~楓花雪岳~: [C#] 使用者控制項

星期三, 12月 03, 2014

[C#] 使用者控制項

了解如何改寫使用者控制項時，在 MSDN 發現這篇文章逐步解說：使用 Visual C# 撰寫使用者控制項，動手實作並把文章內的 Code 整理起來

實作這篇文章時最大的收穫是，原來要 override 時，VS 有快取的方式可以使用，之前看到範例，都會覺得怎麼這麼利害，Method 內的 Object Sender 和 EventArgs e 這兩個參數要怎麼知道，尤其是 EventArgs，不會都必須查詢 MSDN，然後再複制貼上到 VS 內吧，Orz ~~

ctlClockLib

範例重點：

結合控制項及元件到使用者控制項
加入屬性至控制項
寫 Code 來自訂功能

namespace ctlClockLib
{
    public partial class ctlClock: UserControl
    {
        private Color colFColor;
        private Color colBColor;

        // Declares the name and type of the property.
        public Color ClockBackColor
        // Retrieves the value of the private variable colBColor.
        {
            get{return colBColor;}
            // Stores the selected value in the private variable colBColor, and 
            // updates the backcolor of the label control lblDisplay.
            set
            {
                colBColor = value;
                lblDisplay.BackColor = colBColor;
            }
        }

        // Provides a similar set of instructions for the forecolor.
        public Color ClockForeColor
        {
            get{return colFColor;}
            set
            {
                colFColor = value;
                lblDisplay.ForeColor = colFColor;
            }
        }

        public ctlClock()
        {
            InitializeComponent();
        }

        protected virtual void timer1_Tick(object sender, EventArgs e)
        {
            // Causes the label to display the current time
            lblDisplay.Text = DateTime.Now.ToString();
        }
    }
}

ctlAlarmClock

範例重點：

繼承
覆寫（Override）

namespace ctlClockLib
{
    public partial class ctlAlarmClock : ctlClockLib.ctlClock
    {
        public ctlAlarmClock()
        {
            InitializeComponent();
        }

        private DateTime dteAlarmTime;
        private bool blnAlarmSet;
        private bool blnColorTicker;
        // These properties will be declared as public to allow future 
        // developers to access them.

        public DateTime AlarmTime
        {
            get { return dteAlarmTime; }
            set { dteAlarmTime = value; }
        }

        public bool AlarmSet
        {
            get { return blnAlarmSet; }
            set { blnAlarmSet = value; }
        }

        protected override void timer1_Tick(object sender, EventArgs e)
        {
            // Calls the Timer1_Tick method of ctlClock.
            base.timer1_Tick(sender, e);
            // Checks to see if the Alarm is set.
            if (blnAlarmSet == false) return;

            // If the date, hour and minute of the alarm time are the same as
            // now, flash! 
            if (AlarmTime.Date == DateTime.Now.Date && AlarmTime.Hour ==
                DateTime.Now.Hour && AlarmTime.Minute == DateTime.Now.Minute)
            {
                // Makes lblAlarmVisible, and changes the backcolor based on
                // the value of blnColorTicker. The backcolor of the label 
                // will flash once per tick of the clock.
                lblAlarm.Visible = true;
                if (blnColorTicker == false)
                {
                    lblAlarm.BackColor = Color.Red;
                    blnColorTicker = true;
                }
                else
                {
                    lblAlarm.BackColor = Color.Blue;
                    blnColorTicker = false; 
                }
            }
            else
            {
                // Once the alarm has sounded for a minute, the label is made 
                // invisible again.
                lblAlarm.Visible = false;
            }
        }

        private void btnOff_Click(object sender, EventArgs e)
        {
            AlarmSet = false;
            lblAlarm.Visible = false;
        }

        private void dtpTest_ValueChanged(object sender, EventArgs e)
        {
            AlarmTime = dtpTest.Value;
            AlarmSet = true;
            lblTest.Text = string.Format("Alarm Time is {0}", AlarmTime.ToShortTimeString());
        }
    }
}

完成 ctlClockLib Project 後，在同一個 Solution 內再開一個 Test Project 就可以看見工具箱內出現自訂控制項