/* 
 * ImageView.cs
 * 
 * CMSC 498B, Spring 2002, Project #1
 *   -- A C# program that displays all GIF/JPEG images found in a directory along with their names.
 *
 * Bongshin Lee, February 2002
 */

using System;
using System.IO;
using System.Collections;
using System.Drawing;
using System.Windows.Forms;
using System.Security;
using System.Security.Permissions;

public class ImageView : Form {
    VScrollBar vScroll;		// vertical scrollbar
    ImageComponent iComponent;  // a control to draw images

    // default box & pad size
    static int boxSize = 150;
    static int padSize = 15;

    static public void Main(string[] args) {
        if (args.Length < 1) {
            Console.WriteLine("Usage: ImageView imageDir [boxSize] [padSize]");
        } else {
            // parse input parameters
            if (args.Length > 1) {
                boxSize = int.Parse(args[1]);
                if (args.Length > 2) 
                    padSize = int.Parse(args[2]);
            }

            DirectoryInfo dir = new DirectoryInfo(args[0]);

            // check whether the specified directory exists
            if (dir.Exists) {
                Application.Run(new ImageView(dir));
            } else {
                Console.WriteLine(args[0] + " is an invalid directory.");
            }
        }
    }

    public ImageView(DirectoryInfo dir) {
        Text = "CMSC 498B Project #1 - ImageView";	// set the title of the form

        iComponent = new ImageComponent(this, dir, boxSize, padSize);
	iComponent.Size = new Size(500, 500);

        // add a listener to Resize event
        Resize += new EventHandler(ResizeEventHandler);

        vScroll = new VScrollBar();
        vScroll.Dock = DockStyle.Right;
        // add a listener to ValueChanged event of the vertical scrollbar
        vScroll.ValueChanged += new EventHandler(VChangedEventHandler);

	// form width = iComponent width + scrollbar width
	ClientSize = new Size(500 + vScroll.Width, 500);

        // add image component & scrollbar to the form
        Controls.Add(iComponent);
        Controls.Add(vScroll);
    }

    // show/hide vertical scrollbar
    public void ShowVScroll(Boolean show) {
        vScroll.Visible = show;

	// recompute the size of ImageComponent
        if (show)
            iComponent.Width = ClientSize.Width - vScroll.Width;
        else
            iComponent.Width = ClientSize.Width;
        iComponent.Height = ClientSize.Height;
    }

    // event handler for Resize event
    public void ResizeEventHandler(object sender, EventArgs e) {
        // the size of form has changed

        vScroll.Value = 0;	// initialize the position of scrollbar

        // compute the size of ImageComponent
        if (vScroll.Visible)
            iComponent.Width = ClientSize.Width - vScroll.Width;
        else
            iComponent.Width = ClientSize.Width;
        iComponent.Height = ClientSize.Height;

        // relayout & redraw images on ImageComponent
        iComponent.ReLayout();
        iComponent.Invalidate();
    }

    // event handler for ValueChanged event
    public void VChangedEventHandler(object sender, EventArgs e) {
        // the value of scrollbar has changed

        iComponent.SetScrollValue(vScroll.Value);

        // redraw images
        iComponent.Invalidate();
    }

    // set the (control) values for vertical scrollbar
    public void SetScrollValues(int extent, int maximum) {
        vScroll.Minimum = 0;
        vScroll.Maximum = maximum;
        vScroll.LargeChange = extent;
    }
}

class ImageComponent : Control {
    ImageView parent;		// container of this ImageComponent
    Array images;		// stores all images
    Array names;		// stores all image file names
    static Font font = new Font("Helvetica", 10);	// font to display file name
    static SolidBrush lgBrush = new SolidBrush(Color.LightGray);  // brush for light gray border
    static SolidBrush bBrush = new SolidBrush(Color.Black);	  // brush for black file name

    int perRow;			// # of images per row
    int actualHeight;		// height to display all images
    int scrollValue = 0;	// current position of the vertical scrollbar
    int boxSize, padSize;	// box & pad size
    Boolean vScrollShow = true; // visibility of the vertical scrollbar

    public ImageComponent(ImageView iv, DirectoryInfo baseDir, int box, int pad) {
        parent = iv;	// remember the container of this ImageComponent

        boxSize = box + 6;	// boxSize includes the gray border
        padSize = pad;

        // search all images in the specified directory
        SearchImages(baseDir);

