"""PyQt5 widgets to render cartoons of winch and line systems.
"""

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# Written in 2018-2019 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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# for documentation on the PyQt5 API, see http://pyqt.sourceforge.net/Docs/PyQt5/index.html
from PyQt5 import QtCore, QtGui, QtWidgets

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[docs]class QtWinchCartoon(QtWidgets.QWidget):
    """Custom widget representing a single winch as a 2D cartoon view."""

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

        # graphical state variables
        self.position = 0.0  # units are microsteps

        # Create a path representing the basic glyph.  The default coordinates
        # have +X to the right, +Y down.
        self.winch_symbol = QtGui.QPainterPath()
        self.winch_symbol.addEllipse(QtCore.QPointF(0.0, 0.0), 0.9, 0.9)  # center, rx, ry
        self.winch_symbol.moveTo( 0.25, -0.8)
        self.winch_symbol.lineTo( 0.00, -0.5)
        self.winch_symbol.lineTo(-0.25, -0.8)

        # finish initialization
        self.show()
        return

[docs]    def update_position(self, position):
        self.position = position
        self.repaint()

[docs]    def paintEvent(self, e):
        geometry = self.geometry()
        width = geometry.width()
        height = geometry.height()

        qp = QtGui.QPainter()
        qp.begin(self)
        # qp.fillRect(QtCore.QRectF(0, 0, width, height), QtCore.Qt.white)
        # qp.setRenderHint(QtGui.QPainter.Antialiasing)

        # set up a unit coordinate system centered in the visible area
        qp.save()
        scaling = width/2 if width < height else height/2
        qp.translate(QtCore.QPointF(width/2, height/2))
        qp.scale(scaling, scaling)

        # The default coordinate system rotation uses +Z pointing into the
        # screen; this changes sign so positive displacements are
        # counter-clockwise, i.e.  right-hand-rule on the vector pointing *out*
        # of the screen.  This rescales from microsteps to degrees.
        qp.rotate(-self.position*(360/800))

        if False:
            # draw the winch symbol
            pen = QtGui.QPen(QtCore.Qt.black)
            pen.setWidthF(0.1)
            qp.setPen(pen)
            qp.setBrush(QtCore.Qt.NoBrush)
            qp.drawPath(self.winch_symbol)
        else:
            # use simplified line graphics for better drawing speed
            pen = QtGui.QPen(QtCore.Qt.black)
            pen.setWidthF(0.05)
            qp.setPen(pen)
            qp.drawLine(QtCore.QPointF(0,0), QtCore.QPointF(0,-0.8))
            qp.drawRect(QtCore.QRectF(-0.2, -0.2, 0.4, 0.4))

        qp.restore()

        # draw the text annotation
        qp.drawText(10, height-4, "%d" % int(self.position))
        qp.end()

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[docs]class QtWinchSet(QtWidgets.QWidget):
    """Composite widget representing a set of winches as a 2D cartoon view."""

    def __init__(self, count=4):
        super().__init__()
        self._layout = QtWidgets.QHBoxLayout()
        self._winches = list()
        for winch in range(count):
            winch = QtWinchCartoon()
            self._layout.addWidget(winch)
            self._winches.append(winch)
        self.setLayout(self._layout)
        return

[docs]    def winches(self):
        """Return a list of QtWinch objects contained in the set."""
        return self._winches

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