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PyQT6 elastic nodes example
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| #!/usr/bin/env python | |
| # This file was shamelessly copied from | |
| # https://github.com/baoboa/pyqt5/blob/master/examples/graphicsview/elasticnodes.py | |
| # and ported to PyQt6 by Pascal Ernster | |
| ############################################################################# | |
| ## | |
| ## Copyright (C) 2013 Riverbank Computing Limited. | |
| ## Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). | |
| ## All rights reserved. | |
| ## | |
| ## This file is part of the examples of PyQt. | |
| ## | |
| ## $QT_BEGIN_LICENSE:BSD$ | |
| ## You may use this file under the terms of the BSD license as follows: | |
| ## | |
| ## "Redistribution and use in source and binary forms, with or without | |
| ## modification, are permitted provided that the following conditions are | |
| ## met: | |
| ## * Redistributions of source code must retain the above copyright | |
| ## notice, this list of conditions and the following disclaimer. | |
| ## * Redistributions in binary form must reproduce the above copyright | |
| ## notice, this list of conditions and the following disclaimer in | |
| ## the documentation and/or other materials provided with the | |
| ## distribution. | |
| ## * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor | |
| ## the names of its contributors may be used to endorse or promote | |
| ## products derived from this software without specific prior written | |
| ## permission. | |
| ## | |
| ## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| ## "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| ## LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
| ## A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |
| ## OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
| ## SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | |
| ## LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
| ## DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
| ## THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
| ## (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
| ## OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE." | |
| ## $QT_END_LICENSE$ | |
| ## | |
| ############################################################################# | |
| import math | |
| from PyQt6.QtCore import (qAbs, QLineF, QPointF, QRectF, QSizeF, Qt, QTime) | |
| from PyQt6.QtGui import (QBrush, QColor, QLinearGradient, QPainter, | |
| QPainterPath, QPen, QPolygonF, QRadialGradient) | |
| from PyQt6.QtWidgets import (QApplication, QGraphicsItem, QGraphicsScene, | |
| QGraphicsView, QStyle) | |
| class Edge(QGraphicsItem): | |
| Pi = math.pi | |
| TwoPi = 2.0 * Pi | |
| Type = QGraphicsItem.UserType + 2 | |
| def __init__(self, sourceNode, destNode): | |
| super(Edge, self).__init__() | |
| self.arrowSize = 10.0 | |
| self.sourcePoint = QPointF() | |
| self.destPoint = QPointF() | |
| self.setAcceptedMouseButtons(Qt.MouseButton.NoButton) | |
| self.source = sourceNode | |
| self.dest = destNode | |
| self.source.addEdge(self) | |
| self.dest.addEdge(self) | |
| self.adjust() | |
| def type(self): | |
| return Edge.Type | |
| def sourceNode(self): | |
| return self.source | |
| def setSourceNode(self, node): | |
| self.source = node | |
| self.adjust() | |
| def destNode(self): | |
| return self.dest | |
| def setDestNode(self, node): | |
| self.dest = 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() | |
| self.prepareGeometryChange() | |
| if length > 20.0: | |
| edgeOffset = QPointF((line.dx() * 10) / length, | |
| (line.dy() * 10) / length) | |
| self.sourcePoint = line.p1() + edgeOffset | |
| self.destPoint = line.p2() - edgeOffset | |
| else: | |
| self.sourcePoint = line.p1() | |
| self.destPoint = line.p1() | |
| def boundingRect(self): | |
| if not self.source or not self.dest: | |
| return QRectF() | |
| penWidth = 1.0 | |
| extra = (penWidth + self.arrowSize) / 2.0 | |
| return QRectF(self.sourcePoint, | |
| QSizeF(self.destPoint.x() - self.sourcePoint.x(), | |
