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C# Sharepoint upload large file into subfolder

I have an issue when trying too upload a large file to a sub sharepoint folder.
The issue is related to the variable libraryName. I am not sure have i can change this so i can use an url instead.
Example:
var site = ""https://sharepoint.com/sites/Test_Site1/"
var relative = "Documents/Folder1/folder2/
https://learn.microsoft.com/en-us/sharepoint/dev/solution-guidance/upload-large-files-sample-app-for-sharepoint
public Microsoft.SharePoint.Client.File UploadFileSlicePerSlice(ClientContext ctx, string libraryName, string fileName, int fileChunkSizeInMB = 3)
{
// Each sliced upload requires a unique ID.
Guid uploadId = Guid.NewGuid();
// Get the name of the file.
string uniqueFileName = Path.GetFileName(fileName);
// Ensure that target library exists, and create it if it is missing.
if (!LibraryExists(ctx, ctx.Web, libraryName))
{
CreateLibrary(ctx, ctx.Web, libraryName);
}
// Get the folder to upload into.
List docs = ctx.Web.Lists.GetByTitle(libraryName);
ctx.Load(docs, l => l.RootFolder);
// Get the information about the folder that will hold the file.
ctx.Load(docs.RootFolder, f => f.ServerRelativeUrl);
ctx.ExecuteQuery();
// File object.
Microsoft.SharePoint.Client.File uploadFile = null;
// Calculate block size in bytes.
int blockSize = fileChunkSizeInMB * 1024 * 1024;
// Get the information about the folder that will hold the file.
ctx.Load(docs.RootFolder, f => f.ServerRelativeUrl);
ctx.ExecuteQuery();
// Get the size of the file.
long fileSize = new FileInfo(fileName).Length;
if (fileSize <= blockSize)
{
// Use regular approach.
using (FileStream fs = new FileStream(fileName, FileMode.Open))
{
FileCreationInformation fileInfo = new FileCreationInformation();
fileInfo.ContentStream = fs;
fileInfo.Url = uniqueFileName;
fileInfo.Overwrite = true;
uploadFile = docs.RootFolder.Files.Add(fileInfo);
ctx.Load(uploadFile);
ctx.ExecuteQuery();
// Return the file object for the uploaded file.
return uploadFile;
}
}
else
{
// Use large file upload approach.
ClientResult<long> bytesUploaded = null;
FileStream fs = null;
try
{
fs = System.IO.File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
using (BinaryReader br = new BinaryReader(fs))
{
byte[] buffer = new byte[blockSize];
Byte[] lastBuffer = null;
long fileoffset = 0;
long totalBytesRead = 0;
int bytesRead;
bool first = true;
bool last = false;
// Read data from file system in blocks.
while ((bytesRead = br.Read(buffer, 0, buffer.Length)) > 0)
{
totalBytesRead = totalBytesRead + bytesRead;
// You've reached the end of the file.
if (totalBytesRead == fileSize)
{
last = true;
// Copy to a new buffer that has the correct size.
lastBuffer = new byte[bytesRead];
Array.Copy(buffer, 0, lastBuffer, 0, bytesRead);
}
if (first)
{
using (MemoryStream contentStream = new MemoryStream())
{
// Add an empty file.
FileCreationInformation fileInfo = new FileCreationInformation();
fileInfo.ContentStream = contentStream;
fileInfo.Url = uniqueFileName;
fileInfo.Overwrite = true;
uploadFile = docs.RootFolder.Files.Add(fileInfo);
// Start upload by uploading the first slice.
using (MemoryStream s = new MemoryStream(buffer))
{
// Call the start upload method on the first slice.
bytesUploaded = uploadFile.StartUpload(uploadId, s);
ctx.ExecuteQuery();
// fileoffset is the pointer where the next slice will be added.
fileoffset = bytesUploaded.Value;
}
// You can only start the upload once.
first = false;
}
}
else
{
if (last)
{
// Is this the last slice of data?
using (MemoryStream s = new MemoryStream(lastBuffer))
{
// End sliced upload by calling FinishUpload.
uploadFile = uploadFile.FinishUpload(uploadId, fileoffset, s);
ctx.ExecuteQuery();
// Return the file object for the uploaded file.
return uploadFile;
}
}
else
{
using (MemoryStream s = new MemoryStream(buffer))
{
// Continue sliced upload.
bytesUploaded = uploadFile.ContinueUpload(uploadId, fileoffset, s);
ctx.ExecuteQuery();
// Update fileoffset for the next slice.
fileoffset = bytesUploaded.Value;
}
}
}
} // while ((bytesRead = br.Read(buffer, 0, buffer.Length)) > 0)
}
}
finally
{
if (fs != null)
{
fs.Dispose();
}
}
}
return null;
}
This is the first page where i run the method
using Microsoft.SharePoint.Client;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security;
using System.Text;
using System.Threading.Tasks;
namespace Contoso.Core.LargeFileUpload
{
class Program
{
static void Main(string[] args)
{
// Request Office365 site from the user
string siteUrl = #"https://bundegruppen.sharepoint.com/sites/F24-2905/";
/* Prompt for Credentials */
//Console.WriteLine("Filer blir overført til site: {0}", siteUrl);
string userName = "xx.xx#bxxbygg.no";
SecureString pwd = new SecureString();
string password = "xxx";
foreach (char c in password.ToCharArray()) pwd.AppendChar(c);
/* End Program if no Credentials */
if (string.IsNullOrEmpty(userName) || (pwd == null))
return;
ClientContext ctx = new ClientContext(siteUrl);
ctx.AuthenticationMode = ClientAuthenticationMode.Default;
ctx.Credentials = new SharePointOnlineCredentials(userName, pwd);
// These should both work as expected.
try
{
// Alternative 3 for uploading large files: slice per slice which allows you to stop and resume a download
new FileUploadService().UploadFileSlicePerSliceToFolder(ctx, "Dokumenter/General", #"C:\Temp\F24_Sammenstillingsmodell.smc");
}
catch (Exception ex)
{
Console.WriteLine(string.Format("Exception while uploading files to the target site: {0}.", ex.ToString()));
Console.WriteLine("Press enter to continue.");
Console.Read();
}
// Just to see what we have in console
Console.ForegroundColor = ConsoleColor.White;
}
}
}

