Files
sideline/engine/frame.py
David Gwilliam cdc8094de2 refactor: phase 2 - modularization of scroll engine
Split monolithic scroll.py into focused modules:
- viewport.py: terminal size (tw/th), ANSI positioning helpers
- frame.py: FrameTimer class, scroll step calculation
- layers.py: message overlay, ticker zone, firehose rendering
- scroll.py: simplified orchestrator, imports from new modules

Add stream controller and event types for future event-driven architecture:
- controller.py: StreamController for source initialization and stream lifecycle
- events.py: EventType enum and event dataclasses (HeadlineEvent, FrameTickEvent, etc.)

Added tests for new modules:
- test_viewport.py: 8 tests for viewport utilities
- test_frame.py: 10 tests for frame timing
- test_layers.py: 13 tests for layer compositing
- test_events.py: 11 tests for event types
- test_controller.py: 6 tests for stream controller

This enables:
- Testable chunks with clear responsibilities
- Reusable viewport utilities across modules
- Better separation of concerns in render pipeline
- Foundation for future event-driven architecture

Also includes Phase 1 documentation updates in code comments.
2026-03-15 19:13:32 -07:00

58 lines
1.7 KiB
Python

"""
Frame timing utilities — FPS control and precise timing.
"""
import time
class FrameTimer:
"""Frame timer for consistent render loop timing."""
def __init__(self, target_frame_dt: float = 0.05):
self.target_frame_dt = target_frame_dt
self._frame_count = 0
self._start_time = time.monotonic()
self._last_frame_time = self._start_time
@property
def fps(self) -> float:
"""Current FPS based on elapsed frames."""
elapsed = time.monotonic() - self._start_time
if elapsed > 0:
return self._frame_count / elapsed
return 0.0
def sleep_until_next_frame(self) -> float:
"""Sleep to maintain target frame rate. Returns actual elapsed time."""
now = time.monotonic()
elapsed = now - self._last_frame_time
self._last_frame_time = now
self._frame_count += 1
sleep_time = max(0, self.target_frame_dt - elapsed)
if sleep_time > 0:
time.sleep(sleep_time)
return elapsed
def reset(self) -> None:
"""Reset frame counter and start time."""
self._frame_count = 0
self._start_time = time.monotonic()
self._last_frame_time = self._start_time
def calculate_scroll_step(
scroll_dur: float, view_height: int, padding: int = 15
) -> float:
"""Calculate scroll step interval for smooth scrolling.
Args:
scroll_dur: Duration in seconds for one headline to scroll through view
view_height: Terminal height in rows
padding: Extra rows for off-screen content
Returns:
Time in seconds between scroll steps
"""
return scroll_dur / (view_height + padding) * 2