Hello,

I am developing an application which makes use of several pop up menus that are built on-the-fly. The menus are created using:

MENU_Handle hMenu = MENU_CreateEx(0, 0, 0, 0, WM_UNATTACHED, 0, MENU_CF_VERTICAL, 0);

and populated:

static void prvAddEntry(MENU_Handle hMenu, const char *label, U16 id, U16 flags) {
MENU_ITEM_DATA entry;

entry.pText = label;
entry.Id = id;
entry.Flags = flags;
entry.hSubmenu = 0;

MENU_AddItem(hMenu, &entry);
}

If I need to display the menu, then calling:

MENU_Popup(hMenu, hDialog, 0, 0, 0, 0, 0);
WM_SetFocus(hMenu);

shows the menu and gives it keyboard focus. The problem I am having occurs when I come to delete the menu. The manual states that the menu will not be automatically deleted, but when I call WM_DeleteWindow(hMenu) I get a bus fault exception with a PC in GUI_ALLOC_h2p and link register in WM__GetTopLevelLayer.

What is the correct way to delete a pop up menu widget and free the resources that have been allocated?

Regards,

Craig

Hello Adrian,

I have adapted your exemplar code to test in my application:

typedef struct {
char * sText;
U16 Id;
U16 Flags;
} MENU_ITEM;

static MENU_ITEM _aMenuItems[] = {
{"New game", 1, 0},
{"Pass", 2, 0},
{0, 0, MENU_IF_SEPARATOR},
{"Exit", 3, 0},
};

static void _AddMenuItem(MENU_Handle hMenu, MENU_Handle hSubmenu, const char* pText, U16 Id, U16 Flags) {
MENU_ITEM_DATA Item;

Item.pText = pText;
Item.hSubmenu = hSubmenu;
Item.Flags = Flags;
Item.Id = Id;
MENU_AddItem(hMenu, &Item);
}

static void _testCode(void) {
MENU_Handle hMenu;
int i;

hMenu = MENU_CreateEx(0, 0, 0, 0, WM_UNATTACHED, 0, MENU_CF_VERTICAL, 0);
for (i = 0; i < GUI_COUNTOF(_aMenuItems); i++) {
_AddMenuItem(hMenu, 0, _aMenuItems.sText, _aMenuItems[i].Id, _aMenuItems[i].Flags);
}

WM_DeleteWindow(hMenu);
}

As you see in _testCode(), I simply create the menu and delete the window that is returned. When stepping through the function, hMenu is a positive integer (in the last test it was 53) and the code aborts on the WM_DeleteWindow() call. My exception handler returns the following output:

*** Bus Fault Exception ***
R0: 0x01cc0458, R1: 0xc1801f38, R2: 0xc1801f38, R3: 0x20029cb0
SP: 0x2000d618, LR: 0x0806f4f1, PC: 0x0807b342, PSR: 0x41000000
Bus Fault Cause:
Data Bus Error at LR
Address: 0x01cc045c

where the Link Register (LR) is given the symbol WM__GetTopLevelLayer by addr2line and the Program Counter (PC) is GUI_ALLOC_h2p. The address that is returned in the Bus Fault Address Register (0x01cc045c) is not in the addressable space.

My main application is a state machine in which each state creates its own dynamic dialog window. When states are transitioned, the dialog window is destroyed by calling WM_DeleteWindow() and the new dialog is created. I have created a dozen or so states and their associated dialog boxes and everything works except cleaning up the pop-up menu.

Any help you can offer in resolving this issue will be gratefully received.

Regards,

Craig

Hello Adrian,

I do use two layers. Both are allocated memory and I can switch between them.

Regards,

Craig

Hello Adrian,

Have you any thoughts on this problem? I am still struggling to see how to free the resources allocated to a pop-up menu. I have isolated the issue to just two lines of code. Simply creating the menu and deleting it straight away causes the bus fault when WM_DeleteWindow is called:

MENU_Handle hMenu = MENU_CreateEx(0, 0, 0, 0, WM_UNATTACHED, 0, MENU_CF_VERTICAL, 0);
WM_DeleteWindow(hMenu);

However, if the menu is attached to a window:

MENU_Handle hMenu = MENU_CreateEx(0, 0, 0, 0, WM_HBKWIN, 0, MENU_CF_VERTICAL, 0);
WM_DeleteWindow(hMenu);

then no bus fault occurs.

What is the correct way to create a pop-up menu that may or may not be displayed before deletion?

Regards,

Craig

Hello Adrian,

I have checked (and double checked) the linker, etc. I have been very generous with stack sizes, memory pools and frame buffers. In total emWin has been allocated over 12MB of RAM. I have confirmed that task stacks and the emWin memory pool have not over run.

Do you have any idea why I see the issue if the menu is created with a parent window of WM_UNATTACHED, but not if the parent window is WM_HBKWIN?

Regards,

Craig

Hello Adrian,

Some further investigation shows that it is a problem with deleting menus that are currently not displayed. If I have a menu with four submenus (the submenus have item Ids of 100..103) then the following function call will delete the menu without faulting:

void menuDestroy(MENU_Handle hMenu) {
uint8_t i;

MENU_Popup(hMenu, WM_HBKWIN, 0, 0, 0, 0, 0);

for(i = 100; i < 104; i++) {
MENU_ITEM_DATA item;

MENU_GetItem(hMenu, i, &item);

MENU_Popup(item.hSubmenu, WM_HBKWIN, 0, 0, 0, 0, 0);
}

WM_DeleteWindow(hMenu);
}

If I do not call MENU_Popup() then a bus fault occurs. Can this be fixed?

Regards,

Craig