        procedure Button2Click(Sender: TObject); 
      private 
        procedure StreamToVariant(Stream: TMemoryStream; 
                                  var v:  OleVariant); 
        procedure VariantToStream(const v: olevariant; 
                                  Stream: TMemoryStream); 
        procedure JPEGToVariant(aJPEG : TJPEGImage; 
                                 var aVariant:OleVariant); 
        procedure VariantToJPEG(aValue : OleVariant; 
                                 var aJPEG:TJPEGImage); 
        { Private-Deklarationen } 
      public 
        { Public-Deklarationen } 
      end;

    var 
      Form1: TForm1;

    implementation

    {$R *.DFM}

    procedure TForm1.VariantToStream (const v : olevariant; Stream : TMemoryStream); 
    var 
      p : pointer; 
    begin 
      Stream.Position := 0; 
      Stream.Size := VarArrayHighBound (v, 1) - VarArrayLowBound (v, 1) + 1; 
      p := VarArrayLock (v); 
      Stream.Write (p^, Stream.Size); 
      VarArrayUnlock (v); 
      Stream.Position := 0; 
    end;

    procedure TForm1.StreamToVariant (Stream : TMemoryStream; var v : OleVariant); 
    var 
      p : pointer; 
    begin 
      v := VarArrayCreate ([0, Stream.Size - 1], varByte); 
      p := VarArrayLock (v); 
      Stream.Position := 0; 
      Stream.Read (p^, Stream.Size); 
      VarArrayUnlock (v); 
    end;

    procedure TForm1.JPEGToVariant(aJPEG : TJPEGImage; var aVariant:OleVariant); 
    var 
      Stream        : TMemoryStream; 
    begin 
        try 
          Stream := TMemoryStream.Create;

          aJPEG.Assign(Image1.Picture.Bitmap); 
          aJPEG.SaveToStream(Stream);

          StreamToVariant(Stream, aVariant); 
        finally 
           Stream.Free; 
       end; 
    end;


    procedure TForm1.VariantToJPEG(aValue : OleVariant;var aJPEG:TJPEGImage); 
    var 
       Stream : TMemoryStream; 
    begin 
    try 
      Stream := TMemoryStream.Create;

      VariantToStream (aValue,Stream); 
      aJPEG.LoadfromStream(Stream);

    finally 
       VariantClear(aValue); 
       Stream.free; 
    end; 
    end;

    procedure TForm1.Button2Click(Sender: TObject); 
    var 
       aJPEG :TJPEGImage; 
       aVariant : OleVariant; 
    begin 
    try 
       aJPEG:=TJPEGImage.Create;

       //JPEG To Variant 
       aJPEG.Assign(Image1.Picture.Bitmap); 
       JPEGToVariant(aJPEG,aVariant);


       //Variant To JPEG 
       VariantToJPEG(aVariant,aJPEG); 
       Image2.Picture.assign(aJPEG); 
    finally 
       aJPEG.free; 
    end; 
    end;

    end.

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  • 原文地址:https://www.cnblogs.com/yzryc/p/6374921.html
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