WinForm scroll bar beautification

Do it for the first time winfrom application , It took a lot of effort to beautify the scroll bar , Novices in online materials say they either can't understand or can't use . Here I write down my implementation process , Try to write in detail , I hope to help other friends who are struggling with this problem like me .

First, redraw the control and copy it directly Sunday Like snow Written ：
https://blog.csdn.net/qq_33212020/article/details/53447135
Create a new user control in the project , Copy it all and you can use it directly , Again Sunday Like snow Thank you . Here, write the usage of the control you have found out to your friends who need it .
The original effect ：

Personal effects ：

principle ： Put two in the design interface panel(pn_info,pn_scroll.AutoScroll Property is set to false, Better name it the same as me , Easy to use code ),pn_info Put it in pn_scroll Inside ,pn_info Release information ,pn_scroll Put the scroll bar .pn_info Add wheel Events , Drive the scroll bar to move . Scroll bar drag event pn_info Rolling （pn_info By changing top Value to simulate scrolling ）.pn_info Of location Set to （0,0）. I'm here pn_info Add data for dynamic .

Source code ：

 
        SundayRXScrollBar sb = new SundayRXScrollBar();// Scroll bar instance 
        // Window initialization 
        public void init()
        {
            history his = new history();
            List<history> hisList = his.read();// Get history list 
            for(var i=0;i<hisList.Count;i++)
            {
                int timestamp = hisList[i].timestamp;
                historyItem item = new historyItem();
                item.setDate(toDate(timestamp));
                item.chName(timestamp.ToString());// Assign a value to the check box （ Judge the choice of ）
                item.Location = new System.Drawing.Point(0, i * 115); // Record location 
                item.setAvgForce(hisList[i].avg_force.ToString("0.#"));
                item.setMaxForce(hisList[i].max_force.ToString());
                item.setMaxFrequence(hisList[i].max_frequence.ToString());
                item.setPunchCount(hisList[i].punch_count.ToString());
                item.setTrainTime(hisList[i].train_time.ToString());
                item.setRemark(hisList[i].remark.ToString());
                pn_info.Controls.Add(item);
            }
            // The above part is my pn_info add to item, You can't copy , Please change your adding method 
            // The following contents can be copied completely 
            // The height of the inner container shall be set to the actual height , Here I each item Is the height of 115
            pn_info.Height = hisList.Count * 115;
            pn_info.Focus(); // Get focus 
            sb_init(); // Scroll bar initialization 
        }
        private void sb_init()
        {
            if (pn_info.Height <= pn_scroll.Height)
            {
                // When the height of the inner container is less than that of the scroll bar container, the scroll bar will not be produced 
                pn_info.Width = pn_scroll.Width;
                return;
            }
            sb.Width = 10;  // Width of scroll bar （px）
            pn_info.Width = pn_scroll.Width-10;
            sb.Height = pn_scroll.Height;
            // Slider height = Visual height / Actual height * Scroll bar height （pn_scroll.Height）
            float length = (float)pn_scroll.Height / (float)pn_info.Height * (float)pn_scroll.Height;
            sb.SliderHeight = (int)length; 
            //sb.SliderColor = Color.FromArgb(2,153,255);// Slider color 
            //sb.MouseDownSliderColor   After clicking the mouse, the slider color 
            //sb.MouseOverSliderColor    The color of the slider when the mouse touches 
            //sb.BottomColor       Scroll bar color 
            sb.SliderWidthPercent = 1; // The ratio of slider width to scroll bar width ,1 It means full 
            sb.Dock = DockStyle.Right; // Scroll bar position 
            sb.ValueChanged += sb_ValueChanged;  // Scroll bar drag event 
            sb.GotFocus += sb_GotFocus;  // Scroll bar to get focus events 
            pn_scroll.Controls.Add(sb); //pn_scroll Add scroll bar 
            pn_info.MouseWheel += pn_info_MouseWheel; //pn_info Add wheel Events 
        }
        bool isMouseWheel = false; // Prevent the scroll bar driven by the roller from triggering again sb_ValueChanged
        //pn_info Wheel event 
        private void pn_info_MouseWheel(object sender, MouseEventArgs e)
        {
       	    isMouseWheel = true;
            int scrollRang = 40; // Each roll height (px)
            int sbRang = calSbRang(scrollRang); // The actual scrolling range of the scroll bar 
            if (e.Delta > 0) // Wheel Up 
            {
                if (sb.Value - sbRang<= 0)
                {
                    // Scroll to the top , Set directly to the default value , Prevent errors caused by rolling 
                    sb.Value = 0;
                    pn_info.Top = 0;
                }
                else
                {
                    sb.Value -= sbRang;
                    pn_info.Top += scrollRang;
                }
            }
            else// The roller is down 
            {
                if (sb.Value + sbRang>= 100)
                {
                    // Scroll to the end , Set directly to the default value , Prevent errors caused by rolling 
                    sb.Value = 100;
                    pn_info.Top = -(pn_info.Height-pn_scroll.Height);
                }
                else
                {
                    sb.Value += sbRang;
                    pn_info.Top -= scrollRang;
                }
            }
        }
        // Because the scroll bar scrolling range may be decimal , turn int Accuracy will be lost after , Cause a certain error when rolling to the bottom or to the bottom 
        float residue = 0; //float turn int The decimal part after rounding is accumulated 1
        private int calSbRang(int scrollRang)
        {
            float temp = ((float)scrollRang) / (float)(pn_info.Height - pn_scroll.Height) * 100;// Scroll bar scrolling scale 
            int sbRang = Convert.ToInt32(temp);// Keep the integer part 
            residue += temp - (float)sbRang; // Accumulate the rounded decimal part 
            if (residue >= 1)
            {
                residue -= 1;
                sbRang += 1;
            }
            return sbRang;
        }
        // Scroll bar drag 
        private void sb_ValueChanged(object sender, EventArgs e)
        {
            if (isMouseWheel) return;
            pn_info.Top =-Convert.ToInt32((float)sb.Value / 100 * (float)(pn_info.Height-pn_scroll.Height));
        }
        // When the scroll bar gets the focus, give the focus to pn_info, Prevent wheel events that trigger the scroll bar ( The sliding speed of the roller of the scroll bar is inconsistent with that in the container )
        private void sb_GotFocus(object sender, EventArgs e)
        {
            isMouseWheel = false;
            pn_info.Focus();
        }

After several tests , When there is less content , The scroll bar slider extends out of the container .
terms of settlement ： Redraw control code SliderHeight Comment this sentence in the method （ The original meaning should be when the scroll bar height - Slider height <100 If so, set the scroll bar height +100, I don't know why the author should deal with it like this ）