环形进度条

接触Winform时间也不长，控件自绘也是刚开始学，现在的打算是一点一点积累，争取能够有点小成果。今天分享的是一个自定义的进度条控件，实现很简单，也没有做什么美化，所以有兴趣的就粗略看看。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing;
using System.Drawing.Drawing2D;

namespace AnnularProgressBarDemo
{
    public partial class AnnularProgressBar : Control
    {
        /// <summary>
        /// 前景色，即进度条颜色
        /// </summary>
        private SolidBrush _ForeBrush = new SolidBrush(Color.Red);
        public SolidBrush ForeBrush
        {
            get { return _ForeBrush; }
            set
            {
                _ForeBrush = value;
                Invalidate();
            }
        }

        /// <summary>
        /// 遮盖颜色，即环内部的颜色
        /// </summary>
        private SolidBrush _MaskBrush = new SolidBrush(SystemColors.Control);
        public SolidBrush MaskBrush
        {
            get { return _MaskBrush; }
            set
            {
                _MaskBrush = value;
                Invalidate();
            }
        }

        /// <summary>
        /// 起始角度
        /// </summary>
        private float _StartAngle = 0.0f;
        public float StartAngle
        {
            get { return _StartAngle; }
            set
            {
                _StartAngle = value;
                Invalidate();
            }
        }

        /// <summary>
        /// 跨度
        /// </summary>
        private float _SweepAngle = 0.0f;
        public float SweepAngle
        {
            get { return _SweepAngle; }
            set
            {
                _SweepAngle = value;
                Invalidate();
            }
        }

        /// <summary>
        /// 进度
        /// </summary>
        private float _Value = 0.0f;
        public float Value
        {
            get { return _Value; }
            set
            {
                if (value < _MinValue)
                {
                    _Value = _MinValue;
                }
                else if (value > _MaxValue)
                {
                    _Value = _MaxValue;
                }
                else 
                {
                    _Value = value;
                    SweepAngle = (_Value-_MinValue) * 360 / (_MaxValue-_MinValue);
                }
                Invalidate();
            }
        }

        //最小值
        private float _MinValue = 0.0f;
        public float MinValue
        {
            get { return _MinValue; }
            set
            {
                if (value < 0)
                {
                    _MinValue = 0;
                }
                else
                {
                    _MinValue = value;
                }

            }
        }

        /// <summary>
        /// 初始值
        /// </summary>
        private float _InitValue = 0.0f;
        public float InitValue
        {
            get { return _InitValue; }
            set
            {
                if (value < _MinValue)
                {
                    _InitValue = _MinValue;
                }
                else
                {
                    _InitValue = value;
                }
                _Value = _InitValue;
                SweepAngle = (_InitValue - _MinValue) * 360 / (_MaxValue - _MinValue);
            }
        }

        /// <summary>
        /// 最大值
        /// </summary>
        private float _MaxValue = 0.0f;
        public float MaxValue
        {
            get { return _MaxValue; }
            set
            {
                if (value < _MinValue)
                {
                    _MaxValue = _MinValue;
                }
                else
                {
                    _MaxValue = value;
                }
            }
        }

        /// <summary>
        /// 边框颜色
        /// </summary>
        private Color _BorderColor = Color.Black;
        public Color BorderColor
        {
            get { return _BorderColor; }
            set
            {
                _BorderColor = value;
                borderpen = new Pen(BorderColor, BorderWidth);
                Invalidate();
            }
        }

        /// <summary>
        /// 边框宽度
        /// </summary>
        private int _BorderWidth = 1;
        public int BorderWidth
        {
            get { return _BorderWidth; }
            set
            {
                _BorderWidth = value;
                borderpen = new Pen(BorderColor, BorderWidth);
                Invalidate();
            }
        }

        /// <summary>
        /// 边框画笔
        /// </summary>
        private Pen borderpen;

        /// <summary>
        /// 外轮廓矩形
        /// </summary>
        private Rectangle OuterRect;

        /// <summary>
        /// 内轮廓矩形
        /// </summary>
        private Rectangle InnerRect;

        public AnnularProgressBar()
        {
            InitializeComponent();
            this.SetStyle(ControlStyles.UserPaint, true);//自绘
            this.SetStyle(ControlStyles.DoubleBuffer, true);// 双缓冲
            this.SetStyle(ControlStyles.ResizeRedraw, true);//调整大小时重绘
            this.SetStyle(ControlStyles.AllPaintingInWmPaint, true); // 禁止擦除背景.
            this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true);// 双缓冲
            this.SetStyle(ControlStyles.SupportsTransparentBackColor, true);   //透明效果
        }

        private void Init()
        {
            borderpen = new Pen(Color.Black, 1);
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);
            
            Graphics graph = e.Graphics;
            Image img = new Bitmap(ClientRectangle.Width, ClientRectangle.Height);
            Graphics gbmp = Graphics.FromImage(img);
            gbmp.SmoothingMode = SmoothingMode.HighQuality;
            gbmp.PageUnit = GraphicsUnit.Display;
            gbmp.FillPie(ForeBrush, OuterRect, StartAngle, SweepAngle);
            gbmp.DrawEllipse(borderpen, OuterRect);
            gbmp.FillEllipse(MaskBrush, InnerRect);
            gbmp.DrawEllipse(borderpen, InnerRect);
            graph.DrawImage(img, ClientRectangle);
        }

        protected override void OnSizeChanged(EventArgs e)
        {
            base.OnSizeChanged(e);
            OuterRect = ClientRectangle;
            OuterRect.Inflate(-1, -1);
            InnerRect = new Rectangle(ClientRectangle.X, 
                ClientRectangle.Y, ClientRectangle.Width, 
                ClientRectangle.Height);
            InnerRect.Inflate(-11, -11);
        }
    }
}

　　方法很简单，就是靠GDI+画一个Pie，然后再画一个圆遮住中间的部分，其他的就是靠调节相关的值来实现了。用的话也很简单，初始化MinValue、MaxValue和InitValue值后就可以通过改变Value的值来完成了。