Widget Creation

Widget Creation Skill

Overview

This skill scaffolds new pyTermTk widgets following project patterns:

• Proper class structure with __slots__
• Signal definitions with type hints
• Event handlers with correct return semantics
• Sphinx documentation with ASCII art
• Test file structure
• Example/demo integration

When to Use

• Building new interactive widgets (button, input, selector variants)
• Creating container widgets (custom layouts, panels)
• Adding display widgets (custom text renderers, charts)

File Structure

1. Widget File

Location: libs/pyTermTk/TermTk/TTkWidgets/ttk_<widget_name>.py

Template:

"""
Module: TTkMyWidget
Implements a custom widget for [purpose]
"""

from TermTk import TTkWidget, TTkColor, pyTTkSignal, pyTTkSlot

class TTkMyWidget(TTkWidget):
    '''TTkMyWidget: [One-line description]

    [Longer description of purpose and behavior]

    (`demo <https://ceccopierangiolieugenio.github.io/pyTermTk-Docs/sandbox/...>`__)

    ::

        [ASCII art showing visual representation]
        [Multiple lines if needed]

    .. code:: python

        import TermTk as ttk

        root = ttk.TTk()
        widget = ttk.TTkMyWidget(parent=root)
        root.mainloop()
    '''

    # Performance: always use __slots__
    __slots__ = (
        '_privateVar',
        '_anotherVar',
        'stateChanged',
    )

    _privateVar: int
    _anotherVar: int
    stateChanged: pyTTkSignal
    '''
    Emitted when widget state changes.

    :param value: new state value
    :type value: [type]
    '''

    # Class-level styling
    classStyle = {
        'default':  {'color': TTkColor.fg("#dddd88"), 'borderColor': TTkColor.RST},
        'hover':    {'color': TTkColor.fg("#ffffff"), 'borderColor': TTkColor.BOLD},
        'focus':    {'borderColor': TTkColor.fg("#ffff00")},
        'disabled': {'color': TTkColor.fg('#888888')}
    }

    def __init__(self, **kwargs):
        '''Initialize the widget.

        :param parent: parent widget
        :type parent: TTkWidget
        [Other parameters as needed]
        '''
        # Instantiate signals in __init__ (do not instantiate at class level)
        self.stateChanged = pyTTkSignal(int)

        # Initialize private variables
        self._privateVar = 0  # Replace with appropriate default for your widget

        # Call parent with merged kwargs and default size
        super().__init__(**kwargs|{'size': (10, 3)})  # Replace with appropriate default dimensions

    # Property getters/setters
    def getValue(self) -> int:
        '''Get the current value.

        :return: current value
        :rtype: int
        '''
        return self._privateVar

    def setValue(self, value: int) -> None:
        '''Set the value.

        :param value: new value
        :type value: int
        '''
        if self._privateVar != value:
            self._privateVar = value
            self.stateChanged.emit(value)
            self.update()

    # Return True when this widget fully processes the event; otherwise return False to let parent widgets handle it.
    def keyEvent(self, evt) -> bool:
        '''Handle keyboard events.'''
        if evt.key == 'Enter':
            self.stateChanged.emit(self._privateVar)
            return True
        return False

    def mousePressEvent(self, evt) -> bool:
        '''Handle mouse press events.'''
        # Handle click, return True if consumed
        return False

    def paintEvent(self) -> None:
        '''Render the widget.'''
        # Use currentStyle() for theme-aware colors
        canvas = self.canvas
        style = self.currentStyle()

        # Draw widget content
        canvas.drawText(pos=(0, 0), text="MyWidget")

__all__ = ['TTkMyWidget']

2. Test File

Location: tests/pytest/widgets/<widget_name>/test_<widget_name>.py

Template:

import pytest
from TermTk import TTkMyWidget

class TestTTkMyWidget:
    '''Test suite for TTkMyWidget'''

    def test_initialization(self):
        """Widget initializes with defaults"""
        widget = TTkMyWidget()
        assert widget.getValue() == 0  # Or expected default

    def test_signal_emission(self):
        """Signal emits when state changes"""
        widget = TTkMyWidget()
        emitted = []
        widget.stateChanged.connect(lambda val: emitted.append(val))

        widget.setValue(42)
        assert emitted == [42]

    def test_key_event_handling(self):
        """Key events handled correctly"""
        widget = TTkMyWidget()
        from TermTk import TTkKeyEvent

        evt = TTkKeyEvent(key='Enter')
        result = widget.keyEvent(evt)
        assert result == True  # Event was handled

    def test_disabled_state(self):
        """Widget respects disabled state"""
        widget = TTkMyWidget()
        widget.setDisabled(True)
        # Verify widget doesn't respond to events, etc.

3. Example/Demo

Add to demo/showcase/ or tutorial/examples/ if creating showcase:

"""
Example: TTkMyWidget

Demonstrates the TTkMyWidget in action.
"""

import TermTk as ttk

def main():
    root = ttk.TTk()

    # Create and configure widget
    widget = ttk.TTkMyWidget(parent=root)
    widget.setValue(10)

    # Connect signal
    @ttk.pyTTkSlot(int)
    def on_state_changed(value):
        print(f"State changed to: {value}")

    widget.stateChanged.connect(on_state_changed)

    root.mainloop()

if __name__ == '__main__':
    main()

Key Patterns to Follow

Signals

• Keep signal entries in __slots__ and type-annotate them there
• Instantiate signals in __init__ with specific type: pyTTkSignal(int) not pyTTkSignal()
• Emit with actual value: self.stateChanged.emit(value)

slots

__slots__ = (
    '_variable1',
    '_variable2',
    'valueChanged',
    # Always use slots for memory efficiency
)

_variable1: int
_variable2: int
valueChanged: pyTTkSignal

Rules:

• All non-signal slot names must start with _.
• Public (non-underscore) slot names are allowed only for exposed signals.
• Add a class-level type annotation for each slot entry immediately below __slots__.

Class Styling

classStyle = {
    'default':  {...},
    'hover':    {...},
    'focus':    {...},
    'disabled': {...}
}

Event Return Values

• Return True if event fully handled (don't propagate)
• Return False to let event propagate up widget tree

Documentation

• ASCII art for visual widgets
• Demo/sandbox links
• Runnable code examples
• Sphinx cross-references: :py:class:, :py:meth:

Checklist

File and Class Structure

• File location: libs/pyTermTk/TermTk/TTkWidgets/ttk_*.py
• Inherits from TTkWidget or TTkContainer
• __slots__ defined
• Non-signal slot names use leading _
• Public slot names are signals only
• Every slot entry has a class-level type annotation
• __all__ export defined
• Register the widget export in libs/pyTermTk/TermTk/TTkWidgets/__init__.py with from .ttk_<widget_name> import TTkMyWidget

Signals and Events

• Signals with type hints
• Signals initialized in __init__
• Event methods return bool

Documentation and Examples

• Sphinx docstring with ASCII art
• Example added to demo or tutorial

Testing and Quality

• Test file created
• Tests cover initialization, signals, events, edge cases
• Flake8 passes

Common Mistakes to Avoid

• ❌ Signals instantiated at class level instead of __init__
• ❌ Event handlers don't return bool (should always return True/False)
• ❌ Missing __slots__ (memory waste)
• ❌ Hardcoded colors instead of using theme via currentStyle()
• ❌ Tests that only check implementation, not behavior
• ❌ No documentation or examples