GUI Application Lifecycle and Resource Management

1. Course Objectives

Writing a runnable App is easy, but writing a stable and memory-leak-free App requires extra attention. In this lesson, we will delve into App lifecycle management.

2. Lifecycle States

An App goes through the following states during its execution:

1. Load: System starts, AppManager scans app.py, executes __init__. At this time, the App is in a dormant state, occupying minimal memory.
2. Launch: User clicks the icon, executes launch_with_animation -> initialize. At this time, UI resources are created, memory usage increases.
3. Running: User interacts with the interface.
4. Suspend/Background: In Yahboom K230's GUI, it currently mainly supports single-task foreground operation. The so-called "background" means being destroyed.
5. Destroy: User clicks the return button, App exits, releases resources.

3. Proper Resource Release

In BaseApp, although there is no explicit destroy method, when the self.screen created by launch_with_animation is deleted, all controls mounted on it will be automatically deleted.

However, there are some resources that LVGL cannot manage, which must be manually released:

3.1 Timers

If you created timers in your App:

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self.timer = Timer(1)
self.timer.init(period=1000, mode=Timer.PERIODIC, callback=self.update)

You must close it when exiting, otherwise even if the App is closed, the timer will still run in the background, eventually causing errors or system freezing.

Best Practice: Override the on_close method:

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    def on_deinit(self):
        if self.timer:
            self.timer.deinit()

3.2 Large Image Caches

If you loaded huge images into memory (f.read()), it's recommended to manually call garbage collection when exiting:

import gc
​
def on_deinit(self):
    self.big_image_data = None
    gc.collect() # Force memory reclamation