Question

我正在做以下步骤将TBitmap（Firemonkey）转换为字符串：

function BitmapToBase64(Bitmap: Tbitmap): string;
var
  BS: TBitmapSurface;
  AStream: TMemoryStream;
begin
  BS := TBitmapSurface.Create;
  BS.Assign(Bitmap);
  BS.SetSize(300, 200);
  AStream := TMemoryStream.Create;
  try
    TBitmapCodecManager.SaveToStream(AStream, BS, '.png');
    Result := TNetEncoding.Base64.EncodeBytesToString(AStream, AStream.Size);
  finally
    AStream.Free;
    BS.Free;
  end;
end;

如何将字符串还原为TBitmap？我做了以下哪个不生成TBitmap：

procedure Base64ToBitmap(AString: String; Result : Tbitmap);
var
  ms : TMemoryStream;
  BS: TBitmapSurface;
  bytes : TBytes;
begin
  bytes := TNetEncoding.Base64.DecodeStringToBytes(AString);
  ms := TMemoryStream.Create;
  try
    ms.WriteData(bytes, Length(bytes));
    ms.Position := 0;
    BS := TBitmapSurface.Create;
    BS.SetSize(300, 200);
    try
      TBitmapCodecManager.LoadFromStream(ms, bs);
      Result.Assign(bs);
    finally
      BS.Free;
    end;
  finally
    ms.Free;
  end;
end;

我需要更小的base64字符串，以便我可以将它传输到Datasnap服务器。正常的base64字符串给我内存不足，因为字符串的大小超过200000 - 1000000的长度。

Answer 1

在BitmapToBase64()中，您将TMemoryStream本身传递给TNetEncoding.Base64.EncodeBytesToString()，Memory不接受流作为输入开始。您需要传递流的function BitmapToBase64(Bitmap: Tbitmap): string; var BS: TBitmapSurface; AStream: TMemoryStream; begin BS := TBitmapSurface.Create; BS.Assign(Bitmap); BS.SetSize(300, 200); AStream := TMemoryStream.Create; try TBitmapCodecManager.SaveToStream(AStream, BS, '.png'); Result := TNetEncoding.Base64.EncodeBytesToString(AStream.Memory, AStream.Size); finally AStream.Free; BS.Free; end; end;属性的值：

error

Delphi TBitmap通过TBitmapSurface字符串并返回TBitmap

1 个答案: