C# 实现QQ式截图功能实例代码

这个功能一共有两部分组成,第一部分是窗体代码，另外的一部分是一个辅助方法。直接贴出代码，以供大家参考：

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
  }
}

第二部分是辅助方法类

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
  }
}

 实现的效果如下：

 以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。