C# 实现QQ式截图功能实例代码

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;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using ImageClassLib;
namespace ImageShear
{
  public partial class Demo: Form
  {
    public Demo()
    {
      InitializeComponent();
    }
    #region 点击打开图像
    public string strHeadImagePath; //打开图片的路径
    Bitmap Bi; //定义位图对像
    private void button1_Click(object sender, EventArgs e)
    {
      openFileDialog1.Filter = "*.gif|*.jpg|*.JPEG|*.JPEG|*.bmp|*.bmp";     //设置读取图片类型
      if (openFileDialog1.ShowDialog() == DialogResult.OK)
      {
        try
        {
          strHeadImagePath = openFileDialog1.FileName;
          //this.Show(strHeadImagePath);
          Bi = new Bitmap(strHeadImagePath); //使用打开的图片路径创建位图对像
          ImageCut1 IC = new ImageCut1(40, 112, this.pictureBox1.Width, this.pictureBox1.Height);   //实例化ImageCut类，四个参数据分别表示为：x、y、width、heigth，（40、112）表示pictureBox1的Lcation的坐标，（120、144）表示pictureBox1控件的宽度和高度
          this.pictureBox1.Image = IC.KiCut1((Bitmap)(this.GetSelectImage(this.pictureBox1.Width, this.pictureBox1.Height)));   //（120、144）表示pictureBox1控件的宽度和高度
          //this.pictureBox1.Image = (this.GetSelectImage(120, 144));
        }
        catch (Exception ex)
        {
          MessageBox.Show("格式不对");
          ex.ToString();
        }
      }
    }
    #endregion
    #region 定义显示图像方法，即将打开的图像在pictureBox1控件显示
    public void Show(string strHeadImagePath)
    {
      this.pictureBox1.Load(@strHeadImagePath);  //
    }
    #endregion
    #region 获取图像
    /// <summary>
    /// 获取指定宽度和高度的图像即使图片和pictureBox1控件一样宽和高，返回值为图片Image
    /// </summary>
    /// <param name="Width表示宽"></param>
    /// <param name="Height表示高"></param>
    /// <returns></returns>
    public Image GetSelectImage(int Width, int Height)
    {
      //Image initImage = this.pictureBox1.Image;
      Image initImage = Bi;
      //原图宽高均小于模版，不作处理，直接保存 
      if (initImage.Width <= Width && initImage.Height <= Height)
      {
        //initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
        return initImage;
      }
      else
      {
        //原始图片的宽、高 
        int initWidth = initImage.Width;
        int initHeight = initImage.Height;

        //非正方型先裁剪为正方型 
        if (initWidth != initHeight)
        {
          //截图对象 
          System.Drawing.Image pickedImage = null;
          System.Drawing.Graphics pickedG = null;

          //宽大于高的横图 
          if (initWidth > initHeight)
          {
            //对象实例化 
            pickedImage = new System.Drawing.Bitmap(initHeight, initHeight);
            pickedG = System.Drawing.Graphics.FromImage(pickedImage);
            //设置质量 
            pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            //定位 
            Rectangle fromR = new Rectangle((initWidth - initHeight) / 2, 0, initHeight, initHeight);
            Rectangle toR = new Rectangle(0, 0, initHeight, initHeight);
            //画图 
            pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);
            //重置宽 
            initWidth = initHeight;
          }
          //高大于宽的竖图 
          else
          {
            //对象实例化
            pickedImage = new System.Drawing.Bitmap(initWidth, initWidth);
            pickedG = System.Drawing.Graphics.FromImage(pickedImage);
            //设置质量 
            pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            //定位 
            Rectangle fromR = new Rectangle(0, (initHeight - initWidth) / 2, initWidth, initWidth);
            Rectangle toR = new Rectangle(0, 0, initWidth, initWidth);
            //画图 
            pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);
            //重置高 
            initHeight = initWidth;
          }

          initImage = (System.Drawing.Image)pickedImage.Clone();
          //        //释放截图资源 
          pickedG.Dispose();
          pickedImage.Dispose();
        }

