nanovna-saver/src/NanoVNASaver/Charts/LogMag.py

#  NanoVNASaver
#
#  A python program to view and export Touchstone data from a NanoVNA
#  Copyright (C) 2019, 2020  Rune B. Broberg
#  Copyright (C) 2020,2021 NanoVNA-Saver Authors
#
#  This program is free software: you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation, either version 3 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program.  If not, see <https://www.gnu.org/licenses/>.
from dataclasses import dataclass
import math
import logging
from typing import List

from PyQt5 import QtGui

from NanoVNASaver.Charts.Chart import Chart
from NanoVNASaver.Charts.Frequency import FrequencyChart
from NanoVNASaver.RFTools import Datapoint
from NanoVNASaver.SITools import log_floor_125

logger = logging.getLogger(__name__)


@dataclass
class TickVal:
    count: int = 0
    first: float = 0.0
    step: float = 0.0


def span2ticks(span: float, min_val: float) -> TickVal:
    span = abs(span)
    step = log_floor_125(span / 5)
    count = math.floor(span / step)
    first = math.ceil(min_val / step) * step
    if first == min_val:
        first += step
    return TickVal(count, first, step)


class LogMagChart(FrequencyChart):
    def __init__(self, name=""):
        super().__init__(name)

        self.name_unit = "dB"

        self.minDisplayValue = -80
        self.maxDisplayValue = 10

        self.minValue = 0.0
        self.maxValue = 1.0
        self.span = 1.0

        self.isInverted = False

    def drawValues(self, qp: QtGui.QPainter) -> None:
        if len(self.data) == 0 and len(self.reference) == 0:
            return
        self._set_start_stop()

        # Draw bands if required
        if self.bands.enabled:
            self.drawBands(qp, self.fstart, self.fstop)

        self.calc_scaling()
        self.draw_grid(qp)

        self.drawData(qp, self.data, Chart.color.sweep)
        self.drawData(qp, self.reference, Chart.color.reference)
        self.drawMarkers(qp)

    def calc_scaling(self) -> None:
        if self.fixedValues:
            maxValue = self.maxDisplayValue
            minValue = self.minDisplayValue
        else:
            # Find scaling
            minValue = 100
            maxValue = -100
            for d in self.data:
                logmag = self.logMag(d)
                if math.isinf(logmag):
                    continue
                maxValue = max(maxValue, logmag)
                minValue = min(minValue, logmag)

            # Also check min/max for the reference sweep
            for d in self.reference:
                if d.freq < self.fstart or d.freq > self.fstop:
                    continue
                logmag = self.logMag(d)
                if math.isinf(logmag):
                    continue
                maxValue = max(maxValue, logmag)
                minValue = min(minValue, logmag)
            minValue = 10 * math.floor(minValue / 10)
            maxValue = 10 * math.ceil(maxValue / 10)

        self.minValue = minValue
        self.maxValue = maxValue

    def draw_grid(self, qp):
        self.span = (self.maxValue - self.minValue) or 0.01
        ticks = span2ticks(self.span, self.minValue)
        self.draw_db_lines(qp, self.maxValue, self.minValue, ticks)

        qp.setPen(QtGui.QPen(Chart.color.foreground))
        qp.drawLine(self.leftMargin - 5, self.topMargin,
                    self.leftMargin + self.dim.width, self.topMargin)
        qp.setPen(Chart.color.text)
        qp.drawText(3, self.topMargin + 4, f"{self.maxValue}")
        qp.drawText(3, self.dim.height + self.topMargin, f"{self.minValue}")
        self.drawFrequencyTicks(qp)
        self.draw_swr_markers(qp)

    def draw_db_lines(self, qp, maxValue, minValue, ticks) -> None:
        for i in range(ticks.count):
            db = ticks.first + i * ticks.step
            y = self.topMargin + round(
                (maxValue - db) / self.span * self.dim.height)
            qp.setPen(QtGui.QPen(Chart.color.foreground))
            qp.drawLine(self.leftMargin - 5, y,
                        self.leftMargin + self.dim.width, y)
            if db > minValue and db != maxValue:
                qp.setPen(QtGui.QPen(Chart.color.text))
                qp.drawText(3, y + 4,
                            f"{round(db, 1)}" if ticks.step < 1 else f"{db}")

    def draw_swr_markers(self, qp) -> None:
        qp.setPen(Chart.color.swr)
        for vswr in self.swrMarkers:
            if vswr <= 1:
                continue
            logMag = 20 * math.log10((vswr - 1) / (vswr + 1))
            if self.isInverted:
                logMag = logMag * -1
            y = self.topMargin + round(
                (self.maxValue - logMag) / self.span * self.dim.height)
            qp.drawLine(self.leftMargin, y,
                        self.leftMargin + self.dim.width, y)
            qp.drawText(self.leftMargin + 3, y - 1, f"VSWR: {vswr}")

    def getYPosition(self, d: Datapoint) -> int:
        logMag = self.logMag(d)
        if math.isinf(logMag):
            return self.topMargin
        return self.topMargin + int(
            (self.maxValue - logMag) / self.span * self.dim.height)

    def valueAtPosition(self, y) -> List[float]:
        absy = y - self.topMargin
        val = -1 * ((absy / self.dim.height * self.span) - self.maxValue)
        return [val]

    def logMag(self, p: Datapoint) -> float:
        return -p.gain if self.isInverted else p.gain

    def copy(self):
        new_chart: LogMagChart = super().copy()
        new_chart.isInverted = self.isInverted
        new_chart.span = self.span
        return new_chart