[英]C# System.InvalidOperationException: Object is currently in use elsewhere
[英]System.InvalidOperationException: Object is currently in use elsewhere
嘗試在面板上繪制時,似乎出現此錯誤。 我不是C#專家,所以希望這里有人可以幫助我。 提前致謝。
堆棧跟蹤顯示
在C. \\ Users \\ kasunt \\ Microsoft Robotics Dev Studio 2008 R3 \\ Marvin \\ Teleoperation \\ MainForm.cs中的Victoria.Robotics.Marvin.Teleoperation.MainForm.DrawXYAxis(Graphics g)中的System.Drawing.Graphics.set_Transform(Matrix value) C:\\ Users \\ kasunt \\ Microsoft Robotics Dev Studio 2008 R3 \\ Marvin \\ Teleoperation \\ MainForm.cs中的Victoria.Robotics.Marvin.Teleoperation.MainForm.envMap_Paint(Object sender,PaintEventArgs e)中的第2173行:系統中的2143行。 System.Windows.Forms.Control.WmPaint(Message&m)的System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e,Int16層,布爾值disposeEventArgs)的Windows.Forms.Control.OnPaint(PaintEventArgs e) System.Windows.Forms.ScrollableControl.WndProc(Message&m)(位於System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message&m)(位於System.Windows.Forms.Control.ControlNativeWindow)處的Forms.Control.WndProc(Message&m)。 System.Windows.Forms.NativeWindow.Callback上的WndProc(Message&m)(IntPtr hWnd,Int32 msg,IntPtr wparam,IntPtr lparam)
代碼如下。 設置轉換時似乎發生了錯誤,
private void envMap_Paint(object sender, PaintEventArgs e)
{
DrawXYAxis(e.Graphics);
}
/// <summary>
/// Helper to draw the XY axis and plot the map
/// </summary>
public void DrawXYAxis(Graphics g)
{
Rectangle rect = envMap.ClientRectangle;
myPen = new Pen(Color.Black, 1);
g.PageUnit = GraphicsUnit.Millimeter;
g.PageScale = 0.1F;
IntPtr hdc = g.GetHdc();
int hMemDC = hdc.ToInt32();
// Reverse the axis of the drawing surface
Matrix mx = new Matrix(1, 0, 0, -1, 0, envMap.ClientSize.Height * 2);
g.Transform = mx;
g.TranslateTransform(50, 100, MatrixOrder.Append);
// For drawing X - AXIS
g.DrawLine(myPen, 0, 0, (2 * rect.Right - 60), 0);
// For drawing Y - AXIS
g.DrawLine(myPen, 0, 0, 0, 2 * rect.Bottom);
// For drawing Arrow on X-AXIS
g.DrawLine(myPen, (2 * rect.Right - 60) - 15, 8, (2 * rect.Right - 60), 0);
g.DrawLine(myPen, (2 * rect.Right - 60), 0, (2 * rect.Right - 60) - 15, -8);
// For drawing Arrow on Y-AXIS
g.DrawLine(myPen, 8, 2 * rect.Bottom - 15, 0, 2 * rect.Bottom);
g.DrawLine(myPen, 0, 2 * rect.Bottom, -8, 2 * rect.Bottom - 15);
// Save the state to restore later
GraphicsState state = g.Save();
// Create a matrix to offset the text to the desired position and flip it the
// right way up again
Matrix mx2 = new Matrix(1, 0, 0, -1, 0, 0);
Matrix mx1 = mx.Clone();
mx1.Multiply(mx2);
g.Transform = mx1;
SolidBrush drawBrush = new SolidBrush(Color.Black);
Font drawFont = new Font("Microsoft Sans Serif", 9, FontStyle.Bold);
StringFormat sF = new StringFormat(StringFormatFlags.NoClip);
sF.Alignment = StringAlignment.Center;
g.DrawString("X", drawFont, drawBrush, (2 * rect.Right - 40), -2 * Font.Height, sF);
g.DrawString("Y", drawFont, drawBrush, -40, -(2 * rect.Height + 2 * Font.Height), sF);
// Restore state
g.Restore(state);
drawFont = new Font("Microsoft Sans Serif", 7);
// Drawing Tick Marks and Labels
// NOTE THE LABELS ON THE AXES WILL CHANGE TO REFFECT THE REAL POSITION OF THE ROBOT....
myPen.Dispose();
}
2173行,
g.Transform = mx;
2143行,
DrawXYAxis(e.Graphics);
這是一個異常,通常是由於在另一個線程中非法使用Graphics上下文引起的。 我不得不猜測您的程序中還有其他代碼也在處理圖形。
如果您不知道該代碼是什么,請使用Debug + Windows + Threads並瀏覽那里列出的線程的調用堆棧。 還要在源代碼中查找對Control.CheckForIllegalCrossThreadCalls的任何分配。 您將希望刪除該語句,以便在違反線程要求時得到更好的診斷。
原來是由於以下兩行,
IntPtr hdc = g.GetHdc();
int hMemDC = hdc.ToInt32();
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