如何在场景中添加多个对象？

Question

已创建一组手柄，可用于调整形状的大小。 通过跟踪手柄位置的变化，可以计算形状的新几何形状。

我不能在场景中添加多个对象。

$text-color: #373737;
$gray-base: #494949;
$gray-darker: #222;
$gray-dark: #333;
$gray: #555;
$gray-light: #777;
$gray-lighter: #eee;
$brand-primary: #1f9eba;
$brand-success: #59ba1f;
$brand-info: #5bc0de;
$brand-warning: #d1bd10;
$brand-danger: #ba1f1f;

/* Timeline */
.timeline {
  list-style: none;
  padding: 20px;
  position: relative;
  &:before {
    top: 40px;
    bottom: 0;
    position: absolute;
    content: " ";
    width: 3px;
    background-color: #eeeeee;
    left: 50%;
    margin-left: -1.5px;
  }
  .timeline-item {
    margin-bottom: 20px;
    position: relative;
    &:before,
    &:after {
      content: "";
      display: table;
    }
    &:after {
      clear: both;
    }
    .timeline-badge {
      color: #fff;
      width: 54px;
      height: 54px;
      line-height: 52px;
      font-size: 22px;
      text-align: center;
      position: absolute;
      top: 18px;
      left: 50%;
      margin-left: -25px;
      background-color: $gray-dark;
      border: 3px solid #ffffff;
      z-index: 100;
      border-top-right-radius: 50%;
      border-top-left-radius: 50%;
      border-bottom-right-radius: 50%;
      border-bottom-left-radius: 50%;
      i,
      .fa,
      .glyphicon {
        top: 2px;
        left: 0px;
      }
      &.primary {
        background-color: $brand-primary;
      }
      &.info {
        background-color: $brand-info;
      }
      &.success {
        background-color: $brand-success;
      }
      &.warning {
        background-color: $brand-warning;
      }
      &.danger {
        background-color: $brand-danger;
      }
    }
    .timeline-panel {
      position: relative;
      text-align: right;
      width: 46%;
      float: left;
      right: 16px;
      // border: 1px solid $gray-light;
      background: #ffffff;
      border-radius: 2px;
      padding: 20px;
      -webkit-box-shadow: 0 1px 6px rgba(0, 0, 0, 0.175);
      box-shadow: 0 1px 6px rgba(0, 0, 0, 0.175);
      &:before {
        position: absolute;
        top: 26px;
        right: -16px;
        display: inline-block;
        border-top: 16px solid transparent;
        border-left: 16px solid $gray-light;
        border-right: 0 solid $gray-light;
        border-bottom: 16px solid transparent;
        // content: " ";
      }
      .timeline-title {
        margin-top: 0;
        color: inherit;
      }
      .timeline-body > p,
      .timeline-body > ul {
        margin-bottom: 0;
      }
      .timeline-body > p + p {
        margin-top: 5px;
      }
    }    
  }
  .timeline-panel-right {
    position: relative;
    text-align: left;
    width: 46%;
    float: right;
    left: 16px;
    background: #ffffff;
    border-radius: 2px;
    padding: 20px;
    -webkit-box-shadow: 0 1px 6px rgba(0, 0, 0, 0.175);
    box-shadow: 0 1px 6px rgba(0, 0, 0, 0.175);
  }
  .timeline-item:nth-child(even) {
    .timeline-panel {
      float: right;
      text-align: left;
      left: 16px;
      &:before {
        border-left-width: 0;
        border-right-width: 14px;
        left: -14px;
        right: auto;
      }
    }
    .timeline-panel-right {
      float: left;
      text-align: right;
      right: 16px;
      left: auto;
    }   
  } 
}

我希望场景中会定位几个对象（矩形），并且每个对象都可以自由移动。

Answer 1

您仅添加了一个GraphicsRectItem，所以您仅看到一个项目，如果要查看更多项目，则必须创建更多GraphicsRectItem并使用addItem将它们添加到场景中。

# ...

import random

def main():

    app = QApplication(sys.argv)

    grview = QGraphicsView()
    scene = QGraphicsScene(grview)
    scene.setSceneRect(0, 0, 680, 459)
    grview.setScene(scene)
    for _ in range(10):
        item = GraphicsRectItem(0, 0, 300, 150)
        scene.addItem(item)
        item.setPos(QPointF(*random.sample(range(300), 2)))

    grview.fitInView(scene.sceneRect(), Qt.KeepAspectRatio)
    grview.show()
    sys.exit(app.exec_())

# ...

更新：

import sys

from PyQt5.QtCore import Qt, QRectF, QPointF, pyqtSlot
from PyQt5.QtGui import QBrush, QPainterPath, QPainter, QColor, QPen, QPixmap
from PyQt5.QtWidgets import (
    QGraphicsRectItem,
    QApplication,
    QGraphicsView,
    QGraphicsScene,
    QGraphicsItem,
    QPushButton,
    QWidget,
    QVBoxLayout,
)


class GraphicsRectItem(QGraphicsRectItem):
    # ...


class Widget(QWidget):
    def __init__(self, parent=None):
        super(Widget, self).__init__(parent)
        button = QPushButton("Add Rectangle", clicked=self.on_clicked)
        self.grview = QGraphicsView()
        scene = QGraphicsScene(self.grview)
        scene.setSceneRect(0, 0, 680, 459)
        self.grview.setScene(scene)
        self.grview.fitInView(scene.sceneRect(), Qt.KeepAspectRatio)

        lay = QVBoxLayout(self)
        lay.addWidget(button)
        lay.addWidget(self.grview)

    @pyqtSlot()
    def on_clicked(self):
        item = GraphicsRectItem(0, 0, 300, 150)
        item.setPos(QPointF(*random.sample(range(300), 2)))
        self.grview.scene().addItem(item)


import random


def main():

    app = QApplication(sys.argv)
    w = Widget()
    w.show()
    sys.exit(app.exec_())


if __name__ == "__main__":
    main()