C# Winform编程（8）GDI+绘图

简介

GDI(Graphics Device Interface)图像设备接口，属于绘图方面的API。System.Drawing命名空间提供了对GDI+基本图形功能的访问。

System.Drawing命名空间

System.Drawing命名空间中的常用类：

System.Drawing命名空间中的常用结构：

Graphics 类

Graphics类封装了一个GDI+绘图界面，提供将对象绘制到显示设备的方法。
Graphics类的常用方法：

Pen类

Pen类可以设置画笔的颜色，线条的粗细和线条的样式（实现、虚线等）。画笔是绘图的工具，Graphics对象是绘画的场所。

Brush类

Brush类（画刷），用于填充图形。该类是一个抽象基类，不能直接实例化。
Brush类的派生类：

Font类

Font类，绘制文本时，可以设置字体的样式、大小、以及字体的种类。

using System.Drawing.Drawing2D;
using System.Numerics;
using System.Security.Cryptography.Xml;
using System.Threading;


namespace GDIDemo
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        /// 

        /// 绘制直线
        /// 
        /// 
        /// 
        private void button1_Click(object sender, EventArgs e)
        {
            Graphics g = this.CreateGraphics();
            Pen p = new Pen(Color.Black);
            g.DrawLine(p, 0, this.Height / 2, this.Width, this.Height / 2);
            p.Dispose();
            g.Dispose();
        }


        /// 

        /// 绘制矩形
        /// 
        /// 
        /// 
        private void button2_Click(object sender, EventArgs e)
        {
            Graphics g = this.CreateGraphics();
            Pen p = new Pen(Color.Red);
            g.DrawRectangle(p, 50, 50, 200, 200);
            p.Dispose();
            g.Dispose();
        }

        /// 

        /// 绘制圆形
        /// 
        /// 
        /// 
        private void button3_Click(object sender, EventArgs e)
        {
            Graphics g = this.CreateGraphics();
            Pen p = new Pen(Color.Blue);
            g.DrawEllipse(p, 50, 50, 100, 100);
            p.Dispose();
            g.Dispose();
        }

        /// 

        /// 绘制圆柱
        /// 
        /// 
        /// 
        private void button4_Click(object sender, EventArgs e)
        {
            int height = this.ClientSize.Height - 100;
            int width = this.ClientSize.Width - 50;
            int vHeight = 200;
            int vWidth = 100;

            Graphics g = this.CreateGraphics();
            g.Clear(Color.White);
            Pen pen = new Pen(Color.Gray);
            SolidBrush brush = new SolidBrush(Color.Gainsboro);
            for (int i = height / 2; i > 0; i--)
            {
                g.DrawEllipse(pen, width / 2, i, vHeight, vWidth);
            }
            g.FillEllipse(brush, width / 2, 0, vHeight, vWidth);
        }

        /// 

        /// 绘制填充矩形
        /// 
        /// 
        /// 
        private void button5_Click(object sender, EventArgs e)
        {
            Graphics g = this.CreateGraphics();
            Pen pen = new Pen(Color.Blue);
            Brush brush = pen.Brush;
            Rectangle rect = new Rectangle(50, 50, 100, 100);
            g.FillRectangle(brush, rect);
            pen.Dispose();
            g.Dispose();
        }

        /// 

        /// 绘制渐变圆形
        /// 
        /// 
        /// 
        private void button6_Click(object sender, EventArgs e)
        {
            Graphics g = this.CreateGraphics();
            Rectangle rect = new Rectangle(150, 50, 200, 200);
            LinearGradientBrush brush = new LinearGradientBrush(rect, Color.Orange, Color.Purple, 90);
            g.FillEllipse(brush, rect);
            brush.Dispose();
            g.Dispose();
        }

        /// 

        /// 绘制文字
        /// 
        /// 
        /// 
        private void button7_Click(object sender, EventArgs e)
        {
            Graphics g = this.CreateGraphics();
            Pen pen = new Pen(Color.Blue);
            Font f = new Font("隶书", 24, FontStyle.Italic);
            g.DrawString("Windows 应用程序设计", f, pen.Brush, 50, 50);
            pen.Dispose();
            g.Dispose();
        }


        private void button9_Click(object sender, EventArgs e)
        {
            using (Graphics g = this.CreateGraphics())
            {
                g.Clear(Color.White);
            }
        }
        private void Form1_Paint(object sender, PaintEventArgs e)
        {
#if false
            Graphics g = this.CreateGraphics();
            g.Clear(Color.White);
            Pen myPen = new Pen(Color.Red, 3);
            g.DrawRectangle(myPen, 0, 0, 200, 100);
            g.DrawEllipse(myPen, 0, 0, 200, 100);
            g.Dispose();
            myPen.Dispose();
#endif
        }

        /// 

        /// 坐标平移
        /// 
        /// 
        /// 
        private void button8_Click(object sender, EventArgs e)
        {

