Develop Reference

C# how to use variable outside of block of code

I have the following code. I want to use pictureBox1.Image = image outside of the code block like so:
private void button1_Click(object sender, EventArgs e) {
using(MemoryStream memoryStream = new MemoryStream()) {
pic.Image.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Bmp);
byte[] imageBytes = memoryStream.ToArray();
}
Image image = Image.FromStream(memoryStream);
pictureBox1.Image = image;
}
I get the folloowing error: The name 'memoryStream' does not exist in the current context. I know I can do the following move the last 2 lines into the brackets and the code works but How can I use variable outside of the { } block of code
I know the code below works but i just want to know if there is a way to use pictureBox1.Image = image outside of the block of code.
private void button1_Click(object sender, EventArgs e)
{
using(MemoryStream memoryStream = new MemoryStream())
{
pic.Image.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Bmp);
byte[] imageBytes = memoryStream.ToArray();
Image image = Image.FromStream(memoryStream);
pictureBox1.Image = image;
}
}

You can't and shouldn't use the stream outside of the using scope, after that it will get disposed and you don't run into leaking issues.
You could just assign the value after the scope, when you declare the variable before it.
private void button1_Click(object sender, EventArgs e)
{
Image image;
using(MemoryStream memoryStream = new MemoryStream())
{
pic.Image.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Bmp);
// byte[] imageBytes = memoryStream.ToArray(); //unused?
image = Image.FromStream(memoryStream);
}
pictureBox1.Image = image;
}
Or better yet make a function to read the image and return it.
private void button1_Click(object sender, EventArgs e)
{
pictureBox1.Image = readImage();
}
private Image readImage()
{
using(MemoryStream memoryStream = new MemoryStream())
{
pic.Image.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Bmp);
// byte[] imageBytes = memoryStream.ToArray(); //unused?
return Image.FromStream(memoryStream);
}
}

There's no problem putting that line outside the using block. The problem is line before. You can't use memoryStream outside the using block. The whole point of the using block is to create a scope for that variable and ensure that the object assigned to it is disposed at the end of the block. You can do this:
private void button1_Click(object sender, EventArgs e) {
Image image;
using(MemoryStream memoryStream = new MemoryStream()) {
pic.Image.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Bmp);
byte[] imageBytes = memoryStream.ToArray();
image = Image.FromStream(memoryStream);
}
pictureBox1.Image = image;
}

You can define MemoryStream outside the code block:
MemoryStream memoryStream = new MemoryStream();
using (memoryStream)
{
pic.Image.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Bmp);
byte[] imageBytes = memoryStream.ToArray();
}
Image image = Image.FromStream(memoryStream);
pictureBox1.Image = image;
Edit:(just for test)
If you think using releases all resources for the variable defined outside, test the following code:
MemoryStream memoryStream = new MemoryStream();
using (memoryStream)
{
byte[] messageBytes = Encoding.ASCII.GetBytes("test Massage");
memoryStream.Write(messageBytes, 0, messageBytes.Length);
}
var data = Encoding.Default.GetString(memoryStream.ToArray()); // data = "test Massage"

Converting image to base64

I have the following code to convert image to base64:
private void btnSave_Click(object sender, RoutedEventArgs e)
{
StreamResourceInfo sri = null;
Uri uri = new Uri("Checked.png", UriKind.Relative);
sri = Application.GetResourceStream(uri);
BitmapImage bitmap = new BitmapImage();
bitmap.SetSource(sri.Stream);
WriteableBitmap wb = new WriteableBitmap(bitmap);
MemoryStream ms = new MemoryStream();
wb.SaveJpeg(ms, bitmap.PixelWidth, bitmap.PixelHeight, 0, 100);
byte[] imageBytes = ms.ToArray();
base64 = System.Convert.ToBase64String(imageBytes);
}
And the following code to get Bitmap image form base 64:
public static BitmapImage base64image(string base64string)
{
byte[] fileBytes = Convert.FromBase64String(base64string);
using (MemoryStream ms = new MemoryStream(fileBytes, 0, fileBytes.Length))
{
ms.Write(fileBytes, 0, fileBytes.Length);
BitmapImage bitmapImage = new BitmapImage();
bitmapImage.SetSource(ms);
return bitmapImage;
}
}
So when i convert and deconvert it is blank.
I know that deconverter works, because, when i give him exact string:
string base64="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";
Which is my Checked.png converted in online converter. It decompreses perfectly.
And this is my base64, which i get by converting:
"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"
My problem is that string which i get as base64 from my code - is incorrect *What i did wrong?*

