初学c# -- 学习笔记（五） winfrom自定义滚动条

找了些例子，要么庞大、要么搞个安装组件什么的，我要求能用就行了。实在找例子修改麻烦，就做了一个。其实实现挺简单，就是panel或图片什么的跟着鼠标走就行了。

这里panel自己可以加背景图或直接搞个图就行了。为了演示清楚，有个滚动条控件做对比，与自定义的同步。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace customscroll
{
    public partial class Form1 : Form
    {
        int limt, set_x; //滚动位置最大值和固定的左右的位置
        bool mouse_Press = false; //鼠标按下
        bool mouse_Wheel = false; //滑轮是否滚动
        Point mouseOff; //存放当前鼠标位置

        public Form1()
        {
            InitializeComponent();
            //向panel填充一堆内容
            for (int i = 0; i < 25; i++)
            {
                Panel num_panel = new Panel();
                Label num = new Label();

                num.Text = i + ".";
                num.ForeColor = Color.FromArgb(255, 255, 255);
                num.Width = 30;
                num.Dock = DockStyle.Left;
                //设置鼠标滑轮事件，需将mouse_Wheel 值为true，在move里置，下面有，这里就不写了
                //num.MouseWheel += new MouseEventHandler(OnMouseWheel);

                num_panel.Name = "Panel_" + i;
                num_panel.Height = 35;
                num_panel.Margin = new Padding(0, 0, 0, 0);
                num_panel.BackColor = Color.SteelBlue;
                num_panel.BorderStyle = BorderStyle.Fixed3D;
                num_panel.Dock = DockStyle.Top;
                num_panel.BorderStyle = System.Windows.Forms.BorderStyle.None;
                num_panel.Controls.Add(num);
                //设置鼠标滑轮事件，需将mouse_Wheel 值为true，在move里置，下面有，这里就不写了
                //num_panel.MouseWheel += new MouseEventHandler(OnMouseWheel);
                Content_panel.Controls.Add(num_panel); //将内容装入
                //设置鼠标滑轮事件，需将mouse_Wheel 值为true，在move里置，下面有，这里就不写了
                //Content_panel.MouseWheel += new MouseEventHandler(OnMouseWheel);
            }
            //装内容panel自动大小
            Content_panel.AutoSize = true;

            set_x = ScrollHard_panel.Location.X; //固定左右位置为当前位置
            limt = ScrollBar_panel.Height - ScrollHard_panel.Height; //滚动最大高度
            ScrollHard_panel.Location = new Point(set_x,0) ; //先将位置设置到最顶
            vScrollBar1.Maximum = limt; //放了个vScrollBar组件，演示用的，和自定义的同步

            //鼠标滑轮事件
            ScrollBar_panel.MouseWheel += new MouseEventHandler(OnMouseWheel);
            ScrollHard_panel.MouseWheel += new MouseEventHandler(OnMouseWheel);
            vScrollBar1.MouseWheel += new MouseEventHandler(OnMouseWheel);
        }

        //鼠标滑轮事件
        private void OnMouseWheel(object sender, System.Windows.Forms.MouseEventArgs e)
        {
            int set_y = 0;

            if (mouse_Wheel) //是否判断鼠标滑轮
            {
                if (e.Delta > 0) //滑轮向上
                {
                    set_y = ScrollHard_panel.Location.Y - 10; //每次移动10
                    if (set_y < 0) { set_y = 0;  } //超范围
                }
                if (e.Delta < 0)  //滑轮向下
                {
                    set_y = ScrollHard_panel.Location.Y + 10; //每次移动10
                    if (set_y > limt) { set_y = limt; } //超范围
                }
                ScrollHard_panel.Location = new Point(set_x, set_y); //滚动块的定位
                vScrollBar1.Value = set_y; //演示用的滚动条，和自定义的同步

                Content_panel.Top = -set_y; //装内容的panel滚动显示
            }

        }

        //自定义滚动“块”框鼠标按下
        private void ScrollHard_panel_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left) //鼠标左键
            {
                mouseOff.Y = e.Y;  //取当前位置
                mouse_Press = true; //鼠标按下
            }
        }

        //自定义滚动“块”鼠标放开
        private void ScrollHard_panel_MouseUp(object sender, MouseEventArgs e)
        {
            mouse_Press = false; //鼠标放开
        }

        //自定义滚动“块”鼠标离开范围
        private void ScrollHard_panel_MouseLeave(object sender, EventArgs e)
        {
            mouse_Wheel = false; //滑轮不可用
        }

        ////自定义滚动“块”鼠标在范围
        private void ScrollHard_panel_MouseMove(object sender, MouseEventArgs e)
        {
            mouse_Wheel = true; //可以用滑轮
            if (mouse_Press) //鼠标按下状态
            {
                int set_y = ScrollHard_panel.Top + e.Y - mouseOff.Y; //计算当前纵向坐标
                if (set_y < 0) { set_y = 0; } //超范围
                else if (set_y > limt) { set_y = limt; } //超范围
                else { ScrollHard_panel.Location = new Point(set_x, set_y); } //滚动块的定位
                vScrollBar1.Value = set_y; //演示的滚动条和自定义的同步
                Content_panel.Top = -set_y; //装内容的panel滚动显示
            }
        }

        //在滚动“框”范围内
        private void ScrollBar_panel_MouseMove(object sender, MouseEventArgs e)
        {
            mouse_Wheel = true;  //可以使用滑轮
        }

        //离开滚动“框”
        private void ScrollBar_panel_MouseLeave(object sender, EventArgs e)
        {
            mouse_Wheel = false; //不可使用滑轮
        }

        //自定义滚动“框”鼠标放开
        private void ScrollBar_panel_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left) //鼠标左键
            {
                int set_y = e.Y; //当前纵坐标
                if (set_y > limt) { set_y = limt; } //超范围
                ScrollHard_panel.Location = new Point(set_x, set_y); //滚动块定位
                vScrollBar1.Value = set_y; //演示的滚动条，和自定义的同步
                Content_panel.Top = -set_y;//装内容的panel滚动显示
                mouse_Press = false; //鼠标为放开状态
            }
        }

        //演示用的vScrollBar1组件，也可以控制装内容的panel滚动显示
        private void vScrollBar1_Scroll(object sender, ScrollEventArgs e)
        {
            Content_panel.Top = -vScrollBar1.Value;
        }
    }
}