检查面板是否包含某些东西

Question

private void PBoxJigsaw1_MouseUp(object sender, MouseEventArgs e)
    {
        if (sender != null && sender.GetType() == typeof(PictureBox))
        {
            if (e.Button == System.Windows.Forms.MouseButtons.Left)
            {
                PictureBox answer = (PictureBox)sender;

                if (answer.Location.X < pnlJigsaw5.Location.X && answer.Location.Y > pnlJigsaw5.Location.Y)
                {
                    if (answer.Location.X + answer.Width > pnlJigsaw5.Location.X)
                    {
                        if ((answer.Location.X + answer.Width) < pnlJigsaw5.Location.X + pnlJigsaw5.Width)
                        {
                            answer.Location = pnlJigsaw5.Location;
                        }
                    }
                }
                else if (answer.Location.X < pnlJigsaw1.Location.X && answer.Location.Y > pnlJigsaw1.Location.Y)
                {
                    if (answer.Location.X + answer.Width > pnlJigsaw1.Location.X)
                    {
                        if ((answer.Location.X + answer.Width) < pnlJigsaw1.Location.X + pnlJigsaw1.Width)
                        {
                            answer.Location = pnlJigsaw1.Location;
                        }
                    }
                }

我在 c# 上创建了一个拼图，用户将图片框拖动到面板中以创建图像。我想知道是否有可能检查一个面板是否包含某些东西，因为在许多图片框可以进入一个面板的那一刻，它们看起来好像消失了，尽管它们只是彼此落后。我只是想让一次面板中只能有一个图片框。谢谢

Answer 1

您可以检查panel您要删除的pictureBox内容是否包含任何内容controls

if(panel.Controls.Count > 0)
{
  // Panel contains items inside
  // Ignore Panel
}

EDIT1：您是否尝试将此代码放在事件的顶部？像这样

private void PBoxJigsaw1_MouseUp(object sender, MouseEventArgs e)
{
    if(panel.Controls.Count > 0) 
    {
        return; // Panel already contains a control, stop executing the code
    }

    if (sender != null && sender.GetType() == typeof(PictureBox))
    {
        ....

这会使图片框消失吗？