        return initImage;
      }
    }
    #endregion
    #region 点击button2按钮事件
    private void button2_Click(object sender, EventArgs e)
    {
      this.label1.Text = "裁剪后的图片宽度："+this.pictureBox2.Width.ToString();
      this.label2.Text = "裁剪后的图片高度："+this.pictureBox2.Height.ToString();
    }
    #endregion
    #region 缩放、裁剪图像用到的变量
    /// <summary>
    /// 
    /// </summary>
    int x1;   //鼠标按下时横坐标
    int y1;   //鼠标按下时纵坐标
    int width; //所打开的图像的宽
    int heigth; //所打开的图像的高
    bool HeadImageBool = false;  // 此布尔变量用来判断pictureBox1控件是否有图片
    #endregion
    #region 画矩形使用到的变量
    Point p1;  //定义鼠标按下时的坐标点
    Point p2;  //定义移动鼠标时的坐标点
    Point p3;  //定义松开鼠标时的坐标点
    #endregion
    #region 鼠标按下时发生的事件
    private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
    {
      this.Cursor = Cursors.Cross;
      this.p1 = new Point(e.X, e.Y);
      x1 = e.X;
      y1 = e.Y;
      if (this.pictureBox1.Image != null)
      {
        HeadImageBool = true;
      }
      else
      {
        HeadImageBool = false;
      }
    }
    #endregion
    #region 移动鼠标发生的事件
    private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
    {
      if (this.Cursor == Cursors.Cross)
      {
        this.p2 = new Point(e.X, e.Y);
        if ((p2.X - p1.X) > 0 && (p2.Y - p1.Y) > 0)   //当鼠标从左上角向开始移动时P3坐标
        {
          this.p3 = new Point(p1.X, p1.Y);
        }
        if ((p2.X - p1.X) < 0 && (p2.Y - p1.Y) > 0)   //当鼠标从右上角向左下方向开始移动时P3坐标
        {
          this.p3 = new Point(p2.X, p1.Y);
        }
        if ((p2.X - p1.X) > 0 && (p2.Y - p1.Y) < 0)   //当鼠标从左下角向上开始移动时P3坐标
        {
          this.p3 = new Point(p1.X, p2.Y);
        }
        if ((p2.X - p1.X) < 0 && (p2.Y - p1.Y) < 0)   //当鼠标从右下角向左方向上开始移动时P3坐标
        {
          this.p3 = new Point(p2.X, p2.Y);
        }
        this.pictureBox1.Invalidate(); //使控件的整个图面无效，并导致重绘控件
      }
    }
    #endregion
    #region 松开鼠标发生的事件，实例化ImageCut1类对像
    ImageCut1 IC1; //定义所画矩形的图像对像
    private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
    {
      if (HeadImageBool)
      {
        width = this.pictureBox1.Image.Width;
        heigth = this.pictureBox1.Image.Height;
        if ((e.X - x1) > 0 && (e.Y - y1) > 0)  //当鼠标从左上角向右下方向开始移动时发生
        {
          IC1 = new ImageCut1(x1, y1, Math.Abs(e.X - x1), Math.Abs(e.Y - y1));  //实例化ImageCut1类
        }
        if ((e.X - x1) < 0 && (e.Y - y1) > 0)  //当鼠标从右上角向左下方向开始移动时发生
        {
          IC1 = new ImageCut1(e.X, y1, Math.Abs(e.X - x1), Math.Abs(e.Y - y1));  //实例化ImageCut1类
        }
        if ((e.X - x1) > 0 && (e.Y - y1) < 0)  //当鼠标从左下角向右上方向开始移动时发生
        {
          IC1 = new ImageCut1(x1, e.Y, Math.Abs(e.X - x1), Math.Abs(e.Y - y1));  //实例化ImageCut1类
        }
        if ((e.X - x1) < 0 && (e.Y - y1) < 0)  //当鼠标从右下角向左上方向开始移动时发生
        {
          IC1 = new ImageCut1(e.X, e.Y, Math.Abs(e.X - x1), Math.Abs(e.Y - y1));   //实例化ImageCut1类
        }
        this.pictureBox2.Width = (IC1.KiCut1((Bitmap)(this.pictureBox1.Image))).Width;
        this.pictureBox2.Height = (IC1.KiCut1((Bitmap)(this.pictureBox1.Image))).Height;
        this.pictureBox2.Image = IC1.KiCut1((Bitmap)(this.pictureBox1.Image));
        this.Cursor = Cursors.Default;
      }
      else
      {
        this.Cursor = Cursors.Default;
      }
    }
    #endregion
    #region 获取所选矩形图像
    /// <summary>
    /// 
    /// </summary>
    /// <param name="Width"></param>
    /// <param name="Height"></param>
    /// <returns></returns>
    public Image GetSelectImage1(int Width, int Height)
    {
      Image initImage = this.pictureBox1.Image;
      //Image initImage = Bi;
      //原图宽高均小于模版，不作处理，直接保存 
      if (initImage.Width <= Width && initImage.Height <= Height)
      {
        //initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
        return initImage;
      }
      else
      {
        //原始图片的宽、高 
        int initWidth = initImage.Width;
        int initHeight = initImage.Height;

        //非正方型先裁剪为正方型 
        if (initWidth != initHeight)
        {
          //截图对象 
          System.Drawing.Image pickedImage = null;
          System.Drawing.Graphics pickedG = null;

