eric6/E5Graphics/E5ArrowItem.py

# -*- coding: utf-8 -*-

# Copyright (c) 2007 - 2021 Detlev Offenbach <detlev@die-offenbachs.de>
#

"""
Module implementing a graphics item subclass for an arrow.
"""

import enum
import math

from PyQt5.QtCore import QPointF, QRectF, QSizeF, QLineF, Qt
from PyQt5.QtGui import QPen, QPolygonF, QColor
from PyQt5.QtWidgets import QAbstractGraphicsShapeItem, QGraphicsItem, QStyle

ArrowheadAngleFactor = 0.26179938779914941
# That is: 0.5 * math.atan(math.sqrt(3.0) / 3.0)


class E5ArrowType(enum.Enum):
    """
    Class defining the arrow types.
    """
    NORMAL = 1
    WIDE = 2


class E5ArrowItem(QAbstractGraphicsShapeItem):
    """
    Class implementing an arrow graphics item subclass.
    """
    def __init__(self, origin=None, end=None,
                 filled=False, arrowType=E5ArrowType.NORMAL, colors=None,
                 parent=None):
        """
        Constructor
        
        @param origin origin of the arrow
        @type QPointF
        @param end end point of the arrow
        @type QPointF
        @param filled flag indicating a filled arrow head
        @type bool
        @param arrowType arrow type
        @type E5ArrowType
        @param colors tuple containing the foreground and background colors
        @type tuple of (QColor, QColor)
        @param parent reference to the parent object
        @type QGraphicsItem
        """
        super().__init__(parent)
        
        self._origin = QPointF() if origin is None else QPointF(origin)
        self._end = QPointF() if end is None else QPointF(end)
        self._filled = filled
        self.__type = arrowType
        
        if colors is None:
            self._colors = (QColor(Qt.GlobalColor.black),
                            QColor(Qt.GlobalColor.white))
        else:
            self._colors = colors
        
        self._halfLength = 13.0
        
        self.setFlag(QGraphicsItem.GraphicsItemFlag.ItemIsMovable, True)
        self.setFlag(QGraphicsItem.GraphicsItemFlag.ItemIsSelectable, True)
        
    def setPoints(self, xa, ya, xb, yb):
        """
        Public method to set the start and end points of the line.
        
        <b>Note:</b> This method does not redraw the item.
        
        @param xa x-coordinate of the start point (float)
        @param ya y-coordinate of the start point (float)
        @param xb x-coordinate of the end point (float)
        @param yb y-coordinate of the end point (float)
        """
        self._origin = QPointF(xa, ya)
        self._end = QPointF(xb, yb)
        
    def setStartPoint(self, x, y):
        """
        Public method to set the start point.
        
        <b>Note:</b> This method does not redraw the item.
        
        @param x x-coordinate of the start point (float)
        @param y y-coordinate of the start point (float)
        """
        self._origin = QPointF(x, y)
        
    def setEndPoint(self, x, y):
        """
        Public method to set the end point.
        
        <b>Note:</b> This method does not redraw the item.
        
        @param x x-coordinate of the end point (float)
        @param y y-coordinate of the end point (float)
        """
        self._end = QPointF(x, y)
        
    def boundingRect(self):
        """
        Public method to return the bounding rectangle.
        
        @return bounding rectangle (QRectF)
        """
        extra = self._halfLength / 2.0
        return QRectF(self._origin, QSizeF(self._end.x() - self._origin.x(),
                                           self._end.y() - self._origin.y())
                      ).normalized().adjusted(-extra, -extra, extra, extra)
        
    def paint(self, painter, option, widget=None):
        """
        Public method to paint the item in local coordinates.
        
        @param painter reference to the painter object (QPainter)
        @param option style options (QStyleOptionGraphicsItem)
        @param widget optional reference to the widget painted on (QWidget)
        """
        width = 2 if (
            (option.state & QStyle.StateFlag.State_Selected) ==
            QStyle.State(QStyle.StateFlag.State_Selected)
        ) else 1
        
        # draw the line first
        line = QLineF(self._origin, self._end)
        painter.setPen(
            QPen(self._colors[0], width, Qt.PenStyle.SolidLine,
                 Qt.PenCapStyle.FlatCap, Qt.PenJoinStyle.MiterJoin))
        painter.drawLine(line)
        
        # draw the arrow head
        arrowAngle = (
            ArrowheadAngleFactor
            if self.__type == E5ArrowType.NORMAL else
            2 * ArrowheadAngleFactor
        )
        slope = math.atan2(line.dy(), line.dx())
        
        # Calculate left arrow point
        arrowSlope = slope + arrowAngle
        a1 = QPointF(self._end.x() - self._halfLength * math.cos(arrowSlope),
                     self._end.y() - self._halfLength * math.sin(arrowSlope))
        
        # Calculate right arrow point
        arrowSlope = slope - arrowAngle
        a2 = QPointF(self._end.x() - self._halfLength * math.cos(arrowSlope),
                     self._end.y() - self._halfLength * math.sin(arrowSlope))
        
        if self._filled:
            painter.setBrush(self._colors[0])
        else:
            painter.setBrush(self._colors[1])
        polygon = QPolygonF()
        polygon.append(line.p2())
        polygon.append(a1)
        polygon.append(a2)
        painter.drawPolygon(polygon)