Changing scene in Model.cpp fails

[starcin]

I have a hardware trigger that needs to change a scene (think a Home button but I cannot use a hardware key event).

I am trying to change the scene for days but I cannot find a working solution.

The best looking solution was this: https://community.st.com/t5/stm32-mcus-touchgfx-and-gui/how-to-implement-quot-switchscreen-quot-in-touchgfx/m-p/384809

Using this method crashes the code. Well technically the code is stuck in this loop in syscalls.c:

void _exit (int status)
{
  _kill(status, -1);
  while (1) {}    /* Make sure we hang here */
}

My code in the model is like this:

void Model::tick()
{
	uint16_t buttonState = getButtonState(16);
    if (buttonState != previousButtonState)
    {
        if (modelListener != 0)
        {
            modelListener->onButtonStateChange(buttonState);
        }
        if (static_cast<ButtonEnum>(buttonState) == ButtonEnum::MENU)
        {
            static_cast<FrontendApplication*>(Application::getInstance())->gotoSplashScreenScreenNoTransition();
        }
        previousButtonState = buttonState;
    }
}

I also tried to increase the minimum heap size since I saw it may be the cause.

The gotoSplashScreenNoTransition() is automatically generated since it is may entrance point.

[GaetanGodart]

Hello @starcin ,

Could you share the stack call?

Could you put breakpoints to see what is causing the issue?

Could you try to do a simple action when your button is clicked and try to call your screen change from another action to see what works and what doesn't?

Regards,

[starcin]

Hi @GaetanGodart 

Thanks for the quick reply. I don't know how to get the stack call since the program didn't crash but actually navigated to an infinite loop. I am not familiar with CubeIDE.

I tried to call the goto____NoTransition function from a presenter and it went to the infinite loop again.

The thing I forgot to say is, actually the screen transition happens. I can see the new screen on my display then nothing responds. When I pause the program using IDE, I can see that it is in syscall.c -> _exit function.

I placed a breakpoint to my line:

static_cast<FrontendApplication*>(Application::getInstance())->gotoScreen2ScreenNoTransition();

Then I moved step by step and when I got to the _exit function, the list on the left side (I hope this is the stack trace) was like this:

[starcin]

Now I realize that something is wrong about the resizeToCurrentText. I'll investigate.

[GaetanGodart]

What is on line 59 of the Model.cpp?

Keep me updated when you have finished investigating!

Regards,

[starcin · Accepted solution]

Somehow the problem was me calling resizeToCurrentText() function of TextArea.

Let me show you my whole Model.cpp
The line 59 is the line 52 here. Where I call something from debugWidgetPointer.

#include <gui/model/Model.hpp>
#include <gui/model/ModelListener.hpp>
#include <gui/containers/Header.hpp>
#include <gui/containers/Debug.hpp>
#include <gui/common/FrontendApplication.hpp>
#include <ButtonEnum.hpp>

Model::Model() : modelListener(0) {
}

uint16_t Model::getButtonState(uint8_t buttonNum)
{
    uint16_t buttonState = 0x0000;
    HC165_CLK_GPIO_Port->ODR |= (HC165_CLK_Pin);
    HC165_EN_GPIO_Port->ODR &= ~(HC165_EN_Pin);
    HC165_EN_GPIO_Port->ODR |= (HC165_EN_Pin);
    for(int i = 0; i < buttonNum; i++)
    {
        HC165_CLK_GPIO_Port->ODR &= ~(HC165_CLK_Pin);
        if(HC165_MISO_GPIO_Port->IDR & (1<<5))
            buttonState &= ~(1 << i);
        else
            buttonState |= (1 << i);
        HC165_CLK_GPIO_Port->ODR |= (HC165_CLK_Pin);
    }
    return buttonState;
}

uint8_t Model::getBatteryLevel()
{
    return rand() % 101; // Return random battery level between 0-100
}

void Model::tick()
{
    tickCount++;
    if (headerPointer != nullptr && tickCount % 10 == 0)
    {
        uint8_t batteryLevel = getBatteryLevel();
        debugWidgetPointer->setText(batteryLevel);
        headerPointer->setBatteryLevel(batteryLevel);
    }
	uint16_t buttonState = getButtonState(16);
    if (buttonState != previousButtonState)
    {
        if (modelListener != 0)
        {
            modelListener->onButtonStateChange(buttonState);
        }
        if (debugWidgetPointer != nullptr)
        {
            debugWidgetPointer->onButtonStateChange(buttonState);
        }
        if (static_cast<ButtonEnum>(buttonState) == ButtonEnum::MENU)
        {
            static_cast<FrontendApplication*>(Application::getInstance())->gotoScreen2ScreenNoTransition();
        }
        previousButtonState = buttonState;
    }
}

I have a custom container called Debug that I add to every scene using TouchGFX UI. Then when a scene is loaded, it's presenter sends that container's pointer to model using a bind method in ModelListener:

#ifndef MODELLISTENER_HPP
#define MODELLISTENER_HPP

#include <gui/model/Model.hpp>
#include <mvp/View.hpp>
#include <touchgfx/hal/Types.hpp>

class ModelListener
{
public:
    ModelListener() : model(0) {}
    
    virtual ~ModelListener() {}

    void bind(Model* m)
    {
        model = m;
    }

    virtual void onButtonStateChange(uint16_t newButtonState) {}
    
    template<typename T>
    void bindCommonComponents(touchgfx::View<T>& view) {
        Debug* debug = static_cast<Debug*>(view.getDebugWidgetPointer());
        Header* header = static_cast<Header*>(view.getHeaderPointer());

        model->debugWidgetPointer = debug;
        model->headerPointer = header;
    }

protected:
    Model* model;
};

#endif // MODELLISTENER_HPP

Looks like if I forget to implement the call for this bind function, the debugWidgetPointer is not null but simply points to a weird place (I guess?) and cause unexpected results. I think the only thing I need is a way to nullify these pointers when a screen change happens. Do we have a single place that is called everytime screen changes? Preferably somewere that can access modellistener or model?

EDIT: I tried to nullify them in modellistener's constructor but the code still exits if I don't bind the pointer.

[GaetanGodart]

Hello @starcin ,

It is great new that you were able to track down the root cause of the issue.

We have a function that is called every time we exit a screen, this is the tearDownScreen() function (setupScreen() is called whenever we instantiate a screen).

Regards,

[GaetanGodart]

Hello @starcin ,

Have you been able to move forward with your issue?
If you did, could you select the comment that helped you the most as "best answer".

Regards,

[starcin]

I couldn't find a way to automate nullifying the pointers, or maybe I have another problem in that area, so I am just being careful about adding and removing stuff in my classes. But since it was actually a pointer issue and not a scene change issue, I guess we can say that I moved forward.

[GaetanGodart]

Hello @starcin ,

Would this fix your issue if you put it in every setupScreen() function :

debugWidgetPointer = nullptr;

Regards,