Question

我有两个不同的问题要解决，我无法弄清楚。我之前并没有使用QGraphicsView等工具，但是我创建了一个QGraphicsView，我试图在其中加载图像，并且试图使用QSpinBox动态地控制每行使用图像。例如，如果我有16张图像，并且QSpinBox设置为4“我默认拥有”，则应该有4行4列图像。那部分我似乎工作正常，但是代码不是很好。我想不出一种方法来控制有多少列和多少行图像，除非每次计数改变时都删除并重新加载它们。我最终清理了整个场景并重新加载了所有内容，因为我无法单独删除项目。

我现在遇到的主要问题是自动正确设置行和列的rect。我正在尝试使场景随着更改而调整大小，而不会在scrollabars上留出一堆空白。

这是加载图像时的开始样子。

这是滚动QSpinBox后的外观。此时应该只有一个垂直滚动条，而没有一堆空白的水平滚动条。

经过反复试验，我发现我可以在代码中像这样self.scene.setSceneRect(QRectF(self.graphics_widget.rect()))来设置场景rect，它似乎可以很好地解决滚动条的问题，但是只有当我手动操作时，它才能工作以某种方式触发它，对于此示例，这就是“设置矩形”按钮的作用。

这里是一个例子。单击“设置矩形”按钮后，垂直滚动条被正确删除，水平滚动条是整行的正确宽度。

如果我尝试在所有内容加载后自动设置场景rect，它会给我错误的宽度和高度，但是由于某些原因，如果我使用按钮等手动设置场景，则可以正常工作。

我遇到的另一个小问题是使红色条形图的顶部延伸到视口区域之外。如果在显示水平滚动条时尝试水平滚动，则它看起来像这样，并且我希望它可以拉伸整个宽度。

那没什么大不了的，我敢肯定我能弄清楚。我主要关心的是如何自动设置场景校正，以便所有内容正确流动而不会在滚动条上留下一堆空白。
有没有人有什么建议？谢谢。

这是我的代码：

from PySide2.QtCore import QRectF, QSizeF, QRect, Qt, QPointF
from PySide2.QtGui import QPixmap, QFont, QColor, QPen, QBrush
from PySide2.QtWidgets import QGraphicsWidget, QWidget, QVBoxLayout, QPushButton, QHBoxLayout, \
    QSpinBox, QGraphicsView, QGraphicsScene, QGraphicsGridLayout, QApplication


class PixmapItem(QGraphicsWidget):
    def __init__(self, image, parent=None):
        super(PixmapItem, self).__init__(parent)
        self.pic = QPixmap(image)
        self._boundingRect = QRectF()
        self.pic_size = self.pic.rect().size()

    def boundingRect(self):
        width = self.pic_size.width()
        height = self.pic_size.height()
        pix_rect = QRectF(0.0, 0.0, width, height)
        self._boundingRect = pix_rect
        return pix_rect

    def sizeHint(self, which, constraint=QSizeF()):
        return self._boundingRect.size()

    def paint(self, painter, option, widget):
        painter.drawPixmap(QRect(0, 40, self.pic_size.width(), self.pic_size.height()), self.pic, self.pic.rect())

class MyScene(QGraphicsScene):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

    def drawBackground(self, painter, rect):
        bg_brush = QBrush(QColor(255, 255, 255), Qt.SolidPattern)
        painter.fillRect(rect, bg_brush)
        #Red bar on top
        painter.setPen(QPen(Qt.NoPen))
        brush = QBrush(QColor(139, 0, 0), Qt.SolidPattern)
        r = QRectF(QPointF(0, 0), QSizeF(rect.width(), 30))
        painter.fillRect(r, brush)
        self.update()

class Widget(QWidget):
    def __init__(self):
        super(Widget, self).__init__()
        self.resize(330, 330)
        self.imglist = ["py.png", "py.png","py.png","py.png","py.png","py.png",
                        "py.png","py.png","py.png","py.png","py.png","py.png"]

        self._layout = QVBoxLayout()
        self._layout2 = QHBoxLayout()

