Fixed: Position of caret now only consider visible characters

 CaretPos returns the location of the cursor on the line Y and position X, counting both visible and hidden characters.
 Hidden are mainly those corresponding to hyperlinks (HYPERLINK "<URL>"), although there may also be some hidden
 characters used by KeyNote to identify images or set bookmarks for the location of KNT Links.
 The way RichEdit manages selection of hyperlinks does not make it easy to obtain the visible number of characters
 from the left of current line to current position.

 KeyNote now calculates the visible value, optimizing the way it is done so to avoid any slight flickering that
 could be noticeable in certain parts of the editor.

Ref: #672

3rd_party/unRxLib/units/RxRichEd.pas

@@ -624,7 +624,7 @@   TRxCustomRichEdit = class(TCustomMemo)
     procedure Redo;
     procedure StopGroupTyping;
     procedure BeginUpdate;                                             // [dpv]
-    procedure EndUpdate;                                               // [dpv]
+    procedure EndUpdate (InvalidateAndRefresh: boolean= true);         // [dpv]
     procedure RemoveMargins;                                           // [dpv]
     property CanFindNext: Boolean read GetCanFindNext;
     property CanRedo: Boolean read GetCanRedo;
@@ -6820,14 +6820,16 @@ procedure TRxCustomRichEdit.BeginUpdate;
   This method should be called every time a call is made made to BeginUpdate. It resets the event mask to it's
   original value and enables redrawing of the control.}
 
-procedure TRxCustomRichEdit.EndUpdate;
+procedure TRxCustomRichEdit.EndUpdate (InvalidateAndRefresh: boolean= true);
 begin
     FUpdating:= FUpdating -1;                                        // Deal with nested calls
     if FUpdating <= 0 then begin
         SendMessage(Handle, WM_SETREDRAW, 1, 0);                     // Allow the control to redraw itself
         SendMessage(Handle, EM_SETEVENTMASK, 0, FOldEventMask);      // Allow the control to raise event messages
-        Invalidate;
-        Refresh;
+        if InvalidateAndRefresh then begin
+           Invalidate;
+           Refresh;
+        end;
     end;
 end;
 

knt.App.pas

@@ -372,6 +372,7 @@ procedure TKntApp.EditorSelected (Editor: TKntRichEdit; Focused: boolean);
     if Editor.Focused then begin
        UpdateEnabledActionsAndRTFState(Editor);
        ShowCurrentZoom(Editor.GetZoom);
+       Editor.UpdateCursorPos;
     end;
 
     if assigned(Editor.NoteObj) then begin

ui/knt.ui.editor.pas

@@ -95,6 +95,8 @@   TKntRichEdit = class( TRxRichEdit )
     FZoomGoal: integer;
     FZoomCurrent: integer;
 
+    LastSS, LastPy, LastPx, LastX : integer;
+
     FIgnoreSelectionChange: boolean;
     FChangedSelection: TChangedSelectionEvent;
 
@@ -448,6 +450,11 @@ constructor TKntRichEdit.Create( AOwner : TComponent );
   FZoomGoal:= 100;
   FZoomCurrent:= -1;
 
+  LastSS:= -1;
+  LastPy:= -1;
+  LastPx:= -1;
+  LastX:= -1;
+
   OnProtectChangeEx:= RxRTFProtectChangeEx;
   OnURLClick:= RxRTFURLClick;
 
@@ -1184,6 +1191,7 @@ procedure TKntRichEdit.KeyDown(var Key: Word; Shift: TShiftState);
                         SelStart:= L;              // It was not hidden. We leave it where it was and allow the keyboard event to be handled as normal.
                    finally
                       FIgnoreSelectionChange:= false;
+                      UpdateCursorPos;
                    end;
                 end;
              end;
@@ -2320,23 +2328,106 @@ procedure TKntRichEdit.CheckWordCountWaiting;
    end;
 end;
 