What about trying:
public static BitmapImage base64image(string base64string)
{
byte[] fileBytes = Convert.FromBase64String(base64string);
using (MemoryStream ms = new MemoryStream(fileBytes))
{
Image streamImage = Image.FromStream(ms);
context.Response.ContentType = "image/jpeg";
streamImage.Save(context.Response.OutputStream, ImageFormat.Jpeg);
return streamImage;
}
}
I agree with Alexei that your code for reading the image in does look a little strange. I've recently written some code for a similar task that I was doing which might point you in the right direction:
string fileContent = null;
/* Check the file actually has some content to display to the user */
if (uploadFile != null && uploadFile.ContentLength > 0)
{
byte[] fileBytes = new byte[uploadFile.ContentLength];
int byteCount = uploadFile.InputStream.Read(fileBytes, 0, (int)uploadFile.ContentLength);
if (byteCount > 0)
{
fileContent = CreateBase64Image(fileBytes);
}
}
private string CreateBase64Image(byte[] fileBytes)
{
Image streamImage;
/* Ensure we've streamed the document out correctly before we commit to the conversion */
using (MemoryStream ms = new MemoryStream(fileBytes))
{
/* Create a new image, saved as a scaled version of the original */
streamImage = ScaleImage(Image.FromStream(ms));
}
using (MemoryStream ms = new MemoryStream())
{
/* Convert this image back to a base64 string */
streamImage.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
return Convert.ToBase64String(ms.ToArray());
}
}

not an answer: more of a long comment ... OP states that decoding code works perfectly fine, also it looks suspicios. Also code assumed to be verified to work on PNG images, but saving code explicitly produces valid JPG with SaveJpeg call...
Your code that creates stream for reading looks strange - you create stream over existing byte array, than write the same bytes into that stream, and that pass that stream without seeking back to 0 to some method.
Potential fix (assuming BitampImage can accept JPG stream):
don't call Write at all as stream already have the bytes you want
set ms.Position = 0 after writing to the stream.
Note: I'm not sure if it is OK to dispose stream that is a source for BitmapImage, you may need to remove using too.

Save Image source to database

I have a WPF Image with a source assign from picture dialog;
this.imgProduct.Source = new BitmapImage(new Uri(op.FileName));
How can I retieve the source, convert it to byte array and save it into database?
Thank you

You have to convert BitmapImage into the byte[] then save it to the database.
var imageSource = this.imgProduct.Source as BitmapImage;
var stream = imageSource.StreamSource;
Byte[] buffer = null;
if (stream != null && stream.Length > 0)
{
using (BinaryReader br = new BinaryReader(stream))
{
buffer = br.ReadBytes((Int32)stream.Length);
}
}
// write buffer to the database
P.S. I haven't tested the code but I think it works!

As long as you have access to the image file in op.FileName it would be very easy to get the file content by e.g.
byte[] imageBuffer = File.ReadAllBytes(op.FileName);
If the image is loaded from a file Uri (as in your example) you could also do this:
byte[] imageBuffer = File.ReadAllBytes(image.UriSource.AbsolutePath);
If you only have the BitmapImage without information about the file that it was loaded from (e.g. when it was loaded from a temporary file or a web resource), you would have to encode it by one of WPFs BitmapEncoders:
byte[] imageBuffer;
PngBitmapEncoder encoder = new PngBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create(image));
using (MemoryStream stream = new MemoryStream())
{
encoder.Save(stream);
imageBuffer = stream.GetBuffer();
}

How to put image in a picture box from a byte[] in C#

I've a byte array which contains an image binary data in bitmap format. How do I display it using the PictureBox control in C#?
I went thru a couple of posts listed below but not sure if I need to convert the byte array into something else before sending it to a picturebox. I'd appreciate your help. Thanks!
How to put image in a picture box from Bitmap
Load Picturebox Image From Memory?