The code you have is written just to upload the specified file to the RootFolder of the named Library. If you pass in a full path to a folder instead of just a Library Name, it will fail.
The following is a modded version of the function that should allow you to pass a full serverRelativeUrl to the desired folder:
public Microsoft.SharePoint.Client.File UploadFileSlicePerSliceToFolder(ClientContext ctx, string serverRelativeFolderUrl, string fileName, int fileChunkSizeInMB = 3)
{
// Each sliced upload requires a unique ID.
Guid uploadId = Guid.NewGuid();
// Get the name of the file.
string uniqueFileName = Path.GetFileName(fileName);
// Get the folder to upload into.
Folder uploadFolder = ctx.web.GetFolderByServerRelativeUrl(serverRelativeFolderUrl);
// Get the information about the folder that will hold the file.
ctx.Load(uploadFolder);
ctx.ExecuteQuery();
// File object.
Microsoft.SharePoint.Client.File uploadFile = null;
// Calculate block size in bytes.
int blockSize = fileChunkSizeInMB * 1024 * 1024;
// Get the information about the folder that will hold the file.
ctx.Load(uploadFolder, f => f.ServerRelativeUrl);
ctx.ExecuteQuery();
// Get the size of the file.
long fileSize = new FileInfo(fileName).Length;
if (fileSize <= blockSize)
{
// Use regular approach.
using (FileStream fs = new FileStream(fileName, FileMode.Open))
{
FileCreationInformation fileInfo = new FileCreationInformation();
fileInfo.ContentStream = fs;
fileInfo.Url = uniqueFileName;
fileInfo.Overwrite = true;
uploadFile = uploadFolder.Files.Add(fileInfo);
ctx.Load(uploadFile);
ctx.ExecuteQuery();
// Return the file object for the uploaded file.
return uploadFile;
}
}
else
{
// Use large file upload approach.
ClientResult<long> bytesUploaded = null;
FileStream fs = null;
try
{
fs = System.IO.File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
using (BinaryReader br = new BinaryReader(fs))
{
byte[] buffer = new byte[blockSize];
Byte[] lastBuffer = null;
long fileoffset = 0;
long totalBytesRead = 0;
int bytesRead;
bool first = true;
bool last = false;
// Read data from file system in blocks.
while ((bytesRead = br.Read(buffer, 0, buffer.Length)) > 0)
{
totalBytesRead = totalBytesRead + bytesRead;
// You've reached the end of the file.
if (totalBytesRead == fileSize)
{
last = true;
// Copy to a new buffer that has the correct size.
lastBuffer = new byte[bytesRead];
Array.Copy(buffer, 0, lastBuffer, 0, bytesRead);
}
if (first)
{
using (MemoryStream contentStream = new MemoryStream())
{
// Add an empty file.
FileCreationInformation fileInfo = new FileCreationInformation();
fileInfo.ContentStream = contentStream;
fileInfo.Url = uniqueFileName;
fileInfo.Overwrite = true;
uploadFile = uploadFolder.Files.Add(fileInfo);
// Start upload by uploading the first slice.
using (MemoryStream s = new MemoryStream(buffer))
{
// Call the start upload method on the first slice.
bytesUploaded = uploadFile.StartUpload(uploadId, s);
ctx.ExecuteQuery();
// fileoffset is the pointer where the next slice will be added.
fileoffset = bytesUploaded.Value;
}
// You can only start the upload once.
first = false;
}
}
else
{
if (last)
{
// Is this the last slice of data?
using (MemoryStream s = new MemoryStream(lastBuffer))
{
// End sliced upload by calling FinishUpload.
uploadFile = uploadFile.FinishUpload(uploadId, fileoffset, s);
ctx.ExecuteQuery();
// Return the file object for the uploaded file.
return uploadFile;
}
}
else
{
using (MemoryStream s = new MemoryStream(buffer))
{
// Continue sliced upload.
bytesUploaded = uploadFile.ContinueUpload(uploadId, fileoffset, s);
ctx.ExecuteQuery();
// Update fileoffset for the next slice.
fileoffset = bytesUploaded.Value;
}
}
}
} // while ((bytesRead = br.Read(buffer, 0, buffer.Length)) > 0)
}
}
finally
{
if (fs != null)
{
fs.Dispose();
}
}
}
return null;
}

