asp.net C# 画圆画矩形

手动画圆或椭圆

 

private Point startPoint;
    private bool beginDragging;

    public Form1()
    {
        InitializeComponent();
        this.DoubleBuffered = true;
    }

    private void Form1_MouseMove(object sender, MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left && beginDragging)
        {
            circle.Size = new Size(circle.Size.Width + e.X - startPoint.X, circle.Size.Height + e.Y - startPoint.Y);
            startPoint = new Point(e.X, e.Y);
        }
        this.Invalidate();
    }

    private void Form1_MouseDown(object sender, MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left)
        {
            startPoint = e.Location;
            beginDragging = true;
            this.Capture = true;

            circle = new Circle();
            circle.Location = e.Location;
            Circles.Add(circle);

            this.Cursor = System.Windows.Forms.Cursors.Cross;
        }

    }

    private void Form1_MouseUp(object sender, MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left && beginDragging)
        {
            beginDragging = false;
            this.Capture = false;

            this.Cursor = System.Windows.Forms.Cursors.Default;
        }
        this.Invalidate();
    }

    private void Form1_Paint(object sender, PaintEventArgs e)
    {
        Graphics g = e.Graphics;
        foreach (Circle each in Circles)
        {
            g.DrawEllipse(Pens.Black, new Rectangle(each.Location, each.Size));
        }
    }
    private List<Circle> Circles = new List<Circle>();
    private Circle circle = new Circle();

public class Circle
{
    public int Radii;
    public Size Size;
    public Point Location;
}

自动画圆

//方法1
        private void button1_Click_1(object sender, EventArgs e)
        {
            Image im = new Bitmap(this.panel2.Width, this.panel2.Height);
            Graphics g = Graphics.FromImage(im);
            GraphicsPath gp = new GraphicsPath();
            Rectangle rec = new Rectangle(0, 0, 100, 100);
            gp.AddEllipse(rec);
            g.DrawEllipse(new Pen(Color.Red), rec);
            this.panel2.BackgroundImageLayout = ImageLayout.Stretch;
            this.panel2.BackgroundImage = im;
        }
//方法2
        private void button3_Click(object sender, EventArgs e)
        {
            Graphics gra;
            Brush bush;
            gra = this.panel3.CreateGraphics();
            bush = new SolidBrush(Color.Red); //填充的颜色
            gra.FillEllipse(bush, 0, 0, 100, 100);//画填充椭圆的方法，x坐标、y坐标、宽、高，如果是100，则半径为50
        }

自动画矩形

//方法1
       private void button2_Click(object sender, EventArgs e)
       {
           Image im = new Bitmap(this.panel1.Width,this.panel1.Height);
           Graphics g = Graphics.FromImage(im);
           GraphicsPath gp = new GraphicsPath();
           Rectangle rec = new Rectangle(new Point(0,0),new Size(100,100));
           gp.AddRectangle(rec);
           g.DrawRectangle(new Pen(Color.Red), rec);
           this.panel1.BackgroundImageLayout = ImageLayout.Stretch;
           this.panel1.BackgroundImage = im;
       }
//方法2
       private void button4_Click(object sender, EventArgs e)
       {
           Graphics gra;
           Brush bush;
           gra = this.panel4.CreateGraphics();
           bush = new SolidBrush(Color.Red);
           gra.DrawRectangle(new Pen(bush,20), 0, 0, 100, 100);
       }