怎么实现拖拉画圆（见图）
如上图，实现picturebox中拖拉画出不同半径的球，并获取其半径 --------------------编程问答-------------------- Up --------------------编程问答-------------------- 学习 --------------------编程问答--------------------
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace Test
{
public partial class Form3 : Form
{
public Form3()
{
InitializeComponent();
}
private Point startPoint;
private bool beginDragging;
private void Form3_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 Form3_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 Form3_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 Form3_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 { get; set; }
public Size Size { get; set; }
public Point Location { get; set; }
}
}
新建个WinForm，把上面的代码拷进去，就o了。 --------------------编程问答-------------------- 至于半径，在MouseUp事件里，根据location和size可以算出它的半径。 --------------------编程问答--------------------
恩 好东西 _______________________
private void Form3_MouseMove(object sender, MouseEventArgs e)--------------------编程问答-------------------- Form的属性，把DoubleBuffered属性，设置为True，就不闪了 --------------------编程问答-------------------- up --------------------编程问答-------------------- 我的意思你们误会了，这个球是本来画好的，可以拖动改变他的半径，使得球的大小发生变化~
{
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(); // 这个闪的很厉害 ,不加有看不到拉的线路
}
补充：.NET技术 , C#
