Dynamically resize uploaded images & save in PNG format

<br />
//This function will scale an image to fit within the specified dimensions<br />
		private System.Drawing.Image ScaleImage(int maxHeight, int maxWidth, System.Drawing.Image image)<br />
		{<br />
			double origImgHeight = image.Height;<br />
			double origImgWidth = image.Width;<br />
			double scaledImgWidth;<br />
			double scaledImgHeight;<br />
<br />
			if(origImgHeight > origImgWidth)<br />
			{<br />
				scaledImgHeight = maxHeight;<br />
				scaledImgWidth = (maxHeight / origImgHeight) * origImgWidth;<br />
			}<br />
			else<br />
			{<br />
				scaledImgWidth = maxWidth;<br />
				scaledImgHeight = (maxWidth / origImgWidth) * origImgHeight;<br />
			}<br />
		<br />
			System.Drawing.Image.GetThumbnailImageAbort dummyCallBack =<br />
				new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback);<br />
<br />
			return image.GetThumbnailImage(Convert.ToInt16(scaledImgWidth), Convert.ToInt16(scaledImgHeight), dummyCallBack, IntPtr.Zero);<br />
<br />
		}<br />

<br />
		private void btnUpload_Click(object sender, System.EventArgs e)<br />
		{<br />
			//Validate the file type  is supported<br />
			string errMsg = ValidateFile(txtFileName.PostedFile);<br />
<br />
			//If valid then save file as .PNG to proper directory<br />
			if(errMsg == String.Empty)<br />
			{			<br />
				// Obtain current HttpContext of ASP+ Request<br />
				System.Web.HttpContext context = System.Web.HttpContext.Current;<br />
<br />
				// If the user is authenticated, use therapistID as the <br />
				//file name<br />
				if (context.User.Identity.Name != "")<br />
				{<br />
					string strBaseLocation = Server.MapPath(".\\UploadPics");<br />
					string strFileNameOnServer = context.User.Identity.Name + ".tmp";<br />
					string tempFilePath = strBaseLocation + "\\" + strFileNameOnServer;<br />
					string thumbSaveName = context.User.Identity.Name + "~" + DateTime.Now.ToString("ddMMyyhhmmss") + ".png";<br />
					string thumbSavePath = strBaseLocation + "\\" + thumbSaveName ;<br />
<br />
					try <br />
					{						<br />
						txtFileName.PostedFile.SaveAs(tempFilePath);<br />
						lblMessage.Text = "File uploaded successfully.";						<br />
					}<br />
					catch(Exception ex)<br />
					{<br />
						lblMessage.Text = "Error saving file.\n" + ex.Message;<br />
					} <br />
					<br />
					//thumbnail creation starts<br />
					try<br />
					{  <br />
						//the uploaded image will be stored in the UploadPics folder.<br />
						//To resize the image, the original image has to be<br />
						//accessed from the UploadPics folder<br />
						string imageUrl = "UploadPics/" + strFileNameOnServer;<br />
						<br />
						//Get the submitted image and scale it to size<br />
						System.Drawing.Image fullSizeImg = System.Drawing.Image.FromFile(Server.MapPath(imageUrl));				<br />
						System.Drawing.Image thumbNailImg = ScaleImage(150,120,fullSizeImg);<br />
     <br />
						//Save the resized image to file in PNG format. 						<br />
						thumbNailImg.Save (thumbSavePath, ImageFormat.Png);<br />
<br />
						//release references to files to prevent file access errors later<br />
						thumbNailImg.Dispose();<br />
						fullSizeImg.Dispose();<br />
<br />
						//Check to make sure the resized image is not larger than 150KB<br />
						long fileSize = File.OpenRead(thumbSavePath).Length / 1000;<br />
						if(fileSize > 150)<br />
						{<br />
							lblMessage.Text = "File too big.";<br />
						}<br />
						else<br />
						{<br />
							//Display the the newly generated thumbnail   <br />
							Image1.AlternateText = "Resized image";   <br />
							Image1.ImageUrl = "UploadPics\\" + thumbSaveName;<br />
						}<br />
<br />
						//Delete temp file<br />
						try<br />
						{<br />
							if(File.Exists(tempFilePath))<br />
							{<br />
								File.Delete(tempFilePath);								<br />
							}<br />
						}<br />
						catch(Exception ex)<br />
						{<br />
                            lblMessage.Text = ex.Message;<br />
						}<br />
						<br />
					}<br />
					catch(Exception ex)<br />
					{<br />
						Response.Write("An error occurred - " + ex.ToString());<br />
					}				<br />
				}<br />
			}<br />
			else<br />
			{<br />
				lblMessage.Text = errMsg;<br />
			}<br />
		}<br />
<br />
		//this function is reqd for thumbnail creation<br />
		public bool ThumbnailCallback()<br />
		{<br />
			return false;<br />
		}<br />
<br />
		private string ValidateFile(HttpPostedFile file)<br />
		{<br />
			string fileName = txtFileName.PostedFile.FileName;			<br />
			<br />
			//Only allow .jpg, .gif, and .bmp<br />
			string ext = GetFileExt(fileName);<br />
			if(ext == String.Empty)<br />
			{				<br />
				return "Sorry, supported file types are GIF, BMP, JPG, and PNG.";<br />
			}<br />
<br />
			//If file is valid, return no error message.<br />
            return String.Empty;<br />
		}<br />
<br />
		private string GetFileExt(string fileName)<br />
		{<br />
            string ext = fileName.Substring(fileName.Length - 4).ToUpper();<br />
			<br />
			switch(ext)<br />
			{<br />
				case ".JPG":<br />
					return ext;					<br />
<br />
				case ".GIF":<br />
					return ext;					<br />
<br />
				case ".BMP":<br />
					return ext;					<br />
<br />
				default:<br />
					return String.Empty;<br />
			}<br />
		}<br />