How do I set the font color of url in RichTextBox control

I have in fact looked through that article but have not been able to apply it to my case.  

Additionally, there are a number of other readers who've posted comments to that same article stating that they were unable to control the foreground (text) color of the links.

I have not tried this myself but you may be able to set 'DetectUrls' = false; and then search for these using regular expressions and updating the color based on a selcetion found.

Right, but my I have some concern with that approach because I still want to be able to handle the user clicking the link and I'm not sure that a regular expression will accurately find more complex URLs.

I understand your frustation -- I can't find anything that clearly describes a solution.

One possible partial workaround you may not have thought of:
Wait until you get an EN_LINK notif -- indicating that the mouse is over a link. The ENLINK structure provides a CHARRANGE, so you could (at that moment) change it's coloring. Perhaps that's better than nothing...

according to this:
   http://msdn.microsoft.com/en-us/library/bb788022(VS.85).aspx

    When Rich Edit locates a URL, it changes the URL text color, underlines the text,
    and notifies the client using EN_LINK.

so perhaps you don't need to wait for the mouse...

The fact that one PC you know of shows the links differently might be a clue. Perhaps there is some global window setting somewhere, akin to the XP viual styles. Or perhaps there is an obscure manifest setting. Sorry... just thinking aloud.

Dan,

I appreciate the idea.  According to the documentation, it looks like this might lead in the right direction, however; I haven't been able to handle/hook/capture the WM_NOTIFY message.

According to MSDN:

"The parent window of the control receives this notification message through a WM_NOTIFY message".

The parent window in my case is a panel control in a splitter on a form.  The code to handle the WM_NOTIFY (that doesn't seem to be hit) is in the form.  I suspect that perhaps the panel is getting the notification and it's not bubbling up to the form.

Can you offer some insight for how I might get a handle on this event/message?  Will I need to create a custom control that extends the panel control and handles this, etc?

Your thoughts are appreciated!

The WM_NOTIFY message goes to the direct parent window of the RE control.  In the dialog-based app I used for testing, I selected the RE control and selected Pop[erties, and clicked the Messages button -- it was listed as EN_LINK.  I added a handler for it.  In your case, I suggest using Spy++ to see where the EN_LINK messages are being sent.  Also, whn you create the RE control, you probably have an option to specify the parent window and you may be leaving it as he default -- which would normally mean that whatever object the Create() function was called.

Note, too that you need to tell the RE control to send the notifs (I assume you've done that because you mentioned that you are alreay handling EN_LINK clicks).

I do have some bad news... I verified that the notif comes ONLY when the mouse passes over the link (or is clicked on the link) -- and one other time, in a WM_SETCURSOR message, also triggered by mouse position/movements.

I could find no message at all when the text was actually transformed to or from underlined blue text.  There is not even an EN_UPDATE message that I could identify as being specifically about that change.

It looks like the RE's URL detection logic was grafted onto the control as an afterthought.

At this point,  I could suggest the somewhat ridiculous route I took in an HTML editor i worked on (see Use CHtmlEditCtrl to Create a Simple HTML Editor )  That is, occasionally extract the RTF source and look for changes and then change them back.  However, even that woun't work here:  The RTF data does not include the RFE_LINK flag and the text does not even have the underlined/blue attribute!   The link formatting is handled entriely programmatically at runtime.  If you save the RTF file, you won't be able to tell that the link was ever displayed differently from the adjacent text.

It might be possible to scan the in-memory RTF to locate text with the RFE_LINK attribute (0x00000020).  However, I think the better method would be to scan the text for any of the the lead-in sequences (http:, ftp:, etc)  listed here: http://msdn.microsoft.com/en-us/library/bb787991(VS.85).aspx  

Do the scanning on a timer, and when you find such a lead-in sequence, check to see if it has the CFE_LINK attribute, and if so, change it as desired.  I don't think that the RE control will change it back unless it detects a change (say the user adds a charater to the end of the URL string).  

That method would be impractical if you have a really long document.  In that case, you could perhaps do what I suspect that the RE control does -- I think that it triggers its logic on EN_CHANGE or EN_UPDATE and then examines the sequence of characters near the selection point.

-- Dan

Dan,

My application is a managed C# app.  The code you reference appears to be C++.  I am not opposed to using an interop solution if I can get it working.

In my properties pane, I don't see EN_LINK or other such messages/events.  The event I am handling for my links is called "LinkClicked" and is I would presume a c# wrapper for the EN_LINK clicks behind the scene.

Also, in Spy++ I don't see the EN_LINK messages, I was thinking I was looking for a WM_NOTIFY, but didn't see any of those with EN_LINK either.  It could be that my RTB is not configured to send the notifs...

I've set a breakpoint and observed the RTF in the control, it does not appear to have any indication of the link.

This RTB in question is simply for displaying rich text.  If it helps in proposing solutions, this text is updated regularly with new messages, but the existing text is not modified.  Also, the text is inserted into the RTB programatically (in response to events that are raised), not via any type of direct user interaction.

I appreciate your patience and understanding!

Are you outputing/appending lines of text to a log file?

If so, the user's random actions probably don't need to be taken into account.  As soon as you append a line of text, add a line break (that should trigger RE's built-in URL detection and cause the RE to change the formatting to give it the RFE_LINK attribute).  

So, directly after appending the line and the linebreak, look though the previous line and try forcing some color changes, only on characters that haf the RFE_LINK attribute.

