TEXT_SetText() doesn't invalidate window

TEXT_Handle hTxt = WM_GetDialogItem(hWinMain, TEXT_TITLE);
    char s[64];
    GUI_RECT rect;


    printf("\n\n\n");
    TEXT_GetText(hTxt, s, sizeof(s));
    printf("TEXT_GetText(%ld)=%s\n", hTxt, s);
    if (WM_GetInvalidRect(hTxt, &rect) == 0) {
        printf("WM_GetInvalidRect(%ld)=0\n", hTxt);
    } else {
        printf("WM_GetInvalidRect(%ld)=1\n", hTxt);
    }


	TEXT_printf(hTxt, "Registro %d..%d/%d", first_entry + 1, first_entry + num_entries, log_size);


    TEXT_GetText(hTxt, s, sizeof(s));
    printf("TEXT_GetText(%ld)=%s\n", hTxt, s);
    if (WM_GetInvalidRect(hTxt, &rect) == 0) {
        printf("WM_GetInvalidRect(%ld)=0\n", hTxt);
    } else {
        printf("WM_GetInvalidRect(%ld)=1\n", hTxt);
    }
    printf("\n\n\n");

Output is

TEXT_GetText(92)=Registro eventi
WM_GetInvalidRect(92)=0
TEXT_GetText(92)=Registro 1..2/9
WM_GetInvalidRect(92)=0

How is possible that TEXT widget area is not invalidated after setting a new text? Indeed I don't see any visible changes.
If I call WM_InvalidateWindow() on the widget, the behaviour is correct and I see the new text in the TEXT widget.

It's an oddy behaviour, because it may depend on the first text set during TEXT_CreateEx(). I create the TEXT widget with the following code:

TEXT_Handle hTxt;
hTxt = TEXT_CreateEx(TOPBAR_LEFT_WIDTH, 0, xSize - 2 * TOPBAR_LEFT_WIDTH, TOPBAR_HEIGHT, hWin, WM_CF_SHOW, TEXT_CF_HCENTER | TEXT_CF_VCENTER, TEXT_TITLE, "Registro eventi");
TEXT_SetBkColor(hTxt, GUI_RED);
TEXT_SetTextColor(hTxt, GUI_WHITE);
TEXT_SetFont(hTxt, TOPBAR_FONT);

If I change the text in TEXT_CreateEx() it is possible that afterwards TEXT_SetText() will invalidate the widget and the new text is drawn.

It seems to me it depends of the length of the old and new string: if they are the same, TEXT_SetText() sometimes decides to not invalidate the text area.

I read somewhere in the forum that there was a bug exactly with TEXT_SetText() when the length of the text does not change. I think I encountered it.

Could you give me more details of which versions are affected of this bug? I read that 6.18c fixed this bug.

I noticed this bug on a simulator under Windows (SeggerEval_WIN32_MSVC_MinGW_GUI_V616.zip). I'm using it because my embedded platform is equipped with MCU from NXP and the emWin last emWin release is v6.16c. Is this version affected of this bug?

I experienced the same problem with v6.16c (NXP binaries), so this bug is present at least since this version.
Unfortunately the last NXP emWin binary is v6.16c, so I can't upgrade.

What do you think of this workaround?

#if (GUI_VERSION >= 61603) && (GUI_VERSION <= 61803)
    TEXT_GetText(hTxt, old_txt, sizeof(old_txt));
    size_t old_len = strlen(old_txt);


    size_t new_len = strlen(new_text);
    if (new_len == old_len) {
        TEXT_SetText(hTxt, "");
    }
#endif
    TEXT_SetText(hTxt, new_text);

Writing this piece of code, another question arose. Is it possible to know the length of a text in a TEXT widget? TEXT_GetText() copies the text of a TEXT widget in a buffer, but I don't know how to size this buffer in advance. I think it should be nice to have a TEXT_GetTextLen().

Do you confirm that this bug appeared for the first time in 61603 (6.16c)?

Is it safe to call WM_NotifyParent() before TEXT_SetText()? Shouldn't it be better to call it after?

#if (GUI_VERSION >= 61603) && (GUI_VERSION <= 61803)
    TEXT_GetText(hTxt, old_txt, sizeof(old_txt));
    size_t old_len = strlen(old_txt);
    size_t new_len = strlen(new_text);
    if (new_len == old_len) {
        WM_InvalidateWindow(hTxt);
    }
#endif
    TEXT_SetText(hTxt, new_text);
#if (GUI_VERSION >= 61603) && (GUI_VERSION <= 61803)
    if (new_len == old_len) {
      WM_NotifyParent(hTxt, WM_NOTIFICATION_TEXT_CHANGED);
    }
#endif

Anyway it's better to compare the old and the new string, because if they were equal, WM_InvalidateWindow isn't needed.

I'm replying to this my old post because I encountered another strange effect related to this issue, I think.

Even with this workaroud, when I call TEXT_SetText("Commutazione veloce") and the current text is "Commutazione lenta", the widget is not updated. Note that the new string has a different length then the old one.

As usual I'm using NXP emWin binaries 6.16c. The bug is present in this version, but in this case the string lengths are different, so I don't know if it is another bug or the same bug that triggers in other conditions.