            Graphics g = this.CreateGraphics();
            g.Clear(Color.White);
            Pen myPen = new Pen(Color.Red, 3);

            g.DrawRectangle(myPen, 0, 0, 200, 100);
            g.DrawEllipse(myPen, 0, 0, 200, 100);
            Thread.Sleep(1000);

            g.Clear(Color.White);
            g.TranslateTransform(30, 30);
            g.DrawRectangle(myPen, 0, 0, 200, 100);
            g.DrawEllipse(myPen, 0, 0, 200, 100);
            g.Dispose();
            myPen.Dispose();
        }

        /// 

        /// 坐标缩放
        /// 
        /// 
        /// 
        private void button10_Click(object sender, EventArgs e)
        {
            Graphics g = this.CreateGraphics();
            g.Clear(Color.White);
            Pen myPen = new Pen(Color.Red, 3);
            g.DrawRectangle(myPen, 0, 0, 200, 100);
            g.DrawEllipse(myPen, 0, 0, 200, 100);
            Thread.Sleep(1000);

            g.Clear(Color.White);
            g.ScaleTransform(1.5f, 2.0f); // 横轴放到1.5倍，纵轴放大2倍
            g.DrawRectangle(myPen, 0, 0, 200, 100);
            g.DrawEllipse(myPen, 0, 0, 200, 100);
            g.Dispose();
            myPen.Dispose();


        }

        /// 

        /// 绘制波形
        /// 
        /// 
        /// 

        private void button11_Click(object sender, EventArgs e)
        {
            Graphics g = this.CreateGraphics();
            g.Clear(Color.White);
            Pen pen = new Pen(Color.Blue, 3);
            Point p1 = new Point(30, this.ClientSize.Height - 200);
            Point p2 = new Point(this.ClientSize.Width - 100, this.ClientSize.Height - 200);
            Point p3 = new Point(30, 30);
            g.DrawLine(pen, p1, p2);
            g.DrawLine(pen, p1, p3);
            Font f = new Font("宋体", 12, FontStyle.Bold);
            g.DrawString("x", f, pen.Brush, p2);
            g.DrawString("y", f, pen.Brush, 10, 10);


            double x1, x2, y1, y2, a;
            x1 = x2 = y1 = y2 = 0;
            y2 = this.ClientSize.Height - 200;
            for (x2 = 0; x2 < this.ClientSize.Width; x2++)
            {
                a = 2 * Math.PI * x2 / this.ClientSize.Width;
                y2 = Math.Sin(a);
                y2 = (1 - y2) * (this.ClientSize.Height - 200) / 2;
                g.DrawLine(pen, (int)(x1 + 30), (int)y1, (int)(x2 + 30), (int)y2);
                x1 = x2;
                y1 = y2;
            }


        }

        /// 

        /// 绘制饼状图
        /// 
        /// 
        /// 
        private void button12_Click(object sender, EventArgs e)
        {
            Graphics g = this.CreateGraphics();
            Rectangle rect = new Rectangle(50, 50, 200, 100);
            Brush brush = new SolidBrush(Color.Blue);
            g.FillPie(brush, rect, 0, 60);
            g.FillPie(brush, rect, 60, 150);
            brush = new SolidBrush(Color.Yellow);
            g.FillPie(brush, rect, 210, 150);
            brush.Dispose();
            g.Dispose();
        }
    }
}
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PictureBox图像控件

PictureBox控件，图片框是操作图形图像的基本控件，主要用于显示，保存图形图像信息，其主要属性方法：

• 属性：
  • Image：设置或获取与该控件显示的图像
  • SizeMode：指示如何显示图像
• 方法：
  • Load：显示图像

Bitmap类

Bitmap类，封装GDI+位图，此位图由图形图像及其属性的像素数据组成。Bitmap是用于处理由像素数据定义的图像的对象，其常用属性及方法：

        /// 

        /// 创建位图并保存为图片
        /// 
        /// 
        /// 
        private void button13_Click(object sender, EventArgs e)
        {
            Bitmap bm = new Bitmap(this.ClientSize.Width, this.ClientSize.Height,
                System.Drawing.Imaging.PixelFormat.Format32bppArgb);
            Graphics g = Graphics.FromImage(bm);

            Font f = new Font("隶书", 24, FontStyle.Italic);
            Pen pen = new Pen(Color.OrangeRed);
            g.DrawString("创建位图测试保存图像", f, pen.Brush, 0, 0);
            pictureBox1.Image = bm;
            pictureBox1.Show();

            bm.Save("c:\\temp\\1.bmp");
            pen.Dispose();
            g.Dispose();
        }

        /// 

        /// 加载图片并另存图片
        /// 
        /// 
        /// 
        private void button14_Click(object sender, EventArgs e)
        {
            OpenFileDialog openfile = new OpenFileDialog();
            openfile.Filter = "图像文件*.bmp|*.bmp|*.jpg|*.png";
            if (openfile.ShowDialog() == DialogResult.OK)
            { 
                pictureBox1.Image = Image.FromFile(openfile.FileName);
                pictureBox1.Image.Save("c:\\temp\\2.bmp");
            }
        }

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