| self.destPoint.y() - self.sourcePoint.y())).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.sourcePoint, self.destPoint) | |
| if line.length() == 0.0: | |
| return | |
| painter.setPen(QPen(Qt.GlobalColor.black, 1, Qt.PenStyle.SolidLine, Qt.PenCapStyle.RoundCap, | |
| Qt.PenJoinStyle.RoundJoin)) | |
| painter.drawLine(line) | |
| # Draw the arrows if there's enough room. | |
| angle = math.acos(line.dx() / line.length()) | |
| if line.dy() >= 0: | |
| angle = Edge.TwoPi - angle | |
| sourceArrowP1 = self.sourcePoint + QPointF(math.sin(angle + Edge.Pi / 3) * self.arrowSize, | |
| math.cos(angle + Edge.Pi / 3) * self.arrowSize) | |
| sourceArrowP2 = self.sourcePoint + QPointF(math.sin(angle + Edge.Pi - Edge.Pi / 3) * self.arrowSize, | |
| math.cos(angle + Edge.Pi - Edge.Pi / 3) * self.arrowSize); | |
| destArrowP1 = self.destPoint + QPointF(math.sin(angle - Edge.Pi / 3) * self.arrowSize, | |
| math.cos(angle - Edge.Pi / 3) * self.arrowSize) | |
| destArrowP2 = self.destPoint + QPointF(math.sin(angle - Edge.Pi + Edge.Pi / 3) * self.arrowSize, | |
| math.cos(angle - Edge.Pi + Edge.Pi / 3) * self.arrowSize) | |
| painter.setBrush(Qt.GlobalColor.black) | |
| painter.drawPolygon(QPolygonF([line.p1(), sourceArrowP1, sourceArrowP2])) | |
| painter.drawPolygon(QPolygonF([line.p2(), destArrowP1, destArrowP2])) | |
| class Node(QGraphicsItem): | |
| Type = QGraphicsItem.UserType + 1 | |
| def __init__(self, graphWidget): | |
| super(Node, self).__init__() | |
| self.graph = graphWidget | |
| self.edgeList = [] | |
| self.newPos = QPointF() | |
| self.setFlag(QGraphicsItem.GraphicsItemFlag.ItemIsMovable) | |
| self.setFlag(QGraphicsItem.GraphicsItemFlag.ItemSendsGeometryChanges) | |
| self.setCacheMode(QGraphicsItem.CacheMode.DeviceCoordinateCache) | |
| self.setZValue(1) | |
| def type(self): | |
| return Node.Type | |
| def addEdge(self, edge): | |
| self.edgeList.append(edge) | |
| edge.adjust() | |
| def edges(self): | |
| return self.edgeList | |
| def calculateForces(self): | |
| if not self.scene() or self.scene().mouseGrabberItem() is self: | |
| self.newPos = 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) | |
| if l > 0: | |
| xvel += (dx * 150.0) / l | |
| yvel += (dy * 150.0) / l | |
| # Now subtract all forces pulling items together. | |
| weight = (len(self.edgeList) + 1) * 10.0 | |
| for edge in self.edgeList: | |
| if edge.sourceNode() is self: | |
| pos = self.mapFromItem(edge.destNode(), 0, 0) | |
| else: | |
| pos = self.mapFromItem(edge.sourceNode(), 0, 0) | |
| xvel += pos.x() / weight | |
| yvel += pos.y() / weight | |
| if qAbs(xvel) < 0.1 and qAbs(yvel) < 0.1: | |
| xvel = yvel = 0.0 | |
| sceneRect = self.scene().sceneRect() | |
| self.newPos = self.pos() + QPointF(xvel, yvel) | |
| self.newPos.setX(min(max(self.newPos.x(), sceneRect.left() + 10), sceneRect.right() - 10)) | |
| self.newPos.setY(min(max(self.newPos.y(), sceneRect.top() + 10), sceneRect.bottom() - 10)) | |
| def advance(self): | |
| if self.newPos == self.pos(): | |
| return False | |
| self.setPos(self.newPos) | |
| 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.PenStyle.NoPen) | |
| painter.setBrush(Qt.GlobalColor.darkGray) | |
| painter.drawEllipse(-7, -7, 20, 20) | |
| gradient = QRadialGradient(-3, -3, 10) | |
| if option.state & QStyle.StateFlag.State_Sunken: | |
| gradient.setCenter(3, 3) | |
| gradient.setFocalPoint(3, 3) | |
| gradient.setColorAt(1, QColor(Qt.GlobalColor.yellow).lighter(120)) | |
| gradient.setColorAt(0, QColor(Qt.GlobalColor.darkYellow).lighter(120)) | |
| else: | |
| gradient.setColorAt(0, Qt.GlobalColor.yellow) | |
| gradient.setColorAt(1, Qt.GlobalColor.darkYellow) | |
| painter.setBrush(QBrush(gradient)) | |
| painter.setPen(QPen(Qt.GlobalColor.black, 0)) | |
| painter.drawEllipse(-10, -10, 20, 20) | |
| def itemChange(self, change, value): | |
| if change == QGraphicsItem.GraphicsItemChange.ItemPositionHasChanged: | |
| for edge in self.edgeList: | |
| edge.adjust() | |
| self.graph.itemMoved() | |
| return super(Node, self).itemChange(change, value) | |
| def mousePressEvent(self, event): | |
