gti_radiostudio/lufs_meter_widget.py

# lufs_meter_widget.py

from PySide6.QtWidgets import QFrame, QVBoxLayout, QLabel, QWidget
from PySide6.QtCore import Qt, QTimer
from PySide6.QtGui import QFont, QPainter, QColor, QLinearGradient, QPen


class LUFSMeterWidget(QFrame):
    """Vertical LUFS meter with -14 LUFS target for streaming/broadcast."""

    def __init__(self, engine, parent=None):
        super().__init__(parent)
        self.engine = engine

        self.setFixedWidth(80)
        self.setFrameStyle(QFrame.Box | QFrame.Raised)
        self.setStyleSheet("""
            QFrame {
                background-color: #0d0d0d;
                border: 2px solid #444444;
                border-radius: 6px;
            }
        """)

        self._build_ui()

        self.timer = QTimer(self)
        self.timer.setInterval(100)
        self.timer.timeout.connect(self._update_meter)
        self.timer.start()

    def _build_ui(self):
        layout = QVBoxLayout(self)
        layout.setContentsMargins(6, 8, 6, 8)

        header = QLabel("LUFS")
        header.setFont(QFont("Arial", 10, QFont.Bold))
        header.setStyleSheet("color: #888888; background: transparent; border: none;")
        header.setAlignment(Qt.AlignCenter)
        layout.addWidget(header)

        self.meter_canvas = MeterCanvas(self.engine)
        layout.addWidget(self.meter_canvas, stretch=1)

        self.readout = QLabel("-70.0")
        self.readout.setFont(QFont("Courier New", 12, QFont.Bold))
        self.readout.setStyleSheet("color: #00ff41; background: transparent; border: none;")
        self.readout.setAlignment(Qt.AlignCenter)
        layout.addWidget(self.readout)

    def _update_meter(self):
        lufs = self.engine.lufs_current
        self.readout.setText(f"{lufs:.1f}")
        self.meter_canvas.update()


class MeterCanvas(QWidget):
    """Custom painted LUFS bar with -14 LUFS target."""

    def __init__(self, engine, parent=None):
        super().__init__(parent)
        self.engine = engine
        self.setStyleSheet("""
            QWidget {
                background-color: #000000;
                border: 1px solid #333333;
                border-radius: 3px;
            }
        """)
        self.setMinimumHeight(200)

    def paintEvent(self, event):
        painter = QPainter(self)
        painter.setRenderHint(QPainter.Antialiasing)

        rect = self.rect().adjusted(3, 3, -3, -3)
        lufs = self.engine.lufs_current

        # Scale: -50 LUFS (bottom) to 0 (top) - makes -14 more readable
        lufs_min = -50
        lufs_max = 0
        lufs_range = lufs_max - lufs_min

        lufs = max(lufs_min, min(lufs_max, lufs))
        fill_pct = (lufs - lufs_min) / lufs_range
        fill_h   = int(rect.height() * fill_pct)

        # Color zones optimized for -14 LUFS target
        gradient = QLinearGradient(0, rect.bottom(), 0, rect.top())
        
        if lufs < -30:
            # Very quiet - dark green
            gradient.setColorAt(0, QColor("#002200"))
            gradient.setColorAt(1, QColor("#004400"))
        elif lufs < -18:
            # Quiet - green
            gradient.setColorAt(0, QColor("#00aa00"))
            gradient.setColorAt(1, QColor("#00dd00"))
        elif lufs < -12:
            # Target zone -18 to -12 LUFS (±4 LU around -14) - bright green
            gradient.setColorAt(0, QColor("#00ff00"))
            gradient.setColorAt(1, QColor("#00ff00"))
        elif lufs < -6:
            # Getting hot - yellow
            gradient.setColorAt(0, QColor("#ffcc00"))
            gradient.setColorAt(1, QColor("#ffaa00"))
        else:
            # Too hot - red
            gradient.setColorAt(0, QColor("#ff0000"))
            gradient.setColorAt(1, QColor("#ff0000"))

        painter.fillRect(
            rect.x(),
            rect.bottom() - fill_h,
            rect.width(),
            fill_h,
            gradient
        )

        # Draw reference lines
        painter.setPen(QPen(QColor("#ffffff"), 1))
        
        # Target line at -14 LUFS (main target)
        target_pct = ((-14 - lufs_min) / lufs_range)
        target_y   = rect.bottom() - int(rect.height() * target_pct)
        painter.drawLine(rect.x(), target_y, rect.right(), target_y)
        
        # Upper boundary at -12 LUFS (dotted)
        painter.setPen(QPen(QColor("#888888"), 1, Qt.DotLine))
        upper_pct = ((-12 - lufs_min) / lufs_range)
        upper_y   = rect.bottom() - int(rect.height() * upper_pct)
        painter.drawLine(rect.x(), upper_y, rect.right(), upper_y)
        
        # Lower boundary at -16 LUFS (dotted)
        lower_pct = ((-16 - lufs_min) / lufs_range)
        lower_y   = rect.bottom() - int(rect.height() * lower_pct)
        painter.drawLine(rect.x(), lower_y, rect.right(), lower_y)

        painter.end()