This function converts byte array into Bitmap which can be use to set the Image Property of the picturebox.
public static Bitmap ByteToImage(byte[] blob)
{
MemoryStream mStream = new MemoryStream();
byte[] pData = blob;
mStream.Write(pData, 0, Convert.ToInt32(pData.Length));
Bitmap bm = new Bitmap(mStream, false);
mStream.Dispose();
return bm;
}
Sample usage:
pictureBox.Image = ByteToImage(byteArr); // byteArr holds byte array value

byte[] imageSource = **byte array**;
Bitmap image;
using (MemoryStream stream = new MemoryStream(imageSource))
{
image = new Bitmap(stream);
}
pictureBox.Image = image;

using System.IO;
byte[] img = File.ReadAllBytes(openFileDialog1.FileName);
MemoryStream ms = new MemoryStream(img);
pictureBox1.Image = Image.FromStream(ms);
or you can access like this directly,
pictureBox1.Image = Image.FromFile(openFileDialog1.FileName);

You can also convert pictureBox image to byte array like this,
MemoryStream ms = new MemoryStream();
pictureBox1.Image.Save(ms,System.Drawing.Imaging.ImageFormat.Jpeg);
byte[] img = ms.ToArray();

The ImageConverter class in the System.Drawing namespace can do the conversion:
byte[] imageArray = **byte array**
ImageConverter converter = new ImageConverter();
pictureButton.Image = (Image)converter.ConvertFrom(imageArray);

If you want to use BinaryReader to convert then use like this,
FileStream fs = new FileStream(openFileDialog1.FileName, FileMode.Open, FileAccess.Read);
BinaryReader br = new BinaryReader(fs);
byte[] img = br.ReadBytes((int)fs.Length);

Try this for Converting Bitmap Images to array of bytes for jpeg pictures and png file types:
public byte[] UdfConvertPicToByte(Bitmap bitmapImages)
{
using (MemoryStream stream = new MemoryStream())
{
bitmapImages.Compress(Bitmap.CompressFormat.Png, 0, stream);
byte[] bitmapData = stream.ToArray();
bitmap.Compress(Bitmap.CompressFormat.Jpeg, 50, stream);
bitmapData = stream.ToArray();
return bitmapData;
}
}

Easy way to convert a Bitmap and Png Image to text and vice versa

what is the easiest way to translate a Bitmap & Png to string AND BACK AGAIN. Ive been trying to do some saves through memory streams and such but i cant seem to get it to work!
Appearently i wasnt clear,
what i want, is to be able to translate a Bitmap class, with an image in it.. into a system string. from there i want to be able to throw my string around for a bit, and then translate it back into a Bitmap to be displayed in a PictureBox.

Based on #peters answer I've ended up using this:
string bitmapString = null;
using (MemoryStream memoryStream = new MemoryStream())
{
image.Save(memoryStream, ImageFormat.Png);
byte[] bitmapBytes = memoryStream.GetBuffer();
bitmapString = Convert.ToBase64String(bitmapBytes, Base64FormattingOptions.InsertLineBreaks);
}
and
Image img = null;
byte[] bitmapBytes = Convert.FromBase64String(pictureSourceString);
using (MemoryStream memoryStream = new MemoryStream(bitmapBytes))
{
img = Image.FromStream(memoryStream);
}

From bitmap to string:
MemoryStream memoryStream = new MemoryStream();
bitmap.Save (memoryStream, ImageFormat.Png);
byte[] bitmapBytes = memoryStream.GetBuffer();
string bitmapString = Convert.ToBase64String(bitmapBytes, Base64FormattingOptions.InsertLineBreaks);
From string to image:
byte[] bitmapBytes = Convert.FromBase64String(bitmapString);
MemoryStream memoryStream = new MemoryStream(bitmapBytes);
Image image = Image.FromStream(memoryStream);