C# Cut Line Bressenham Algorithm

using System;
using System.Drawing;
using System.Windows.Forms;

namespace CutLine
{
static class Program
{
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}
static public class ai
{
static byte code(Point p, Rectangle rec)
{
byte ans=0;
if (p.Y < rec.Y) ans |= 1;
if (p.Y > rec.Y + rec.Height) ans |= 2;
if (p.X < rec.X) ans |= 4;
if (p.X > rec.X + rec.Width) ans |= 8;
return ans;
}
static public void run(Point from, Point to, Rectangle rec)
{
byte f = code(from, rec);
byte t = code(to, rec);
if ((f & t) != 0)//绝对无交集，两点在同一侧
{
nothing = true;
return;
}
if ((f | t)== 0)//两点都在内部
{
ai.from = from;
ai.to = to;
nothing = false;
return;
}
if (f == 0)
{
change(ref to,ref from,ref rec,ref t);
}
else{
change(ref from,ref  to, ref rec,ref f);
}
run(from, to, rec);
}
static void change(ref Point move, ref Point stay, ref Rectangle rec,ref byte c)
{
if ((c & 1) != 0)
{
move.X =(int)( (move.X - stay.X) *(double) (rec.Y - stay.Y) / (move.Y - stay.Y) + stay.X);
move.Y = rec.Y;
}
else if ((c & 2) != 0)
{
move.X = (int)((double)(move.X - stay.X) / (move.Y - stay.Y) * (rec.Y + rec.Height - stay.Y) + stay.X);
move.Y = rec.Y + rec.Height;
}
else if ((c & 4) != 0)
{
move.Y = (int )((double)(move.Y - stay.Y) / (move.X - stay.X) * (rec.X - stay.X) + stay.Y);
move.X = rec.X;
}
else if ((c & 8) != 0)
{
move.Y = (int)((double)(move.Y - stay.Y) / (move.X - stay.X) * (rec.X +rec.Width- stay.X) + stay.Y);
move.X = rec.X+rec.Width;
}
}
public static Point from = new Point(10,10);
public static Point to = new Point(40,40);
public static bool nothing = true;
}
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
Text = "直线裁剪--made by weidiao.neu";
}

int times = 0;
Point from = new Point();
Point to = new Point();
Point temp = new Point();
Rectangle rec = new Rectangle();

private void button1_Click(object sender, EventArgs e)
{
CreateGraphics().Clear(Color.AliceBlue);
times = 0;
}
bool bigger(Point a, Point b)
{
return a.X >= b.X && b.X >= b.Y;
}
int min(int a, int b)
{
if(a<b)return a;
return b;
}
Pen linePen = new Pen(Color.Red, 5);
Pen recPen = new Pen(Color.Purple, 2);
override protected void OnMouseMove(MouseEventArgs e)
{
if (times == 0 || times == 2) return;
Bitmap bit = new Bitmap(ClientSize.Width, ClientSize.Height);
Graphics g = Graphics.FromImage(bit);
g.Clear(Color.AliceBlue);
switch (times)
{
case 1: g.DrawLine(linePen, from, e.Location);
break;
case 3: g.DrawLine(linePen, from, to);
rec.X = min(temp.X, e.X);
rec.Y = min(temp.Y, e.Y);
rec.Width = Math.Abs(temp.X - e.X);
rec.Height = Math.Abs(temp.Y - e.Y);
g.DrawRectangle(recPen, rec);
break;
}
CreateGraphics().DrawImage(bit, 0, 0);
}
override  protected void OnMouseDown(MouseEventArgs e)
{
switch (times)
{
case 0:
button1_Click(null, null);
from.X = e.X;
from.Y = e.Y;
break;
case 1: to.X = e.X;
to.Y = e.Y;
CreateGraphics().DrawLine(linePen, from, to);
break;
case 2: temp.X = e.X;
temp.Y = e.Y;
break;
case 3:
rec.X = min(temp.X, e.X);
rec.Y = min(temp.Y, e.Y);
rec.Width = Math.Abs(temp.X - e.X);
rec.Height = Math.Abs(temp.Y - e.Y);
CreateGraphics().DrawRectangle(recPen, rec);
ai.run(from, to, rec);
if(ai.nothing==false)
CreateGraphics().DrawLine(new Pen(Color.Green, 8), ai.from, ai.to);
break;
}
times++;
times %= 4;
}
}
}

package mySecondPackage;

import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;

import javax.swing.*;

/*
* 上下左右
* 0000
* 用4位二进制表示
* 上边之外为1，也就是上边之上为1
* 下边之外为1，也就是下边之下为1
* 左边之外为1，也就是左边之左为1
* 右边之外为1，也就是右边之右为1
* */
/**
* @author weidiao
* @see hahaha
* @version 2.0
*/

class ai {
/**
* 按照上下左右的顺序进行编码
* */
static byte code(Point p, Rectangle rec) {
byte ans = 0;
if (p.y < rec.y)// 如果点p在长方形的上边
ans |= 1;
else if (p.y > rec.y + rec.height)// 如果点p在长方形的下边
ans |= 2;
if (p.x < rec.x)// 如果点p在长方形左边
ans |= 4;
else if (p.x > rec.x + rec.width)// 如果点p在长方形右边
ans |= 8;
return ans;
}

