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C＃ Winform 相册功能，图片缩放，拖拽，预览图分页

2022-06-22 13:10:00 【熊思宇】

效果

1.图片放大，缩小，拖拽功能

2.添加图片，分页功能

一、前言

在很多项目中也需要用到预览图片的功能，至于为什么加一个添加图片的功能，是因为有些项目，比如视觉相关的工作，会需要摄像机采集图片，然后显示在界面上，所以，图片也是一张一张的添加的，另外，就是分页功能，当预览图位置不够用时就会用到，所以我也加了进来。

当前软件的功能

1.添加图片

如果8个预览图都满了，会自动分页，就可以点击上一页，或者下一页了。

2.点击预览图显示大图

点击预览图，之前的拖拽和放大会自动复位

3.大图可以拖拽，放大，缩小

如果图片比较小，有这个功能就看到图片的更多细节了。

4.图片倒序排列

最后添加的图片，始终显示在最前面，这也就在分页上和常规的有点区别了，如图

如果你用的正序排列，可以看看这个帖子：

C# 分页计算总页数、当前页数据集合_熊思宇的博客-CSDN博客

二、代码

新建一个winform项目，界面如下：

没有太复杂的界面，大图和预览图都是用的 PictureBox 控件，控件的名字，可以看下面的代码，在文章的最下面，我会附上这个Demo源码，有兴趣的可以下载。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace 相册功能
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        //本地的相册列表
        private string AlbumPath = Application.StartupPath + "\\Album";
        //相册列表
        private List<PictureBox> PictureBoxList = new List<PictureBox>();
        //图片路径列表
        private List<string> FilesinfoList = new List<string>();
        //相册显示的图片列表
        private List<Bitmap> BitmapList = new List<Bitmap>();
        //pictureBox1的初始位置
        private Point PicStartPos;
        //pictureBox1的初始大小
        private Size PicSize;

        //测试用
        int index = -1;
        //当前页数
        private int NowPage = 1;
        //总页数
        private int TotalPage = 1;
        //鼠标滚轮缩放图片的增量值
        private int ZoomStep = 20;
        //鼠标是否在拖拽中
        private bool IsMove = false;
        //鼠标点击的位置
        private Point MouseDownPoint;

        private void Form1_Load(object sender, EventArgs e)
        {
            PicStartPos = pictureBox1.Location;
            PicSize = pictureBox1.Size;
            this.pictureBox1.MouseWheel += new MouseEventHandler(this.pictureBox1_MouseWheel);

            PictureBoxList.Add(PictureBox_ImgList1);
            PictureBoxList.Add(PictureBox_ImgList2);
            PictureBoxList.Add(PictureBox_ImgList3);
            PictureBoxList.Add(PictureBox_ImgList4);
            PictureBoxList.Add(PictureBox_ImgList5);
            PictureBoxList.Add(PictureBox_ImgList6);
            PictureBoxList.Add(PictureBox_ImgList7);
            PictureBoxList.Add(PictureBox_ImgList8);

            //添加图片的点击事件
            for (int i = 0; i < PictureBoxList.Count; i++)
            {
                PictureBoxList[i].Click += new System.EventHandler(PictureBoxClick);
            }

            DirectoryInfo directory = new DirectoryInfo(AlbumPath);
            FileSystemInfo[] filesArray = directory.GetFileSystemInfos();
            foreach (var item in filesArray)
            {
                if (item.Attributes != FileAttributes.Directory)
                {
                    FilesinfoList.Add(item.FullName);
                }
            }
        }

        /// <summary>
        /// 上一页
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Button_Back_Click(object sender, EventArgs e)
        {
            if (NowPage <= 1) return;

            NowPage--;
            for (int i = 0; i < PictureBoxList.Count; i++)
            {
                PictureBoxList[i].Image = null;
            }

            List<Bitmap> list = GetPagesBitmap(NowPage);
            for (int i = 0; i < list.Count; i++)
            {
                PictureBoxList[i].Image = list[i];
            }

            pictureBox1.Image = list[0];
            //设置坐标
            pictureBox1.Location = PicStartPos;
            //设置控件宽高
            pictureBox1.Size = PicSize;

            Label_NumberOfPages.Text = string.Format("{0} / {1}", NowPage, TotalPage);
            BackNextButtonType();
        }

        /// <summary>
        /// 下一页
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Button_Next_Click(object sender, EventArgs e)
        {
            if (NowPage >= TotalPage) return;

            NowPage++;
            for (int i = 0; i < PictureBoxList.Count; i++)
            {
                PictureBoxList[i].Image = null;
            }

            List<Bitmap> list = GetPagesBitmap(NowPage);
            for (int i = 0; i < list.Count; i++)
            {
                PictureBoxList[i].Image = list[i];
            }

            pictureBox1.Image = list[0];
            //设置坐标
            pictureBox1.Location = PicStartPos;
            //设置控件宽高
            pictureBox1.Size = PicSize;

            Label_NumberOfPages.Text = string.Format("{0} / {1}", NowPage, TotalPage);
            BackNextButtonType();
        }

        /// <summary>
        /// 添加图片
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Button_Add_Click(object sender, EventArgs e)
        {
            index++;
            AddPicture(new Bitmap(FilesinfoList[index]));
            if (index >= FilesinfoList.Count - 1)
                index = -1;
        }

        /// <summary>
        /// 添加图片
        /// </summary>
        /// <param name="bitmap"></param>
        private void AddPicture(Bitmap bitmap)
        {
            if (bitmap == null) return;

