LISTBOX_GetItemText() in LISTBOX user draw function cause crashed

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  • LISTBOX_GetItemText() in LISTBOX user draw function cause crashed

    Hello all,

    Now I ran into a very annoying issue:

    The code always crashed when calling LISTBOX_GetItemText() in LISTBOX user draw function.
    All I known is that, the code is inherited from an earlier project which works very well.

    When I look into this issue, I found this is the reason:

    C Source Code

    1. char String[150];
    2. LISTBOX_GetItemText (hWin, pDrawItemInfo->ItemIndex, String, sizeof (String));


    I comment them, and fill the char array "String" with const string, everything works very well:

    C Source Code

    1. char String[150] = "TEST";


    I do add strings to the LISTBOX before setting user draw function:

    C Source Code

    1. LISTBOX_AddString (hObj, UI_StringTable[StringId]);


    Also, if I don't use user draw function, everything also runs well.
    The strings displayed are just the ones I added.

    So, the problem is, where goes wrong?
    How can I tell whether the strings attached to the LISTBOX or not?
    My emWin version is v5.4.0. Any ideas? Thanks in advance.

    Kenmux

  • Well, I took place the library file with source codes and looked into this issue.

    But, it still seems not that easy to find the problem.

    I focused on the function LISTBOX_GetItemText() and the code crashed on this line:

    C Source Code

    1. GUI__MEMCPY(pBuffer, pString, CopyLen);


    But it seems that all local variables are sane:



    Then where goes wrong? Just confused...
    Any ideas?

    Thanks,
    Kenmux

  • Okay, a further step:
    1) GUI__MEMCPY links to memcpy which causes crash
    2) there's an optional replacement for memcpy which test good: GUI__memcpy

    So, can I replace memcpy with GUI__memcpy globally? Any potential risks?
    Similarly, GUI__memset vs memset?

    Also, the reason why memcpy caused crash unknown.

    Who can give some clear answers, thanks in advance.

    Kenmux

  • Hi,

    If memcpy crashes, we can't do much. Also, I can't say why it crashes.

    You can set a custom memcpy routine. Simply add something like this to your GUIConf.h (since it is a preprocessor define, you would need to rebuild the library):

    #define GUI_MEMCPY GUI__memcpy

    Regards,
    Sven
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  • Hello Sven,

    Thanks for your reply.
    Yes I do that in the header file "GUI_ConfDefaults.h".
    And the library file re-created works very well now.
    I hope there's no potential risk, please!!!

    Thanks,
    Kenmux