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chessapp.view.arrow.Arrow

An arrow from source to destination point with a given width and color. The arrow can be indented and scaled.

Attributes:

Name Type Description
source QPoint

source point (root of the arrow)
destination QPoint

destination point (tip of the arrow)
width int

width of the arrow
color QColor

color of the arrow
indentation float

indentation of the arrow (0 = no indentation, 1 = full indentation). TODO: describe indentation
arrow_head_length_scale float

scale of the arrow head length (0 = no arrow head, 1 = full arrow head)
arrow_head_width_scale float

scale of the arrow head width (0 = no arrow head, 1 = full arrow head)
Source code in chessapp\view\arrow.py 
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class Arrow:
    """ An arrow from source to destination point with a given width and color. The arrow can be indented and scaled.

    Attributes:
        source (QPoint): source point (root of the arrow)
        destination (QPoint): destination point (tip of the arrow)
        width (int): width of the arrow
        color (QColor): color of the arrow
        indentation (float): indentation of the arrow (0 = no indentation, 1 = full indentation). TODO: describe indentation
        arrow_head_length_scale (float): scale of the arrow head length (0 = no arrow head, 1 = full arrow head)
        arrow_head_width_scale (float): scale of the arrow head width (0 = no arrow head, 1 = full arrow head)
    """

    def __init__(self, source: QPoint, destination: QPoint):
        """ initialize an arrow

        Args:
            source (QPoint): source point (root of the arrow)
            destination (QPoint): destination point (tip of the arrow)
        """
        self.source = source
        self.destination = destination
        self.width = 10
        self.color = QColor(0, 0, 128, 64)
        self.indentation: float = 0
        self.arrow_head_length_scale: float = 1
        self.arrow_head_width_scale: float = 1

    def drawOn(self, qp: QPainter, bound: QRect, offset: QPointF):
        """ draw the arrow on the given painter

        Args:
            qp (QPainter): the painter to draw on
            bound (QRect): the bounding rectangle of the arrow
            offset (QSize): the offset of the arrow
        """
        head_width = self.width * 2 * max(0, self.arrow_head_width_scale)
        sx: float = self.source.x() + bound.x() + offset.x()
        sy: float = self.source.y() + bound.y() + offset.y()
        s = QPointF(sx, sy)
        dx: float = self.destination.x() + bound.x() + offset.x()
        dy: float = self.destination.y() + bound.y() + offset.y()
        d = QPointF(dx, dy)
        vx: float = dx - sx
        vy: float = dy - sy
        length: float = sqrt(vx * vx + vy * vy)
        if length <= head_width:
            return
        if vx == 0:
            ax = 1
            ay = 0
        else:
            ax = vy / length
            ay = -vx / length
        normal_vector = QPointF(ax, ay)
        direction_vector = QPointF(vx / length, vy / length)
        p0 = s + normal_vector * self.width / 2
        p6 = s - normal_vector * self.width / 2
        head_length: float = min(
            head_width * max(0, self.arrow_head_length_scale), 0.5 * length)
        base_length: float = length - head_length
        p1 = p0 + direction_vector * base_length
        p5 = p6 + direction_vector * base_length
        width_head_width_diff: float = head_width - self.width
        p2 = p1 + normal_vector * width_head_width_diff
        p7 = p5 - normal_vector * width_head_width_diff
        # if there is an indentation
        if self.indentation > 0:
            indentation_base_length = length + head_length * \
                (0.5 * max(0, min(1, self.indentation)) - 1)
            p1 = p0 + direction_vector * indentation_base_length
            p5 = p6 + direction_vector * indentation_base_length
        path: QPainterPath = QPainterPath()
        path.moveTo(s)  # center of base and source point
        path.lineTo(p0)  # corner 1 of base
        path.lineTo(p1)  # corner 1 of indentation
        path.lineTo(p2)  # corner 1 of outer head
        path.lineTo(d)  # destination point
        path.lineTo(p7)  # corner 2 of outer head
        path.lineTo(p5)  # corner 2 of indentation
        path.lineTo(p6)  # corner 2 of base
        qp.fillPath(path, self.color)

__init__(source, destination)

initialize an arrow

Parameters:

Name Type Description Default
source QPoint

source point (root of the arrow)

 required
destination QPoint

destination point (tip of the arrow)

 required
Source code in chessapp\view\arrow.py 
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def __init__(self, source: QPoint, destination: QPoint):
    """ initialize an arrow

    Args:
        source (QPoint): source point (root of the arrow)
        destination (QPoint): destination point (tip of the arrow)
    """
    self.source = source
    self.destination = destination
    self.width = 10
    self.color = QColor(0, 0, 128, 64)
    self.indentation: float = 0
    self.arrow_head_length_scale: float = 1
    self.arrow_head_width_scale: float = 1

drawOn(qp, bound, offset)

draw the arrow on the given painter

Parameters:

Name Type Description Default
qp QPainter

the painter to draw on

 required
bound QRect

the bounding rectangle of the arrow

 required
offset QSize

the offset of the arrow

 required
Source code in chessapp\view\arrow.py 
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def drawOn(self, qp: QPainter, bound: QRect, offset: QPointF):
    """ draw the arrow on the given painter