/**
* @算法的主体，进行判断和循环
* @param 输入参数
*            ：Point from，to描述直线 Rectangle rec描述矩形
* @return输出参数：返回为空，因为Point from和to是传引用，所以就直接改变了
*                          类的静态变量nothing反映了是否产生了结果，若无交点，nothing=true
*/
static public void run(Point from, Point to, Rectangle rec) {
while (true) {
byte f = code(from, rec);
byte t = code(to, rec);// 对两个点进行编码

if ((f & t) != 0)// 绝对无交集，两点在矩形某条边同一侧
{
nothing = true;//
return;
}
if ((f | t) == 0)// 两点都在矩形内部
{
nothing = false;
return;
}
if (f == 0)
change(to, from, rec, t);
else
change(from, to, rec, f);

}
}

/**
* @本函数用于求直线与矩形边所在直线的交点
* @param Point
*            move表示准备移动的那个点，Point stay表示不移动的点 Rectangle rec表示矩形 Byte c
*            表示准备移动的那个点的编码
* @return 被移动的点move值将会发生变化
* @难点在于：计算时要用浮点数进行计算，直接用int误差太大
*/
static void change(Point move, Point stay, Rectangle rec, byte c) {
if ((c & 1) != 0) {
move.x = (int) ((move.x - stay.x) * (double) (rec.y - stay.y)
/ (move.getY() - stay.y) + stay.x);
move.y = rec.y;
} else if ((c & 2) != 0) {
move.x = (int) ((double) (move.x - stay.x) / (move.y - stay.y)
* (rec.y + rec.height - stay.y) + stay.x);
move.y = rec.y + rec.height;
} else if ((c & 4) != 0) {
move.y = (int) ((double) (move.y - stay.y) / (move.x - stay.x)
* (rec.x - stay.x) + stay.y);
move.x = rec.x;
} else if ((c & 8) != 0) {
move.y = (int) ((double) (move.y - stay.y) / (move.x - stay.x)
* (rec.x + rec.width - stay.x) + stay.y);
move.x = rec.x + rec.width;
}
}

public static boolean nothing = true;
}

/**
* @CutLine类，界面部分
* */
class CutLine extends JFrame {
public static void main(String[] args) {
new CutLine();
}

public CutLine() {
setTitle("直线裁剪--made by weidiao.neu");
setSize(700, 700);
setVisible(true);
setLayout(null);
setDefaultCloseOperation(EXIT_ON_CLOSE);

JButton clearButton = new JButton("清屏");
clearButton.setFont(new Font("楷体", Font.BOLD, 50));
clearButton.addActionListener(clearButtonClick);
clearButton.setLocation(500, 500);
clearButton.setSize(200, 200);
add(clearButton);

addMouseListener(mouse);
addMouseMotionListener(mouseMotion);

}

int times = 0;
Point from = new Point();
Point to = new Point();
Point temp = new Point();// 用于存储矩形左上角的位置
Rectangle rec = new Rectangle();

ActionListener clearButtonClick = new ActionListener() {
public void actionPerformed(ActionEvent e) {
getGraphics().clearRect(0, 0, getWidth(), getHeight());
times = 0;
}
};

MouseListener mouse = new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
switch (times) {
case 0:
clearButtonClick.actionPerformed(null);
from = e.getPoint();
break;
case 1:
to = e.getPoint();
getGraphics().drawLine(from.x, from.y, to.x, to.y);
break;
case 2:
temp = e.getPoint();
break;
case 3:
rec.x = Integer.min(temp.x, e.getX());
rec.y = Integer.min(temp.y, e.getY());
rec.width = Math.abs(temp.x - e.getX());
rec.height = Math.abs(temp.y - e.getY());
getGraphics().drawRect(rec.x, rec.y, rec.width, rec.height);
ai.run(from, to, rec);
if (ai.nothing == false) {
Graphics2D g = (Graphics2D) getGraphics();
g.setStroke(new BasicStroke(4));
g.setColor(Color.red);
g.drawLine(from.x, from.y, to.x, to.y);
}
break;
}
times++;
if (times == 4)
times = 0;
}
};
MouseMotionListener mouseMotion = new MouseMotionAdapter() {
public void mouseMoved(MouseEvent e) {
if (times == 0 || times == 2)
return;
getGraphics().clearRect(0, 0, getWidth(), getHeight());

BufferedImage bit = new BufferedImage(getWidth(), getHeight(),
BufferedImage.TYPE_INT_ARGB_PRE);
Graphics2D g = (Graphics2D) bit.getGraphics();
switch (times) {
case 1:
g.setColor(Color.blue);
g.setStroke(new BasicStroke(3));
g.drawLine(from.x, from.y, e.getX(), e.getY());
break;
case 3:
g.setColor(Color.blue);
g.setStroke(new BasicStroke(3));
g.drawLine(from.x, from.y, to.x, to.y);
rec.x = Integer.min(temp.x, e.getX());
rec.y = Integer.min(temp.y, e.getY());
rec.width = Math.abs(temp.x - e.getX());
rec.height = Math.abs(temp.y - e.getY());
g.drawRect(rec.x, rec.y, rec.width, rec.height);
break;
}
getGraphics().drawImage(bit, 0, 0, null);
}
};

boolean bigger(Point a, Point b) {
return a.x >= b.x && b.x >= b.y;
}
}