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RichEdit does not handle hyperlinks

I want my RichEdit to handle hyperlinks, so I followed these instructions: http://delphi.about.com/od/vclusing/l/aa111803a.htm

Here are the changes I made to the code:

interface type TProgCorner = class(TForm) RichEdit2: TRichEdit; RichEdit1: TRichEdit; RichEdit3: TRichEdit; RichEdit4: TRichEdit; procedure FormCreate(Sender: TObject); private procedure InitRichEditURLDetection(RE: TRichEdit); protected procedure WndProc(var Msg: TMessage); override; end; implementation {$R *.DFM} uses ShellAPI, RichEdit; const AURL_ENABLEURL = 1; AURL_ENABLEEAURLS = 8; procedure TProgCorner.InitRichEditURLDetection(RE: TRichEdit); var mask: LResult; begin mask := SendMessage(RE.Handle, EM_GETEVENTMASK, 0, 0); //In the debugger mask is always 1, for all 4 Richedits. SendMessage(RE.Handle, EM_SETEVENTMASK, 0, mask or ENM_LINK); //returns 67108865 SendMessage(RE.Handle, EM_AUTOURLDETECT, AURL_ENABLEURL, 0); //Returns 0 = success (according to MSDN), but no joy. //SendMessage(RE.Handle, EM_AUTOURLDETECT, AURL_ENABLEEAURLS, 0); //When uncommented returns -2147024809 //I don't think the registration works, but don't know how to fix this. end; procedure TProgCorner.WndProc(var Msg: TMessage); var p: TENLink; sURL: string; CE: TRichEdit; begin //'normal' messages do get through here, but... if (Msg.Msg = WM_NOTIFY) then begin //...the following line is never reached. if (PNMHDR(Msg.lParam).code = EN_LINK) then begin p:= TENLink(Pointer(TWMNotify(Msg).NMHdr)^); if (p.Msg = WM_LBUTTONDOWN) then begin try CE:= TRichEdit(ProgCorner.ActiveControl); SendMessage(CE.Handle, EM_EXSETSEL, 0, LPARAM(@(p.chrg))); sURL:= CE.SelText; ShellExecute(Handle, 'open', PChar(sURL), 0, 0, SW_SHOWNORMAL); except {ignore} end; end; end; end; inherited; end; procedure TProgCorner.FormCreate(Sender: TObject); begin InitRichEditURLDetection(RichEdit1); InitRichEditURLDetection(RichEdit2); InitRichEditURLDetection(RichEdit3); InitRichEditURLDetection(RichEdit4); //If I set the text here (and not in the object inspector) //the richedit shows a hyperlink with the 'hand' cursor. //but still no WM_notify message gets received in WndProc. RichEdit1.Text:= 'http://www.example.com'; end; end.

However, the hyperlinks that I put into my RichEditx.Lines using the object inspector appear as plain text (not links), and clicking on them does not work.

I am using Delphi Seattle running on Windows 7 in Win32 mode.

What am I doing wrong?

UPDATE
Using a combination of issuing legacy SendMessage(RE.Handle, EM_AUTOURLDETECT, AURL_ENABLEURL, 0); and setting RichEditx.Text:= 'http://www.example.com' manually in FormCreate I can show the Richedit hyperlink and cursor.
However, WndProc still does not receive the WM_Notify message.
WndProc receives other messages.

UPDATE2
In my quest to simplify the problem, I did not take into account the fact that RichEdit is on top of the Panel . The panel eats WM_Notify messages, so they do not reach the form below.

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2 answers

The code shown in your question is great for me as-is . Despite your complaints, the WndProc() form receives EN_LINK notifications and triggers clicks on the URL as expected.

However, if you put RichEdit in another parent control, for example a TPanel , the Form will no longer receive the WM_NOTIFY message. The parent control will receive them, and so you will have to subclass this parent control.

There are several improvements that can be made to the code shown:

  • in your processing EN_LINK , you can replace this:

     CE := TRichEdit(ProgCorner.ActiveControl);

    instead of this:

     CE := TRichEdit(FindControl(TWMNotify(Msg).NMHdr.hwndFrom));

    The notification tells you the HWND of the RichEdit control that sends it, and the VCL knows how to extract TWinControl from the HWND .

  • use EM_GETTEXTRANGE to get the URL with a click, instead of using EM_EXSETSEL and SelText (which is a combination of EM_EXGETSEL and EM_GETTEXTEX ). Thus, you use less messages and do not have to manipulate the selected RichEdit text yourself. The notification tells you the exact range of characters for the URL, so you can simply capture these characters directly.

  • you need to handle HWND relaxation. VCL can recreate RichEdit HWND at any time. Each time a new HWND is created, you must send your EM_SETEVENTMASK and EM_AUTOURLDETECT messages EM_AUTOURLDETECT , otherwise you will lose your automatic detection. The best way to handle this is to derive the class from TRichEdit and override its CreateWnd() method.

