C# 图片缩放示例源码(放大缩小)

【实例简介】
【实例截图】

【核心代码】

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;

namespace 图片缩放
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private double height = 0;
        private double width = 0;
        private void button1_Click(object sender, EventArgs e)
        {
            OpenFileDialog dialog = new OpenFileDialog();
            dialog.Title = "请选择一个图片文件";
            dialog.Filter = "图片文件(*.jpg)|*.jpg";
            if (dialog.ShowDialog() == DialogResult.OK)
            {
                string file = dialog.FileName;
                pictureBox1.Load(file);
                pictureBox2.Load(file);
            }
        }

        private void button2_Click(object sender, EventArgs e)//图片放大按钮事件
        {
            button3.Enabled = true;
            pictureBox2.Height = Convert.ToInt32(pictureBox2.Height * 1.1);
            pictureBox2.Width = Convert.ToInt32(pictureBox2.Width * 1.1);

            panel1.VerticalScroll.Value = panel1.VerticalScroll.Maximum / 2 - panel1.VerticalScroll.LargeChange / 2;
            if (panel1.VerticalScroll.Value != panel1.VerticalScroll.Maximum / 2 - panel1.VerticalScroll.LargeChange / 2)
                panel1.VerticalScroll.Value = panel1.VerticalScroll.Maximum / 2 - panel1.VerticalScroll.LargeChange / 2;

            panel1.HorizontalScroll.Value = panel1.HorizontalScroll.Maximum / 2 - panel1.HorizontalScroll.LargeChange / 2;
            if (panel1.HorizontalScroll.Value != panel1.HorizontalScroll.Maximum / 2 - panel1.HorizontalScroll.LargeChange / 2)
                panel1.HorizontalScroll.Value = panel1.HorizontalScroll.Maximum / 2 - panel1.HorizontalScroll.LargeChange / 2;

        }

        private void button3_Click(object sender, EventArgs e)//图片缩小按钮事件
        {

            if (pictureBox2.Height > height && pictureBox2.Width > width)
            {
                pictureBox2.Height = Convert.ToInt32(pictureBox2.Height * 0.9);
                pictureBox2.Width = Convert.ToInt32(pictureBox2.Width * 0.9);
                panel1.VerticalScroll.Value = panel1.VerticalScroll.Maximum / 2 - panel1.VerticalScroll.LargeChange / 2;
                if (panel1.VerticalScroll.Value != panel1.VerticalScroll.Maximum / 2 - panel1.VerticalScroll.LargeChange / 2)
                    panel1.VerticalScroll.Value = panel1.VerticalScroll.Maximum / 2 - panel1.VerticalScroll.LargeChange / 2;

                panel1.HorizontalScroll.Value = panel1.HorizontalScroll.Maximum / 2 - panel1.HorizontalScroll.LargeChange / 2;
                if (panel1.HorizontalScroll.Value != panel1.HorizontalScroll.Maximum / 2 - panel1.HorizontalScroll.LargeChange / 2)
                    panel1.HorizontalScroll.Value = panel1.HorizontalScroll.Maximum / 2 - panel1.HorizontalScroll.LargeChange / 2;
            }
            else { button3.Enabled = false; }
        }

        private void pictureBox1_MouseEnter(object sender, EventArgs e)
        {
            pictureBox1.Focus();
        }
        private void pictureBox1_MouseWheel(object sender, MouseEventArgs e)
        {
            if (e.Delta > 0) //放大图片
            {
                pictureBox1.Size = new Size(pictureBox1.Width   50, pictureBox1.Height   50);
            }
            else
            {  //缩小图片
                pictureBox1.Size = new Size(pictureBox1.Width - 50, pictureBox1.Height - 50);
            }
            //设置图片在窗体居中
            pictureBox1.Location = new Point((this.Width - pictureBox1.Width) / 2, (this.Height - pictureBox1.Height) / 2);

        }
    }
}