什么是绘制鼠标线在C＃中的正确方法 [英] What is the proper way to draw a line with mouse in C#

问题描述

这是我的绘图代码来绘制鼠标自定义上线图表。你可以帮我做正确的方法是什么？

This is my drawing code to draw a custom line with mouse onto a Chart. Can you please help me to do it proper way ?

namespace Grafi
    {
        public partial class Form1 : Form
        {

            bool isDrawing = false;
            Point prevPoint;

            public Form1()
            {
                InitializeComponent();
            }

            private void chartTemperature_MouseDown(object sender, MouseEventArgs e)
            {
                isDrawing = true;
                prevPoint = e.Location;
            }

            private void chartTemperature_MouseMove(object sender, MouseEventArgs e)
            {
                Pen p = new Pen(Color.Red, 2); 
                if (isDrawing)
                {
                    Graphics g = chartTemperature.CreateGraphics();    
                    g.DrawLine(p, prevPoint, e.Location);
                    prevPoint = e.Location;

                    numOfMouseEvents = 0;              
                }
                p.Dispose();
            }

            private void chartTemperature_MouseUp(object sender, MouseEventArgs e)
            {
                isDrawing = false;
            }
        }
    }

问题是，当我调整形成我行disappers。它disappers每当OnPaint事件引发。

Problem is that when I resize form my line disappers. It disappers whenever onPaint event is raised.

推荐答案

试试这...这是中风的绘制方法，非常简单地和实施关闭自己的代码越好。斯托克斯是鼠标移动的个人收藏。每当油漆事件被触发向下和向上的每个鼠标移动记录为中风，所有的笔画收集，然后重绘。这个例子很简单，但可能是一个很好的起点。

Try this... It is a stroke drawing method, implemented very simply and as close to your own code as possible. Stokes are individual collections of mouse movements. Every mouse move between down and up is recorded as a stroke, all the strokes are collected and then redrawn whenever the paint event is fired. This example is simple but could be a good starting point.

的请注意，您必须添加油漆处理程序图表对象。的

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;
using System.Drawing.Drawing2D;

namespace Grafi
{
    public partial class Form1 : Form
    {
        bool isDrawing;
        // our collection of strokes for drawing
        List<List<Point>> _strokes = new List<List<Point>>();
        // the current stroke being drawn
        List<Point> _currStroke;
        // our pen
        Pen _pen = new Pen(Color.Red, 2); 

        public Form1()
        {
            InitializeComponent();
        }

        private void chartTemperature_MouseDown(object sender, MouseEventArgs e)
        {
            isDrawing = true;
            // mouse is down, starting new stroke
            _currStroke = new List<Point>();
            // add the initial point to the new stroke
            _currStroke.Add(e.Location);
            // add the new stroke collection to our strokes collection
            _strokes.Add(_currStroke);
        }

        private void chartTemperature_MouseMove(object sender, MouseEventArgs e)
        {
            if (isDrawing)
            {
                // record stroke point if we're in drawing mode
                _currStroke.Add(e.Location);
                Refresh(); // refresh the drawing to see the latest section
            }
        }

        private void chartTemperature_MouseUp(object sender, MouseEventArgs e)
        {
            isDrawing = false;
        }

        private void chartTemperature_Paint(object sender, PaintEventArgs e)
        {
            // now handle and redraw our strokes on the paint event
            e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
            foreach (List<Point> stroke in _strokes.Where(x => x.Count > 1))
                e.Graphics.DrawLines(_pen, stroke.ToArray());
        }
    }
}

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