ディレクトリ内の画像ファイルを連続表示するグラフィックビューワ

using System;
using System.Windows.Forms;
using System.Drawing;

using System.Collections.Generic;
using System.Linq;

using System.IO;
using System.Text.RegularExpressions;

// 
// ディレクトリ内の画像ファイルを連続表示するグラフィックビューワー
// 

// コンパイル
// csc /t:winexe SlideView.cs


namespace SlideView
{
    class ImageItem
    {
        public string Name = "";
        public string Location = "";
    }
    
    class Form1 : Form
    {
        List<ImageItem> ImageItems = new List<ImageItem>();
        int ImagePosition = -1;

    void MoveNext()
    {
        if (ImagePosition < 0) return;
        if (ImagePosition == (ImageItems.Count() - 1)) return;

        ImagePosition = ImagePosition + 1;
        ShowPicture();
    }
    void MovePrevious()
    {
        if (ImagePosition <= 0) return;

        ImagePosition = ImagePosition - 1;
        ShowPicture();
    }
    void PictureBox1_MouseDown(Object s, MouseEventArgs e)
    {
        if (ImagePosition < 0) return;

        if (e.Button == MouseButtons.Right)
        {
            MovePrevious();
        }
        if (e.Button == MouseButtons.Left)
        {
            MoveNext();
        }
    }        
        PictureBox PictureBox1 = new PictureBox
        {
            Dock = DockStyle.Fill,
            AllowDrop = true,
            SizeMode = PictureBoxSizeMode.Zoom,
        };
        void ShowPicture()
        {
            if (ImagePosition < 0) return;

            if (PictureBox1.Image != null)
                PictureBox1.Image.Dispose();
            
            string location = ImageItems[ImagePosition].Location;
            string name = ImageItems[ImagePosition].Name;
            if (Directory.Exists(location))
            {
                string path = Path.Combine(location, name);
                using (var fs = new FileStream(path, FileMode.Open, FileAccess.Read))
                {
                    PictureBox1.Image = Image.FromStream(fs);
                }
            }
        }
        void SetNewLocation(string path)
        {
            string location = "";

            if (File.Exists(path))
            {
                location = Path.GetDirectoryName(path);

            }
            else if(Directory.Exists(path))
            {
                location = path;
            }
            else return;

            var files = Directory.EnumerateFiles(
                location, "*", System.IO.SearchOption.TopDirectoryOnly);
            
            ImageItems.Clear();
            if (files.Count() == 0)
            {
                ImagePosition = -1;
                return;
            }

            ImagePosition = 0;
            foreach(string f in files)
            {
                string ext = Path.GetExtension(f).ToUpper();

                if (!Regex.IsMatch(ext, @"\.(PNG|JPEG|JPG|BMP)"))
                    continue;


                ImageItems.Add(new ImageItem
                {
                    Name = Path.GetFileName(f),
                    Location = location,
                });
                if (f == path)
                {
                    ImagePosition = ImageItems.Count() - 1;
                }
            }
            ShowPicture();
        }
        void PictureBox1_DragDrop(Object s, DragEventArgs e)
        {
            string[] files =
                (string[])e.Data.GetData(DataFormats.FileDrop, false);
            SetNewLocation(files[0]);
        }
        void PictureBox1_DragEnter(Object s, DragEventArgs e)
        {
            e.Effect = DragDropEffects.All;
        }
        void ChangeScreenMode()
        {
            if (this.WindowState == FormWindowState.Normal)
            {
                // フルスクリーン
                this.FormBorderStyle = FormBorderStyle.None;
                this.WindowState = FormWindowState.Maximized;                
            }
            else
            {
                // ウィンドウ
                this.FormBorderStyle = FormBorderStyle.Sizable;
                this.WindowState = FormWindowState.Normal;             
            }
        }
        void Form1_KeyDown(Object s, KeyEventArgs e)
        {
            switch (e.KeyData)
            {
                case (Keys.F11):
                    ChangeScreenMode();
                    break;
            }
        }
        Form1()
        {
            this.KeyPreview = true;

            this.Controls.Add(PictureBox1);

            this.KeyDown += Form1_KeyDown;
            PictureBox1.DragEnter += PictureBox1_DragEnter;
            PictureBox1.DragDrop += PictureBox1_DragDrop;
            PictureBox1.MouseDown += PictureBox1_MouseDown;
        }
        [STAThread]
        static void Main()
        {
            Application.Run(new Form1());
        }
    }// class
}// ns