Question

C#画直线的代码！（和windows画图工具一样的效果*）

我的代码不对，不是射线状，就是没有画的过程。怎么样实现在屏幕上一点，拖出一个可变的直线，像橡皮条，松开后确定的那种！！急~~
private void Drawing_MouseDown(object sender, MouseEventArgs e)
{
if ((isDrawing = !isDrawing) == true)//判断是否开始绘图
{
startPoint = new Point(e.X, e.Y);
}
}
private void Drawing_MouseMove(object sender, MouseEventArgs e)
{
Graphics g = this.Drawing.CreateGraphics();

if (isDrawing)
{
switch (drawTool)
{
case drawTools.Line:
using (Pen p = new Pen(foreColor, 1))
{
graphics.DrawLine(p, startPoint, endPoint);
}
break;
}
}
private void Drawing_MouseUp(object sender, MouseEventArgs e)
{
isDrawing = false;//标识变量
graphics = this.Drawing.CreateGraphics();
switch (drawTool)
{
case drawTools.Line:
using (Pen p = new Pen(foreColor, 1))
{
graphics.DrawLine(p, startPoint, new Point(e.X,e.Y));
}
break;
}
}
}
我没有单写类，需不需要单写个类啊？DDA算法是解决我这个问题的么？

Answer 1

我这里是画直线和画曲线的两种都有，楼主看看，错不了的，代码如下：

namespace Case02_1

{

    public partial class Form1 : Form

    {

        int startX;     //获取鼠标起始点的X坐标

        int startY;    //获取鼠标起始点的Y坐标

        Graphics g;    //定义Graphics对象实例

        public Form1()

        {

            InitializeComponent();

        }

        private void Form1_Load(object sender, EventArgs e)

        {

            this.StartPosition = FormStartPosition.CenterScreen;

            this.BackColor = Color.Snow;

        }

        private void Form1_MouseUp(object sender, MouseEventArgs e)

        {

            g = this.CreateGraphics();        

            Pen p = new Pen(Color.Red , 4);

            if (radioButton1.Checked == true)

            {

                g.DrawLine(p, startX, startY, e.X, e.Y);

            } 

        }

        private void Form1_MouseDown(object sender, MouseEventArgs e)

        {

            startX = e.X;

            startY = e.Y;

        }

        private void Form1_MouseMove(object sender, MouseEventArgs e)

        {

            g = this.CreateGraphics();

            Pen p = new Pen(Color.Blue , 2);

            if (radioButton2.Checked == true)

            {

                g.DrawRectangle(p, e.X, e.Y, 1, 1);

            }

        }

        private void button1_Click(object sender, EventArgs e)

        {

            g = this.CreateGraphics();

            g.Clear(Color.Snow );

        }

        private void button2_Click(object sender, EventArgs e)

        {

            this.Close();

            Application.Exit();

        }

    }

}

Answer 2

Graphics g;
private bool drawBegin = false;
private Point starPoint = Point.Empty;

private void Form3_MouseDown(object sender, MouseEventArgs e)
{
this.drawBegin = true;
this.starPoint = e.Location;
g = this.CreateGraphics();
}

private void Form3_MouseMove(object sender, MouseEventArgs e)
{
if (drawBegin)
{
g.Clear(SystemColors.Control);
g.DrawLine(Pens.Black, starPoint, e.Location);
}
}

private void Form3_MouseUp(object sender, MouseEventArgs e)
{
this.drawBegin = false;
this.starPoint = Point.Empty;
}

Answer 3

建议参考一下paint.net完全使用.net c#技术开发,功能远远超过画图.如果你安装的有.net framwork3.5,源程序只有4.5mb左右.

如果你要自己开发,gdi+必不可少.
某些功能网上有源码.
可以逐步添加功能.
另外,虚机团上产品团购,超级便宜