流式布局

所谓流式布局指的是容器中的元素像流水一样，是可以浮动的，当元素一行或者一列占满的时候，它会自动流入到下一行或者下一列。

pyqt5流式布局

pyqt中采用流式布局的方法原理是，通过contentsMargins获取到子元素距离布局的上下左右宽度，然后我们将所有子元素进行遍历，如果它加上边距可以在一行放入的话，那么就放在一行内，如果不能，就放入到下一行，具体代码如下：

m = self.contentsMargins()effective_rect = rect.adjusted(+m.left(), +m.top(), -m.right(), -m.bottom()) x = effective_rect.x() y = effective_rect.y() line_height = 0 for item in self._item_list: wid = item.widget() space_x = self.spacing() space_y = self.spacing() if wid is not None: space_x += wid.style().layoutSpacing( QSizePolicy.PushButton, QSizePolicy.PushButton, Qt.Horizontal) space_y += wid.style().layoutSpacing( QSizePolicy.PushButton, QSizePolicy.PushButton, Qt.Vertical) next_x = x + item.sizeHint().width() + space_x if next_x - space_x > effective_rect.right() and line_height > 0: x = effective_rect.x() y = y + line_height + space_y next_x = x + item.sizeHint().width() + space_x line_height = 0 if not test_only: item.setGeometry(QRect(QPoint(x, y), item.sizeHint())) x = next_x line_height = max(line_height, item.sizeHint().height())

滚动条的设置

pyqt中有专门的滚动条组件QScrollBar,这个组件需要配合其他组件使用，我们这里使用QScrollArea这个组件进行滚动条的设置。

滚动条的使用方法

首先，我们需要声明QScrollArea

然后，我们需要设置QScrollArea的位置大小

最后，我们将需要产生滚动条的元素放入它的内部。

q = QWidget()qscrollarea = QtWidgets.QScrollArea(q) qscrollarea.setGeometry(QRect(50,100,600,500))qscrollarea.setWidgetResizable(True)listWidget = QtWidgets.QListWidget()qscrollarea.setWidget(listWidget)

流式布局和滚动条的结合案例：

在文件当前目录创建一个images文件夹，然后放入想要展示的多张图片，然后执行当前程序，就会看到带有滚动条的流式布局界面。

运行程序，需要安装pyqt5

from PyQt5.QtCore import QPoint, QRect, QSize, Qt,pyqtSignalimport osfrom PyQt5 import QtCore, QtGui, QtWidgetsfrom PyQt5.QtWidgets import ( QApplication, QLayout, QPushButton, QSizePolicy, QWidget, QGridLayout)import sysclass Window(QWidget): def __init__(self): self.imageheight = 100 super(Window, self).__init__() self.resize(800, 600) #self.listwidget = QtWidgets.QListWidget(self) #self.listwidget.resize(400,300) #self.listwidget.setGeometry(QtCore.QRect(0, 0, 300, 200)) #self.listwidget.addItem("test") highlight_dir = r"./images" self.files_it = iter([os.path.join(highlight_dir, file) for file in os.listdir(highlight_dir)]) # self.centralwidget = QtWidgets.QWidget(MainWindow) # self.gongzuomoshi = QtWidgets.QGroupBox(self.centralwidget) self.listWidget = QtWidgets.QListWidget(self) #self.listWidget.setFixedWidth(600) container_layout = QtWidgets.QVBoxLayout() g = QtWidgets.QGroupBox('') l = FlowLayout() g.setLayout(l) for file in iter(self.files_it): pixmap = QtGui.QPixmap(file) if not pixmap.isNull(): autoWidth = pixmap.width()*self.imageheight/pixmap.height() label = QtWidgets.QLabel(pixmap=pixmap) label.setScaledContents(True) label.setFixedHeight(self.imageheight) label.setFixedWidth(autoWidth) l.addWidget(label) container_layout.addWidget(g) container_layout.addStretch() self.listWidget.setLayout(container_layout) self.qscrollarea = QtWidgets.QScrollArea(self) self.qscrollarea.setGeometry(QRect(50,100,600,500)) self.qscrollarea.setWidgetResizable(True) self.qscrollarea.setWidget(self.listWidget) self.setWindowTitle("Flow Layout Scroll")class FlowLayout(QLayout): """流式布局,使用说明 1.声明流式布局 layout = FlowLayout 2.将元素放入流式布局中 3.将QGroupBox应用流式布局 4.如果期望水平流式,将QGroupBox放入到QHBoxLayout,如果期望垂直布局,将QGroupBox放入到QVBoxLayout """ heightChanged = pyqtSignal(int) def __init__(self, parent=None, margin=0, spacing=-1): super().__init__(parent) if parent is not None: self.setContentsMargins(margin, margin, margin, margin) self.setSpacing(spacing) self._item_list = [] def __del__(self): while self.count(): self.takeAt(0) def addItem(self, item): # pylint: disable=invalid-name self._item_list.append(item) def addSpacing(self, size): # pylint: disable=invalid-name self.addItem(QSpacerItem(size, 0, QSizePolicy.Fixed, QSizePolicy.Minimum)) def count(self): return len(self._item_list) def itemAt(self, index): # pylint: disable=invalid-name if 0 <= index < len(self._item_list): return self._item_list[index] return None def takeAt(self, index): # pylint: disable=invalid-name if 0 <= index < len(self._item_list): return self._item_list.pop(index) return None def expandingDirections(self): # pylint: disable=invalid-name,no-self-use return Qt.Orientations(Qt.Orientation(0)) def hasHeightForWidth(self): # pylint: disable=invalid-name,no-self-use return True def heightForWidth(self, width): # pylint: disable=invalid-name height = self._do_layout(QRect(0, 0, width, 0), True) return height def setGeometry(self, rect): # pylint: disable=invalid-name super().setGeometry(rect) self._do_layout(rect, False) def sizeHint(self): # pylint: disable=invalid-name return self.minimumSize() def minimumSize(self): # pylint: disable=invalid-name size = QSize() for item in self._item_list: minsize = item.minimumSize() extent = item.geometry().bottomRight() size = size.expandedTo(QSize(minsize.width(), extent.y())) margin = self.contentsMargins().left() size += QSize(2 * margin, 2 * margin) return size def _do_layout(self, rect, test_only=False): m = self.contentsMargins() effective_rect = rect.adjusted(+m.left(), +m.top(), -m.right(), -m.bottom()) x = effective_rect.x() y = effective_rect.y() line_height = 0 for item in self._item_list: wid = item.widget() space_x = self.spacing() space_y = self.spacing() if wid is not None: space_x += wid.style().layoutSpacing( QSizePolicy.PushButton, QSizePolicy.PushButton, Qt.Horizontal) space_y += wid.style().layoutSpacing( QSizePolicy.PushButton, QSizePolicy.PushButton, Qt.Vertical) next_x = x + item.sizeHint().width() + space_x if next_x - space_x > effective_rect.right() and line_height > 0: x = effective_rect.x() y = y + line_height + space_y next_x = x + item.sizeHint().width() + space_x line_height = 0 if not test_only: item.setGeometry(QRect(QPoint(x, y), item.sizeHint())) x = next_x line_height = max(line_height, item.sizeHint().height()) new_height = y + line_height - rect.y() self.heightChanged.emit(new_height) return new_heightif __name__ == '__main__': app = QApplication(sys.argv) mainWin = Window() mainWin.show() sys.exit(app.exec_())

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