	// turn on double buffering and some bits that tell .NET that
	// this control is being painted manually - this improves performance.
	SetStyle(System.Windows.Forms.ControlStyles.UserPaint, true);
	SetStyle(System.Windows.Forms.ControlStyles.DoubleBuffer, true);
	SetStyle(System.Windows.Forms.ControlStyles.AllPaintingInWmPaint, true);
    }

    public void SetScrollValue(int sValue) {
        scrollValue = sValue;
    }

    // calculate height to display all images
    // based on the # of images and current width
    public void CalcHeight() {
        perRow = Width / (boxSize + 2 * padSize);    // # of images per row
        if (perRow == 0) perRow = 1;	// min # of images per row is 1

        int rows = images.Length / perRow;    // # of rows to display all images
        if (images.Length == rows * perRow) 
            actualHeight = rows * (boxSize + 2 * padSize + font.Height);
        else
            actualHeight = (rows + 1) * (boxSize + 2 * padSize + font.Height);
    }

    public void ReLayout() {
        CalcHeight();

        if (actualHeight > Height) {
            if (!vScrollShow) {
                // if scrollbar is needed but now shown before
                // we have to show scrollbar
                parent.ShowVScroll(true);
                vScrollShow = true;
               CalcHeight();
            }
        } else {
            if (vScrollShow) {
                // if scrollbar is not needed but shown before
                // we have to hide scrollbar
                parent.ShowVScroll(false);
                vScrollShow = false;
                CalcHeight();
            }
        }

        // set values for vertical scrollbar
        parent.SetScrollValues(Height, actualHeight);
    }

    // search all image files in a directory
    private void SearchImages(DirectoryInfo baseDir) {
        FileInfo[] files = baseDir.GetFiles();
        Queue imageQ = new Queue();
        Queue nameQ = new Queue();

        foreach (FileInfo fi in files) {
            // check the file is image file based on the extension
            String lowerName = fi.Name.ToLower();
            if (lowerName.EndsWith(".jpg") || lowerName.EndsWith(".gif") || lowerName.EndsWith(".jpeg")) {
                Image img = Image.FromFile(fi.FullName);	// load image
                if (img != null) {
                    imageQ.Enqueue(img);
                    nameQ.Enqueue(fi.Name);
                }
            }
        }

        // store images and file names to Array
        images = imageQ.ToArray();
        names = nameQ.ToArray();
    }

    protected override void OnPaint(PaintEventArgs e) {
        Graphics g = e.Graphics;
        BackColor = Color.White;	// white background

        if (images.Length == 0) return;	// we don't have anything to draw

        // the minimum row number to be shown in current viewport
        int startRow = scrollValue / (boxSize + 2 * padSize + font.Height);
        // the maximum row number to be shown in current viewport
        int endRow = (scrollValue + Height) / (boxSize + 2 * padSize + font.Height);

        int n = startRow * perRow;	// the index of image to be shown first
        for (int i = startRow; i < endRow + 1; i++) {
            for (int j = 0; j < perRow; j++) {
                // draw 3pixel lightgray border using rectangle
                int left = j * (boxSize + 2 * padSize) + padSize;
                int right = left + boxSize;
                int top = i * (boxSize + 2 * padSize + font.Height) + padSize - scrollValue;
                int bottom = top + boxSize;
                g.FillRectangle(lgBrush, left, top, boxSize, 3);	// upper line
                g.FillRectangle(lgBrush, left, top, 3, boxSize);	// left line
                g.FillRectangle(lgBrush, right - 3, top, 3, boxSize);	// right line
                g.FillRectangle(lgBrush, left, bottom - 3, boxSize, 3);	// bottom line

                Image img = (Image)images.GetValue(n);

                // calculate scaled image size
                int width = boxSize - 6;
                int height = boxSize - 6;
                int imgWidth = img.Width;
                int imgHeight = img.Height;
                double ratio = (double)imgWidth / imgHeight;
                if (ratio > 1) {
                    height = width * imgHeight / imgWidth;    // wide and short
                } else if (ratio < 1) {
                    width = height * imgWidth / imgHeight;    // thin and long
                }

                // draw n scaled image at the center of the box
                g.DrawImage(img, left + (boxSize - width) / 2, top + (boxSize - height) / 2, 
                            width, height);

                // draw the file name centered, immediately below the gray bordered box
                String fileName = (String)names.GetValue(n++);
                SizeF nameSize = g.MeasureString(fileName, font);	// size of the file name string

                g.DrawString(fileName, font, bBrush, left + (boxSize - nameSize.Width) / 2, bottom);	

                if (n == images.Length) return;		// end of images
            }
        }
    }
}