Creating Custom Encoding - C# Discussion Boards

Wamuti6-Mar-10 23:18

6-Mar-10 23:18

Hi all. I have a client-server distributed system. I want to transfer and image from the server to the client. In the server i have converted a .bmp image to byte array as this:

Image imageIn = Image.FromFile("me.bmp") ;
MemoryStream msr = new MemoryStream();
imageIn.Save(msr, System.Drawing.Imaging.ImageFormat.Gif);
byte[] byteIm = msr.ToArray();

ms.Send(byteIm);

The bytes are being transfered okay to the client. The problem is that i don't know how to assemble this byte back to an image to show in a picture box.
That is:

pictureBox1.Image =

Wamuti: Any man can be an island, but islands to need water around them!
Edmund Burke: No one could make a greater mistake than he who did nothing because he could do only a little.

Re: Assembling bytes to an image

OriginalGriff6-Mar-10 23:48

OriginalGriff

6-Mar-10 23:48

have a look at this[^]

You should never use standby on an elephant. It always crashes when you lift the ears. - Mark Wallace

C/C++ (I dont see a huge difference between them, and the 'benefits' of C++ are questionable, who needs inheritance when you have copy and paste) - fat_boy

Re: Assembling bytes to an image

Wamuti6-Mar-10 23:55

Wamuti

6-Mar-10 23:55

Actually that is where i knew how to convert and image to bytes but the function returning an Image, how will the pictureBox get the URL?

Wamuti: Any man can be an island, but islands to need water around them!
Edmund Burke: No one could make a greater mistake than he who did nothing because he could do only a little.

Re: Assembling bytes to an image

OriginalGriff7-Mar-10 0:52

OriginalGriff

7-Mar-10 0:52

Why would the picture box want a URL? Just give it the image, or save it to disk and then give it the url as the file location.
From your original code:

MemoryStream ms = new MemoryStream(byteArrayIn);
pictureBox1.Image = Image.FromStream(ms);

Re: Assembling bytes to an image

dan!sh 6-Mar-10 23:49

dan!sh

6-Mar-10 23:49

Here you go:

MemoryStream memStream = new MemoryStream(imageBytes);
Image image = Image.FromStream(memStream);

Re: Assembling bytes to an image

Wamuti6-Mar-10 23:58

Wamuti

6-Mar-10 23:58

Thanks guys. It worked.

Wamuti: Any man can be an island, but islands to need water around them!
Edmund Burke: No one could make a greater mistake than he who did nothing because he could do only a little.

Re: Assembling bytes to an image

DX Roster7-Mar-10 20:17

DX Roster

7-Mar-10 20:17

try following code:

private void Button2_Click(object sender, System.EventArgs e)
{
connection.Open();
SqlCommand command1 = new SqlCommand("select imgfile from myimages where imgname=@param", connection);
SqlParameter myparam = command1.Parameters.Add("@param", SqlDbType.NVarChar, 30);
myparam.Value = txtimgname.Text;
byte[] img = (byte[])command1.ExecuteScalar();
MemoryStream str = new MemoryStream();
str.Write(img, 0, img.Length);
Bitmap bit = new Bitmap(str);
Response.ContentType = "image/jpeg";//or you can select your imagetype from database or directly write it here
bit.Save(Response.OutputStream, ImageFormat.Jpeg);
connection.Close();
}

change your database name, field name, image name, attribute name.

If You Get your answer then please Rating me...

Thanks..
"Are You Ready"
DX-ARMY

Creating Custom Encoding

Xmen Real 6-Mar-10 19:08

Xmen Real

6-Mar-10 19:08

As you have seen system encodings, ASCII or UTF. I want to create my own, like some value for some specific character. So to do that I simple make a Character class and a collection to hold 'em. But when I need to convert a value to char it iterates the collection until that value is found and thats too slow. But I have another idea which I have tried and also reached nearby the same performance as Encoding.GetString.

So any suggestions guys ?

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R0~53%eYrd8mt^7Z6]iTF+(EWfJ9zaK-iTV.C\y<pjxsg-b$f4ia>

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Re: Creating Custom Encoding

OriginalGriff6-Mar-10 21:45

OriginalGriff

6-Mar-10 21:45

If it is a small set of values then set up an array of translations - index is the character to translate.
If the set gets big, then put the array into a file and read it on start up. You would need two arrays if you want to go both ways.
Memory is not a major problem these days, so that would be the fastest way.

Re: Creating Custom Encoding

Xmen Real 6-Mar-10 22:32

Xmen Real

6-Mar-10 22:32

thats exactly what I thought but there is a problem, It will be faster from value(index) to char but what about char to value ??

