WinForm实现的图片拖拽与缩放功能示例

本文实例讲述了winform实现的图片拖拽与缩放功能。分享给大家供大家参考，具体如下：

最近做项目的时候遇到上传施工平面布置图，查看，因为图片比较大，一般的显示器分辨率无法显示全，然后还需要放大看清楚图片里面的文字内容，所以需要用到图片的拖拽与缩放功能。这里整理下具体操作。

首先新建一个窗体，拖一个panel控件到窗体中，然后在拖一个pictureobx控件到panel中，然后在添加个上传图片的按钮：

具体代码：

using system;
using system.collections.generic;
using system.componentmodel;
using system.data;
using system.drawing;
using system.linq;
using system.text;
using system.threading.tasks;
using system.windows.forms;
using system.reflection;
namespace 图像平移缩放
{
  public partial class form1 : form
  {
    bitmap mybmp;
    point mousedownpoint = new point(); //记录拖拽过程鼠标位置
    bool ismove = false;  //判断鼠标在picturebox上移动时，是否处于拖拽过程(鼠标左键是否按下)
    int zoomstep = 20;   //缩放步长
    public form1()
    {
      initializecomponent();
    }
    //图片上传
    private void button1_click(object sender, eventargs e)
    {
      string filename = "";
      openfiledialog dlg = new openfiledialog();
      dlg.filter = "tiff文件|*.tif|bmp文件|*.bmp|erdas img文件|*.img|evni文件|*.hdr|jpeg文件|*.jpg|raw文件|*.raw|vrt文件|*.vrt|所有文件|*.*";
      dlg.filterindex = 8;
      if (dlg.showdialog() == dialogresult.ok)
      {
        filename = dlg.filename;
      }
      if (filename == "")
      {
        return;
      }
      mybmp = new bitmap(filename);
      if (mybmp == null)
      {
        messagebox.show("读取失败");
        return;
      }
      textbox1.text = filename;
      picturebox1.image = mybmp;
      picturebox1.sizemode = pictureboxsizemode.zoom; //设置picturebox为缩放模式
      picturebox1.width = mybmp.width;
      picturebox1.height = mybmp.height;
    }
    //鼠标按下功能
    private void picturebox1_mousedown(object sender, mouseeventargs e)
    {
      if (e.button == mousebuttons.left)
      {
        mousedownpoint.x = cursor.position.x;
        mousedownpoint.y = cursor.position.y;
        ismove = true;
        picturebox1.focus();
      }
    }
    //鼠标松开功能
    private void picturebox1_mouseup(object sender, mouseeventargs e)
    {
      if (e.button == mousebuttons.left)
      {
        ismove = false;
      }
    }
    //鼠标移动功能
    private void picturebox1_mousemove(object sender, mouseeventargs e)
    {
      picturebox1.focus();
      if (ismove)
      {
        int x, y;
        int movex, movey;
        movex = cursor.position.x - mousedownpoint.x;
        movey = cursor.position.y - mousedownpoint.y;
        x = picturebox1.location.x + movex;
        y = picturebox1.location.y + movey;
        picturebox1.location = new point(x, y);
        mousedownpoint.x = cursor.position.x;
        mousedownpoint.y = cursor.position.y;
      }
    }
    //鼠标滚轮滚动功能
    private void picturebox1_mousewheel(object sender, mouseeventargs e)
    {
      int x = e.location.x;
      int y = e.location.y;
      int ow = picturebox1.width;
      int oh = picturebox1.height;
      int vx, vy;
      if (e.delta > 0)
      {
        picturebox1.width += zoomstep;
        picturebox1.height += zoomstep;
        propertyinfo pinfo = picturebox1.gettype().getproperty("imagerectangle", bindingflags.instance |
          bindingflags.nonpublic);
        rectangle rect = (rectangle)pinfo.getvalue(picturebox1, null);
        picturebox1.width = rect.width;
        picturebox1.height = rect.height;
      }
      if (e.delta < 0)
      {
        if (picturebox1.width < mybmp.width / 10)
          return;
        picturebox1.width -= zoomstep;
        picturebox1.height -= zoomstep;
        propertyinfo pinfo = picturebox1.gettype().getproperty("imagerectangle", bindingflags.instance |
          bindingflags.nonpublic);
        rectangle rect = (rectangle)pinfo.getvalue(picturebox1, null);
        picturebox1.width = rect.width;
        picturebox1.height = rect.height;
      }
      vx = (int)((double)x * (ow - picturebox1.width) / ow);
      vy = (int)((double)y * (oh - picturebox1.height) / oh);
      picturebox1.location = new point(picturebox1.location.x + vx, picturebox1.location.y + vy);
    }
    private void panel2_mousedown(object sender, mouseeventargs e)
    {
      if (e.button == mousebuttons.left)
      {
        mousedownpoint.x = cursor.position.x;
        mousedownpoint.y = cursor.position.y;
        ismove = true;
      }
    }
    private void panel2_mouseup(object sender, mouseeventargs e)
    {
      if (e.button == mousebuttons.left)
      {
        ismove = false;
      }
    }
    private void panel2_mousemove(object sender, mouseeventargs e)
    {
      panel2.focus();
      if (ismove)
      {
        int x, y;
        int movex, movey;
        movex = cursor.position.x - mousedownpoint.x;
        movey = cursor.position.y - mousedownpoint.y;
        x = picturebox1.location.x + movex;
        y = picturebox1.location.y + movey;
        picturebox1.location = new point(x, y);
        mousedownpoint.x = cursor.position.x;
        mousedownpoint.y = cursor.position.y;
      }
    }
  }
}

这里需要注意一点，类里面用到了一个 picturebox1_mousewheel 时间，这个是picturebox控件没有的时间，所以需要手动去添加这个事件，可以直接在form1的设计类中添加

//
// picturebox1
//
this.picturebox1.backcolor = system.drawing.color.white;
this.picturebox1.location = new system.drawing.point(20, 20);
this.picturebox1.margin = new system.windows.forms.padding(2, 2, 2, 2);
this.picturebox1.name = "picturebox1";
this.picturebox1.size = new system.drawing.size(67, 34);
this.picturebox1.tabindex = 0;
this.picturebox1.tabstop = false;
this.picturebox1.mousedown += new system.windows.forms.mouseeventhandler(this.picturebox1_mousedown);
this.picturebox1.mousemove += new system.windows.forms.mouseeventhandler(this.picturebox1_mousemove);
this.picturebox1.mouseup += new system.windows.forms.mouseeventhandler(this.picturebox1_mouseup);
this.picturebox1.mousewheel += new system.windows.forms.mouseeventhandler(this.picturebox1_mousewheel);

这样就能直接运行成功了

更多关于c#相关内容感兴趣的读者可查看本站专题：《winform控件用法总结》、《c#窗体操作技巧汇总》、《c#数据结构与算法教程》、《c#常见控件用法教程》、《c#面向对象程序设计入门教程》及《c#程序设计之线程使用技巧总结》

希望本文所述对大家c#程序设计有所帮助。