        self.btn = QPushButton("Load")
        self.column_spinbox = QSpinBox()
        self.column_spinbox.setRange(1, 25)
        self.column_spinbox.setValue(4)
        self.column_spinbox.setSingleStep(1)
        self.btn2 = QPushButton("Set Rect")

        self._layout2.addWidget(self.btn)
        self._layout2.addWidget(self.column_spinbox)
        self._layout2.addWidget(self.btn2)
        self._layout.addLayout(self._layout2)

        self._layout3 = QHBoxLayout()
        self.view = QGraphicsView()
        self.view.setAlignment(Qt.AlignLeft | Qt.AlignTop)
        self.scene = MyScene()
        self.view.setScene(self.scene)
        self.graphics_widget = QGraphicsWidget()
        self.scene.addItem(self.graphics_widget)
        self.graphics_layout = QGraphicsGridLayout()
        self.graphics_widget.setLayout(self.graphics_layout)
        self._layout3.addWidget(self.view)
        self._layout.addLayout(self._layout3)
        self.setLayout(self._layout)
        self.btn.clicked.connect(self._load_pix)
        self.btn2.clicked.connect(self._set_rect)
        self.column_spinbox.valueChanged.connect(self.set_columns)

    def _set_rect(self):
        self.scene.setSceneRect(QRectF(self.graphics_widget.rect()))

    def _load_pix(self):
        for img in range(len(self.imglist)):
            pixmap = PixmapItem(self.imglist[img])
            row, column = divmod(img, self.column_spinbox.value())
            self.graphics_layout.addItem(pixmap, row, column)
            self.graphics_layout.setColumnSpacing(column, 15)
            self.graphics_layout.setRowSpacing(row, 15)
        self.scene.setSceneRect(QRectF(self.graphics_widget.rect()))
        # Add text to top
        item = self.scene.addText("Some Sample Text.", QFont("Arial", 16, QFont.Light))
        item.setDefaultTextColor(QColor(255, 255, 255))

    def set_columns(self):
        self.view.scene().clear()
        #After clearing the scene, re-add the widgets
        self.graphics_widget = QGraphicsWidget()
        self.scene.addItem(self.graphics_widget)
        self.graphics_layout = QGraphicsGridLayout()
        self.graphics_widget.setLayout(self.graphics_layout)
        for img in range(len(self.imglist)):
            pixmap = PixmapItem(self.imglist[img], self.graphics_widget)
            row, column = divmod(img, self.column_spinbox.value())
            self.graphics_layout.addItem(pixmap, row, column)
            self.graphics_layout.setColumnSpacing(column, 15)
            self.graphics_layout.setRowSpacing(row, 15)
        self.scene.setSceneRect(QRectF(self.graphics_widget.rect()))
        #Add text to top again
        item = self.scene.addText("Some Sample Text.", QFont("Arial", 16, QFont.Light))
        item.setDefaultTextColor(QColor(255, 255, 255))

if __name__ == '__main__':
    import sys
    app = QApplication(sys.argv)
    widget = Widget()
    widget.show()
    app.exec_()

Answer 1

第二个问题是由于您从drawBackground获得的矩形是关于场景而不是视口的，所以解决方案是复制该矩形并设置高度：

class MyScene(QGraphicsScene):
    def drawBackground(self, painter, rect):
        bg_brush = QBrush(QColor(255, 255, 255), Qt.SolidPattern)
        painter.fillRect(rect, bg_brush)
        #Red bar on top
        painter.setPen(QPen(Qt.NoPen))
        brush = QBrush(QColor(139, 0, 0), Qt.SolidPattern)
        r = QRectF(rect)
        r.setY(0)
        r.setHeight(30)
        painter.fillRect(r, brush)

仍在解决第一个问题...