          //宽大于高的横图 
          if (initWidth > initHeight)
          {
            //对象实例化 
            pickedImage = new System.Drawing.Bitmap(initHeight, initHeight);
            pickedG = System.Drawing.Graphics.FromImage(pickedImage);
            //设置质量 
            pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            //定位 
            Rectangle fromR = new Rectangle((initWidth - initHeight) / 2, 0, initHeight, initHeight);
            Rectangle toR = new Rectangle(0, 0, initHeight, initHeight);
            //画图 
            pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);
            //重置宽 
            initWidth = initHeight;
          }
          //高大于宽的竖图 
          else
          {
            //对象实例化
            pickedImage = new System.Drawing.Bitmap(initWidth, initWidth);
            pickedG = System.Drawing.Graphics.FromImage(pickedImage);
            //设置质量 
            pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            //定位 
            Rectangle fromR = new Rectangle(0, (initHeight - initWidth) / 2, initWidth, initWidth);
            Rectangle toR = new Rectangle(0, 0, initWidth, initWidth);
            //画图 
            pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);
            //重置高 
            initHeight = initWidth;
          }

          initImage = (System.Drawing.Image)pickedImage.Clone();
          //        //释放截图资源 
          pickedG.Dispose();
          pickedImage.Dispose();
        }

        return initImage;
      }
    }
    #endregion
    #region 重新绘制pictureBox1控件，即移动鼠标画矩形
    private void pictureBox1_Paint(object sender, PaintEventArgs e)
    {
      if (HeadImageBool)
      {
        Pen p = new Pen(Color.Black, 1);//画笔
        p.DashStyle = System.Drawing.Drawing2D.DashStyle.Dash;
        //Bitmap bitmap = new Bitmap(strHeadImagePath);
        Bitmap bitmap = Bi;
        Rectangle rect = new Rectangle(p3, new Size(System.Math.Abs(p2.X - p1.X), System.Math.Abs(p2.Y - p1.Y)));
        e.Graphics.DrawRectangle(p, rect);
      }
      else
      {

      }
    }
    #endregion
  }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
namespace ImageClassLib
{
  public class ImageCut1
  {
    #region 剪裁图片方法
    /// <summary> 
    /// 剪裁 -- 用GDI+ 
    /// </summary> 
    /// <param name="b">原始Bitmap,即需要裁剪的图片</param> 
    /// <param name="StartX">开始坐标X</param> 
    /// <param name="StartY">开始坐标Y</param> 
    /// <param name="iWidth">宽度</param> 
    /// <param name="iHeight">高度</param> 
    /// <returns>剪裁后的Bitmap</returns> 
    public Bitmap KiCut1(Bitmap b) 
    { 
      if (b == null) 
      { 
        return null; 
      } 
    
      int w = b.Width; 
      int h = b.Height; 
    
      if (X >= w || Y >= h) 
      { 
        return null; 
      } 
    
      if (X + Width > w) 
      { 
        Width = w - X; 
      } 
    
      if (Y + Height > h) 
      { 
        Height = h - Y; 
      } 
    
      try
      { 
        Bitmap bmpOut = new Bitmap(Width, Height, PixelFormat.Format24bppRgb); 
    
        Graphics g = Graphics.FromImage(bmpOut);
        // Create rectangle for displaying image.
        Rectangle destRect = new Rectangle(0, 0, Width, Height);    //所画的矩形正确，它指定所绘制图像的位置和大小。 将图像进行缩放以适合该矩形。

        // Create rectangle for source image.
        Rectangle srcRect = new Rectangle(X, Y, Width, Height);   //srcRect参数指定要绘制的 image 对象的矩形部分。 将此部分进行缩放以适合 destRect 参数所指定的矩形。

        g.DrawImage(b, destRect, srcRect, GraphicsUnit.Pixel);
        //resultG.DrawImage(initImage, new System.Drawing.Rectangle(0, 0, side, side), new System.Drawing.Rectangle(0, 0, initWidth, initHeight), System.Drawing.GraphicsUnit.Pixel);
        g.Dispose(); 
        return bmpOut; 
      } 
      catch
      { 
        return null; 
      } 
    }
    #endregion
    #region ImageCut1类的构造函数
    public int X; 
    public int Y; 
    public int Width ; 
    public int Height;
    /// <summary>
    /// ImageCut1类的构造函数，ImageCut1类用来获取鼠标在pictureBox1控件所画矩形内的图像
    /// </summary>
    /// <param name="x表示鼠标在pictureBox1控件上按下时的横坐标"></param>
    /// <param name="y表示鼠标在pictureBox1控件上按下时的纵坐标"></param>
    /// <param name="width表示鼠标在pictureBox1控件上松开鼠标的宽度"></param>
    /// <param name="heigth表示鼠标在pictureBox1控件上松开鼠标的高度"></param>
    public ImageCut1(int x, int y, int width, int heigth)
    {
      X = x;
      Y = y;
      Width = width;
      Height = heigth;
    }
    #endregion
  }
}