Section 6: Complete Analysis of BaseApp Base Class

1. Course Objectives

Before developing an App, we must understand the "father" of all Apps—BaseApp. It helps us handle most of the repetitive work. In this lesson, we will study the implementation of base_app.py in detail.

2. Core Source Code Analysis

File Path: src/canmv/port/builtin_py/ybMain/base_app.py

2.1 Initialization (__init__)

class BaseApp:
    def __init__(self, app_manager, name, icon=None):
        self.app_manager = app_manager # Save appmanager reference for convenient return to desktop later
        self.name = name               # App name
        self.icon = icon               # App icon object
        self.screen = None             # App's main screen (created later)
        
        # Get screen resolution
        self.disp = lv.disp_get_default()
        self.disp_w = self.disp.get_hor_res()
        self.disp_h = self.disp.get_ver_res()

Note: In the __init__ phase, we usually don't create UI. Because the system initializes all Apps at once during startup, if each App creates hundreds of controls here, memory might instantly explode (possibly).

2.2 Creating Desktop Icon (create_icon)

This method is called by AppManager.

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    def create_icon(self, parent):
        self.icon_btn = lv.btn(parent) # Create a button
        
        # Set icon text
        icon_label = lv.label(self.icon_btn)
        icon_label.set_text(self.name)
        
        # Bind click event
        self.icon_btn.add_event(self.on_icon_clicked, lv.EVENT.CLICKED, None)
        return self.icon_btn

2.3 Launch and Animation (launch_with_animation)

This is the most exciting part of BaseApp. When you click the icon, it doesn't jump abruptly, but has an animation that zooms from the icon position to full screen.

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    def launch_with_animation(self):
        # 1. Create new screen (this is when the App's UI container is actually created)
        self.screen = lv.obj()
        
        # 2. Get current position of icon
        icon_coords = lv.area_t()
        self.icon_btn.get_coords(icon_coords)
        
        # 3. Set initial state: size equals icon, position equals icon
        self.screen.set_size(icon_w, icon_h)
        self.screen.set_pos(icon_x, icon_y)
        self.screen.set_style_radius(start_radius, 0) # Circular
        
        # 4. Create animation
        anim = lv.anim_t()
        # ... Set animation to zoom from icon_size to display_size ...
        
        # 5. After animation ends, call initialize()
        # This means subclasses must implement the initialize() method

3. What to Pay Attention to When Developing Apps?

After inheriting BaseApp, you only need to care about two things:

1. Prepare Data: Prepare the name and icon in __init__.
2. Build Interface: Override the initialize(self) method and draw your application interface on self.screen.