事实上，你是正确的，只要表单上有一个焦点按钮，它就会独占Key消息，Form1_KeyDown将不再被调用或移动图片框。
解决这个问题的方法是实现IMessageFilter，这样我们就可以选择无条件地拦截Win32WM_KEYDOWN消息。试试这样：

public partial class MainForm : Form, IMessageFilter
{
    public MainForm()
    {
        InitializeComponent();
        Application.AddMessageFilter(this);
        Disposed += (sender, e) =>Application.RemoveMessageFilter(this);
    }
    public bool PreFilterMessage(ref Message m)
    {
        if (m.Msg == WM_KEYDOWN)
        {
            var e = new KeyEventArgs(((Keys)m.WParam) | Control.ModifierKeys);
            OnHotKeyPreview(FromHandle(m.HWnd), e);
            return (e.Handled);
        }
        return false;
    }
    private void OnHotKeyPreview(Control? control, KeyEventArgs e)
    {
        switch (e.KeyData)
        {
            case Keys.Left: onMoveLeft(); e.Handled = true; break;
            case Keys.Up: onMoveUp(); e.Handled = true; break;
            case Keys.Right:  onMoveRight(); e.Handled = true; break;
            case Keys.Down: onMoveDown(); e.Handled = true; break;
        }
    }
    private void onMoveLeft() =>
        pictureBox1.Location = new Point(pictureBox1.Location.X - 15, pictureBox1.Location.Y);
    private void onMoveUp() => 
        pictureBox1.Location = new Point(pictureBox1.Location.X, pictureBox1.Location.Y - 15);
    private void onMoveRight() =>
        pictureBox1.Location = new Point(pictureBox1.Location.X + 15,
            pictureBox1.Location.Y);
    private void onMoveDown() =>
        pictureBox1.Location = new Point(pictureBox1.Location.X, pictureBox1.Location.Y + 15);
    private const int WM_KEYDOWN = 0x0100;
}

字符串

备选方案

然而，更干净的方法是继承PictureBox并在 there 实现IMessageFilter，以创建一个扩展的PictureBoxEx控件，该控件知道如何通过处理拦截的键事件来移动 * 自身 *。

的数据
要使用此控件，请转到Designer.cs文件，并将PictureBox的示例交换为扩展类PictureBoxEx。这是最终的替代解决方案，结果是简化了Form类。这里的方案是将图片框的边框设置为移动。

public partial class MainForm : Form
{
    public MainForm()
    {
        InitializeComponent();
        buttonDeselect.Click += (sender, e) =>
        {
            foreach (var pb in Controls.OfType<PictureBoxEx>())
            {
                pb.BorderStyle = BorderStyle.None;
            }
        };
    }
}

型

PictureBoxEx

class PictureBoxEx : PictureBox, IMessageFilter
{
    public PictureBoxEx()
    {
        Application.AddMessageFilter(this);
        Disposed += (sender, e) => Application.RemoveMessageFilter(this);
    }
    protected override void OnMouseDown(MouseEventArgs e)
    {
        base.OnMouseDown(e);
        if (ModifierKeys != Keys.Control)   // Allow multiple select.
        {
            foreach (var pb in Parent.Controls.OfType<PictureBoxEx>())
            {
                pb.BorderStyle = BorderStyle.None;
            }
        }
        BorderStyle = BorderStyle.FixedSingle;
    }
    private const int WM_KEYDOWN = 0x0100;
    public bool PreFilterMessage(ref Message m)
    {
        if ((m.Msg == WM_KEYDOWN) && (BorderStyle == BorderStyle.FixedSingle))
        {

            var e = new KeyEventArgs(((Keys)m.WParam) | Control.ModifierKeys);
            OnKeyDown(e);
            return (e.Handled);
        }
        return false;
    }
    protected override void OnKeyDown(KeyEventArgs e)
    {
        base.OnKeyDown(e);
        switch (e.KeyData)
        {
            case Keys.Left:
                Location = new Point(Location.X - 15, Location.Y);
                break;
            case Keys.Up:
                Location = new Point(Location.X, Location.Y - 15);
                break;
            case Keys.Right:
                Location = new Point(Location.X + 15, Location.Y);
                break;
            case Keys.Down:
                Location = new Point(Location.X, Location.Y + 15);
                break;
        }
    }
}

型