How to implement the mouse click for URLs at rich edit control

Question

I added a read-only rich edit 2.0 control to my dialog (code is using C windows API, the dialog is created by using function DialogBox)

At the dialog call back, at the WM_INITDIALOG, I add the following code to enable url detection and also enable the event ENM_LINK is sent to the parent dialog instead of the rich edit control itself:

LRESULT mask = SendMessage(hWndText, EM_GETEVENTMASK, 0, 0); //hWndText is rich edit control
SendMessage(hWndText, EM_SETEVENTMASK, 0, mask | ENM_LINK);
::SendMessage(hWndText, EM_AUTOURLDETECT, TRUE, NULL);  

I had a little trouble to enable the url detection when dialog is initially launched (which seems a known issue or behavior since rich edit control would only enable url detection of modified text). However I worked around this issue by setting the dialog text again on every WM_PAINT event.

The code is generally working. I also implemented the following code to launch the URL at the browser when mouse is hovering over the url:

case WM_NOTIFY:
    plink = (ENLINK *) lParam;
    switch(LOWORD(wParam))
    {   
        case IDC_DISPLAY_TEXT_2: //this is ID for my rich edit control
            szURL =m_strDisplay.Mid(plink->chrg.cpMin, plink->chrg.cpMax - plink->chrg.cpMin);          
            LaunchURL(szURL); //function to launch the url with default browser
            break;
        default:
            break;
    }

It seems that I would get WM_NOTIFY event every time when I hovered the mouse over the url. However when I clicked on it, I always get same event as the mouse hover over.

Based on the structure of ENLINK, I should get more detailed NM event at the NMHDR structure, however the value plink->nmhdr.code is always 1803 which is not even NM_HOVER (its defined value is (NM_FIRST-13) and NM_FIRST is (0U- 0U), so NM_HOVER value is 4294967283 on my 64 bit machine). I know that I am missing something here. Could someone shed some lights here? How can I get the mouse click event for the rich edit control?

Answer 1

I think you should capture the EN_LINK notification. I implemented the following code. It enables a url link in a richedit control placed into the parent window, not into a dialog. You could adapt it for your dialog, as well.

Consider beginning with the code:

case WM_NOTIFY: {
switch (((LPNMHDR)lParam)->code) { //NMHDR structure contains information about a notification message.
        case EN_LINK: {
            ENLINK *enLinkInfo = (ENLINK *)lParam; // pointer to a ENLINK structure

then, if you choose to launch url on LBUTTONUP, you have to check the value contained in enLinkInfo->msg (remember to adapt it for your dialog, though)

 if (enLinkInfo->msg == WM_LBUTTONUP) {
// select all the text from enLinkInfo->chrg.cpMin to enLinkInfo->chrg.cpMax
// lauch the url

}

Besides, you can intercept WM_MOUSEMOVE:

if(enLinkInfo->msg == WM_MOUSEMOVE) {
                ; // do nothing
}

Hope it helps.