            //添加到图片列表
            BitmapList.Add(bitmap);
            //界面预留图中显示
            pictureBox1.Image = bitmap;
            //设置坐标
            pictureBox1.Location = PicStartPos;
            //设置控件宽高
            pictureBox1.Size = PicSize;

            //计算当前总页数
            int page = BitmapList.Count / PictureBoxList.Count;
            int remainder = BitmapList.Count % PictureBoxList.Count;
            TotalPage = remainder > 0 ? page + 1 : page;
            Label_NumberOfPages.Text = string.Format("{0} / {1}", NowPage, TotalPage);

            BackNextButtonType();

            //让图片按逆向顺序显示
            List<Bitmap> reverseSort = new List<Bitmap>();
            for (int i = BitmapList.Count - 1; i >= 0; i--)
            {
                reverseSort.Add(BitmapList[i]);
            }
            for (int i = 0; i < reverseSort.Count; i++)
            {
                if (i <= 7)
                    PictureBoxList[i].Image = reverseSort[i];
            }
        }

        /// <summary>
        /// 8张预览图片的点击事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void PictureBoxClick(Object sender, System.EventArgs e)
        {
            PictureBox pictureBox = (PictureBox)sender;
            if (pictureBox != null && pictureBox.Image != null)
            {
                pictureBox1.Image = pictureBox.Image;
                //设置坐标
                pictureBox1.Location = PicStartPos;
            }
        }

        /// <summary>
        /// 获取索引对应的图片
        /// </summary>
        /// <param name="index"></param>
        /// <returns></returns>
        private List<Bitmap> GetPagesBitmap(int index)
        {
            if (BitmapList.Count <= 0) return null;

            //页数
            int page = BitmapList.Count / PictureBoxList.Count;
            //余数
            int remainder = BitmapList.Count % PictureBoxList.Count;
            //总页数
            int allPage = remainder > 0 ? page + 1 : page;

            if (index > allPage) return null;

            //索引起点
            int start = (index * PictureBoxList.Count) - PictureBoxList.Count;
            //索引结束点
            int end = (index * PictureBoxList.Count) - 1;
            if (end > BitmapList.Count) end = BitmapList.Count - 1;

            List<Bitmap> reverseSort = new List<Bitmap>();
            for (int i = BitmapList.Count - 1; i >= 0; i--)
            {
                reverseSort.Add(BitmapList[i]);
            }

            List<Bitmap> list = new List<Bitmap>();
            for (int i = start; i <= end; i++)
            {
                list.Add(reverseSort[i]);
            }

            if (list.Count > 0)
                return list;
            return null;
        }

        /// <summary>
        /// 上一页，下一页按钮状态
        /// </summary>
        private void BackNextButtonType()
        {
            Button_Next.Enabled = true;
            Button_Back.Enabled = true;

            //现在页 = 总页数
            if (NowPage == TotalPage)
                Button_Next.Enabled = false;
            //现在页 小于等于 1
            if (NowPage <= 1)
                Button_Back.Enabled = false;
        }


        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if (pictureBox1.Image == null) return;

            if (e.Button == MouseButtons.Left)
            {
                MouseDownPoint.X = Cursor.Position.X; //记录鼠标左键按下时位置
                MouseDownPoint.Y = Cursor.Position.Y;
                IsMove = true;
                pictureBox1.Focus(); //鼠标滚轮事件(缩放时)需要picturebox有焦点
            }
        }

        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                IsMove = false;
            }
        }

        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            if (pictureBox1.Image == null) return;
            pictureBox1.Focus(); //鼠标在picturebox上时才有焦点，此时可以缩放
            if (IsMove)
            {
                int x, y;   //新的pictureBox1.Location(x,y)
                int moveX, moveY; //X方向，Y方向移动大小。
                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;
            }
        }

        private void pictureBox1_MouseWheel(object sender, MouseEventArgs e)
        {
            if (pictureBox1.Image == null) return;

            PictureBox pbox = pictureBox1;
            int x = e.Location.X;
            int y = e.Location.Y;
            int ow = pbox.Width;
            int oh = pbox.Height;
            int VX, VY;  //因缩放产生的位移矢量
            if (e.Delta > 0) //放大
            {
                //第1步
                pbox.Width += ZoomStep;
                pbox.Height += ZoomStep;
                //第2步
                PropertyInfo pInfo = pbox.GetType().GetProperty("ImageRectangle", BindingFlags.Instance | BindingFlags.NonPublic);
                Rectangle rect = (Rectangle)pInfo.GetValue(pbox, null);
                //第3步
                pbox.Width = rect.Width;
                pbox.Height = rect.Height;

                //Console.WriteLine(string.Format("宽：{0}，高：{1}",pbox.Width,pbox.Height));
            }
            if (e.Delta < 0) //缩小
            {
                //防止一直缩成负值
                if (pbox.Width < 300)
                    return;

                pbox.Width -= ZoomStep;
                pbox.Height -= ZoomStep;
                PropertyInfo pInfo = pbox.GetType().GetProperty("ImageRectangle", BindingFlags.Instance |
                 BindingFlags.NonPublic);
                Rectangle rect = (Rectangle)pInfo.GetValue(pbox, null);
                pbox.Width = rect.Width;
                pbox.Height = rect.Height;
            }

            //第4步，求因缩放产生的位移，进行补偿，实现锚点缩放的效果
            VX = (int)((double)x * (ow - pbox.Width) / ow);
            VY = (int)((double)y * (oh - pbox.Height) / oh);
            pbox.Location = new Point(pbox.Location.X + VX, pbox.Location.Y + VY);
        }


    }
}

代码中，鼠标缩放，拖拽功能，需要在控件里添加对应的事件，否则就没有效果了