dreader-application/examples/calibrate_accelerometer.py

#!/usr/bin/env python3
"""
Accelerometer Calibration Script

This script helps calibrate the accelerometer for gravity-based page flipping.
It displays visual instructions on the e-ink display to guide the user through
aligning the device with the "up" direction.

The calibration process:
1. Shows an arrow pointing up
2. User rotates device until arrow aligns with desired "up" direction
3. User confirms by tapping screen
4. Script saves calibration offset to config file

Usage:
    python examples/calibrate_accelerometer.py
"""

import asyncio
import sys
import json
import math
from pathlib import Path
from PIL import Image, ImageDraw, ImageFont

# Add parent directory to path for imports
sys.path.insert(0, str(Path(__file__).parent.parent))

from dreader.hal_hardware import HardwareDisplayHAL
from dreader.gesture import GestureType


class AccelerometerCalibrator:
    """Interactive accelerometer calibration tool"""

    def __init__(self, hal: HardwareDisplayHAL, config_path: str = "accelerometer_config.json"):
        self.hal = hal
        self.config_path = Path(config_path)
        self.width = hal.width
        self.height = hal.height
        self.calibrated = False

        # Calibration data
        self.up_vector = None  # (x, y, z) when device is in "up" position

    async def run(self):
        """Run the calibration process"""
        print("Starting accelerometer calibration...")
        print(f"Display: {self.width}x{self.height}")

        await self.hal.initialize()

        try:
            # Show welcome screen
            await self.show_welcome()
            await self.wait_for_tap()

            # Calibration loop
            await self.calibration_loop()

            # Show completion screen
            await self.show_completion()
            await asyncio.sleep(3)

        finally:
            await self.hal.cleanup()

    async def show_welcome(self):
        """Display welcome/instruction screen"""
        img = Image.new('RGB', (self.width, self.height), color=(255, 255, 255))
        draw = ImageDraw.Draw(img)

        # Try to load a font, fall back to default
        try:
            title_font = ImageFont.truetype("/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf", 48)
            body_font = ImageFont.truetype("/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf", 32)
        except:
            title_font = ImageFont.load_default()
            body_font = ImageFont.load_default()

        # Title
        title = "Accelerometer Calibration"
        title_bbox = draw.textbbox((0, 0), title, font=title_font)
        title_width = title_bbox[2] - title_bbox[0]
        draw.text(((self.width - title_width) // 2, 100), title, fill=(0, 0, 0), font=title_font)

        # Instructions
        instructions = [
            "This will calibrate the accelerometer",
            "for gravity-based page flipping.",
            "",
            "You will:",
            "1. See an arrow on screen",
            "2. Rotate device until arrow points UP",
            "3. Tap screen to confirm",
            "",
            "Tap anywhere to begin..."
        ]

        y = 250
        for line in instructions:
            line_bbox = draw.textbbox((0, 0), line, font=body_font)
            line_width = line_bbox[2] - line_bbox[0]
            draw.text(((self.width - line_width) // 2, y), line, fill=(0, 0, 0), font=body_font)
            y += 50

        await self.hal.show_image(img)

    async def calibration_loop(self):
        """Main calibration loop - show live arrow and accelerometer reading"""
        print("\nCalibration mode:")
        print("Rotate device until arrow points UP, then tap screen.")

        last_display_time = 0
        display_interval = 0.2  # Update display every 200ms

        while not self.calibrated:
            # Get current acceleration
            x, y, z = await self.hal.hal.orientation.get_acceleration()

            # Update display if enough time has passed
            current_time = asyncio.get_event_loop().time()
            if current_time - last_display_time >= display_interval:
                await self.show_calibration_screen(x, y, z)
                last_display_time = current_time

            # Check for touch event
            event = await self.hal.get_touch_event()
            if event and event.gesture == GestureType.TAP:
                # Save current orientation as "up"
                self.up_vector = (x, y, z)
                self.calibrated = True
                print(f"\nCalibration saved: up_vector = ({x:.2f}, {y:.2f}, {z:.2f})")
                break

            await asyncio.sleep(0.05)  # Poll at ~20Hz

    async def show_calibration_screen(self, ax: float, ay: float, az: float):
        """
        Show arrow pointing in direction of gravity

        Args:
            ax, ay, az: Acceleration components in m/s²
        """
        img = Image.new('RGB', (self.width, self.height), color=(255, 255, 255))
        draw = ImageDraw.Draw(img)

        # Calculate gravity direction (normalized)
        magnitude = math.sqrt(ax**2 + ay**2 + az**2)
        if magnitude < 0.1:  # Avoid division by zero
            magnitude = 1.0

        gx = ax / magnitude
        gy = ay / magnitude
        gz = az / magnitude

        # Project gravity onto screen plane (assuming z is out of screen)
        # We want to show which way is "down" on the device
        # Arrow should point opposite to gravity (toward "up")
        arrow_dx = -gx
        arrow_dy = -gy

        # Normalize for display
        arrow_length = min(self.width, self.height) * 0.3
        arrow_magnitude = math.sqrt(arrow_dx**2 + arrow_dy**2)
        if arrow_magnitude < 0.1:
            arrow_magnitude = 1.0

        arrow_dx = (arrow_dx / arrow_magnitude) * arrow_length
        arrow_dy = (arrow_dy / arrow_magnitude) * arrow_length

