# Copyright (C) 2013 Riverbank Computing Limited. # Copyright (C) 2022 The Qt Company Ltd. # SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause import sys import weakref import math from PySide6.QtCore import (QLineF, QPointF, QRandomGenerator, QRectF, QSizeF, Qt, qAbs) from PySide6.QtGui import (QColor, QBrush, QLinearGradient, QPainter, QPainterPath, QPen, QPolygonF, QRadialGradient) from PySide6.QtWidgets import (QApplication, QGraphicsItem, QGraphicsScene, QGraphicsView, QStyle) def random(boundary): return QRandomGenerator.global_().bounded(boundary) class Edge(QGraphicsItem): def __init__(self, sourceNode, destNode): super().__init__() self._arrow_size = 10.0 self._source_point = QPointF() self._dest_point = QPointF() self.setAcceptedMouseButtons(Qt.NoButton) self.source = weakref.ref(sourceNode) self.dest = weakref.ref(destNode) self.source().add_edge(self) self.dest().add_edge(self) self.adjust() def item_type(self): return QGraphicsItem.UserType + 2 def source_node(self): return self.source() def set_source_node(self, node): self.source = weakref.ref(node) self.adjust() def dest_node(self): return self.dest() def set_dest_node(self, node): self.dest = weakref.ref(node) self.adjust() def adjust(self): if not self.source() or not self.dest(): return line = QLineF(self.mapFromItem(self.source(), 0, 0), self.mapFromItem(self.dest(), 0, 0)) length = line.length() if length == 0.0: return edge_offset = QPointF((line.dx() * 10) / length, (line.dy() * 10) / length) self.prepareGeometryChange() self._source_point = line.p1() + edge_offset self._dest_point = line.p2() - edge_offset def boundingRect(self): if not self.source() or not self.dest(): return QRectF() pen_width = 1 extra = (pen_width + self._arrow_size) / 2.0 width = self._dest_point.x() - self._source_point.x() height = self._dest_point.y() - self._source_point.y() rect = QRectF(self._source_point, QSizeF(width, height)) return rect.normalized().adjusted(-extra, -extra, extra, extra) def paint(self, painter, option, widget): if not self.source() or not self.dest(): return # Draw the line itself. line = QLineF(self._source_point, self._dest_point) if line.length() == 0.0: return painter.setPen(QPen(Qt.black, 1, Qt.SolidLine, Qt.RoundCap, Qt.RoundJoin)) painter.drawLine(line) # Draw the arrows if there's enough room. angle = math.acos(line.dx() / line.length()) if line.dy() >= 0: angle = 2 * math.pi - angle arrow_head1 = QPointF(math.sin(angle + math.pi / 3) * self._arrow_size, math.cos(angle + math.pi / 3) * self._arrow_size) source_arrow_p1 = self._source_point + arrow_head1 arrow_head2 = QPointF(math.sin(angle + math.pi - math.pi / 3) * self._arrow_size, math.cos(angle + math.pi - math.pi / 3) * self._arrow_size) source_arrow_p2 = self._source_point + arrow_head2 arrow_head1 = QPointF(math.sin(angle - math.pi / 3) * self._arrow_size, math.cos(angle - math.pi / 3) * self._arrow_size) dest_arrow_p1 = self._dest_point + arrow_head1 arrow_head2 = QPointF(math.sin(angle - math.pi + math.pi / 3) * self._arrow_size, math.cos(angle - math.pi + math.pi / 3) * self._arrow_size) dest_arrow_p2 = self._dest_point + arrow_head2 painter.setBrush(Qt.black) painter.drawPolygon(QPolygonF([line.p1(), source_arrow_p1, source_arrow_p2])) painter.drawPolygon(QPolygonF([line.p2(), dest_arrow_p1, dest_arrow_p2])) class Node(QGraphicsItem): def __init__(self, graphWidget): super().