| self.update() | |
| super(Node, self).mousePressEvent(event) | |
| def mouseReleaseEvent(self, event): | |
| self.update() | |
| super(Node, self).mouseReleaseEvent(event) | |
| class GraphWidget(QGraphicsView): | |
| def __init__(self): | |
| super(GraphWidget, self).__init__() | |
| self.timerId = 0 | |
| scene = QGraphicsScene(self) | |
| scene.setItemIndexMethod(QGraphicsScene.ItemIndexMethod.NoIndex) | |
| scene.setSceneRect(-200, -200, 400, 400) | |
| self.setScene(scene) | |
| self.setCacheMode(QGraphicsView.CacheModeFlag.CacheBackground) | |
| self.setViewportUpdateMode(QGraphicsView.ViewportUpdateMode.BoundingRectViewportUpdate) | |
| self.setRenderHint(QPainter.RenderHint.Antialiasing) | |
| self.setTransformationAnchor(QGraphicsView.ViewportAnchor.AnchorUnderMouse) | |
| self.setResizeAnchor(QGraphicsView.ViewportAnchor.AnchorViewCenter) | |
| node1 = Node(self) | |
| node2 = Node(self) | |
| node3 = Node(self) | |
| node4 = Node(self) | |
| self.centerNode = 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.centerNode) | |
| 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.centerNode)) | |
| scene.addItem(Edge(node3, node6)) | |
| scene.addItem(Edge(node4, node1)) | |
| scene.addItem(Edge(node4, self.centerNode)) | |
| scene.addItem(Edge(self.centerNode, node6)) | |
| scene.addItem(Edge(self.centerNode, 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.centerNode.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("Elastic Nodes") | |
| def itemMoved(self): | |
| if not self.timerId: | |
| self.timerId = self.startTimer(40) #1000/25 | |
| def keyPressEvent(self, event): | |
| key = event.key() | |
| if key == Qt.Key.Key_Up: | |
| self.centerNode.moveBy(0, -20) | |
| elif key == Qt.Key.Key_Down: | |
| self.centerNode.moveBy(0, 20) | |
| elif key == Qt.Key.Key_Left: | |
| self.centerNode.moveBy(-20, 0) | |
| elif key == Qt.Key.Key_Right: | |
| self.centerNode.moveBy(20, 0) | |
| elif key == Qt.Key.Key_Plus: | |
| self.scaleView(1.2) | |
| elif key == Qt.Key.Key_Minus: | |
| self.scaleView(1 / 1.2) | |
| else: | |
| super(GraphWidget, self).keyPressEvent(event) | |
| def timerEvent(self, event): | |
| nodes = [item for item in self.scene().items() if isinstance(item, Node)] | |
| for node in nodes: | |
| node.calculateForces() | |
| itemsMoved = False | |
| for node in nodes: | |
| if node.advance(): | |
| itemsMoved = True | |
| if not itemsMoved: | |
| self.killTimer(self.timerId) | |
| self.timerId = 0 | |
| def wheelEvent(self, event): | |
| self.scaleView(math.pow(2.0, -event.angleDelta().y() / 240.0)) | |
| def drawBackground(self, painter, rect): | |
| # Shadow. | |
| sceneRect = self.sceneRect() | |
| rightShadow = QRectF(sceneRect.right(), sceneRect.top() + 5, 5, | |
| sceneRect.height()) | |
| bottomShadow = QRectF(sceneRect.left() + 5, sceneRect.bottom(), | |
| sceneRect.width(), 5) | |
| if rightShadow.intersects(rect) or rightShadow.contains(rect): | |
| painter.fillRect(rightShadow, Qt.GlobalColor.darkGray) | |
| if bottomShadow.intersects(rect) or bottomShadow.contains(rect): | |
| painter.fillRect(bottomShadow, Qt.GlobalColor.darkGray) | |
| # Fill. | |
| gradient = QLinearGradient(sceneRect.topLeft(), sceneRect.bottomRight()) | |
| gradient.setColorAt(0, Qt.GlobalColor.white) | |
| gradient.setColorAt(1, Qt.GlobalColor.lightGray) | |
| painter.fillRect(rect.intersected(sceneRect), QBrush(gradient)) | |
| painter.setBrush(Qt.BrushStyle.NoBrush) | |
| painter.drawRect(sceneRect) | |
| # Text. | |
| textRect = QRectF(sceneRect.left() + 4, sceneRect.top() + 4, | |
| sceneRect.width() - 4, sceneRect.height() - 4) | |
| message = "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.GlobalColor.lightGray) | |
| painter.drawText(textRect.translated(2, 2), message) | |
| painter.setPen(Qt.GlobalColor.black) | |
| painter.drawText(textRect, message) | |
| def scaleView(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__': | |
| import sys | |
| app = QApplication(sys.argv) | |
| widget = GraphWidget() | |
| widget.show() | |
| sys.exit(app.exec()) |
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