Detect click on URL in RichEdit
I am trying to update RichEdit so that it detects URL and enables clicking on it to open in the browser. Detecting URL is easy, I just use the following code from http://www.scalabium.com/faq/dct0146.htm
mask := SendMessage(MNote.Handle, EM_GETEVENTMASK, 0, 0);
SendMessage(MNote.Handle, EM_SETEVENTMASK, 0, mask or ENM_LINK);
SendMessage(MNote.Handle, EM_AUTOURLDETECT, Integer(True), 0);
but the second part doesn't work for me. They give the following code to capture EN_LINK message and processing it:
type
TForm1 = class(TForm)
protected
procedure WndProc(var Message: TMessage); override;
end;
...
procedure TForm1.WndProc(var Message: TMessage);
var
p: TENLink;
strURL: string;
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if (Message.Msg = WM_NOTIFY) then
begin
if (PNMHDR(Message.LParam).code = EN_LINK) then
begin
p := TENLink(Pointer(TWMNotify(Message).NMHdr)^);
if (p.msg = WM_LBUTTONDOWN) then
begin
SendMessage(RichEdit1.Handle, EM_EXSETSEL, 0, LongInt(@(p.chrg)));
strURL := RichEdit1.SelText;
ShellExecute(Handle, 'open', PChar(strURL), 0, 0, SW_SHOWNORMAL);
end
end
end;
inherited;
end;
When I run the program, URL is detected, but clicking on it doesn't do anything. Using debug I found out that Message.Msg = WM_NOTIFY is not true when I click on URL. I then tried to override TRichEdit's WndProc, but result is the same. Any suggestions?
Subclass the RichEdit's WindowProc property and look for the CN_NOTIFY message, for example:
type
TForm1 = class(TForm)
RichEdit1: TRichEdit;
procedure FormCreate(Sender: TObject);
private
PrevRichEditWndProc: TWndMethod;
procedure RichEditWndProc(var Message: TMessage);
procedure SetRichEditMasks;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
PrevRichEditWndProc := RichEdit1.WindowProc;
RichEdit1.WindowProc := RichEditWndProc;
SetRichEditMasks;
end;
procedure TForm1.SetRichEditMasks;
var
mask: Longint;
begin
mask := SendMessage(RichEdit1.Handle, EM_GETEVENTMASK, 0, 0);
SendMessage(RichEdit1.Handle, EM_SETEVENTMASK, 0, mask or ENM_LINK);
SendMessage(RichEdit1.Handle, EM_AUTOURLDETECT, 1, 0);
end;
procedure TForm1.RichEditWndProc(var Message: TMessage);
begin
PrevRichEditWndProc(Message);
case Message.Msg of
CN_NOTIFY:
begin
if (TWMNotify(Message).NMHdr^.code = EN_LINK) then
begin
with PENLink(Message.LParam)^ do
begin
if (msg = WM_LBUTTONDOWN) then
begin
SendMessage(RichEdit1.Handle, EM_EXSETSEL, 0, LongInt(@chrg));
ShellExecute(Handle, 'open', PChar(RichEdit1.SelText), 0, 0, SW_SHOWNORMAL);
end;
end;
end;
end;
CM_RECREATEWND:
begin
SetRichEditMasks;
end;
end;
end;
For me, it only works if the displayed text is the same text as the underlying hyperlink.
I think my problem is that the underlying hyperlink has the attribute CFE_HIDDEN, and so can't be selected by EM_EXSETSEL.
As an example, if I create (in WORD) a link with the url http://www.rubbish.com, but which displays the text RUBBISH, although the chrg of the selected text is 11-33 which is 22 characters - the same length as the URL, the actual text returned by the method is RUBBISH.
However, I've discovered that if I use WM_GETTEXT, the whole of the link is returned:
HYPERLINK "http://www.rubbish.com" RUBBISH
From which I can extract the URL based on the chrg.
It feels a little clumsy... but it works. :-)
Have you tried it with a stripped down application to make sure it isn't something else in your program causing problems? I followed the steps from that website in Delphi 2009 and clicking URLs worked just fine.
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