using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System;

partial class _Default : System.Web.UI.Page
{


    protected void  BtnUpload_Click(object sender, System.EventArgs e)
    {

        const int bmpW = 300;
        //New image canvas width

        const int  bmpH = 226;
        //New Image canvas height

        if ((FileUpload1.HasFile))
        {

            lblError.Text = "";

            //Check to make sure the file to upload has a picture file format extention

            if ((CheckFileType(FileUpload1.FileName)))
            {

                int newWidth = bmpW;

                int newHeight = bmpH;

                //Use the uploaded filename without the '.' extension

                string upName = Mid(FileUpload1.FileName, 1, (InStr(FileUpload1.FileName, ".") - 1));

                string filePath = "~/Upload/" + upName + ".png";

                //Create a new Bitmap using the uploaded picture as a Stream

                //Set the new bitmap resolution to 72 pixels per inch

                Bitmap upBmp = Bitmap.FromStream(FileUpload1.FileName);

                Bitmap newBmp = new Bitmap(newWidth, newHeight, System.Drawing.Imaging.PixelFormat.Format24bppRgb);

                newBmp.SetResolution(72, 72);

                //Get the uploaded image width and height

                int upWidth = upBmp.Width;

                int upHeight = upBmp.Height;

                int newX = 0;

                int newY = 0;

                decimal reDuce;

                //Keep the aspect ratio of image the same if not 4:3 and work out the newX and newY positions

                //to ensure the image is always in the centre of the canvas vertically and horizontally

                //Landscape picture
                if (upWidth > upHeight)
                {

                    reDuce = newWidth / upWidth;
                    //calculate the width percentage reduction as decimal

                    newHeight = Int(upHeight * reDuce);
                    //reduce the uploaded image height by the reduce amount

                    newY = Int((bmpH - newHeight) / 2);
                    //Position the image centrally down the canvas

                    newX = 0;
                }
                //Picture will be full width

                //Portrait picture
                else if (upWidth < upHeight)
                {

                    reDuce = newHeight / upHeight;
                    //calculate the height percentage reduction as decimal

                    newWidth = Int(upWidth * reDuce);
                    //reduce the uploaded image height by the reduce amount

                    newX = Int((bmpW - newWidth) / 2);
                    //Position the image centrally across the canvas

                    newY = 0;
                }
                //Picture will be full hieght

                //square picture
                else if (upWidth == upHeight)
                {

                    reDuce = newHeight / upHeight;
                    //calculate the height percentage reduction as decimal

                    newWidth = Int(upWidth * reDuce);
                    //reduce the uploaded image height by the reduce amount

                    newX = Int((bmpW - newWidth) / 2);
                    //Position the image centrally across the canvas

                    newY = Int((bmpH - newHeight) / 2);
                    //Position the image centrally down the canvas

                }

                //Create a new image from the uploaded picture using the Graphics class

                //Clear the graphic and set the background colour to white

                //Use Antialias and High Quality Bicubic to maintain a good quality picture

                //Save the new bitmap image using 'Png' picture format and the calculated canvas positioning

                Graphics newGraphic = Graphics.FromImage(newBmp);

                try
                {

                    newGraphic.Clear(Color.White);

                    newGraphic.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;

                    newGraphic.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;

                    newGraphic.DrawImage(upBmp, newX, newY, newWidth, newHeight);

                    newBmp.Save(MapPath(filePath), System.Drawing.Imaging.ImageFormat.Png);

                    //Show the uploaded resized picture in the image control

                    Image1.ImageUrl = filePath;

                    Image1.Visible = true;
                }

                catch (Exception ex)
                {

                    lblError.Text = ex.ToString();
                }

                finally
                {

                    upBmp.Dispose();

                    newBmp.Dispose();

                    newGraphic.Dispose();

                }
            }

            else
            {

                lblError.Text = "Please select a picture with a file format extension of either Bmp, Jpg, Jpeg, Gif or Png.";

            }

        }

    }
    public static string Mid(string param, int startIndex, int length)
    {
        //start at the specified index in the string ang get N number of
        //characters depending on the lenght and assign it to a variable
        string result = param.Substring(startIndex, length);
        //return the result of the operation
        return result;
    }
    bool CheckFileType(string fileName)
    {

        string ext = Path.GetExtension(fileName);

        switch (ext.ToLower())
        {

            case ".gif":

                return true;

            case ".png":

                return true;

            case ".jpg":

                return true;

            case ".jpeg":

                return true;

            case ".bmp":

                return true;

            default:

                return false;

        }

    }

}