我真的不能肯定地说,为什么你得到一个JPG错误。但是你所显示的代码有一些逻辑问题。
虽然不是真的有问题,也没有必要分别拨打TIdIOHandler.Write(Int64)
和TIdIOHandler.Write(TStream)
。后者可以为您发送流大小。只要其AWriteByteCount
参数设置为True,并确保设置TIdIOHandler.LargeStream
属性为True,因此将发送字节数为Int64
:
AConn.Client.IOHandler.LargeStream := True;
AConn.Client.IOHandler.Write(JpegStream, 0, True);
同样地,你不需要调用TIdIOHandler.ReadInt64()
和TIdIOHandler.ReadStream()
分开,无论是。后者可以为你读取流的大小。只需将其AByteCount
参数为-1及其AReadUntilDisconnect
参数为False(这些都是默认值无论如何),并设置TIdIOHandler.LargeStream
为True,所以它读取数据流大小为Int64
:
TMyContext(Ctx).Connection.IOHandler.LargeStream := True;
TMyContext(Ctx).Connection.IOHandler.ReadStream(PicStream, -1, False);
这将会把负担在Indy上一致地发送和接收流,而不是您尝试手动执行。
现在,就这么说,你的代码中更重要的问题是你的ScreenRecord()
函数显然在工作线程中运行,但它实际上并不是线程安全的。具体而言,在访问lvMain.Selected
或致电Picture.LoadFromFile()
时,您不会与主UI线程同步。这本身可能会导致JPG错误。 VCL/FMX UI控件无法安全地在主UI线程之外访问,您必须同步对它们的访问。
实际上,您的流读取逻辑确实属于TIdTCPServer.OnExecute
事件。在这种情况下,可以完全消除TScreenRecord
线程(因为TIdTCPServer
已经是多线程的)。当用户选择一个新的列表项目时,在相应的TMyContext
中设置一个标志(并且清除先前选择的项目中的标志,如果有的话)。只要在给定连接上设置该标志,就让OnExecute
事件处理程序请求/接收流。
尝试更多的东西是这样的:
客户端现在
if List[0] = 'RecordScreen' then
begin
JpegStream := TMemoryStream.Create;
try
pic := TBitmap.Create;
try
ScreenShot(0,0,pic);
BMPtoJPGStream(pic, JpegStream);
finally
pic.Free;
end;
AConn.Client.IOHandler.LargeStream := True;
AConn.Client.IOHandler.Write(JpegStream, 0, True);
finally
JpegStream.Free;
end;
end;
服务器端
type
TMyContext = class(TIdServerContext)
public
//...
RecordScreen: Boolean;
end;
procedure TMainForm.FormCreate(Sender: TObject);
begin
idtcpsrvrMain.ContextClass := TMyContext;
//...
end;
var
SelectedItem: TListItem = nil;
procedure TMainForm.lvMainChange(Sender: TObject; Item: TListItem; Change: TItemChange);
var
List: TList;
Ctx: TMyContext;
begin
if Change <> ctState then
Exit;
List := idtcpsrvrMain.Contexts.LockList;
try
if (SelectedItem <> nil) and (not SelectedItem.Selected) then
begin
Ctx := TMyContext(SelectedItem.Data);
if List.IndexOf(Ctx) <> -1 then
Ctx.RecordScreen := False;
SelectedItem := nil;
end;
if Item.Selected then
begin
SelectedItem := Item;
Ctx := TMyContext(SelectedItem.Data);
if List.IndexOf(Ctx) <> -1 then
Ctx.RecordScreen := True;
end;
finally
idtcpsrvrMain.Contexts.UnlockList;
end;
end;
procedure TMainForm.idtcpsrvrMainConnect(AContext: TIdContext);
begin
//...