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Re: Creating Custom Encoding

harold aptroot6-Mar-10 22:38

harold aptroot

6-Mar-10 22:38

You can also index an array with a char, or isn't that what you meant?

Re: Creating Custom Encoding

Xmen Real 6-Mar-10 22:41

Xmen Real

6-Mar-10 22:41

example ?

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Re: Creating Custom Encoding

harold aptroot6-Mar-10 22:53

harold aptroot

6-Mar-10 22:53

inverseArray[someChar]
Where someChar is of the type char and inverseArray is an array of something

Re: Creating Custom Encoding

OriginalGriff6-Mar-10 22:47

OriginalGriff

6-Mar-10 22:47

That's why I said "You will need two arrays..." One for each direction? Big Grin | :-D

Re: Creating Custom Encoding

Xmen Real 6-Mar-10 22:51

Xmen Real

6-Mar-10 22:51

you mean like this ?

short[] values = new short[count];
short[] chars = new short[count];
values[(int)'c'] = value;
chars[value] = 'c';

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Re: Creating Custom Encoding

harold aptroot6-Mar-10 22:54

harold aptroot

6-Mar-10 22:54

You don't need to cast the char to an int

Re: Creating Custom Encoding

Xmen Real 6-Mar-10 22:57

Xmen Real

6-Mar-10 22:57

its not dictionary, its an array

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Re: Creating Custom Encoding

harold aptroot6-Mar-10 22:59

harold aptroot

6-Mar-10 22:59

It doesn't matter, indexing an array with a char works just as well

Re: Creating Custom Encoding

Xmen Real 6-Mar-10 23:45

Xmen Real

6-Mar-10 23:45

nice, never noticed.

Thanks btw Wink | ;)

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Re: Creating Custom Encoding

OriginalGriff6-Mar-10 22:57

OriginalGriff

6-Mar-10 22:57

Works fins just with a char:

int[] array = new int[256];
Random r = new Random();
for (int i = 0; i < 256; i++)
    {
    array[i] = r.Next(256);
    }
string s = "Hello there!";
int[] output = new int[s.Length];
int ind = 0;
foreach (char c in s)
    {
    output[ind++] = array[c];
    }
}

Re: Creating Custom Encoding

Xmen Real 6-Mar-10 23:45

Xmen Real

6-Mar-10 23:45

yupp thanks Wink | ;)

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change the cell type of a datagrid view in runtime

TAFIN6-Mar-10 18:52

TAFIN

6-Mar-10 18:52

hellow
i m in a prob.
i hav a datagrid which has 3 columns.All the cell in first column will be in combobox when the form loads. but when the user selects a data from the combo then the Datagridcombo must be changed into datagridtextbox and selected data will be shown in the datagrid text box.
as well as the next row will show the datagridcombo in first column.

i need solution with code snippet.

thanks in advance and sorry for poor english.

Thanks
Tanim

stopping a waitcallback in a threadpool

Jason Jerome6-Mar-10 12:18

Jason Jerome

6-Mar-10 12:18

I'm trying to stop a waitcallback in a threadpool within an event handler for a stop button. I've searched and searched and have not found a way to do this. Please help!

private void startbutton_Click(object sender, EventArgs e)
{       
  WaitCallback doLoadSequential = new WaitCallback this.loadsequential);  
  ThreadPool.QueueUserWorkItem(doLoadSequential);           
}
private void stopbutton_Click(object sender, EventArgs e)
{
//what goes here?
}

Re: stopping a waitcallback in a threadpool

Luc Pattyn6-Mar-10 16:25

Luc Pattyn

6-Mar-10 16:25

you need cooperative termination, e.g. add a volatile bool flag as a class member, set it false in startbutton_Click, set it true in stopbutton_Click, and test it regularly in doLoadSequential, so that method finishes as soon as the flag gets set.

Smile | :)

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I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that.

How to search for a specific string in a file?

SimpleData6-Mar-10 11:09

SimpleData

6-Mar-10 11:09

Hi,
Let's say that I've a file and I would like to find a specific string's location inside it. It is logical to load my file into a byte array and then parse it into a string or a StringBuilder byte by byte, right? It is an easy issue if the file is small.

If the file is huge (like 400megabytes), it is not that easy. The application demands lots of RAM and it is annoying. I thought about copying the file into the byte array by 100 bytes, step by step. But this brings another problem, if the half of my string is inside the first 100 bytes, and the rest in the next 100 bytes; my application is not able to identify my string and therefore give its location to me.

How can I solve this, any ideas?

If there is anything unclear, feel free to ask.
Thanks.

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