C#绘制含流动块的管道

1，效果。

2，绘制技巧。

1，流动块的实质是使用Pen的自定义DashStyle绘制的线，并使用线的偏移值呈现出流动的效果。

 Pen barPen = new Pen(BarColor, BarHeight);
                barPen.DashStyle = DashStyle.Custom;
                barPen.DashOffset = startOffset;
                barPen.DashPattern = new float[] { BarLength, GapLength };
                graphicsPath.StartFigure();
                g.DrawPath(barPen, graphicsPath);

2，使用GraphicsPath，绘制包含弧的多段线。

 GraphicsPath graphicsPath = new GraphicsPath();
 //特别需要注意角度旋转方向，如果角度旋转方向选错就形成闭环
graphicsPath.AddArc(new Rectangle(this.Height / 2, this.Height / 2 * (-1) - 1, this.Height, this.Height), 180.0f, -90.0f);

3，对于扇形区域使用渐变色时需要使用PathGradientBrush画刷而不是 LinearGradientBrush， LinearGradientBrush画刷无法实现从圆心到边缘的颜色渐变。

void PaintRectangle(Graphics g, Rectangle rec, PointF[] points, LinearGradientMode linearGradientMode = LinearGradientMode.Vertical)
        {
            //画刷效果呈现线型分布，注意与PathGradientBrush的区别
            LinearGradientBrush brush = new LinearGradientBrush(rec, PipeEdgeColor, PipeCenterColor, linearGradientMode);
            brush.InterpolationColors = new ColorBlend() { Colors = new Color[] { PipeEdgeColor, PipeCenterColor, PipeEdgeColor }, Positions = new float[] { 0, 0.5f, 1 } };
            brush.InterpolationColors = new ColorBlend() { Colors = new Color[] { PipeEdgeColor, PipeCenterColor, PipeEdgeColor }, Positions = new float[] { 0, 0.5f, 1 } };
            g.FillRectangle(brush, rec);
            g.DrawLine(new Pen(BorderColor, BorderWidth), points[0], points[1]);
            g.DrawLine(new Pen(BorderColor, BorderWidth), points[2], points[3]);
        }

3，使用自定义的流动管道控件(FlowControl)

引用控件

属性窗口设置自定义的相关属性

设置后效果

4，代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Drawing.Drawing2D;
namespace CustomControl
{
    public partial class FlowControl : UserControl
    {
        private float startOffset = 0.0f;
        private Timer mytimer = new Timer();
        Graphics g;
        public FlowControl()
        {
            InitializeComponent();
            设置控件样式
            this.SetStyle(ControlStyles.AllPaintingInWmPaint, true);
            this.SetStyle(ControlStyles.DoubleBuffer, true);
            this.SetStyle(ControlStyles.ResizeRedraw, true);
            this.SetStyle(ControlStyles.Selectable, true);
            this.SetStyle(ControlStyles.SupportsTransparentBackColor, true);
            this.SetStyle(ControlStyles.UserPaint, true);
            mytimer.Interval = 50;
            mytimer.Tick += Mytimer_Tick;
            mytimer.Start();
        }
        private void Mytimer_Tick(object sender, EventArgs e)
        {
            startOffset += moveSpeed;
            if (Math.Abs(startOffset) > BarLength + GapLength)
            {
                startOffset = 0;
            }
            this.Invalidate();
        }
        #region Fileds
        private int barHeight = 5;
        [Browsable(true), Category("自定义属性"), Description("流动条宽度")]
        public int BarHeight
        {
            get { ret