FileStream is not working with relative path

I'm trying to use a FileStream with a relative path but it is not working.
var pic = ReadFile("~/Images/money.png");
It is working when I use something like:
var p = GetFilePath();
var pic = ReadFile(p);
the rest of the code(from SO):
public static byte[] ReadFile(string filePath)
{
byte[] buffer;
FileStream fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read);
try
{
int length = (int)fileStream.Length; // get file length
buffer = new byte[length]; // create buffer
int count; // actual number of bytes read
int sum = 0; // total number of bytes read
// read until Read method returns 0 (end of the stream has been reached)
while ((count = fileStream.Read(buffer, sum, length - sum)) > 0)
sum += count; // sum is a buffer offset for next reading
}
finally
{
fileStream.Close();
}
return buffer;
}
public string GetFilePath()
{
return HttpContext.Current.Server.MapPath("~/Images/money.png");
}
I don't get why it is not working because the FileStream constructor allow using relative path.

I'm assuming the folder in your program has the subfolder images, which contains your image file.
\folder\program.exe
\folder\Images\money.jpg
Try without the "~".

I also had the same issue but I solved it by using this code,
Try one of this code, hope it will solve your issue too.
#region GetImageStream
public static Stream GetImageStream(string Image64string)
{
Stream imageStream = new MemoryStream();
if (!string.IsNullOrEmpty(Image64string))
{
byte[] imageBytes = Convert.FromBase64String(Image64string.Substring(Image64string.IndexOf(',') + 1));
using (Image targetimage = BWS.AWS.S3.ResizeImage(System.Drawing.Image.FromStream(new MemoryStream(imageBytes, false)), new Size(1600, 1600), true))
{
targetimage.Save(imageStream, ImageFormat.Jpeg);
}
}
return imageStream;
}
#endregion
2nd one
#region GetImageStream
public static Stream GetImageStream(Stream stream)
{
Stream imageStream = new MemoryStream();
if (stream != null)
{
using (Image targetimage = BWS.AWS.S3.ResizeImage(System.Drawing.Image.FromStream(stream), new Size(1600, 1600), true))
{
targetimage.Save(imageStream, ImageFormat.Jpeg);
}
}
return imageStream;
}
#endregion

File got corrupted when I Read the file's all bytes on list type of object then write a file again Using c#