__init__() self.graph = weakref.ref(graphWidget) self._edge_list = [] self._new_pos = QPointF() self.setFlag(QGraphicsItem.ItemIsMovable) self.setFlag(QGraphicsItem.ItemSendsGeometryChanges) self.setCacheMode(QGraphicsItem.DeviceCoordinateCache) self.setZValue(-1) def item_type(self): return QGraphicsItem.UserType + 1 def add_edge(self, edge): self._edge_list.append(weakref.ref(edge)) edge.adjust() def edges(self): return self._edge_list def calculate_forces(self): if not self.scene() or self.scene().mouseGrabberItem() is self: self._new_pos = self.pos() return # Sum up all forces pushing this item away. xvel = 0.0 yvel = 0.0 for item in self.scene().items(): if not isinstance(item, Node): continue line = QLineF(self.mapFromItem(item, 0, 0), QPointF(0, 0)) dx = line.dx() dy = line.dy() l = 2.0 * (dx * dx + dy * dy) # noqa: E741 if l > 0: xvel += (dx * 150.0) / l yvel += (dy * 150.0) / l # Now subtract all forces pulling items together. weight = (len(self._edge_list) + 1) * 10.0 for edge in self._edge_list: if edge().source_node() is self: pos = self.mapFromItem(edge().dest_node(), 0, 0) else: pos = self.mapFromItem(edge().source_node(), 0, 0) xvel += pos.x() / weight yvel += pos.y() / weight if qAbs(xvel) < 0.1 and qAbs(yvel) < 0.1: xvel = yvel = 0.0 scene_rect = self.scene().sceneRect() self._new_pos = self.pos() + QPointF(xvel, yvel) self._new_pos.setX(min(max(self._new_pos.x(), scene_rect.left() + 10), scene_rect.right() - 10)) self._new_pos.setY(min(max(self._new_pos.y(), scene_rect.top() + 10), scene_rect.bottom() - 10)) def advance(self): if self._new_pos == self.pos(): return False self.setPos(self._new_pos) return True def boundingRect(self): adjust = 2.0 return QRectF(-10 - adjust, -10 - adjust, 23 + adjust, 23 + adjust) def shape(self): path = QPainterPath() path.addEllipse(-10, -10, 20, 20) return path def paint(self, painter, option, widget): painter.setPen(Qt.NoPen) painter.setBrush(Qt.darkGray) painter.drawEllipse(-7, -7, 20, 20) gradient = QRadialGradient(-3, -3, 10) if option.state & QStyle.State_Sunken: gradient.setCenter(3, 3) gradient.setFocalPoint(3, 3) gradient.setColorAt(1, QColor(Qt.yellow).lighter(120)) gradient.setColorAt(0, QColor(Qt.darkYellow).lighter(120)) else: gradient.setColorAt(0, Qt.yellow) gradient.setColorAt(1, Qt.darkYellow) painter.setBrush(QBrush(gradient)) painter.setPen(QPen(Qt.black, 0)) painter.drawEllipse(-10, -10, 20, 20) def itemChange(self, change, value): if change == QGraphicsItem.ItemPositionChange: for edge in self._edge_list: edge().adjust() self.graph().item_moved() return QGraphicsItem.itemChange(self, change, value) def mousePressEvent(self, event): self.update() QGraphicsItem.mousePressEvent(self, event) def mouseReleaseEvent(self, event): self.update() QGraphicsItem.mouseReleaseEvent(self, event) class GraphWidget(QGraphicsView): def __init__(self): super().__init__() self._timer_id = 0 scene = QGraphicsScene(self) scene.setItemIndexMethod(QGraphicsScene.NoIndex) scene.setSceneRect(-200, -200, 400, 400) self.setScene(scene) self.setCacheMode(QGraphicsView.CacheBackground) self.setRenderHint(QPainter.Antialiasing) self.setTransformationAnchor(QGraphicsView.AnchorUnderMouse) self.setResizeAnchor(QGraphicsView.AnchorViewCenter) node1 = Node(self) node2 = Node(self) node3 = Node(self) node4 = Node(self) self._center_node = Node(self) node6 = Node(self) node7 = Node(self) node8 = Node(self) node9 = Node(self) scene.addItem(node1) scene.addItem(node2) scene.addItem(node3) scene.addItem(node4) scene.addItem(self._center_node) scene.addItem(node6) scene.addItem(node7) scene.addItem(node8) scene.addItem(node9) scene.addItem(Edge(node1, node2)) scene.addItem(Edge(node2, node3)) scene.addItem(Edge(node2, self._center_node)) scene.addItem(Edge(node3, node6)) scene.addItem(Edge(node4, node1)) scene.addItem(Edge(node4, self._center_node)) scene.addItem(Edge(self._center_node, node6)) scene.addItem(Edge(self._center_node, node8)) scene.addItem(Edge(node6, node9)) scene.addItem(Edge(node7, node4)) scene.addItem(Edge(node8, node7)) scene.addItem(Edge(node9, node8)) node1.setPos(-50, -50) node2.setPos(0, -50) node3.setPos(50, -50) node4.setPos(-50, 0) self._center_node.setPos(0, 0) node6.setPos(50, 0) node7.setPos(-50, 50) node8.setPos(0, 50) node9.setPos(50, 50) self.scale(0.8, 0.8) self.setMinimumSize(400, 400) self.setWindowTitle(self.tr("Elastic Nodes")) def item_moved(self): if not self._timer_id: self._timer_id = self.startTimer(1000 / 25) def keyPressEvent(self, event): key = event.key() if key == Qt.Key_Up: self._center_node.moveBy(0, -20) elif key == Qt.Key_Down: self._center_node.moveBy(0, 20) elif key == Qt.Key_Left: self._center_node.moveBy(-20, 0) elif key == Qt.Key_Right: self._center_node.moveBy(20, 0) elif key == Qt.Key_Plus: self.scale_view(1.2) elif key == Qt.Key_Minus: self.scale_view(1 / 1.2) elif key == Qt.Key_Space or key == Qt.Key_Enter: for item in self.scene().items(): if isinstance(item, Node): item.setPos(-150 + random(300), -150 + random(300)) else: QGraphicsView.keyPressEvent(self, event) def timerEvent(self, event): nodes = [item for item in self.scene().items() if isinstance(item, Node)] for node in nodes: node.calculate_forces() items_moved = False for node in nodes: if node.advance(): items_moved = True if not items_moved: self.killTimer(self._timer_id) self._timer_id = 0 def wheelEvent(self, event): delta = event.angleDelta().y() self.scale_view(math.pow(2.0, -delta / 240.0)) def draw_background(self, painter, rect): # Shadow. scene_rect = self.sceneRect() right_shadow = QRectF(scene_rect.right(), scene_rect.top() + 5, 5, scene_rect.height()) bottom_shadow = QRectF(scene_rect.left() + 5, scene_rect.bottom(), scene_rect.width(), 5) if right_shadow.intersects(rect) or right_shadow.contains(rect): painter.fillRect(right_shadow, Qt.darkGray) if bottom_shadow.intersects(rect) or bottom_shadow.contains(rect): painter.fillRect(bottom_shadow, Qt.darkGray) # Fill. gradient = QLinearGradient(scene_rect.topLeft(), scene_rect.bottomRight()) gradient.setColorAt(0, Qt.white) gradient.setColorAt(1, Qt.lightGray) painter.fillRect(rect.intersected(scene_rect), QBrush(gradient)) painter.setBrush(Qt.NoBrush) painter.drawRect(scene_rect) # Text. text_rect = QRectF(scene_rect.left() + 4, scene_rect.top() + 4, scene_rect.width() - 4, scene_rect.height() - 4) message = self.tr("Click and drag the nodes around, and zoom with the " "mouse wheel or the '+' and '-' keys") font = painter.font() font.setBold(True) font.setPointSize(14) painter.setFont(font) painter.setPen(Qt.lightGray) painter.drawText(text_rect.translated(2, 2), message) painter.setPen(Qt.black) painter.drawText(text_rect, message) def scale_view(self, scaleFactor): factor = self.transform().scale(scaleFactor, scaleFactor).mapRect( QRectF(0, 0, 1, 1)).width() if factor < 0.07 or factor > 100: return self.scale(scaleFactor, scaleFactor) if __name__ == "__main__": app = QApplication(sys.argv) widget = GraphWidget() widget.show() sys.exit(app.exec())