C＃System.InvalidOperationException：對象當前正在其他地方使用

Question

我已經看到關於同一主題的問題，但無法弄清楚如何解決這個問題。在我的遊戲中，我使用兩個線程Logic線程和UI線程。這是我遇到的問題

System.InvalidOperationException: Object is currently in use elsewhere. 
    at System.Drawing.Graphics.FromImage(Image image) 
    at GECS.Core.Game.UpdateLoop() in c:\Us....ore\Game.cs:line 82 
    at System.Threading.ThreadHelper.ThreadStart_Context(Object state) 
    at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) 
    at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) 
    at System.Threading.ThreadHelper.ThreadStart() 

我只在UI線程上渲染。這是我的渲染循環。我把它放在構造函數中。

while (true) { 
    if (!Created) { 
     break; 
    } 
    if (Win32.PeekMessage(out msg, IntPtr.Zero, 0, 0, (uint)Win32.PM.REMOVE)) { 
     if (msg.message == (uint)Win32.WindowsMessage.WM_QUIT) { 
      break; 
     } else { 
      Win32.TranslateMessage(ref msg); 
      Win32.DispatchMessage(ref msg); 
     } 
    } else { 
     Text = Global.TITLE; 
     now = GetCurrentTime(); 
     Graphics front = Graphics.FromHwnd(Handle); 
     front.DrawImage(backBuffer, 0, 0); 
     front.Dispose(); 
    } 
} 

而我的邏輯

while (Created) { 
    now = GetCurrentTime(); 
    while (now > game_time) { 
     elapsedTime = 1000/Global.ACTUAL_STEPS_FOR_SECOND; 
     Update(elapsedTime); 
     Map.UpdateObjects(elapsedTime); 
     game_time += step_size; 
    } 
    Graphics g = Graphics.FromImage(backBuffer); // This line is error 
    g.Clear(Color.WhiteSmoke); 
    Render(g); 
    g.Dispose(); 
} 

環路我怎樣才能解決這個問題？已經嘗試在渲染循環之上粘貼邏輯循環，這使得我的遊戲非常慢。

謝謝

Answer 1

「兩個線程」當然是問題。它們不允許兩個線程同時訪問backBuffer。您必須使用鎖來防止這種情況發生。大致爲：

private object bufferLock = new object(); 
... 
    using (var front = Graphics.FromHwnd(Handle)) { 
     lock (bufferLock) { 
      front.DrawImage(backBuffer, 0, 0); 
     } 
    } 

和

lock (bufferLock) { 
     using (var g = Graphics.FromImage(backBuffer) { // No more error 
      g.Clear(Color.WhiteSmoke); 
      Render(g); 
     } 
    } 

其餘的看起來並不健康的要麼，你是不是使得兩個線程之間確保正確乒乓球，這是非常不清楚線程擁有的窗口。