WebClient DownloadString with TextChanged Event C#

Question

I have an trouble in C# program which using php scripts to translate words and download the result string into TextBox .

My program has two TextBoxes

txtWord , txtTranslatedWord

and that's the simplified code

WebClient c = new WebClient();
private void txtWord_TextChanged(object sender, EventArgs e)
{
    string response = c.DownloadString("http://example.com/Services/Translator/lang/EnglishToArabic.php?Word=" + txtWord.Text);
    switch (response.ToLower())
    {
        case "not exist":
            {
                txtTranslatedWord.Text = "{Sorry but no translation for this word!}";
                break;
            }
        default:
            {
                txtTranslatedWord.Text = response;
                break;
            }
    }
}

The problem its when the text is changed the program lagging and looks like it would Stopped Working .

The program worked successfully but after so much lagging , especially if the writer is writing so fast.

I tried BackgroundWorker and make an delay like when user stop writing for 2 second then program start to translate but still lagging without any luck.

Is there any easy way to do this without problems?

Answer 1

Try to use asynchrony.

WebClient does not support concurrent I/O operations, so will be use HttpClient .

HttpClient client = new HttpClient();

private async void txtWord_TextChanged(object sender, EventArgs e)
{
    var response = await client.GetStringAsync(
        "http://example.com/Services/Translator/lang/EnglishToArabic.php?Word=" + txtWord.Text);
    switch (response.ToLower())
    {
        case "not exist":
            {
                txtTranslatedWord.Text = "{Sorry but no translation for this word!}";
                break;
            }
        default:
            {
                txtTranslatedWord.Text = response;
                break;
            }
    }
}

Answer 2

Your problem is that every character your user types into the textbox results in a WebClient download that has to complete before the next keypress can be accepted. I'd suggest you do the following...

Create a timer that starts or restarts each time the user enters a character and that when expires disables the textbox and runs the search before re-enabling the textbox. You'd also do well to use an asynchronous WebClient call.