QGraphicsAnchorLayout不在QGraphicsScene中锚定

Question

我目前在理解QGraphicsScene中QGraphicsAnchorLayout的行为时遇到问题。我创建了4个框，并固定了每个框的角，但是似乎没有正确应用锚，或者至少没有我认为的那样。

即使在展开GraphicsView时，黄色框也应始终位于QGraphicsScene的左上方。蓝色框锚定为与右侧黄色框相邻，其顶部与QGraphicsScene / viewport的顶部重合。

绿色框的左上角固定在蓝色框的右下角，同样，红色框固定在绿色框上。但这就是我得到的：

我希望黄色框始终处于图形场景/视口的顶部。我希望它即使在向右滚动时也始终保持可见，但是我相信这可能是一个单独的问题。但是，当我垂直扩展窗口时，所有框都居中，包括我希望保留在顶部的黄色框。

[蓝色，绿色和红色框似乎与我应用的锚点没有相似之处。

以下是我用来生成此代码的代码。这些锚点如何工作，我该怎么做才能纠正此问题？

import numpy as np
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtCore import Qt
from debug_utils import *
from PyQt5.QtWidgets import QGraphicsAnchorLayout, QGraphicsWidget, QGraphicsLayoutItem

def qp(p):
    return "({}, {})".format(p.x(), p.y())

class box(QtWidgets.QGraphicsWidget):
    pressed = QtCore.pyqtSignal()

    def __init__(self, rect, color, parent=None):
        super(box, self).__init__(parent)
        self.raw_rect = rect
        self.rect = QtCore.QRectF(rect[0], rect[1], rect[2], rect[3])
        self.color = color

    def boundingRect(self):
        pen_adj = 0
        return self.rect.normalized().adjusted(-pen_adj, -pen_adj, pen_adj, pen_adj)

    def paint(self, painter, option, widget):
        r = self.boundingRect()

        brush = QtGui.QBrush()
        brush.setColor(QtGui.QColor(self.color))
        brush.setStyle(Qt.SolidPattern)

        #rect = QtCore.QRect(0, 0, painter.device().width(), painter.device().height())
        painter.fillRect(self.boundingRect(), brush)
        painter.setRenderHint(QtGui.QPainter.Antialiasing)
        painter.setPen(Qt.darkGray)

        painter.drawRect(self.boundingRect())
        #painter.drawRect(0, 0, max_time*char_spacing, self.bar_height)

    def mousePressEvent(self, ev):
        self.pressed.emit()
        self.update()

    def mouseReleaseEvent(self, ev):
        self.update()

class GraphicsView(QtWidgets.QGraphicsView):
    def __init__(self, parent=None):
        super(GraphicsView, self).__init__(parent)
        scene = QtWidgets.QGraphicsScene(self)
        self.setScene(scene)
        self.numbers = []
        self.setMouseTracking(True)

        l = QGraphicsAnchorLayout()
        l.setSpacing(0)
        w = QGraphicsWidget()
        #painter = QtGui.QPainter(self)
        w.setPos(0, 0)
        w.setLayout(l)
        scene.addItem(w)
        self.main_widget = w
        self.main_layout = l

        self.makeBoxs()

    def makeBoxs(self):
        rect = [0, 0, 600, 250]
        blue_box = box(rect, QtGui.QColor(0, 0, 255, 128))
        green_box = box(rect, QtGui.QColor(0, 255, 0, 128))
        red_box = box([0, 0, 200, 50], QtGui.QColor(255, 0, 0, 128))
        yellow_box_left = box([0, 0, 75, 600], QtGui.QColor(255, 255, 0, 128))
        #self.scene().setSceneRect(blue_box.rect)
        #self.scene().setSceneRect(bar_green.rect)