In fact, if you scan each line as you output it, you will know in advance that RE will tweak it, so you need take special actions only after appending a line that contains "http:" (etc.)

Wow.  My frame of reference in the TichText control -- not the .NET RTB.  I just spent an hour looking through the docs... There are about one zillion members, attributes, and events, but not one of them seems to be of any use.  We can't use EM_SETCHARFORMAT  to get a CHARFORMAT2 that would tell us that RFE_LINK has been set.  I just hate it when otherwise smart people think they are doing me a favor by hiding the underlying access to the control.   You might be abel to detect some stuff by adding handlers for one or more of these:

Control..::.OnNotifyMessage Method
Control..::.PreProcessControlMessage Method
Control..::.PreProcessMessage Method

But I have a different idea that may work.  I noticed that when I added BOLD to an RFE_LINK-attributed  it became bold, but also went underlined and blue.  What if you try adding various other attributes, such as SelectionProtected or perhaps strikethrough or something?  Maybe just setting SelectionBackColor would solve the problem.

To make this work, you would still need to recognize the special URL lead-in sequences just before appending the text into the control.  Save the current cursor location, insert the text (plus a space or linebreak, perhaps -- to trigger the automatic action), then set the desired attribute beginning at the saved location and extending for the length of the inserted text.
 

Dan,

I apologize for not getting back more promptly.  I'm still working on this, but am having no luck picking out the links.  I really feel like we're on the right path, but am getting a bit frustrated with my inability to break through...

I am almost ready to just change to a webbrowser control and use the additional formatting options of HTML/CSS since this is strictly for output not user input.

It does seem however, that there should be a way to do this and I'd like to find an answer for future people looking for the same solution.

I'll keep you posted, and thanks!

Are you going the route of pre-processing the output text, looking for lead-in sequences (http, ftp, etc.)?  That seems to be the most promising direction.  It's no good for a general-use RTB, it it sure seems like it would work for an on-screen logger in which all text was programmatically added, line-by-line.

I guess I may not have understood that suggestion.  Are you suggesting that I "detect" the URLs myself by parsing for the "lead-in sequences" as you call them?

I would prefer to utilize the built in DetectUrls...  I have tried looking in the methods you suggested to determine if there is anything about the links (text or RTF) that the DetectUrls adds, and I can't find a way to handle them.

You would still use the DetectUrls setting, and clicks would work normally.

The difference is that you also detect the URLs -- before inserting a line of text, then take action after the control has underlined the URL.  The action would be to select that text and add some highlighing/color-setting of your own.

The only tricky/unknown part:  
You might need to wait a while before modifying the format.  I can't be sure whether the RTB will overwrite all of the character attributes when it does its URL formatting.   It will probably only modify the forecolor and the underlining.   So, if you set, say, the background color, that might stick.

If, on the other hand, the RTB immediately resets all character attribute when it does its blue/underline thing, then you will need to give it some time... let it set the attributes, then you go back and set them to what you want...  Try it out.  If that's the case, I'll describe a possible way to handle that scenario.

-- Dan

Dan,

I think I'm doing what you describe (if you look at the code snippet in the original question).  I am inserting a line of text, creating a selection and applying font formatting to that selection (which should include the link).

The problem is that even after changing the font formatting, the RTB seems to override the colors I've selected for the link within the selection.

You said you might have a way to handle this scenario?

Watching how the RichText control works, it looks like the control is doing the URL detection as perhaps an idle-time background sort of thing.  

You are inserting th text, and then settings the color -- all in one action.... the RTB then gets a chance to undo your formatting.  

What I propose is that you allow the RTB time to do its thing, then go back and change it (I do not think it will change it back afterwards -- unless there is a user keystroke or other triggering action near the URL text (I admit I haven't tested this theory).

My try at implementing this would be along the lines of:

At the end of DisplayMessage, add logic to detect a url in newMessage.  If so, save the startpos and the length into member variables.  If not, set m_nNeedToFixStartPos variable to -1.

At the start of DisplayMessage, if m_nNeedToFixStartPos is not -1, then re-select it and re-color, using perhaps a different background color and then set m_nNeedToFixStartPos to -1 ...

Then proceed with the normal end-of-data insertion.

In otherwords, look for a "pending fixup" and handle it.  Then append the new message.  Then check to see if you need to schedule another "pending fixup"

--------
I'd normally provide code, but I'm unfamiliar with C# and have not worked with RTB.

A variation:  If RTB changes the formatting back later, then rather than formatting the entire URL, try changing just the text after "http:" -- or look for some other quirky way to avoid having the RTB notice your change.

Dan,

I hadn't thought of this approach.  It sounds like a viable option in my case because I'm not trying to specifically set the URL color to something other than my text color.  I'm just trying to keep it from matching the background color.

I am away from the project at the moment, but when I get back to the office I'll give this a try and report back.

Thanks again!

Dan,

I wasn't sure what event to look for to handle this "afterward" so I added a button for testing and modified colors in the click handler for that button.

In my test, I wasn't even looking specifically for the URL patterns.  I simply made a selection from 0 to the length of the text and applied coloring to it.

In this simple test, the colors applied (background and foreground) to all the text EXCEPT the URLs.  The system default or whatever it is was still applied to the URLs.

No luck...

Dan,

I updated the code to detect the lead-in sequences and to change the background color to one that has a high enough contrast with the default foreground.  I can now see my links (it looks like a highlighter on paper if you will).

This is less than ideal (I'd still like to be able to control the foreground), but it does seem like a possible interim solution.