  • Since you must still derive the class, you can process the VCL CN_NOTIFY instead of processing the original WM_NOTIFY message directly in the parent WndProc . VCL knows how to redirect the WM_NOTIFY message to the VCL control that sent it. This allows VCL controls to handle their own notifications. Thus, your EN_LINK handler will work no matter which parent control is included in RichEdit, you do not need to subclass / override the parent WndProc() at all, and you can use the Self RichEdit pointer, which processes the message when accessing RichEdit members, for example to the Handle property.

With all that said, the following code works for me:

 unit RichEditUrlTest; interface uses Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ComCtrls; type TRichEdit = class(Vcl.ComCtrls.TRichEdit) private procedure CNNotify(var Message: TWMNotify); message CN_NOTIFY; protected procedure CreateWnd; override; end; TProgCorner = class(TForm) RichEdit2: TRichEdit; RichEdit1: TRichEdit; RichEdit3: TRichEdit; RichEdit4: TRichEdit; procedure FormCreate(Sender: TObject); private { Private declarations } public { Public declarations } end; var ProgCorner: TProgCorner; implementation {$R *.dfm} uses Winapi.ShellAPI, Winapi.RichEdit; const AURL_ENABLEURL = 1; AURL_ENABLEEAURLS = 8; procedure TRichEdit.CreateWnd; var mask: LResult; begin inherited; mask := SendMessage(Handle, EM_GETEVENTMASK, 0, 0); SendMessage(Handle, EM_SETEVENTMASK, 0, mask or ENM_LINK); SendMessage(Handle, EM_AUTOURLDETECT, AURL_ENABLEURL, 0); end; procedure TRichEdit.CNNotify(var Message: TWMNotify); type PENLink = ^TENLink; var p: PENLink; tr: TEXTRANGE; url: array of Char; begin if (Message.NMHdr.code = EN_LINK) then begin p := PENLink(Message.NMHdr); if (p.Msg = WM_LBUTTONDOWN) then begin { optionally, enable this: if CheckWin32Version(6, 2) then begin // on Windows 8+, returning EN_LINK_DO_DEFAULT directs // the RichEdit to perform the default action... Message.Result := EN_LINK_DO_DEFAULT; Exit; end; } try SetLength(url, p.chrg.cpMax - p.chrg.cpMin + 1); tr.chrg := p.chrg; tr.lpstrText := PChar(url); SendMessage(Handle, EM_GETTEXTRANGE, 0, LPARAM(@tr)); ShellExecute(Handle, nil, PChar(url), 0, 0, SW_SHOWNORMAL); except {ignore} end; Exit; end; end; inherited; end; procedure TProgCorner.FormCreate(Sender: TObject); begin RichEdit1.Text:= 'http://www.example.com'; end; end.
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The problem is that the WM_Notify message never reaches the main form.
Instead, it is intercepted by the Richedit parent (panel I, which I placed there for alignment).
I mistakenly refused this fact in the question, thinking that it did not matter.
However, the following worked for me.

However, I strongly recommend Remy an architecturally more robust approach, and people struggling with this problem should first try this approach.

In VCL.ComCtrls

  TCustomRichEdit = class(TCustomMemo) private //Why private !? procedure CNNotify(var Message: TWMNotifyRE); message CN_NOTIFY;

The solution is to insert our own TRichEdit:

 uses ...., RichEdit; type TRichEdit = class(ComCtrls.TRichEdit) procedure CNNotify(var Message: TWMNotifyRE); message CN_NOTIFY; end; //never mind that its ancester is private, it will still work. TProgCorner = class(TForm)

I store RichRdits in an array, so I can look at them on their HWnd without having a loop, although all are children of my form.

 implementation function TProgCorner.RichEditByHandle(Handle: HWnd): TRichEdit; var i: integer; begin //Keep track of the richedits in an array, initialized on creation. for i:= Low(RichEdits) to High(RichEdits) do begin if RichEdits[i].Handle = Handle then exit(RichEdits[i]); end; Result:= nil; end; procedure TRichEdit.CNNotify(var Message: TWMNotifyRE); var p: TENLink; sURL: string; CE: TRichEdit; begin if (Message.NMHdr.code = EN_LINK) then begin p:= TENLink(Pointer(TWMNotify(Message).NMHdr)^); if (p.Msg = WM_LBUTTONDOWN) then begin try //CE:= TRichEdit(ProgCorner.ActiveControl); //SendMessage(CE.Handle, EM_EXSETSEL, 0, Longint(@(p.chrg))); SendMessage(p.nmhdr.hwndFrom, EM_EXSETSEL, 0, Longint(@(p.chrg))); CE:= ProgCorner.RichEditByHandle(p.nmhdr.hwndFrom); if assigned(CE) then begin sURL:= CE.SelText; ShellExecute(Handle, 'open', PChar(sURL), 0, 0, SW_SHOWNORMAL); end; except {ignore} end; end; end; inherited; end;

Fortunately, the interaction of message handlers works, although the original is declared closed.