        # Adding anchors adds the item to the layout which is part of the scene
        self.main_layout.addCornerAnchors(yellow_box_left, Qt.TopLeftCorner, self.main_layout, Qt.TopLeftCorner)
        self.main_layout.addCornerAnchors(blue_box, Qt.TopLeftCorner, yellow_box_left, Qt.TopRightCorner)
        self.main_layout.addCornerAnchors(green_box, Qt.TopLeftCorner, blue_box, Qt.BottomRightCorner)
        self.main_layout.addCornerAnchors(red_box, Qt.TopLeftCorner, green_box, Qt.BottomRightCorner)

        #self.main_layout.addAnchor(bar_green, Qt.AnchorTop, blue_box, Qt.AnchorBottom)
        #self.main_layout.addAnchor(bar_green, Qt.AnchorLeft, blue_box, Qt.AnchorRight)

    def printStatus(self, pos):
        msg = "Viewport Position: " + str(qp(pos))
        v = self.mapToScene(pos)
        v = QtCore.QPoint(v.x(), v.y())
        msg = msg + ",  Mapped to Scene: " + str(qp(v))
        v = self.mapToScene(self.viewport().rect()).boundingRect()
        msg = msg + ",  viewport Mapped to Scene: " + str(qp(v))
        v2 = self.mapToScene(QtCore.QPoint(0, 0))
        msg = msg + ",  (0, 0) to scene: " + qp(v2)
        self.parent().statusBar().showMessage(msg)

    def mouseMoveEvent(self, event):
        pos = event.pos()
        self.printStatus(pos)
        super(GraphicsView, self).mouseMoveEvent(event)

    def resizeEvent(self, event):
        self.printStatus(QtGui.QCursor().pos())
        h = self.mapToScene(self.viewport().rect()).boundingRect().height()
        r = self.sceneRect()
        r.setHeight(h)

        height = self.viewport().height()
        for item in self.items():
            item_height = item.boundingRect().height()

        super(GraphicsView, self).resizeEvent(event)

class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)

        gv = GraphicsView()
        self.setCentralWidget(gv)
        self.setGeometry(475, 250, 600, 480)
        scene = self.scene = gv.scene()
        sb = self.statusBar()

def main():
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = MainWindow()
    w.show()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()

编辑：添加期望的输出根据锚的定义方式，我希望输出看起来像以下内容。由于无法真正创建所需的内容，因此我已经在PowerPoint中创建了它。但是，当然，除了使它起作用之外，我还希望了解如何从更一般的意义上使用锚点。

编辑2：再次感谢您的更新。这不是我所期望的，滚动时有一个奇怪的伪像。只是为了澄清，

我希望黄色小部件始终可见，在Z顺序最高的视口的左上方。我想你提供了。
所有其他小部件都应滚动，并保持其相对锚。我将蓝色框的锚点移到了黄色框，但是所有框都向左对齐。
在您当前的实现中，非黄色框不会滚动，但是当我调整大小或左右移动滚动条时，会看到此工件：

Answer 1

您有2个错误：

您的Box类的构建质量很差，它不会设置boundingRect，而是仅设置尺寸，因为该位置将由布局处理。
布局的位置始终相对于设置它的小部件。并且在您的情况下，您希望main_layout的左上角与视口的左上角相匹配，因此您必须修改main_widget的左上角以进行匹配。

考虑到上述，解决方法是：

from PyQt5 import QtCore, QtGui, QtWidgets


def qp(p):
    return "({}, {})".format(p.x(), p.y())


class Box(QtWidgets.QGraphicsWidget):
    pressed = QtCore.pyqtSignal()

    def __init__(self, size, color, parent=None):
        super(Box, self).__init__(parent)
        self.setMinimumSize(size)
        self.setMaximumSize(size)
        self.color = color

    def paint(self, painter, option, widget):
        brush = QtGui.QBrush()
        brush.setColor(QtGui.QColor(self.color))
        brush.setStyle(QtCore.Qt.SolidPattern)

