IMessageFilter.PreFilterMessage 方法没有执行

Question

我写了一个类，继承了IMessageFilter接口，但是PreFilterMessage这个方法没有执行。

 

    public class MyMessageFilter : IMessageFilter
    {
        private Control control = null;
        private Boolean isMove = true;

        public MyMessageFilter(Control control)
        {
            this.control = control;
        }

        #region IMessageFilter 成员

        public bool PreFilterMessage(ref Message m)
        {
            if (m.Msg == (int)Msgs.WM_MOUSEMOVE)
            {
                move();
            }
            else if (m.Msg == (int)Msgs.WM_LBUTTONUP)
                isMove = false;
            else if (m.Msg == (int)Msgs.WM_CAPTURECHANGED)
                isMove = false;
            else if (m.Msg == (int)Msgs.WM_KEYDOWN && (int)m.WParam == (int)Keys.Escape)
                isMove = false;

            return false;
        }

        private void move()
        {
            if (isMove)
            {
                control.Top = Control.MousePosition.Y;
                control.Left = Control.MousePosition.X;
            }
        }

        #endregion

    }

这样调用的   Application.AddMessageFilter(new MyMessageFilter(button1));

---

snyod

Answer 1

Application.AddMessageFilter(IMessageFilter) 是在哪里执行的？把它放到 Application.Run(Form) 之前试试看。

---

Mark Zhou

Answer 2

我是在MyMessageFilter类里实现的，

这个类里还有一个鼠标单击事件，在鼠标单击事件里调用的。

---

snyod

Answer 3

我在WinForm里试验过了(VS2005)，没有问题。效果是按钮随着鼠标移动。

        public class MyMessageFilter : IMessageFilter
        {
            private Control control = null;
            private Boolean isMove = true;
            public MyMessageFilter(Control control)
            {
                this.control = control;
            }
            public bool PreFilterMessage(ref Message m)
            {
                if (m.Msg == 0x200)
                {
                    move();
                }
                else if (m.Msg == 0x202)
                    isMove = false;
                else if (m.Msg == 0x215)
                    isMove = false;
                else if (m.Msg == 0x0100 && (int)m.WParam == (int)Keys.Escape)
                    isMove = false;
                return false;
            }
            private void move()
            {
                if (isMove)
                {
                    control.Top = Control.MousePosition.Y;
                    control.Left = Control.MousePosition.X;
                }
            }
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            Application.AddMessageFilter(new MyMessageFilter(button1));

Answer 4

要不你把 public bool PreFilterMessage(ref Message m) 改成 bool IMessageFilter.PreFilterMessage(ref Message m) 显式实现试试？