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RTF text font/color changing [duplicate]

I want to create a simple editor like Notepad++ with simple functionality... I need to color a specific word in the rich text box area. How can I do that?
For example: when the user write these word, I want to color them to the blue color. These words are: for, while, if, try, etc.
How can I make the richtextbox to select a specific word and then color them?
And, if I want to make a comment and color everything after the //, how is that done in the richtextbox?
How do I number the line in the text box, so I can now the line number when I'm coding in my editor?

Here's some code you can build on in order to achieve the functionality you want.
private void ColourRrbText(RichTextBox rtb)
{
Regex regExp = new Regex("\b(For|Next|If|Then)\b");
foreach (Match match in regExp.Matches(rtb.Text))
{
rtb.Select(match.Index, match.Length);
rtb.SelectionColor = Color.Blue;
}
}
The CodeProject article Enabling syntax highlighting in a RichTextBox shows how to use RegEx in a RichTextBox to perform syntax highlighting. Specifically, look at the SyntaxRichtTextBox.cs for the implementation.

In general, you have to work on the selection in RichTextBox. You can manipulate the current selection using the Find method or using SelectionStart and SelectionLength properties. Then you can change properties of selected text using SelectionXXX properties. For example, SelectionColor would set the color of current selection, etc. So you have to parse text in richtextbox and then select part of texts and change their properties as per your requirements.
Writing a good text editor using RichTextBox can be quite cumbersome. You should use some library such as Scintilla for that. Have a look at ScintillaNet, a .NET wrapper over Scintilla.

Did you know that Notepad++ uses Scintilla?
You actually do not have to reinvent the wheel by going through all the trouble as there is a .NET port of Scintilla named ScintillaNET which you can freely embed in your application as the source code editor :)
But to answer your question, there are few parts that you need to understand
Finding what to color
When to color
How to color
For the first part, there may be different approaches, but I think using regular expressions would be a good choice. I am sorry, but I don't know regular expressions much so I cannot help you in that case.
When to color is very crucial and if you do it wrong, your application will suffer a heavy performance penalty. I suggest you refer to XPath Visualizer which was done by our own Stack Overflow member, Cheeso. Take a look at the source on how the coloring of the syntax was done. But if you ScintillaNET, everything would be taken care of. Anyway, I really can't seem to find this documentation where he clearly showed how the coloring of the text was done. I would most definitely post it here if I find it.
The third question I think is covered by VinayC. But basically you use SelectionColor along with SelectionStart.

here is a good link on c-sharpcorner.com website on basic richtextbox syntax highlighting. I assume that you and any one visiting this page for similar problem want to do it for learning purpose. But if any one wants to do it for some making some comercial level IDE then it must use scintilla or some similar.
An other approach for this is to directly change the RTF of the richtextbox. Look in codeproject.com there are lot of articles similar to this problem.

I had some problems with that and here is my solution, beats me why it has to be done like this, but it works:
// position on end of control...
richTextBox.UpdateLayout();
richTextBox.ScrollToEnd();
richTextBox.UpdateLayout();
// ...then select text and it will be position on top of control.
richTextBox.Focus();
richTextBox.Selection.Select(foundRange.Start, foundRange.End);
richTextBox.BringIntoView();

Vb.net implementation
Imports System.Text.RegularExpressions
Private Sub formatString()
Dim rg =New Regex("\b(for|while|if|try)\b")
Dim m As Match
For Each m In rg.Matches(RichTextBox1.Text)
RichTextBox1.Select(m.Index,m.Length)
RichTextBox1.SelectionColor=Color.Green
Next
End Sub

Which control to display text to be programmatically edited later on

I am currently developing a chat application in C# and I would like to know which form control allows to add text retaining control to each specific message to modify it later on when is required. I want this in order to be able to add a double tick when the message is received in the other side of the communication, pretty much like in "Whatsapp".
I've thought about an approach consisting on each message object firing events (like "sent", "received"..) when it changes that are listened by the corresponding form control that serves as the view, adding the above mentioned tick.
Any advice on how to achieve this goal? I've tried TextBox but Lines property force to have control os indexes and I want it to be completely event driven. Currently I stuck with DataGridView, however I've made little to no progress.
Thanks!