Now it works. Like witchcraft.

Below is a complete copy of the device for future reference:

 unit ProgCorn; interface uses Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls, ExtCtrls, ComCtrls, Menus, Clipbrd, LifeConst, Tabnotbk, LifeUtil, MyLinkLabel, RichEdit; type TRichEdit = class(ComCtrls.TRichEdit) procedure CNNotify(var Message: TWMNotifyRE); message CN_NOTIFY; end; TProgCorner = class(TForm) Panel1: TPanel; Panel2: TPanel; Label1: TLabel; TabbedNotebook1: TTabbedNotebook; PopupMenu1: TPopupMenu; Copy1: TMenuItem; Panel3: TPanel; Button1: TButton; RichEdit1: TRichEdit; RichEdit2: TRichEdit; RichEdit3: TRichEdit; RichEdit4: TRichEdit; Button2: TButton; procedure Copy1Click(Sender: TObject); procedure PopupMenu1Popup(Sender: TObject); procedure FormCreate(Sender: TObject); procedure Button2Click(Sender: TObject); private RichEdits: array[1..4] of TRichEdit; procedure InitRichEditURLDetection(RE: TRichEdit); function RichEditByHandle(Handle: HWnd): TRichEdit; public { Public declarations } end; var ProgCorner: TProgCorner; implementation {$R *.DFM} uses ShellAPI; const AURL_ENABLEEAURLS = 8; AURL_ENABLEURL = 1; procedure TProgCorner.InitRichEditURLDetection(RE: TRichEdit); var mask: NativeInt; begin mask := SendMessage(RE.Handle, EM_GETEVENTMASK, 0, 0); SendMessage(RE.Handle, EM_SETEVENTMASK, 0, mask or ENM_LINK); SendMessage(RE.Handle, EM_AUTOURLDETECT, {AURL_ENABLEEAURLS} AURL_ENABLEURL, 0); end; procedure TProgCorner.FormCreate(Sender: TObject); begin ProgCorner:= Self; InitRichEditURLDetection(RichEdit1); InitRichEditURLDetection(RichEdit2); InitRichEditURLDetection(RichEdit3); InitRichEditURLDetection(RichEdit4); RichEdits[1]:= RichEdit1; RichEdits[2]:= RichEdit2; RichEdits[3]:= RichEdit3; RichEdits[4]:= RichEdit4; //WordWarp should be set during runtime only, because //otherwise the text will not warp, but rather be cut off //before run time. RichEdit1.Text:= RichEdit1.Text + ' '; RichEdit2.Text:= RichEdit2.Text + ' '; RichEdit3.Text:= RichEdit3.Text + ' '; RichEdit4.Text:= RichEdit4.Text + ' '; RichEdit1.WordWrap:= true; RichEdit2.WordWrap:= true; RichEdit3.WordWrap:= true; RichEdit4.WordWrap:= true; end; procedure TProgCorner.Copy1Click(Sender: TObject); var ActiveRichEdit: TRichEdit; begin ActiveRichEdit:= TRichEdit(Self.FindComponent('RichEdit'+ IntToStr(TabbedNotebook1.PageIndex+1))); with ActiveRichEdit do begin if SelText <> '' then Clipboard.AsText:= SelText else ClipBoard.AsText:= Lines.Text; end; {with} end; procedure TProgCorner.PopupMenu1Popup(Sender: TObject); begin Copy1.Enabled:= true; end; procedure TProgCorner.Button2Click(Sender: TObject); begin Application.HelpContext(4); end; { TRichEdit } function TProgCorner.RichEditByHandle(Handle: HWnd): TRichEdit; var i: integer; begin for i:= Low(RichEdits) to High(RichEdits) do begin if RichEdits[i].Handle = Handle then exit(RichEdits[i]); end; Result:= nil; end; procedure TRichEdit.CNNotify(var Message: TWMNotifyRE); var p: TENLink; sURL: string; CE: TRichEdit; begin //if (Message.Msg = WM_NOTIFY) then begin if (Message.NMHdr.code = EN_LINK) then begin p:= TENLink(Pointer(TWMNotify(Message).NMHdr)^); if (p.Msg = WM_LBUTTONDOWN) then begin try //CE:= TRichEdit(ProgCorner.ActiveControl); //SendMessage(CE.Handle, EM_EXSETSEL, 0, Longint(@(p.chrg))); SendMessage(p.nmhdr.hwndFrom, EM_EXSETSEL, 0, Longint(@(p.chrg))); CE:= ProgCorner.RichEditByHandle(p.nmhdr.hwndFrom); if assigned(CE) then begin sURL:= CE.SelText; ShellExecute(Handle, 'open', PChar(sURL), 0, 0, SW_SHOWNORMAL); end; except {ignore} end; end; end; //end; inherited; end; end.
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Source: https://habr.com/ru/post/1276874/

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