+
+
+
 procedure TKntRichEdit.UpdateCursorPos;
 var
   p : TPoint;
-  SelectedVisibleText: string;
-  SL: integer;
+  Str: string;
+  SSi, SS, SSexp, SL, V, X, IncX: integer;
 begin
     SL:= SelLength;
+    SS:= SelStart;
     if ( SL > 0 ) then ShowingSelectionInformation:= true;
 
     if EditorOptions.TrackCaretPos then begin
+      {
+       CaretPos returns the position of the cursor on the line as x (p.X), counting both visible and hidden characters.
+       Hidden are mainly those corresponding to hyperlinks (HYPERLINK "<URL>"), although there may also be some hidden
+       characters used by KeyNote to identify images or set bookmarks for the location of KNT Links.
+       The first thing is to check if we have any hidden characters in the line position we are in. A quick way can be to search
+       for the word HYPERLINK and one of the hidden characters that KNT uses. If there are none, we can safely use the value
+       returned by CaretPos. If the word HYPERLINK was not hidden, nothing happens, we will simply do the calculation by one of
+       the other ways.
+
+       If there are hidden characters on the left, the second thing is to check if the cursor is inside a hyperlink or not.
+       The reason? We will need to select the text from the beginning of the line to be able to obtain the visible text, but
+       if we are within a hyperlink this will select not only to the position we are in, but to the end of the hyperlink.
+       Everything that is selected beyond our position (the rest of the hyperlink) is visible text.
+       After selection -> Consult both the length of the visible text obtained and the most extreme position reached, therefore
+       including the end of the hyperlink. Anything that has expanded the selection too much will be hidden characters that we
+       must subtract from the length of the visible text:
+
+        .....Text of some hyperlink
+        ^         ^               ^
+        SSi       SS              SSexp
+                  <------ D ------>
+        <-------------------------> V
+        <---------> X
+
+       If SS = SSexpand => the cursor is not over any hyperlink.
+
+       Although we use BeginUpdate and EndUpdate(false) (false so that it does not trigger an Invalidate and Refresh after the
+       EndUpdate), a slight flicker is still noticeable in certain parts of the editor at certain times when quickly scrolling
+       through a line in which there are hidden characters (e.g., by having a hidden marker).
+       To avoid this I am going to apply a certain optimization:
+       I am going to save the latest calculated data and try to take advantage of it to minimize the number of times it is necessary
+       to change the selection to see the length of the visible text.
+      }
+
        p := CaretPos;
        if ( SL = 0 ) then begin
-          App.WordCountInfoInStatusBar:= Format( STR_10, [succ( p.y ), Lines.Count, succ( p.x )] );
+          IncX:= 0;
+          X:= -1;
+          SSi:= -1;
+          if (p.Y = LastPy) then begin
+             if (p.X = LastPx+1) or (p.X = LastPx-1) then
+                X:= LastX + (p.X - LastPx)
+             else
+             if (SS > LastSS) and (LastX > 0) then begin
+                SSi:= LastSS;
+                IncX:= LastX;
+             end
+             else
+                LastPx:= 0;
+          end
+          else
+              LastPx:= 0;
+
+          if X < 0 then begin
+             if SSi = -1 then
+                SSi:= Perform(EM_LINEINDEX, p.y, 0);
+
+             Str:= GetTextRange(SSi, SSi + p.X - LastPx);
+             if (pos(KNT_RTF_HIDDEN_MARK_L_CHAR, Str, 1) = 0) and (pos('HYPERLINK ', Str, 1) = 0) then
+                X:= (p.X - LastPx) + IncX
+
+             else begin
+                FIgnoreSelectionChange:= True;
+                BeginUpdate;
+                try
+                  SetSelection(SSi, SS, false);
+                  SSexp:= SelStart + SelLength;
+                  V:= Length(Self.SelVisibleText);
+                  X:= V - (SSexp-SS) + IncX;
+                  SelStart:= SS;
+                finally
+                  EndUpdate (False);
+                  FIgnoreSelectionChange:= False;
+                end;
+             end;
+          end;
+          LastSS:= SS;
+          LastPx:= p.X;
+          LastPy:= p.Y;
+          LastX:= X;
+          App.WordCountInfoInStatusBar:= Format( STR_10, [succ( p.y ), Lines.Count, succ(X)] );
        end
        else begin
-          SelectedVisibleText:= SelVisibleText;
-          App.WordCountInfoInStatusBar:= Format( STR_11, [Length(SelectedVisibleText), GetWordCount( SelectedVisibleText )] );
+          LastPy:= -1;
+          Str:= SelVisibleText;
+          App.WordCountInfoInStatusBar:= Format( STR_11, [Length(Str), GetWordCount(Str)] );
        end;
     end
     else begin