Question

所以我用C＃编写了Windows窗体应用程序，以打开视频，在pictureBox_display中显示视频，并允许用户在picturebox上定义（绘制）边框。唯一的事情是，我可以很容易地使程序引发System.AccessViolationException并通过以下方式崩溃： 1）打开视频（任何视频） 2）点击+在图片框上拖动鼠标几秒钟。

以下是一些代码：

VideoCapture VC;
bool IsMouseDown = false;
bool MouseMoved = false;
string VideoFileName;


private void OpenFileButton_Click(object sender, EventArgs e) {
        OpenFileDialog OFD = new OpenFileDialog();
        if (OFD.ShowDialog() == DialogResult.OK) {
                FrameNumber = 0;
                VideoFileName = OFD.FileName;
                VC = new VideoCapture(VideoFileName);

                if (VC.Width<=0 || VC.Height<=0) {
                    System.Windows.Forms.MessageBox.Show("ERROR: Please load a valid video file");
                    return;
                }


        // Initialize picturebox dimensions according to image
        double W_H_ratio = Convert.ToDouble(VC.Width) / VC.Height;
                if (W_H_ratio >= (double)(5 / 4)) {
                    pictureBox_display.Width = Math.Min(VC.Width, 800);
                    pictureBox_display.Height = Math.Min(VC.Height, (int)((1 / W_H_ratio )* 800));
                }
                else {
                    pictureBox_display.Height = Math.Min(VC.Height, 640);
                    pictureBox_display.Width = Math.Min(VC.Width, (int)(W_H_ratio * 640));
                }

                Mat tempimg = GetMat(FrameNumber);
                Console.WriteLine("Size of tempimg: " + tempimg.Size);
                pictureBox_display.Image = tempimg.Bitmap;
        }
}

private Mat GetMat(int someFrameNumber) {

        try {
                Mat m = new Mat();
                VC.SetCaptureProperty(Emgu.CV.CvEnum.CapProp.PosFrames, someFrameNumber);
                VC.Read(m);

                Mat resized = new Mat();
                CvInvoke.ResizeForFrame(m, resized, pictureBox_display.Size);
                m.Dispose();
                return resized;
        }

        catch {
                Mat m = new Mat();
                System.Windows.Forms.MessageBox.Show("ERROR: Cannot read video frame");
                return m;
        }
}

private void pictureBox_display_MouseDown(object sender, MouseEventArgs e) {
        if (VideoFileName != null && checkBox1.Checked == false && VideoPlaying == false) {
                IsMouseDown = true;
                MouseMoved = false;
                ThereIsNewSelection = true;
                StartLocation = e.Location;
                Console.WriteLine(StartLocation);
        }
}


// Constantly alter the end location of the mouse to provide the coordinates for the rectangle
private void pictureBox_display_MouseMove(object sender, MouseEventArgs e) {
        if (IsMouseDown == true) {
                MouseMoved = true;

                EndLocation = e.Location;
                pictureBox_display.Invalidate();
        }
}

private void pictureBox_display_Paint(object sender, PaintEventArgs e) {
        if (!VideoPlaying && ThereIsNewSelection) {
                e.Graphics.DrawRectangle(Pens.Red, GetRectangle());
        }
}

我知道这肯定与Invalidate（）有关，因为我逐行注释了代码，并且只有在有Invalidate（）时它才会崩溃。谁能告诉我可能是什么原因引起的问题？

如果有用的话，这里是堆栈跟踪：

  在
  System.Drawing.SafeNativeMethods.Gdip.GdipDrawImageRectI（HandleRef   图形，HandleRef图像，Int32 x，Int32 y，Int32宽度，Int32   高度）在System.Drawing.Graphics.DrawImage（Image image，Int32 x，   Int32 y，Int32宽度，Int32高度）在   System.Drawing.Graphics.DrawImage（图像图像，矩形rect）位于   System.Windows.Forms.PictureBox.OnPaint（PaintEventArgs pe）位于   System.Windows.Forms.Control.PaintWithErrorHandling（PaintEventArgs e，   System.Windows.Forms.Control.WmPaint（Message＆m）中的Int16层）
  在System.Windows.Forms.Control.WndProc（Message＆m）在   System.Windows.Forms.NativeWindow.DebuggableCallback（IntPtr hWnd，   Int32 msg，IntPtr wparam，IntPtr lparam）

Answer 1

您需要克隆（深拷贝）位图，如下所示：

B.Clone(new Rectangle(0, 0, B.Width, B.Height), B.PixelFormat)

为什么PictureBox.Invalidate（）导致程序崩溃？ System.AccessViolationException

1 个答案: