Why does "▶/❚❚" in RichEdit control increase font weight of the text that follows it?

[CYCho]

I found this haphazardly and used it to my benefit. But I'd like to know why and how it works. ❚ (ChrW(0x0275A)) alone had similar effect, but ▶/❚❚ combination was most suitable for my purpose.

#include <GUIConstantsEx.au3>
#include <GuiRichEdit.au3>
#include <WindowsConstants.au3>

Example()

Func Example()
    Local $hGui, $hRichEdit, $iMsg
    $hGui = GUICreate("Example (" & StringTrimRight(@ScriptName, StringLen(".exe")) & ")", 320, 350, -1, -1)
    $hRichEdit = _GUICtrlRichEdit_Create($hGui, "", 10, 10, 300, 220, _
                    BitOR($ES_MULTILINE, $WS_VSCROLL, $ES_AUTOVSCROLL))
    _GUICtrlRichEdit_SetFont($hRichEdit, 11, "Arial")
    _GUICtrlRichEdit_AppendText($hRichEdit, @CRLF & "1. This is text" & @CRLF & "2. ▶/❚❚ This is more text")
    GUISetState(@SW_SHOW)

    While True
        $iMsg = GUIGetMsg()
        Select
            Case $iMsg = $GUI_EVENT_CLOSE
                _GUICtrlRichEdit_Destroy($hRichEdit) ; needed unless script crashes
                ; GUIDelete()   ; is OK too
                Exit
        EndSelect
    WEnd
EndFunc   ;==>Example

 

Edited November 30 by CYCho

[CYCho]

I made this code in order to see the difference between the bold text and the effect created by some unicode characters in the RichEdit control. I can take benefit of this unicode phenomenon, but the problem is that I cannot cancel the effect until the end of the text.

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#include <GUIConstantsEx.au3>
#include <GuiRichEdit.au3>
#include <WindowsConstants.au3>

Example()

Func Example()
    Local $hGui, $hRichEdit, $iMsg
    $hGui = GUICreate("Example (" & StringTrimRight(@ScriptName, StringLen(".exe")) & ")", 320, 350, -1, -1)
    $hRichEdit = _GUICtrlRichEdit_Create($hGui, "", 10, 10, 300, 220, _
                    BitOR($ES_MULTILINE, $WS_VSCROLL, $ES_AUTOVSCROLL))
    _GUICtrlRichEdit_SetFont($hRichEdit, 12, "Arial")

    Local $sText1 = "2. This is bold text"
    Local $sText2 = "1. This is plain text" & @LF & $sText1 & @LF & "▶/❚❚" & @LF & "3. This is more plain text"
    _GUICtrlRichEdit_AppendText($hRichEdit, $sText2)

    ; Hide "▶/❚❚" in the production
;~  Local $iBegin = StringInStr($sText2, "▶/❚❚") - 1
;~  Local $iEnd = $iBegin + 4
;~  _GUICtrlRichEdit_SetSel($hRichEdit, $iBegin, $iEnd, True)
;~  _GUICtrlRichEdit_SetCharColor($hRichEdit, 0xFFFFFF)
;~  _GUICtrlRichEdit_ChangeFontSize($hRichEdit, -12)

    ; Set 2nd line to bold typeface
    $iBegin = StringInStr($sText2, $sText1) - 1
    $iEnd = $iBegin + StringLen($sText1)
    _GUICtrlRichEdit_SetSel($hRichEdit, $iBegin, $iEnd, True)
    _GUICtrlRichEdit_SetCharAttributes($hRichEdit, "+bo")

    GUISetState(@SW_SHOW)

    While True
        $iMsg = GUIGetMsg()
        Select
            Case $iMsg = $GUI_EVENT_CLOSE
                _GUICtrlRichEdit_Destroy($hRichEdit) ; needed unless script crashes
                ; GUIDelete()   ; is OK too
                Exit
        EndSelect
    WEnd
EndFunc   ;==>Example

Edited December 1 by CYCho

[CYCho]

I found that the effect of ▶/❚❚ varies depending on the OS character sets. It was very much noticeable in my computer which has Hangeul character set as default. So if you want to see the same effect as I see, you should use
 

_GUICtrlRichEdit_SetFont($hRichEdit, 12, "Arial", 129)

instead of
 

_GUICtrlRichEdit_SetFont($hRichEdit, 12, "Arial")

in the example above.

Edited November 29 by CYCho

[jchd]

Unicode codepoint 0x0275A (❚ HEAVY VERTICAL BAR) has no special effect on subsequent text.

In other codepages, it's difficult to determine out of the blue what the character renderer will do.

[pixelsearch]

@CYCho today I was able to test your 1st script at my brother's home (Win11 x64)  Here is the display on his computer, using charset 129 :

...
_GUICtrlRichEdit_SetFont($hRichEdit, 14, "Arial", 129) ; $HANGEUL_CHARSET = 129
_GUICtrlRichEdit_AppendText($hRichEdit, @CRLF & "1. This is text" & @CRLF & "2. ▶/❚❚ This is more text")
...

So the 2nd "This is more text" appears bolder compared to the 1st one (as you noticed)
IIRC charset 130 (the Korean $JOHAB_CHARSET) displayed same as 129
And when no charset parameter was set, then both "This is more text" looked same.
For what it's worth...