I've lot of tried to write file from collection of bytes. but file always get corrupted. not sure why its happening. If somebody knows about it would be helpful me more.
Note: Its always working good when I uncomment under while loop this line //AppendAllBytes(pathSource, bytes);
but I need bytes from object. later on I will use this concept on p2p.
namespace Sender
{
static class Program
{
static void Main(string[] args)
{
string pathSource = "../../Ok&SkipButtonForWelcomeToJakayaWindow.jpg";
using (FileStream fsSource = new FileStream(pathSource,
FileMode.Open, FileAccess.Read))
{
// Read the source file into a byte array.
const int numBytesToRead = 100000; // Your amount to read at a time
byte[] bytes = new byte[numBytesToRead];
int numBytesRead = 0;
if (File.Exists(pathSource))
{
Console.WriteLine("File of this name already exist, you want to continue?");
System.IO.FileInfo obj = new System.IO.FileInfo(pathSource);
pathSource = "../../Files/" + Guid.NewGuid() + obj.Extension;
}
int i = 0;
byte[] objBytes = new byte[numBytesRead];
List<FileInfo> objFileInfo = new List<FileInfo>();
Guid fileID = Guid.NewGuid();
FileInfo fileInfo = null;
while (numBytesToRead > 0)
{
// Read may return anything from 0 to numBytesToRead.
int n = fsSource.Read(bytes, numBytesRead, numBytesToRead);
i++;
//AppendAllBytes(pathSource, bytes);
fileInfo = new FileInfo { FileID = fileID, FileBytes = bytes, FileByteID = i };
objFileInfo.Add(fileInfo);
// Break when the end of the file is reached.
if (n == 0)
{
break;
}
// Do here what you want to do with the bytes read (convert to string using Encoding.YourEncoding.GetString())
}
//foreach (var b in objFileInfo.OrderBy(m => m.FileByteID))
//{
// AppendAllBytes(pathSource, b.FileBytes);
//}
foreach (var item in objFileInfo)
{
AppendAllBytes(pathSource, item.FileBytes);
}
fileInfo = null;
}
}
static void AppendAllBytes(string path, byte[] bytes)
{
using (var stream = new FileStream(path, FileMode.Append))
{
stream.Write(bytes, 0, bytes.Length);
}
}
}
class FileInfo
{
public Guid FileID { get; set; }
public int FileByteID { get; set; }
public byte[] FileBytes { get; set; }
}
}

You don't increase numBytesRead and don't decrease numBytesToRead.

objFileInfo contains a List of FileInfo which contains a reference type byte[].
You copy the reference to the bytes when you create a new FileInfo and then repeatedly overwrite those bytes until you reach the end of the file.
byte[] bytes = new byte[numBytesToRead];
//...
List<FileInfo> objFileInfo = new List<FileInfo>();
//...
//...
while (numBytesToRead > 0)
{
int n = fsSource.Read(bytes, numBytesRead, numBytesToRead);
//First time here bytes[0] == the first byte of the file
//Second time here bytes[0] == 10000th byte of file
//...
//The following line should copy the bytes into file info instead of the reference to the existing byte array
fileInfo = new FileInfo { ..., FileBytes = bytes, ... };
objFileInfo.Add(fileInfo);
//First time here objFileInfo[0].FileBytes[0] == first byte of file
//Second time here objFileInfo[0].FileBytes[0] == 10000th byte of file because objFileInfo[All].FileBytes == bytes
//...
}
You can test this by looking in the FileBytes variable for multiple FileInfo. I'd bet the contents look similar

There is two problem in your code :
The block of data is all of size 100000, which cannot work most of time unless the file size is exactly a multiple of it. So, the last block of data will contains 0s.
FileInfo.FileBytes will change, if you change the buffer to something new causing the every single block of data being the identical to the last block read.
using System;
using System.Collections.Generic;
using System.IO;
static class Program
{
static void Main(string[] args)
{
string pathSource = "test.jpg";
using (FileStream fsSource = new FileStream(pathSource, FileMode.Open, FileAccess.Read))
{
// Read the source file into a byte array.
const int BufferSize = 100000; // Your amount to read at a time
byte[] buffer = new byte[BufferSize];
if (File.Exists(pathSource))
{
Console.WriteLine("File of this name already exist, you want to continue?");
System.IO.FileInfo obj = new System.IO.FileInfo(pathSource);
pathSource = "Files/" + Guid.NewGuid() + obj.Extension;
}
int i = 0, offset = 0, bytesRead;
List<FileInfo> objFileInfo = new List<FileInfo>();
Guid fileID = Guid.NewGuid();
while (0 != (bytesRead = fsSource.Read(buffer, offset, BufferSize)))
{
var data = new byte[bytesRead];
Array.Copy(buffer, data, bytesRead);
objFileInfo.Add(new FileInfo { FileID = fileID, FileBytes = data, FileByteID = ++i });
}
foreach (var item in objFileInfo)
{
AppendAllBytes(pathSource, item.FileBytes);
}
}
}
static void AppendAllBytes(string path, byte[] bytes)
{
using (var stream = new FileStream(path, FileMode.Append))
{
stream.Write(bytes, 0, bytes.Length);
}
}
}
class FileInfo
{
public Guid FileID { get; set; }
public int FileByteID { get; set; }
public byte[] FileBytes { get; set; }
}

Why StringWriter.ToString return `System.Byte[]` and not the data?

UnZipFile method writes the data from inputStream to outputWriter.
Why sr.ToString() returns System.Byte[] and not the data?
using (var sr = new StringWriter())
{
UnZipFile(response.GetResponseStream(), sr);
var content = sr.ToString();
}
public static void UnZipFile(Stream inputStream, TextWriter outputWriter)
{
using (var zipStream = new ZipInputStream(inputStream))
{
ZipEntry currentEntry;
if ((currentEntry = zipStream.GetNextEntry()) != null)
{
var size = 2048;
var data = new byte[size];
while (true)
{
size = zipStream.Read(data, 0, size);
if (size > 0)
{
outputWriter.Write(data);
}
else
{
break;
}
}
}
}
}

The problem is on the line:
outputWriter.Write(data);
StringWriter.Write has no overload expecting a byte[]. Therefore, Write(Object) is called instead. And according to MSDN:
Writes the text representation of an object to the text string or stream by calling the ToString method on that object.
Calling ToString on a byte array returns System.byte[], explaining how you get that string in your StringWriter.

The reason is simple:
data is of type byte[]. There is no overload for byte[] on StringWriter so it uses the overload for object. And then calls ToString() on the boxed byte array which simply prints the type.
Your code is equivalent to this:
outputWriter.Write(data.ToString());

theateist,
Looking at the other answers here, I am going to have to agree that the reason for the "ToString()" returning System.Byte[] is because that is what you are putting into it, and everything put into the StringWriter calls it's own "ToString" method when doing so. (i.e. byte[].toString() = "System.byte[]"). In fact the whole idea is that the StringWriter is only ment for writing into a string "buffer" (StringBuilder), so in theory if your file was large enough(bigger than 2048), your output would be "System.Byte[]System.Byte[]" (etc.). Try this to deflate into a memory stream and then read from that stream, may be a better understanding of what you are looking at. (Code not tested, just example).
using (Stream ms = new MemoryStream())
{
UnZipFile(response.GetResponseStream(), ms);
string content;
ms.Position = 0;
using(StreamReader s = new StreamReader(ms))
{
content = s.ReadToEnd();
}
}
public static void UnZipFile(Stream inputStream, Stream outputWriter)
{
using (var zipStream = new ZipInputStream(inputStream))
{
ZipEntry currentEntry;
if ((currentEntry = zipStream.GetNextEntry()) != null)
{
int size = 2048;
byte[] data = new byte[size];
while (true)
{
size = zipStream.Read(data, 0, size);
if (size > 0)
{
outputWriter.Write(data);
}
else
{
break;
}
}
}
}
}
Another idea would actually be to using the endcoding to get the string
public string UnZipFile(Stream inputStream)
{
string tmp;
using(Stream zipStream = new ZipInputStream(inputStream))
{
ZipEntry currentEntry;
if(currentEntry = zipStream.GetNextEntry()) != null)
{
using(Stream ms = new MemoryStream())
{
int size = 2048;
byte[] data = new byte[size];
while(true)
{
if((size = zipStream.Read(data,0,size)) > 0)
ms.Write(data);
else
break;
}
tmp = Encoding.Default.GetString(ms.ToByteArray());
}
}
}
}
return tmp;
}
Or as one last idea, you could actually change your original code to have
outputWriter.Write(Encoding.Default.GetString(data));
Instead of
outputWriter.Write(data);
By the way, please avoid the var keyword in posts, maybe just my pet peev, but code is less readable when utilizing weak types.
StringWriter.Write:MSDN
StringWriter.ToString:MSDN

How to use httpwebrequest to pull image from website to local file

I'm trying to use a local c# app to pull some images off a website to files on my local machine. I'm using the code listed below. I've tried both ASCII encoding and UTF8 encoding but the final file is not an correct. Does anyone see what I'm doing wrong? The url is active and correct and show the image just fine when I put the address in my browser.
private void button1_Click(object sender, EventArgs e)
{
HttpWebRequest lxRequest = (HttpWebRequest)WebRequest.Create("http://www.productimageswebsite.com/images/stock_jpgs/34891.jpg");
// returned values are returned as a stream, then read into a string
String lsResponse = string.Empty;
HttpWebResponse lxResponse = (HttpWebResponse)lxRequest.GetResponse();
using (StreamReader lxResponseStream = new StreamReader(lxResponse.GetResponseStream()))
{
lsResponse = lxResponseStream.ReadToEnd();
lxResponseStream.Close();
}
byte[] lnByte = System.Text.UTF8Encoding.UTF8.GetBytes(lsResponse);
System.IO.FileStream lxFS = new FileStream("34891.jpg", FileMode.Create);
lxFS.Write(lnByte, 0, lnByte.Length);
lxFS.Close();
MessageBox.Show("done");
}

nice image :D
try using the following code:
you needed to use a BinaryReader, 'cause an image file is binary data and thus not encoded in UTF or ASCII
edit: using'ified
HttpWebRequest lxRequest = (HttpWebRequest)WebRequest.Create(
"http://www.productimageswebsite.com/images/stock_jpgs/34891.jpg");
// returned values are returned as a stream, then read into a string
String lsResponse = string.Empty;
using (HttpWebResponse lxResponse = (HttpWebResponse)lxRequest.GetResponse()){
using (BinaryReader reader = new BinaryReader(lxResponse.GetResponseStream())) {
Byte[] lnByte = reader.ReadBytes(1 * 1024 * 1024 * 10);
using (FileStream lxFS = new FileStream("34891.jpg", FileMode.Create)) {
lxFS.Write(lnByte, 0, lnByte.Length);
}
}
}
MessageBox.Show("done");

Okay, here's the final answer. It uses a memorystream as a way to buffer the data from the reaponsestream.
private void button1_Click(object sender, EventArgs e)
{
byte[] lnBuffer;
byte[] lnFile;
HttpWebRequest lxRequest = (HttpWebRequest)WebRequest.Create("http://www.productimageswebsite.com/images/stock_jpgs/34891.jpg");
using (HttpWebResponse lxResponse = (HttpWebResponse)lxRequest.GetResponse())
{
using (BinaryReader lxBR = new BinaryReader(lxResponse.GetResponseStream()))
{
using (MemoryStream lxMS = new MemoryStream())
{
lnBuffer = lxBR.ReadBytes(1024);
while (lnBuffer.Length > 0)
{
lxMS.Write(lnBuffer, 0, lnBuffer.Length);
lnBuffer = lxBR.ReadBytes(1024);
}
lnFile = new byte[(int)lxMS.Length];
lxMS.Position = 0;
lxMS.Read(lnFile, 0, lnFile.Length);
}
}
}
using (System.IO.FileStream lxFS = new FileStream("34891.jpg", FileMode.Create))
{
lxFS.Write(lnFile, 0, lnFile.Length);
}
MessageBox.Show("done");
}

A variation of the answer, using async await for async file I/O. See Async File I/O on why this is important.
Download png and write to disk using BinaryReader/Writer
string outFile = System.IO.Path.Combine(outDir, fileName);
// Download file
var request = (HttpWebRequest) WebRequest.Create(imageUrl);
using (var response = await request.GetResponseAsync()){
using (var reader = new BinaryReader(response.GetResponseStream())) {
// Read file
Byte[] bytes = async reader.ReadAllBytes();
// Write to local folder
using (var fs = new FileStream(outFile, FileMode.Create)) {
await fs.WriteAsync(bytes, 0, bytes.Length);
}
}
}
Read all bytes extension method
public static class Extensions {
public static async Task<byte[]> ReadAllBytes(this BinaryReader reader)
{
const int bufferSize = 4096;
using (var ms = new MemoryStream())
{
byte[] buffer = new byte[bufferSize];
int count;
while ((count = reader.Read(buffer, 0, buffer.Length)) != 0) {
await ms.WriteAsync(buffer, 0, count);
}
return ms.ToArray();
}
}
}

You can use the following method to download an image from a web site and save it, using the Image class:
WebRequest req = WebRequest.Create(imageUrl);
WebResponse resp = req.GetResponse();
Image img = Image.FromStream(resp.GetResponseStream());
img.Save(filePath + fileName + ".jpg");