Crystal Image Toolkit: thumbnail image control and picture viewing.

using System;
using System.Drawing;
using System.IO;
using System.Windows.Forms;
using Attilan.Crystal.Controls;

namespace CrystalTrackBarViewerDemo
{
    public partial class Form1 : Form
    {
        private float[] zoomFactor = { .25f, .33f, .50f, .66f, .80f, 1f, 1.25f, 1.5f, 2.0f, 2.5f, 3.0f };
        private string[] ZoomFactors = { "25%", "33%", "50%", "66%", "80%", "100%", "125%", "150%", "200%", "250%", "300%", "Fit" };
        private string _currentFile;

        public Form1()
        {
            InitializeComponent();
        }

        protected void InitTrackBar()
        {
            SetTrackBarValue(5);
            zoomToolStripTrackBar.CrystalTrackBar.KeyboardControl = true;
        }

        private void InitScaleCombo()
        {
            foreach (string scaleItem in ZoomFactors)
            {
                zoomComboBox.Items.Add(scaleItem);
            }

            SetZoomComboText(ZoomFactors[ZoomFactors.Length - 1]);
        }

        private void SetZoomComboText(string value)
        {
            this.zoomComboBox.SelectedIndexChanged -= new EventHandler(this.zoomComboBox_SelectedIndexChanged);

            if (IsFitImage())
            {
                zoomComboBox.Text = ZoomFactors[ZoomFactors.Length - 1];
            }
            else
            {
                zoomComboBox.Text = value;
            }

            this.zoomComboBox.SelectedIndexChanged += new EventHandler(this.zoomComboBox_SelectedIndexChanged);
        }

        private void SetZoomImage(float newZoom)
        {
            viewerMain.ImageSizeMode = SizeMode.Scrollable;
            viewerMain.ZoomFactor = newZoom;
        }

        private void SetFitImage()
        {
            viewerMain.ImageSizeMode = SizeMode.RatioStretch;
            viewerMain.ZoomFactor = 1;
        }

        private bool IsFitImage()
        {
            return viewerMain.ImageSizeMode == SizeMode.RatioStretch;
        }

        private void SetTrackBarValue(int value)
        {
            zoomToolStripTrackBar.ValueChanged -= new EventHandler(this.zoomToolStripTrackBar_ValueChanged);
            zoomToolStripTrackBar.Value = value;
            zoomToolStripTrackBar.ValueChanged += new EventHandler(this.zoomToolStripTrackBar_ValueChanged);
        }

        private void SetScale()
        {
            double scale = viewerMain.ZoomFactor;

            int index = 0;
            foreach (double dValue in zoomFactor)
            {
                index++;
                if (scale <= dValue)
                {
                    scale = dValue;
                    break;
                }
            }

            if (index < zoomToolStripTrackBar.CrystalTrackBar.Minimum)
                SetTrackBarValue(zoomToolStripTrackBar.CrystalTrackBar.Minimum);
            else
                if (index > zoomToolStripTrackBar.CrystalTrackBar.Maximum)
                    SetTrackBarValue(zoomToolStripTrackBar.CrystalTrackBar.Maximum);
                else
                    SetTrackBarValue(index);

            if (!IsFitImage())
            {
                int wholeScale = Convert.ToInt32(scale * 100);
                string comboScale = wholeScale.ToString();
                comboScale += "%";
                SetZoomComboText(comboScale);
            }
        }

        private void DisplayImage(string imageName)
        {
            Image imageItem = Image.FromFile(imageName);

            if (imageItem != null)
            {
                viewerMain.Image = imageItem;
                SetScale();

                this.Text = "Image Viewer - ";
                this.Text += Path.GetFileName(imageName);

                imageLabel.Text = imageName;
            }
        }

        private void exitToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }

        private void openImageToolStripMenuItem_Click(object sender, EventArgs e)
        {
            openFileDialog1.Filter = "Images (*.BMP;*.JPG;*.GIF;*.PNG)|*.BMP;*.JPG;*.GIF;*.PNG";
            openFileDialog1.FileName = _currentFile;
            openFileDialog1.InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.MyPictures);

            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                _currentFile = openFileDialog1.FileName;
                DisplayImage(_currentFile);
            }
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            SetFitImage();

            InitScaleCombo();
            InitTrackBar();
        }

        private void zoomComboBox_SelectedIndexChanged(object sender, EventArgs e)
        {
            string zoomValue = zoomComboBox.SelectedItem.ToString();

            if (zoomValue.Length < 1)
                return;

            if (zoomValue == ZoomFactors[ZoomFactors.Length - 1])
            {
                SetFitImage();
                SetScale();
            }
            else
            {
                float newZoom = zoomFactor[zoomComboBox.SelectedIndex];
                SetZoomImage(newZoom);
                SetTrackBarValue(zoomComboBox.SelectedIndex);
            }
        }

        protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
        {
            if (zoomToolStripTrackBar.CrystalTrackBar.ProcessKeystroke(keyData))
                return true;

            return base.ProcessCmdKey(ref msg, keyData);
        }

        private void zoomToolStripTrackBar_ValueChanged(object sender, EventArgs e)
        {
            // The scrollZoom changed so reset the zoom factor
            // based on the scrollZoom TrackBar position.
            float newZoom = zoomFactor[zoomToolStripTrackBar.Value];
            SetZoomComboText(ZoomFactors[zoomToolStripTrackBar.Value]);

            SetZoomImage(newZoom);
        }

        protected override void OnSizeChanged(EventArgs e)
        {
            base.OnSizeChanged(e);
            SetScale();
        }

        private void toolStrip1_SizeChanged(object sender, EventArgs e)
        {

        }
    }
}