C# HTTP Trigger Azure function code to get requested image from blob storage and optionally resize it based on request body parameters

GetCarImage.cs

using System.Collections.Generic;
using System.Net;
using System.Net.Http;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.Azure.WebJobs.Host;
using Newtonsoft.Json;
using Microsoft.WindowsAzure.Storage;
using Microsoft.WindowsAzure.Storage.Blob;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;

namespace ImageResizer
{
    public static class GetCarImage
    {
        [FunctionName("GetCarImage")]
        public static HttpResponseMessage Run([HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = "GetCarImage/{CarReg}/{ImageAngle}")]HttpRequestMessage request, string CarReg, string ImageAngle, TraceWriter log)
        {
            log.Info("C# HTTP trigger function processed a request.");
            
            //Set default image size to return if query is missing requested height and width parameters
            int requestedHeight = 500;
            int requestedWidth = 500;

            //Get the query parameters for requested image size
            string jsonContent = request.Content.ReadAsStringAsync().Result;
            Dictionary<string, int> jsonDictionary = JsonConvert.DeserializeObject<Dictionary<string, int>>(jsonContent);

            if (jsonDictionary.ContainsKey("height"))
            {
                requestedHeight = jsonDictionary["height"];
            }
            if (jsonDictionary.ContainsKey("width"))
            {
                requestedWidth = jsonDictionary["width"];
            }

            //Set up link to blob storage for stored car images (for production code, consider moving credentials to KeyVault to abstract credentials away from code level)
            string storageConnectionString = "DefaultEndpointsProtocol=https;"
                + "AccountName=griffsdemostorage"
                + ";AccountKey=<INSERT BLOB STORAGE ACCOUNT KEY HERE>"
                + ";EndpointSuffix=core.windows.net";
            CloudStorageAccount blobAccount = CloudStorageAccount.Parse(storageConnectionString);
            CloudBlobClient blobClient = blobAccount.CreateCloudBlobClient();
            

            // Fetch the Car Reg & Image File Name from the path parameters in the request URL and retrieve image
            if (ImageAngle != null && CarReg != null)
            {
                //Get reference to specific car's container from Car Reg (converts to lower case as container names must be lower case)
                CloudBlobContainer blobContainer = blobClient.GetContainerReference(CarReg.ToLower());
                //Get reference to image block blob image from ImageFileName parameter the user passed in (images must be in jpg format in the blob service for this to work)
                CloudBlockBlob cloudBlockBlob = blobContainer.GetBlockBlobReference(ImageAngle +".jpg");
                //Download the image
                MemoryStream streamIn = new MemoryStream();
                cloudBlockBlob.DownloadToStream(streamIn);
                Image originalImage = Bitmap.FromStream(streamIn);

                //Pass the image and requested file size into our image resizing method to resize the image
                Image resizedImage = ResizeImage(originalImage, requestedWidth, requestedHeight);

                //Change image back to a stream for passing through to user as Http Content
                MemoryStream streamOut = new MemoryStream();
                resizedImage.Save(streamOut, ImageFormat.Png);
                streamOut.Position = 0;

                //Create the Http response message with the resized image
                HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
                response.Content = new StreamContent(streamOut);
                response.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("image/jpg");
                return response;
            }
            else
            {
                return request.CreateResponse(HttpStatusCode.BadRequest, "Please include a valid Car Reg and Image Angle (the view of the car you want - i.e. front/rear/left-side/right-side in your request URL, in the following format: API-URL/{CarReg}/{ImageAngle}");
            }
        }

        //Method to resize images without distortion
        public static Bitmap ResizeImage(Image image, int width, int height)
        {
            var destRect = new Rectangle(0, 0, width, height);
            var destImage = new Bitmap(width, height);

            destImage.SetResolution(image.HorizontalResolution, image.VerticalResolution);

            using (var graphics = Graphics.FromImage(destImage))
            {
                graphics.CompositingMode = CompositingMode.SourceCopy;
                graphics.CompositingQuality = CompositingQuality.HighQuality;
                graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
                graphics.SmoothingMode = SmoothingMode.HighQuality;
                graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;

                using (var wrapMode = new ImageAttributes())
                {
                    wrapMode.SetWrapMode(WrapMode.TileFlipXY);
                    graphics.DrawImage(image, destRect, 0, 0, image.Width, image.Height, GraphicsUnit.Pixel, wrapMode);
                }
            }

            return destImage;
        }
    }
}