from PyQt5.QtCore import QRectF
from PyQt5.QtGui import QBrush, QColor, QPen
from PyQt5.QtWidgets import QApplication, QGraphicsItem, QGraphicsRectItem, QGraphicsScene, QGraphicsView, QVBoxLayout, QWidget


class QGraphicsFlowLayout(QGraphicsLayout):
    def __init__(self):
        super().__init__()

        self.item_list = []

    def addItem(self, item):
        self.item_list.append(item)

    def count(self):
        return len(self.item_list)

    def itemAt(self, index):
        return self.item_list[index]

    def takeAt(self, index):
        item = self.item_list.pop(index)
        return item

    def boundingRect(self):
        rect = QRectF()
        for item in self.item_list:
            rect |= item.rect()
        return rect

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

    def minimumSize(self):
        return self.sizeHint(QGraphicsLayout.MinimumSize, QSizeF())

    def preferredSize(self):
        return self.sizeHint(QGraphicsLayout.PreferredSize, QSizeF())

    def get_row_width(self):
        row_width = 0
        for item in self.item_list:
            row_width += item.rect().width()
        return row_width

    def get_row_height(self):
        row_height = 0
        for item in self.item_list:
            row_height = max(row_height, item.rect().height())
        return row_height

    def get_num_rows(self, view_width):
        row_width = self.get_row_width()
        num_rows = 1
        if row_width > view_width:
            num_rows = row_width // view_width + 1
        return num_rows

    def get_row_spacing(self):
        return 10

    def get_column_spacing(self):
        return 10

    def get_item_position(self, item, row, column):
        x = column * (item.rect().width() + self.get_column_spacing())
        y = row * (item.rect().height() + self.get_row_spacing())
        return QPointF(x, y)

    def setGeometry(self, rect):
        view_width = rect.width()
        num_rows = self.get_num_rows(view_width)
        row_height = self.get_row_height()

        for i, item in enumerate(self.item_list):
            row = i // num_rows
            column = i % num_rows
            pos = self.get_item_position(item, row, column)
            item.setPos(pos)


class QGraphicsFlowView(QGraphicsView):
    def __init__(self):
        super().__init__()

        self.scene = QGraphicsScene(self)
        self.layout = QGraphicsFlowLayout()
        self.scene.setLayout(self.layout)

        self.setRenderHints(QGraphicsView.Antialiasing | QGraphicsView.SmoothPixmapTransform)
        self.setViewportUpdateMode(QGraphicsView.FullViewportUpdate)

    def add_item(self, item):
        self.layout.addItem(item)

    def resizeEvent(self, event):
        super().resizeEvent(event)
        self.layout.setGeometry(self.rect())


class QGraphicsFlowItem(QGraphicsRectItem):
    def __init__(self, color):
        super().__init__()

        self.setRect(0, 0, 100, 100)
        self.setBrush(QBrush(color))
        self.setPen(QPen(QColor(0, 0, 0), 1))


if __name__ == "__main__":
    app = QApplication([])

    view = QGraphicsFlowView()
    view.add_item(QGraphicsFlowItem(QColor(255, 0, 0)))
    view.add_item(QGraphicsFlowItem(QColor(0, 255, 0)))
    view.add_item(QGraphicsFlowItem(QColor(0, 0, 255)))
    view.add_item(QGraphicsFlowItem(QColor(255, 255, 0)))
    view.add_item(QGraphicsFlowItem(QColor(255, 0, 255)))
    view.add_item(QGraphicsFlowItem(QColor(0, 255, 255)))
    view.show()

    app.exec_()