        painter.fillRect(self.boundingRect(), brush)
        painter.setRenderHint(QtGui.QPainter.Antialiasing)
        painter.setPen(QtCore.Qt.darkGray)

        painter.drawRect(self.boundingRect())

    def mousePressEvent(self, event):
        self.pressed.emit()
        super().mousePressEvent(event)


class GraphicsView(QtWidgets.QGraphicsView):
    messageChanged = QtCore.pyqtSignal(str)

    def __init__(self, parent=None):
        super(GraphicsView, self).__init__(parent)
        self.setMouseTracking(True)
        self.setAlignment(QtCore.Qt.AlignTop | QtCore.Qt.AlignLeft)
        scene = QtWidgets.QGraphicsScene(self)
        self.setScene(scene)

        l = QtWidgets.QGraphicsAnchorLayout()
        l.setSpacing(0)
        w = QtWidgets.QGraphicsWidget()
        self.scene().sceneRectChanged.connect(self.update_widget)
        self.horizontalScrollBar().valueChanged.connect(self.update_widget)
        self.verticalScrollBar().valueChanged.connect(self.update_widget)
        w.setLayout(l)
        scene.addItem(w)
        self.main_widget = w
        self.main_layout = l

        self.makeBoxs()

    def makeBoxs(self):
        blue_box = Box(QtCore.QSizeF(300, 125), QtGui.QColor(0, 0, 255, 128))
        green_box = Box(QtCore.QSizeF(300, 125), QtGui.QColor(0, 255, 0, 128))
        red_box = Box(QtCore.QSizeF(100, 25), QtGui.QColor(255, 0, 0, 128))
        yellow_box = Box(QtCore.QSizeF(37.5, 300), QtGui.QColor(255, 255, 0, 128))

        # yellow_box_left top-left
        self.main_layout.addCornerAnchors(
            yellow_box,
            QtCore.Qt.TopLeftCorner,
            self.main_layout,
            QtCore.Qt.TopLeftCorner,
        )
        self.main_layout.addCornerAnchors(
            blue_box, QtCore.Qt.TopLeftCorner, yellow_box, QtCore.Qt.TopRightCorner
        )
        self.main_layout.addCornerAnchors(
            green_box, QtCore.Qt.TopLeftCorner, blue_box, QtCore.Qt.BottomRightCorner
        )
        self.main_layout.addCornerAnchors(
            red_box, QtCore.Qt.TopLeftCorner, green_box, QtCore.Qt.BottomRightCorner
        )

        # self.setSceneRect(self.scene().itemsBoundingRect())

    def update_widget(self):
        vp = self.viewport().mapFromParent(QtCore.QPoint())
        tl = self.mapToScene(vp)
        geo = self.main_widget.geometry()
        geo.setTopLeft(tl)
        self.main_widget.setGeometry(geo)

    def resizeEvent(self, event):
        self.update_widget()
        super().resizeEvent(event)

    def mouseMoveEvent(self, event):
        pos = event.pos()
        self.printStatus(pos)
        super(GraphicsView, self).mouseMoveEvent(event)

    def printStatus(self, pos):
        msg = "Viewport Position: " + str(qp(pos))
        v = self.mapToScene(pos)
        v = QtCore.QPoint(v.x(), v.y())
        msg = msg + ",  Mapped to Scene: " + str(qp(v))
        v = self.mapToScene(self.viewport().rect()).boundingRect()
        msg = msg + ",  viewport Mapped to Scene: " + str(qp(v))
        v2 = self.mapToScene(QtCore.QPoint(0, 0))
        msg = msg + ",  (0, 0) to scene: " + qp(v2)
        self.messageChanged.emit(msg)


class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)

        gv = GraphicsView()
        self.setCentralWidget(gv)

        self.setGeometry(475, 250, 600, 480)

        gv.messageChanged.connect(self.statusBar().showMessage)


def main():
    import sys

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


if __name__ == "__main__":
    main()

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