    Args:
        qp (QPainter): the painter to draw on
        bound (QRect): the bounding rectangle of the arrow
        offset (QSize): the offset of the arrow
    """
    head_width = self.width * 2 * max(0, self.arrow_head_width_scale)
    sx: float = self.source.x() + bound.x() + offset.x()
    sy: float = self.source.y() + bound.y() + offset.y()
    s = QPointF(sx, sy)
    dx: float = self.destination.x() + bound.x() + offset.x()
    dy: float = self.destination.y() + bound.y() + offset.y()
    d = QPointF(dx, dy)
    vx: float = dx - sx
    vy: float = dy - sy
    length: float = sqrt(vx * vx + vy * vy)
    if length <= head_width:
        return
    if vx == 0:
        ax = 1
        ay = 0
    else:
        ax = vy / length
        ay = -vx / length
    normal_vector = QPointF(ax, ay)
    direction_vector = QPointF(vx / length, vy / length)
    p0 = s + normal_vector * self.width / 2
    p6 = s - normal_vector * self.width / 2
    head_length: float = min(
        head_width * max(0, self.arrow_head_length_scale), 0.5 * length)
    base_length: float = length - head_length
    p1 = p0 + direction_vector * base_length
    p5 = p6 + direction_vector * base_length
    width_head_width_diff: float = head_width - self.width
    p2 = p1 + normal_vector * width_head_width_diff
    p7 = p5 - normal_vector * width_head_width_diff
    # if there is an indentation
    if self.indentation > 0:
        indentation_base_length = length + head_length * \
            (0.5 * max(0, min(1, self.indentation)) - 1)
        p1 = p0 + direction_vector * indentation_base_length
        p5 = p6 + direction_vector * indentation_base_length
    path: QPainterPath = QPainterPath()
    path.moveTo(s)  # center of base and source point
    path.lineTo(p0)  # corner 1 of base
    path.lineTo(p1)  # corner 1 of indentation
    path.lineTo(p2)  # corner 1 of outer head
    path.lineTo(d)  # destination point
    path.lineTo(p7)  # corner 2 of outer head
    path.lineTo(p5)  # corner 2 of indentation
    path.lineTo(p6)  # corner 2 of base
    qp.fillPath(path, self.color)

Source

from PyQt5.QtGui import QPainter, QPainterPath, QColor
from PyQt5.QtCore import QRect, QPoint, QPointF
from chessapp.view.pieces import QSize
from math import sqrt


class Arrow:
    """ An arrow from source to destination point with a given width and color. The arrow can be indented and scaled.

    Attributes:
        source (QPoint): source point (root of the arrow)
        destination (QPoint): destination point (tip of the arrow)
        width (int): width of the arrow
        color (QColor): color of the arrow
        indentation (float): indentation of the arrow (0 = no indentation, 1 = full indentation). TODO: describe indentation
        arrow_head_length_scale (float): scale of the arrow head length (0 = no arrow head, 1 = full arrow head)
        arrow_head_width_scale (float): scale of the arrow head width (0 = no arrow head, 1 = full arrow head)
    """

    def __init__(self, source: QPoint, destination: QPoint):
        """ initialize an arrow

        Args:
            source (QPoint): source point (root of the arrow)
            destination (QPoint): destination point (tip of the arrow)
        """
        self.source = source
        self.destination = destination
        self.width = 10
        self.color = QColor(0, 0, 128, 64)
        self.indentation: float = 0
        self.arrow_head_length_scale: float = 1
        self.arrow_head_width_scale: float = 1

    def drawOn(self, qp: QPainter, bound: QRect, offset: QPointF):
        """ draw the arrow on the given painter

        Args:
            qp (QPainter): the painter to draw on
            bound (QRect): the bounding rectangle of the arrow
            offset (QSize): the offset of the arrow
        """
        head_width = self.width * 2 * max(0, self.arrow_head_width_scale)
        sx: float = self.source.x() + bound.x() + offset.x()
        sy: float = self.source.y() + bound.y() + offset.y()
        s = QPointF(sx, sy)
        dx: float = self.destination.x() + bound.x() + offset.x()
        dy: float = self.destination.y() + bound.y() + offset.y()
        d = QPointF(dx, dy)
        vx: float = dx - sx
        vy: float = dy - sy
        length: float = sqrt(vx * vx + vy * vy)
        if length <= head_width:
            return
        if vx == 0:
            ax = 1
            ay = 0
        else:
            ax = vy / length
            ay = -vx / length
        normal_vector = QPointF(ax, ay)
        direction_vector = QPointF(vx / length, vy / length)
        p0 = s + normal_vector * self.width / 2
        p6 = s - normal_vector * self.width / 2
        head_length: float = min(
            head_width * max(0, self.arrow_head_length_scale), 0.5 * length)
        base_length: float = length - head_length
        p1 = p0 + direction_vector * base_length
        p5 = p6 + direction_vector * base_length
        width_head_width_diff: float = head_width - self.width
        p2 = p1 + normal_vector * width_head_width_diff
        p7 = p5 - normal_vector * width_head_width_diff
        # if there is an indentation
        if self.indentation > 0:
            indentation_base_length = length + head_length * \
                (0.5 * max(0, min(1, self.indentation)) - 1)
            p1 = p0 + direction_vector * indentation_base_length
            p5 = p6 + direction_vector * indentation_base_length
        path: QPainterPath = QPainterPath()
        path.moveTo(s)  # center of base and source point
        path.lineTo(p0)  # corner 1 of base
        path.lineTo(p1)  # corner 1 of indentation
        path.lineTo(p2)  # corner 1 of outer head
        path.lineTo(d)  # destination point
        path.lineTo(p7)  # corner 2 of outer head
        path.lineTo(p5)  # corner 2 of indentation
        path.lineTo(p6)  # corner 2 of base
        qp.fillPath(path, self.color)