TThread.Queue(nil,
procedure
var
Item: TListItem;
begin
Item := lvMain.Items.Add;
Item.Data := AContext;
//...
end
);
end;
procedure TMainForm.idtcpsrvrMainDisconnect(AContext: TIdContext);
begin
TThread.Queue(nil,
procedure
var
Item: TListItem;
begin
Item := lvMain.FindData(0, AContext, True, False);
if Item <> nil then Item.Delete;
end
);
end;
procedure TMainForm.idtcpsrvrMainExecute(AContext: TIdContext);
var
Dir, PicName: string;
PicStream: TMemoryStream;
Ctx: TMyContext;
begin
Ctx := TMyContext(AContext);
Sleep(50);
if not Ctx.RecordScreen then
Exit;
PicStream := TMemoryStream.Create;
try
AContext.Connection.IOHandler.WriteLn('RecordScreen');
AContext.Connection.IOHandler.LargeStream := True;
AContext.Connection.IOHandler.ReadStream(PicStream, -1, False);
AContext.Connection.IOHandler.WriteLn('RecordScreenDone');
if not Ctx.RecordScreen then
Exit;
try
Dir := IncludeTrailingBackslash(Ctx.ClinetDir + ScreenshotsDir);
ForceDirectories(Dir);
PicName := Dir + 'Screen-' + DateTimeToFilename + '.JPG';
PicStream.SaveToFile(PicName);
TThread.Queue(nil,
procedure
begin
fScreenRecord.imgScreen.Picture.LoadFromFile(PicName);
end;
);
except
end;
finally
PicStream.Free;
end;
end;
,随着中说,为了更好地优化您的协议,我将建议发送RecordScreen
命令只有一次,当你准备开始接收图像(当在ListView中选择客户端时)并仅发送RecordScreenDone
命令o当您准备好停止接收图像时(当客户端在ListView中未被选中时)。让客户端在收到ReccordScreen
之前发送连续的图像流,直到它收到RecordScreenDone
或客户端断开连接。
事情是这样的:
客户端
if List[0] = 'RecordScreen' then
begin
// Start a short timer...
end
else if List[0] = 'RecordScreenDone' then
begin
// stop the timer...
end;
...
procedure TimerElapsed;
var
JpegStream: TMemoryStream;
pic: TBitmap;
begin
JpegStream := TMemoryStream.Create;
try
pic := TBitmap.Create;
try
ScreenShot(0,0,pic);
BMPtoJPGStream(pic, JpegStream);
finally
pic.Free;
end;
try
AConn.Client.IOHandler.LargeStream := True;
AConn.Client.IOHandler.Write(JpegStream, 0, True);
except
// stop the timer...
end;
finally
JpegStream.Free;
end;
服务器端
type
TMyContext = class(TIdServerContext)
public
//...
RecordScreen: Boolean;
IsRecording: Boolean;
end;
procedure TMainForm.idtcpsrvrMainExecute(AContext: TIdContext);
var
Dir, PicName: string;
PicStream: TMemoryStream;
Ctx: TMyContext;
begin
Ctx := TMyContext(AContext);
Sleep(50);
if not Ctx.RecordScreen then
begin
if Ctx.IsRecording then
begin
AContext.Connection.IOHandler.WriteLn('RecordScreenDone');
Ctx.IsRecording := False;
end;
Exit;
end;
if not Ctx.IsRecording then
begin
AContext.Connection.IOHandler.WriteLn('RecordScreen');
Ctx.IsRecording := True;
end;
PicStream := TMemoryStream.Create;
try
AContext.Connection.IOHandler.LargeStream := True;
AContext.Connection.IOHandler.ReadStream(PicStream, -1, False);
if not Ctx.RecordScreen then
begin
AContext.Connection.IOHandler.WriteLn('RecordScreenDone');
Ctx.IsRecording := False;
Exit;
end;
try
Dir := IncludeTrailingBackslash(Ctx.ClinetDir + ScreenshotsDir);
ForceDirectories(Dir);
PicName := Dir + 'Screen-' + DateTimeToFilename + '.JPG';
PicStream.SaveToFile(PicName);
TThread.Queue(nil,
procedure
begin
fScreenRecord.imgScreen.Picture.LoadFromFile(PicName);
end;
);
except
end;
finally
PicStream.Free;
end;
end;
'TMyContext(CTX).Connection.IOHandler.ReadStream(PicStream,大小,真);'或'AConn.Client.IOHandler.Write(JpegStream.Size,False);''Write'的默认转换值为'True' –