No one ready made Control I can think of will do the job, I'm afraid.
I would use a FlowLayoutPanel and add a Label for each chunk of text that gets added to the chat.
You can use MeasureString with a given width to get the height of the Label. (AutoSize should be off.)
The Labels would get the Width of the FLP and you could keep a List<> of the Labels with maybe a few meta data, like user, time etc..
Sounds like a good candidate for a ChatDisplay class to bundle the whole functionality!
Of course as the Labels are Controls you can add events to them as you like to communicate with the ChatDisplay or even with an outside communications object.. And the ChatDisplay class is free to implement whatever you need anyway. If necessary you can wrap the Labels in a ChatItem class, too.
Much more extensible than digging into a DGV to force it into doing things it was not meant to do..

Slider and radio button styling in wpf

I'm trying to style some wpf user controls to make them look the same i have in my web application. I found some really great example for every control i need except for sliders and radio buttons.
Here is how they should look like:
Slider:
Radio Button:
I know i should create some ControlTemplate but i don't really know where to start...
If you can provide a complete example it would be perfect, but i guess that even some good deep advise would fit my needs.
Thank you 1000!

I have style sample here. It renders this:

I would start with Control Styles and Templates on MSDN pages. There are examples for most controls which give a good overview of how the control template works. Also you can extract/download the original control template and try to make your changes to it. Download default control templates
P.S. Actually the slider example on the first link resembles the one you describe.

Try using Expression Blend.
Learn Expression
and specifically this video: Creating ControlTemplates.
Expression Blend is something like a XAML design application - you can size, colour, adjust fill and stroke etc on all the elements in a control. It takes a little while to get used to, but you will be able to design controls with a graphical UI and Expression will provide you with the appropriate XAML to use in your project.

Silverlight: Custom Radio button

I am trying to develop a custom radio button that looks like a two-option button control that looks somewhat as shown below with toggling of highlighted state. Not sure where to start.
Is there any such controls already available that I can use.

OK, here is a brief overview of what you will need to do ...
Firstly, you will need to change the ControlTemplate for the existing RadioButton control. There are lots of tutorials available that describe this,, for example this one.
Replace the standard template with some suitable markup for your illustration above. Perhaps a two column Grid?
Within each Grid cell add a Rectangle, one behind Option1, and the other behind Option2
Use the VisualStateManager to change the Fill property of each Rectangle based on the controls current VisualState. i.e. when Pressed toggle the background colours.
The steps above should help you achieve your goal. Please read the linked web pages and the Silverlight documentation. If you are still struggling after that,, come back and ask another question.

WPF (irc) chat log control

I'm trying to learn WPF and was thinking about creating a simple IRC client. The most complicated part is to create the chat log. I want it to look more or less like the one in mIRC:
or irssi:
The important parts are that the text should be selectable, lines should wrap and it should be able to handle quite large logs.
The alternatives that I can come up with are:
StackPanel inside a ScrollViewer where each line is a row
ListView, since that seems more suitable for dynamic content/data binding.
Create an own control that does the rendering on its own.
Is there any WPF guru out there that has some ideas on which direction to take and where to start?

I suggest you start with a good object model independent of the UI, and then try a multi-line TextBox or a RichTextBox.
Whether these will suffice will depend on exactly how long you want the log to be able to get. If you run into performance issues, you may need to look at virtualization.

First of all, you should consider if you want to select only entire row (like in a listbox), or if you want to select certain characters from a row (like in a textbox).
In the first case, I think a ListView or even a ListBox should be enough, both of them support virtualization when bound to collection and there should be no problem with huge amounts of data. A stack panel inside a ScrollViewer is a little bit like reinventing the wheel for this case and creating a new control is not a very inspired approach in my opinion (as the functionality you want can be achieved with the existing controls, in WPF).
In the second case, if you want to select some text inside of a line, or if you want word wrapping for your longest lines in the log and want to select individual parts of the wrapped lines, then you need to use a control more oriented on displaying text. Kent already suggested a RichTextBox, I would add AvalonEdit control or even the WebBrowser control in which you directly modify its HTMLDocument.

I would suggest to use RichTextBox too, and store items in a log file or database, if you run into performance issues.
Another solution is to use the WPF WebBrowser control and modifiy its HTML content with:
webBrowser.NavigateToString("<HTML><H2><B>This page comes using String</B><P></P></H2></HTML>");
More information about using WebBrowser control