完整的解决方案：

由于有很多重复的内容，所以我已经接受了您的代码，但是主要任务是实现Adjust_scene方法，该方法使用itemsBoundingRect（）和视口来计算视口。技巧是在设置新的QGraphicsWidget之后立即调用该函数，也可以在QGraphicsView的resizeEvent中调用它。

from PySide2 import QtCore, QtGui, QtWidgets

class PixmapItem(QtWidgets.QGraphicsWidget):
    def __init__(self, image, parent=None):
        super(PixmapItem, self).__init__(parent)
        self.pic = QtGui.QPixmap(image)

    def boundingRect(self):
        return QtCore.QRectF(self.pic.rect())

    def sizeHint(self, which, constraint=QtCore.QSizeF()):
        return self.boundingRect().size()

    def paint(self, painter, option, widget):
        painter.drawPixmap(QtCore.QPoint(), self.pic)

class GraphicsScene(QtWidgets.QGraphicsScene):
    def drawBackground(self, painter, rect):
        bg_brush = QtGui.QBrush(QtGui.QColor(255, 255, 255), QtCore.Qt.SolidPattern)
        painter.fillRect(rect, bg_brush)
        #Red bar on top
        painter.setPen(QtGui.QPen(QtCore.Qt.NoPen))
        brush = QtGui.QBrush(QtGui.QColor(139, 0, 0), QtCore.Qt.SolidPattern)
        r = QtCore.QRectF(rect)
        r.setY(0)
        r.setHeight(30)
        painter.fillRect(r, brush)

class GraphicsView(QtWidgets.QGraphicsView):
    def adjust_scene(self):
        if self.scene() is None: return
        r = self.scene().itemsBoundingRect()
        view_rect = self.mapToScene(self.viewport().rect()).boundingRect()
        w = max(r.size().width(), view_rect.size().width())
        h = max(r.size().height(), view_rect.size().height())
        self.scene().setSceneRect(QtCore.QRectF(QtCore.QPointF(), QtCore.QSizeF(w, h)))

    def resizeEvent(self, event):
        super(GraphicsView, self).resizeEvent(event)
        self.adjust_scene()

class Widget(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Widget, self).__init__(parent)
        self.load_button = QtWidgets.QPushButton(text="Load")
        self.load_button.clicked.connect(self.load)
        self.column_spinbox = QtWidgets.QSpinBox(
            value=4,
            minimum=1,
            maximum=25,
            enabled=False
        )
        self.column_spinbox.valueChanged[int].connect(self.set_columns)
        self.scene = GraphicsScene()
        self.view = GraphicsView(self.scene)
        lay = QtWidgets.QVBoxLayout(self)
        hlay = QtWidgets.QHBoxLayout()
        hlay.addWidget(self.load_button)
        hlay.addWidget(self.column_spinbox)
        lay.addLayout(hlay)
        lay.addWidget(self.view)

    @QtCore.Slot()
    def load(self):
        self.imglist = ["py.png", "py.png","py.png","py.png","py.png","py.png",
            "py.png","py.png","py.png","py.png","py.png","py.png"]
        self.set_columns(self.column_spinbox.value())
        self.column_spinbox.setEnabled(True)

    @QtCore.Slot(int)
    def set_columns(self, column):
        self.view.scene().clear()
        item = self.scene.addText("Some Sample Text.", QtGui.QFont("Arial", 16, QtGui.QFont.Light))
        item.setDefaultTextColor(QtGui.QColor(255, 255, 255))

        top = item.mapToScene(item.boundingRect().bottomLeft())
        self.graphics_widget = QtWidgets.QGraphicsWidget()
        graphics_layout = QtWidgets.QGraphicsGridLayout(self.graphics_widget)
        self.view.scene().addItem(self.graphics_widget)
        self.graphics_widget.setPos(top)

        for i, img in enumerate(self.imglist):
            item = PixmapItem(img)
            row, col = divmod(i, column)
            graphics_layout.addItem(item, row, col)
            graphics_layout.setColumnSpacing(column, 15)
            graphics_layout.setRowSpacing(row, 15)
        QtCore.QTimer.singleShot(0, self.view.adjust_scene)

if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = Widget()
    w.show()
    sys.exit(app.exec_())

如何在QGraphicsView中自动正确设置rect？

1 个答案: