GDI绘图

什么是GDI+
GDI+ (Graphics Device Interface) 是一种绘图装置接口, 可将应用程序和绘图硬件分隔, 让我们能够编写与装置无关的应用程序。它可以让我们不需注意特定显示装置的详细数据, 便可在屏幕或打印机显示信息。我们可以呼叫 GDI+ 类别所提供的方法, 然后这些方法会适当地呼叫特定的装置驱动程序, 而完成绘图。而且与.NET进行了更好的融合。
GDI (Graphics Device Interface), 是属于绘图方面的 API (Application Programming Interface)。
因为应用程序不能直接控制硬件, 所以当我们要进行绘图的动作时, 必须透过 GDI 才能完成。

 

 

 

 

 

 

 

 

确定坐标系：1.确定原点 2.确定x，y轴和方向

Graphics提供了非常多的绘图的方法可以让我们进行绘制。
绘图方法
Graphics 类别的常用绘图方法有：
DrawLine(直线)、
DrawRectangle (矩形)、
DrawEllipse (椭圆)、
DrawCurve (曲线)、
DarwArc (弧线)、
DrawPie (扇形)、
DrawLines (多边形)、
DrawPolygon (封闭多边形)、
DrawBezier (贝兹曲线)等。

 

 

使用GDI绘制简单的图形

 

   //绘制一条直线
        private void button1_Click(object sender, EventArgs e)
        {
            //创建GDI对象
            Graphics g = this.CreateGraphics();// new Graphics();
            //创建画笔对象
            Pen pen = new Pen(Brushes.Red);
            //创建两个点
            Point p1 = new Point(30, 50);
            Point p2 = new Point(250, 250);
            g.DrawLine(pen, p1, p2);

        }

  //绘制一个矩形
        private void button2_Click(object sender, EventArgs e)
        {
            Graphics g = this.CreateGraphics();
            Pen pen=new Pen(Brushes.Yellow);
            Size size=new System.Drawing.Size(80,80);
            Rectangle rec=new Rectangle(new Point(50,50),size);
            g.DrawRectangle(pen,rec);
        }

  //绘制一个扇形
        private void button3_Click(object sender, EventArgs e)
        {
            Graphics g = this.CreateGraphics();
            Pen pen=new Pen(Brushes.Blue);
            Size size=new System.Drawing.Size(180,180);
            Rectangle rec=new Rectangle(new Point(150,150),size);
            g.DrawPie(pen, rec, 60, 60);
        }

//绘制一个文本
        private void button4_Click(object sender, EventArgs e)
        {
            Graphics g = this.CreateGraphics();
            g.DrawString("老赵是最帅的", new Font("宋体", 20, FontStyle.Underline), Brushes.Black, new Point(300, 300));
        }

//实心画圆

private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
        {
            Graphics g=e.Graphics;
            //定义实心填充画笔
            SolidBrush myBrush=new SolidBrush(Color.Yellow);
            g.FillEllipse(myBrush,50,50,300,200);
            myBrush.Dispose();
            g.Dispose();
        }

 

生成验证码图片实例

1.通过Random生成随机数或字符及验证码
2.通过验证码内容长度生成指定大小的图片
3.获取生成图片的Graphics对象
4.定义验证码字体格式
5.通过指定字体将验证码绘制到图片
6.向图片上添加背景噪音线
7.添加前景噪音点

 

 Random r = new Random();
        /// <summary>
        /// 点击更换验证码
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void pictureBox1_Click(object sender, EventArgs e)
        {
            //创建一张图片对象
            Bitmap bmp = new Bitmap(120, 20);
            //存储的就是验证码
            string str = string.Empty;
            for (int i = 0; i < 5; i++)
            {
                str += r.Next(0, 10);
            }
            //创建GDI+对象
            Graphics g = Graphics.FromImage(bmp);

            string[] fonts = { "微软雅黑", "隶书", "宋体", "黑体", "仿宋" };
            Color[] colors = { Color.Black, Color.Yellow, Color.Red, Color.Green, Color.Gold };

            //开始绘制验证码
            for (int i = 0; i < str.Length; i++)
            {
                Point p = new Point(i * 20, 0);
                g.DrawString(str[i].ToString(), new Font(fonts[r.Next(0, 5)], 15, FontStyle.Bold), new SolidBrush(colors[r.Next(0, 5)]), p);
            }
            //给验证码图片中绘制一些直线
            for (int i = 0; i < 20; i++)
            {
                Point p1 = new Point(r.Next(0, bmp.Width), r.Next(0, bmp.Height));
                Point p2 = new Point(r.Next(0, bmp.Width), r.Next(0, bmp.Height));
                g.DrawLine(new Pen(Brushes.Pink), p1, p2);
            }
            //给验证码添加像素颗粒
            for (int i = 0; i < 100; i++)
            {
                bmp.SetPixel(r.Next(0, bmp.Width), r.Next(0, bmp.Height), Color.Black);
            }

            //把创建的位图对象放在pictureBox上
            pictureBox1.Image = bmp;
        }

 

神奇的参数

        /// <summary>
        /// 
        /// </summary>
        /// <param name="sender">触发这个事件的对象</param>
        /// <param name="e">关于事件的一些数据</param>
        private void Form1_MouseMove(object sender, MouseEventArgs e)
        {
            label1.Text = e.X + "," + e.Y;
        }

        private void Form1_KeyDown(object sender, KeyEventArgs e)
        {
            // e.KeyCode 获取用户按下了哪个键
            if (e.KeyCode == Keys.W || e.KeyCode == Keys.Up)
            {
                MessageBox.Show("前进！！！");
            }
            else if (e.KeyCode == Keys.S || e.KeyCode == Keys.Down)
            {
                MessageBox.Show("后退");
            }
            else if (e.KeyCode == Keys.A || e.KeyCode == Keys.Left)
            {
                MessageBox.Show("向左");
            }
            else if (e.KeyCode == Keys.D || e.KeyCode == Keys.Right)
            {
                MessageBox.Show("向右");
            }


        }

 

小坦克移动案例

 

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using 小坦克移动.Properties;
namespace 小坦克移动
{
    enum Direction
    {
        Up,
        Down,
        Left,
        Right
    }
    class Tank
    {
        //存储图片
        private Image[] imgs = { 
                               Resources.p1tankU,
                               Resources.p1tankD,
                               Resources.p1tankL,
                               Resources.p1tankR
                                };
        //小坦克的X、Y坐标
        public int X { get; set; }
        public int Y { get; set; }
        //定义4个方向
        public Direction Dir { get; set; }
        //定义坦克移动的速度
        public int Speed { get; set; }
        //定义坦克的构造函数
        public Tank(int x, int y, int speed, Direction dir)
        {
            this.X = x;
            this.Y = y;
            this.Speed = speed;
            this.Dir = dir;
        }

        //小坦克移动的行为
        public void Move()
        {
            //根据方向 来判断小坦克要改变的坐标
            switch (this.Dir)
            {
                case Direction.Up:
                    this.Y -= this.Speed;
                    break;
                case Direction.Down:
                    this.Y += this.Speed;
                    break;
                case Direction.Left:
                    this.X -= this.Speed;
                    break;
                case Direction.Right:
                    this.X += this.Speed;
                    break;
            }
            //移动完成后 判断小坦克是否超过了窗体
            if (this.X <= 0)
            {
                this.X = 0;
            }
            if (this.Y <= 0)
            {
                this.Y = 0;
            }
            if (this.X >= 700-80)
            {
                this.X = 620;
            }
            if (this.Y >= 600-100)
            {
                this.Y = 500;
            }
        }
        public void DrawTank(Graphics g)
        {
            switch (this.Dir)
            { 
                case Direction.Up:
                    g.DrawImage(imgs[0], this.X, this.Y);
                    break;
                case Direction.Down:
                    g.DrawImage(imgs[1], this.X, this.Y);
                    break;
                case Direction.Left:
                    g.DrawImage(imgs[2], this.X, this.Y);
                    break;
                case Direction.Right:
                    g.DrawImage(imgs[3], this.X, this.Y);
                    break;
            }
        }

        public void TankKeyDown(KeyEventArgs e)
        {
            if (e.KeyCode == Keys.W || e.KeyCode == Keys.Up)
            {
                this.Dir = Direction.Up;
            }
            else if (e.KeyCode == Keys.S || e.KeyCode == Keys.Down)
            {
                this.Dir = Direction.Down;
            }
            else if (e.KeyCode == Keys.A || e.KeyCode == Keys.Left)
            {
                this.Dir = Direction.Left;
            }
            else if (e.KeyCode == Keys.D || e.KeyCode == Keys.Right)
            {
                this.Dir = Direction.Right;
            }
            this.Move();//让坦克移动
        }


    }
}

 public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        Tank tank;
        private void Form1_Load(object sender, EventArgs e)
        {
            //创建小坦克对象
            tank = new Tank(200, 200, 10, Direction.Up);
            //设置双缓冲 减少屏幕闪烁
            this.SetStyle(ControlStyles.OptimizedDoubleBuffer
                       | ControlStyles.ResizeRedraw
                       | ControlStyles.Selectable
                       | ControlStyles.AllPaintingInWmPaint
                       | ControlStyles.UserPaint
                       | ControlStyles.SupportsTransparentBackColor,
                     true);
        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            //在绘制窗体的时候 将坦克也绘制出来
            tank.DrawTank(e.Graphics);

        }

        private void Form1_KeyDown(object sender, KeyEventArgs e)
        {
            //获取用户按下了哪个键盘
            tank.TankKeyDown(e);
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            //不停的执行Paint事件
            this.Invalidate();
        }
    }