檢測2個UserControl實例之間的切換

Question

我有一個派生自UserControl的類（如下）。 用戶一次可以打開此控件的多個實例。 我希望能夠檢測到用戶何時從一個切換到另一個，即單擊了一個然后又單擊了另一個。

僅在首次顯示控件時OnEnter和OnLoad
永遠不會調用OnLeave 。
從不調用OnGotFocus和OnLostFocus ，但顯然不鼓勵使用它們。
我需要做什么？

 public partial class MyView : System.Windows.Forms.UserControl
 {
         // Before `OnLoad`
         // WM_NCCREATE, WM_NCCALCSIZE WM_CREATE, WM_SIZE, WM_MOVE,WM_REFLECT, WM_SHOWWINDOW, WM_PARENTNOTIFY
         // After `OnLoad`, Before `OnEnter`
         // WM_WINDOWPOSCHANGING, WM_NCCALCSIZE, WM_WINDOWPOSCHANGED, WM_SIZE, WM_GETTEXTLENGTH, WM_GETTEXT, (WM_WINDOWPOSCHANGING, WM_NCCALCSIZE, WM_WINDOWPOSCHANGED, WM_SIZE, WM_CHILDACTIVATE, WM_MOVE, WM_SHOWWINDOW
        private const int WM_ACTIVATE = 0x006;
        protected override void WndProc(ref Message message)
        {
            if (message.Msg == WM_ACTIVATE)
            {
                System.Diagnostics.Trace.WriteLine("MyView.WndProc(): message: " + message);
            }
            base.WndProc(ref message);
        }

        // called before OnEnter
        protected override void OnLoad(System.EventArgs eventArgs)
        {
            base.OnLoad(eventArgs);

            Form form1 = this.FindForm();      // null
            Form parentForm = this.ParentForm; // null
        }

        // called only on first display, not when the user switches between the 2 controls
        protected override void OnEnter(EventArgs eventArgs)
        {
            base.OnEnter(eventArgs);
        }

        protected override void OnLeave(EventArgs eventArgs)
        {
            base.OnLeave(eventArgs);
        }

        // Never called
        protected override void OnGotFocus(EventArgs eventArgs)
        {
            base.OnGotFocus(eventArgs);
        }

        // Never called
        protected override void OnLostFocus(EventArgs eventArgs)
        {
            base.OnGotFocus(eventArgs);
        }
 }

Answer 1

這是用戶派生控件的完整源代碼。 它按原樣工作。

在表單上，​​我創建了該控件的兩個實例，然后可以單擊它們。 正如我所做的那樣，方塊從紅色切換為藍色。

您應該能夠在OnGotFocus和OnLostFocus方法中設置斷點。 無效者在那里強制重新粉刷。

魔術是有兩個控件（也有兩個控件），但此外，OnButtonclicked覆蓋設置了焦點。 我相信這是您的示例中缺少的部分。

using System;
using System.Drawing;
using System.Windows.Forms;

namespace DesktopApp1
{
    public partial class MyView : System.Windows.Forms.UserControl
    {

        protected Color SelectedColor { get; set; } = Color.Red;
        protected Color NormalColor { get; set; } = Color.Blue;
        protected override void OnPaint(PaintEventArgs e)
        {
            using (SolidBrush blueBrush = new SolidBrush(this.Focused?SelectedColor:NormalColor))
            using (Pen blackPen = new Pen(Color.Black, 3))
            {
                e.Graphics.FillRectangle(blueBrush, ClientRectangle);

                Rectangle inset = new Rectangle(this.ClientRectangle.X + 1, this.ClientRectangle.Y + 1, this.ClientRectangle.Width -3 , this.ClientRectangle.Height - 3);
                e.Graphics.DrawRectangle(blackPen, inset);
            }
            base.OnPaint(e);
        }

        private void OnButton1Clicked(object sender, EventArgs e)
        {
            this.Select();
        }

        protected override void OnGotFocus(EventArgs e)
        {
            Invalidate();
            base.OnGotFocus(e);
        }

        protected override void OnLostFocus(EventArgs e)
        {
            base.OnLostFocus(e);
            Invalidate();
        }
    }
}

要完成答案，這里是form1.Designer.cs

namespace DesktopApp1
{
    partial class Form1
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.myView2 = new DesktopApp1.MyView();
            this.myView1 = new DesktopApp1.MyView();
            this.SuspendLayout();
            // 
            // myView2
            // 
            this.myView2.Location = new System.Drawing.Point(189, 12);
            this.myView2.Name = "myView2";
            this.myView2.Size = new System.Drawing.Size(150, 150);
            this.myView2.TabIndex = 1;
            // 
            // myView1
            // 
            this.myView1.Location = new System.Drawing.Point(9, 12);
            this.myView1.Name = "myView1";
            this.myView1.Size = new System.Drawing.Size(150, 150);
            this.myView1.TabIndex = 0;
            // 
            // Form1
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(8F, 16F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(355, 175);
            this.Controls.Add(this.myView2);
            this.Controls.Add(this.myView1);
            this.Name = "Form1";
            this.Text = "Form1";
            this.ResumeLayout(false);

        }

        #endregion

        private MyView myView1;
        private MyView myView2;
    }
}

Answer 2

要求：“我希望能夠檢測到操作員...何時單擊了一個，然后單擊了另一個。”

顯然，您希望在控件或其子控件上單擊時得到通知。 為此，您必須預訂所有子控件的Click事件。

protected override void OnControlAdded(ControlEventArgs e)
{
     // subscribe to click event of e.Control
     e.Control.Click += OnChildClicked;
}
// TODO: de-subscribe in OnControlRemoved

public void OnChildClicked(object Sender, EventArgs e)
{
    // Clicked on child control, act as if Clicked on me
    this.OnClick(e);
}

單擊事件將由任何類似單擊的事件調用，即使它是通過鍵盤完成的，例如通過按Enter鍵。

您寫了您想要的鼠標單擊。 如果您確實只希望單擊鼠標，請使用MouseClick事件。 如果操作員使用TAB選擇您的子控件之一，然后按Enter鍵單擊它，則不會收到通知。