GDI+从流中加载图片（转自万一的blog）

 

uses GDIPOBJ, GDIPAPI;

procedure TForm1.FormPaint(Sender: TObject);
const
  ImgPath = 'c:/temp/test.bmp';
var
  img: TGPImage;
  bit: TBitmap;
  g: TGPGraphics;
begin
  bit := TBitmap.Create;
  bit.LoadFromFile(ImgPath); {因为 TBitmap 操作流特别方便, 这里就没有演示}

  img := TGPBitmap.Create(bit.Handle, bit.Palette);

  g := TGPGraphics.Create(Canvas.Handle);
  g.DrawImage(img, 0, 0);

  g.Free;
  bit.Free;
  img.Free;
end;

方法二:



TGPImage 需要的是 IStream 而非 TStream, 直接给它一个 IStream 参数不就完了?

那怎么实现 IStream 接口呢? Classes 单元下有一个 TStreamAdapter 类就是专门实现 IStream 接口的.

uses GDIPOBJ, GDIPAPI;

procedure TForm1.FormPaint(Sender: TObject);
const
  ImgPath = 'c:/temp/test.bmp';
var
  img: TGPImage;
  MemStream: TMemoryStream;
  MyIStream: TStreamAdapter;
  g: TGPGraphics;
begin
  MemStream := TMemoryStream.Create;
  MemStream.LoadFromFile(ImgPath);
  MyIStream := TStreamAdapter.Create(MemStream);
  img := TGPImage.Create(MyIStream);

  g := TGPGraphics.Create(Canvas.Handle);
  g.DrawImage(img, 0, 0);

  g.Free;
  img.Free;
  MemStream.Free;
  MyIStream := nil; {注意这里}
end;