"""PyQt5 widgets to render a particle orbit system.
"""
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# Written in 2019 by Garth Zeglin <garthz@cmu.edu>

# To the extent possible under law, the author has dedicated all copyright
# and related and neighboring rights to this software to the public domain
# worldwide. This software is distributed without any warranty.

# You should have received a copy of the CC0 Public Domain Dedication along with this software.
# If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.

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import math, logging
import numpy as np

# for documentation on the PyQt5 API, see http://pyqt.sourceforge.net/Docs/PyQt5/index.html
from PyQt5 import QtCore, QtGui, QtWidgets

# set up logger for module
log = logging.getLogger('QtOrbits')

# filter out most logging; the default is NOTSET which passes along everything
# log.setLevel(logging.WARNING)

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[docs]class QtOrbits(QtWidgets.QWidget):
    """Custom widget representing a particle orbit system generator."""

    def __init__(self, channels=4):
        super().__init__()
        self.setMinimumSize(QtCore.QSize(100, 100))
        self.setAutoFillBackground(True)

        # graphical state variables
        self.channels = channels
        self.positions  = [[0,0,0]]*self.channels # spatial positions, unit scaling [-1,1]
        self.attractors = [[0,0,0]]*4

        # finish initialization
        self.show()
        return

[docs]    def update_positions(self, positions):
        self.positions = positions
        self.repaint()

[docs]    def update_attractors(self, attractors):
        self.attractors = attractors
        self.repaint()

    # === element drawing methods ============================================================

    # === Qt API methods ============================================================
[docs]    def paintEvent(self, e):
        """Subclass implementation of parent QWidget class callback to repaint the graphics."""
        geometry = self.geometry()
        view_width = geometry.width()
        view_height = geometry.height()

        # clear the background
        qp = QtGui.QPainter()
        qp.begin(self)
        qp.fillRect(QtCore.QRectF(0, 0, view_width, view_height), QtCore.Qt.white)
        # qp.setRenderHint(QtGui.QPainter.Antialiasing)

        # Set up a coordinate system scaled to real-world millimeters, centered
        # in the visible area, keeping the minimum visible area in view.

        # define minimum visible area
        scene_width   = 3.5
        scene_height  = scene_width
        scene_aspect  = scene_width / scene_height
        view_aspect = view_width / view_height
        if scene_aspect > view_aspect:
            scaling = view_width / scene_width
        else:
            scaling = view_height/scene_height

        qp.save()
        qp.translate(QtCore.QPointF(view_width/2, view_height/2))
        qp.scale(scaling, scaling)

        # draw the bounds
        pen = QtGui.QPen(QtCore.Qt.black)
        pen.setWidthF(0.01)
        qp.setPen(pen)
        qp.drawEllipse(QtCore.QPointF(0.0,0.0),math.sqrt(3),math.sqrt(3))

        # draw the attractors in black
        brush = QtGui.QBrush(QtGui.QColor(240, 240, 240, 255))
        qp.setBrush(brush)

        for pos in self.attractors:
            qp.drawEllipse(QtCore.QPointF(pos[0], pos[1]), 0.2, 0.2)

        # draw the particles in a color derived from their coordinates
        color = QtGui.QColor()
        for pos in self.positions:
            color.setRgbF(min(1.0, abs(pos[0])), min(1.0, abs(pos[1])), min(1.0, abs(pos[2])), 1.0)
            brush = QtGui.QBrush(color)
            qp.setBrush(brush)
            qp.drawEllipse(QtCore.QPointF(pos[0], pos[1]), 0.05, 0.05)

        # restore the initial unscaled coordinates
        qp.restore()
        qp.end()

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