uses
Zlib
//压缩
procedure CompressBitmap(var CompressedStream: TMemoryStream;
const CompressionLevel: TCompressionLevel);
var
SourceStream: TCompressionStream;
DestStream: TMemoryStream;
Count: Integer;
Begin
Count := CompressedStream.Size; //获得图像流的原始尺寸
DestStream := TMemoryStream.Create;
SourceStream:=TCompressionStream.Create(CompressionLevel, DestStream);
Try
CompressedStream.SaveToStream(SourceStream); //SourceStream中保存着原始的图像流
//将原始图像流进行压缩，DestStream中保存着压缩后的图像流
SourceStream.Free;
CompressedStream.Clear;
CompressedStream.WriteBuffer(Count, SizeOf(Count)); //写入原始图像的尺寸
CompressedStream.CopyFrom(DestStream, 0); //写入经过压缩的图像流
finally
DestStream.Free;
end;
end;
//解压
procedure UnCompressBitmap(const CompressedStream: TFileStream; var Bmp: TBitmap);
var
SourceStream: TDecompressionStream;
DestStream: TMemoryStream;
Buffer: PChar;
Count: Integer;
Begin
CompressedStream.ReadBuffer(Count, SizeOf(Count)); //从被压缩的图像流中读出原始图像的尺寸
GetMem(Buffer, Count); //根据图像尺寸大小为将要读入的原始图像流分配内存块
DestStream := TMemoryStream.Create;
SourceStream := TDecompressionStream.Create(CompressedStream);
Try
SourceStream.ReadBuffer(Buffer^, Count); //将被压缩的图像流解压缩，然后存入 Buffer内存块中
DestStream.WriteBuffer(Buffer^, Count); //将原始图像流保存至 DestStream流中
DestStream.Position := 0; //复位流指针
Bmp.LoadFromStream(DestStream); //从 DestStream流中载入原始图像流
finally
FreeMem(Buffer);
DestStream.Free;
end;
end;
//压缩按钮 OnClick事件
procedure TForm1.Button1Click(Sender: TObject);
var
Bmp: TBitmap;
CompressedStream: TMemoryStream;
begin
Bmp := TBitmap.Create;
CompressedStream := TMemoryStream.Create;
Try
Bmp.SaveToStream(CompressedStream); //将 Bmp对象中的图像保存至内存流中
CompressBitmap(CompressedStream, clDefault); //按缺省的压缩比例对原始图像流进行压缩
finally
Bmp.Free;
CompressedStream.Free;
end;
end;
//解压缩按钮 OnClick事件
procedure TForm1.Button2Click(Sender: TObject);
var
CompressedStream: TFileStream;
Bmp: TBitmap;
begin
Bmp := TBitmap.Create;
Try
UnCompressBitmap(CompressedStream, Bmp); //将被压缩的图像流进行解压缩
Image1.Picture.Bitmap := Bmp;
finally
Bmp.Free;
CompressedStream.Free;
end;
end;
还能有什么不清楚吗。