        # Center point
        cx = self.width // 2
        cy = self.height // 2

        # Arrow endpoint
        end_x = cx + int(arrow_dx)
        end_y = cy + int(arrow_dy)

        # Draw large arrow
        self.draw_arrow(draw, cx, cy, end_x, end_y, width=10)

        # Draw circle at center
        circle_radius = 30
        draw.ellipse(
            [(cx - circle_radius, cy - circle_radius),
             (cx + circle_radius, cy + circle_radius)],
            outline=(0, 0, 0),
            width=5
        )

        # Draw text with acceleration values
        try:
            font = ImageFont.truetype("/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf", 28)
        except:
            font = ImageFont.load_default()

        text = f"X: {ax:6.2f} m/s²"
        draw.text((50, 50), text, fill=(0, 0, 0), font=font)

        text = f"Y: {ay:6.2f} m/s²"
        draw.text((50, 100), text, fill=(0, 0, 0), font=font)

        text = f"Z: {az:6.2f} m/s²"
        draw.text((50, 150), text, fill=(0, 0, 0), font=font)

        text = "Rotate device until arrow points UP"
        text_bbox = draw.textbbox((0, 0), text, font=font)
        text_width = text_bbox[2] - text_bbox[0]
        draw.text(((self.width - text_width) // 2, self.height - 150),
                 text, fill=(0, 0, 0), font=font)

        text = "Then TAP screen to save"
        text_bbox = draw.textbbox((0, 0), text, font=font)
        text_width = text_bbox[2] - text_bbox[0]
        draw.text(((self.width - text_width) // 2, self.height - 100),
                 text, fill=(0, 0, 0), font=font)

        await self.hal.show_image(img)

    def draw_arrow(self, draw: ImageDraw.Draw, x1: int, y1: int, x2: int, y2: int, width: int = 5):
        """Draw an arrow from (x1, y1) to (x2, y2)"""
        # Main line
        draw.line([(x1, y1), (x2, y2)], fill=(0, 0, 0), width=width)

        # Arrow head
        dx = x2 - x1
        dy = y2 - y1
        length = math.sqrt(dx**2 + dy**2)

        if length < 0.1:
            return

        # Normalize
        dx /= length
        dy /= length

        # Arrow head size
        head_length = 40
        head_width = 30

        # Perpendicular vector
        px = -dy
        py = dx

        # Arrow head points
        p1_x = x2 - dx * head_length + px * head_width
        p1_y = y2 - dy * head_length + py * head_width

        p2_x = x2 - dx * head_length - px * head_width
        p2_y = y2 - dy * head_length - py * head_width

        # Draw arrow head
        draw.polygon([(x2, y2), (p1_x, p1_y), (p2_x, p2_y)], fill=(0, 0, 0))

    async def show_completion(self):
        """Show calibration complete screen"""
        img = Image.new('RGB', (self.width, self.height), color=(255, 255, 255))
        draw = ImageDraw.Draw(img)

        try:
            title_font = ImageFont.truetype("/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf", 48)
            body_font = ImageFont.truetype("/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf", 32)
        except:
            title_font = ImageFont.load_default()
            body_font = ImageFont.load_default()

        # Title
        title = "Calibration Complete!"
        title_bbox = draw.textbbox((0, 0), title, font=title_font)
        title_width = title_bbox[2] - title_bbox[0]
        draw.text(((self.width - title_width) // 2, 200), title, fill=(0, 0, 0), font=title_font)

        # Details
        if self.up_vector:
            x, y, z = self.up_vector
            details = [
                f"Up vector saved:",
                f"X: {x:.3f} m/s²",
                f"Y: {y:.3f} m/s²",
                f"Z: {z:.3f} m/s²",
                "",
                f"Saved to: {self.config_path}"
            ]

            y_pos = 350
            for line in details:
                line_bbox = draw.textbbox((0, 0), line, font=body_font)
                line_width = line_bbox[2] - line_bbox[0]
                draw.text(((self.width - line_width) // 2, y_pos), line, fill=(0, 0, 0), font=body_font)
                y_pos += 50

        await self.hal.show_image(img)

        # Save calibration to file
        self.save_calibration()

    def save_calibration(self):
        """Save calibration data to JSON file"""
        if not self.up_vector:
            print("Warning: No calibration data to save")
            return

        x, y, z = self.up_vector

        config = {
            "up_vector": {
                "x": x,
                "y": y,
                "z": z
            },
            "tilt_threshold": 0.3,  # Radians (~17 degrees)
            "debounce_time": 0.5,    # Seconds between tilt gestures
        }

        with open(self.config_path, 'w') as f:
            json.dump(config, f, indent=2)

        print(f"Calibration saved to {self.config_path}")

    async def wait_for_tap(self):
        """Wait for user to tap screen"""
        while True:
            event = await self.hal.get_touch_event()
            if event and event.gesture == GestureType.TAP:
                break
            await asyncio.sleep(0.05)


async def main():
    """Main entry point"""
    # Create HAL with accelerometer enabled
    print("Initializing hardware...")
    hal = HardwareDisplayHAL(
        width=1872,
        height=1404,
        enable_orientation=True,
        enable_rtc=False,
        enable_power_monitor=False,
        virtual_display=False  # Set to True for testing without hardware
    )

    # Create calibrator
    calibrator = AccelerometerCalibrator(hal)

    # Run calibration
    await calibrator.run()

    print("\nCalibration complete!")
    print("You can now use accelerometer-based page flipping.")


if __name__ == "__main__":
    try:
        asyncio.run(main())
    except KeyboardInterrupt:
        print("\nCalibration cancelled by user")
        sys.exit(0)
    except Exception as e:
        print(f"\nError during calibration: {e}")
        import traceback
        traceback.print_exc()
        sys.exit(1)