PyQt5学习记录(3)---布局管理

布局管理的两种方法

布局管理是所有GUI编程中核心内容之一。在Qt里有两种方法可以控制布局，分别是绝对定位和布局类.

绝对定位

代码:

#coding=utf-8import sysfrom PyQt5.QtWidgets import QWidget, QLabel, QApplicationclass Example1(QWidget):    def __init__(self):        super().__init__()        self.initUI()        pass    def initUI(self):        label1 = QLabel('第一个', self)        label1.move(15, 10)        label2 = QLabel('第2个', self)        label2.move(35, 40)        label3 = QLabel('第3个', self)        label3.move(55, 70)        self.setGeometry(300, 300, 450, 450)        self.setWindowTitle('绝对定位示例')        self.show()        passdef main1():    app = QApplication(sys.argv)    example1 = Example1()    sys.exit(app.exec_())if __name__ == '__main__':    main1()

效果:

注意:绝对定位通过move函数进行，相对于父widget的左上角为原点.

箱布局

箱布局是我们进行布局的首选，核心就是QHBoxLayout和QVBoxLayout。这两个类继承自QBoxLayout,而QBoxLayout又继承自QLayout,QLayout继承自QObject和QLayoutItem.

#coding=utf-8import sysfrom PyQt5.QtWidgets import QWidget, QLabel, QApplication, QPushButton, QHBoxLayout, \    QVBoxLayoutclass Example2(QWidget):    def __init__(self):        super().__init__()        self.initUI()        pass    def initUI(self):        okBtn = QPushButton('OK')        cancelBtn = QPushButton('Cancel')        hbox = QHBoxLayout()        hbox.addStretch(1)        hbox.addWidget(okBtn)        hbox.addWidget(cancelBtn)        vbox = QVBoxLayout()        vbox.addStretch(1)        vbox.addLayout(hbox)        self.setLayout(vbox)        self.setGeometry(300, 300, 450, 450)        self.setWindowTitle('箱布局')        self.show()        passdef main2():    app = QApplication(sys.argv)    example2 = Example2()    sys.exit(app.exec_())if __name__ == '__main__':    main2()

效果:

要点提示

只有一点，那就是addStretch()函数的理解，它为widget增加一个拉伸因子，至于是怎么拉伸跟父布局有关。如上面代码，就是先拉伸，再添加两个button，所有button会被挤到最右侧。如果我们先添加两个button，再添加这个因子，效果就是这样:

 hbox = QHBoxLayout() hbox.addWidget(okBtn) hbox.addWidget(cancelBtn) hbox.addStretch(1)

对应效果:

如果将设置拉伸因子的函数去掉，则添加的两个按钮平分空间，占满整个布局就是这个效果了:

网格布局QGridLayout

该类继承自QLayout,也是用的很多。这个可以回想web的布局，早些年一直是表格布局当道。
下面看个计算器的例子:

#coding=utf-8import sysfrom PyQt5.QtWidgets import QWidget, QLabel, QApplication, QPushButton, QHBoxLayout, \    QVBoxLayout, QGridLayoutclass Example3(QWidget):    def __init__(self):        super().__init__()        self.initUI()        pass    def initUI(self):        grid = QGridLayout()        self.setLayout(grid)        names = ['cls', 'bck', '', 'close',                 '7', '8', '9', '/',                 '4', '5', '6', '*',                 '1', '2', '3', '-',                 '0', '.', '=', '+']        poses = [(i, j) for i in range(5) for j in range(4)]        for pos, name in zip(poses, names):            if name == '':                continue            btn = QPushButton(name)            grid.addWidget(btn, *pos)        self.setGeometry(300, 300, 450, 450)        self.setWindowTitle('网格布局--计算器')        self.show()        passdef main3():    app = QApplication(sys.argv)    example3 = Example3()    sys.exit(app.exec_())if __name__ == '__main__':    main3()

效果如下:

核心提示

1. zip的使用http://www.cnblogs.com/frydsh/archive/2012/07/10/2585370.html
2. *pos的含义，在没有*的时候pos就是(0, 0)是个元组，加个星号之后成了0, 0两个int。

QGridLayout加强

QGridLayout还可以设置每个item占多个列，即不均匀分配.

#coding=utf-8import sysfrom PyQt5.QtWidgets import QWidget, QLabel, QApplication, QPushButton, QHBoxLayout, \    QVBoxLayout, QGridLayout, QLineEdit, QTextEditclass Example4(QWidget):    def __init__(self):        super().__init__()        self.initUI()        pass    def initUI(self):        title = QLabel('Title')        author = QLabel('Author')        review = QLabel('Review')        titleEdit = QLineEdit()        authorEdit = QLineEdit()        reviewEdit = QTextEdit()        grid = QGridLayout()        grid.setSpacing(30)        grid.addWidget(title, 0, 0)        grid.addWidget(titleEdit, 0, 1)        grid.addWidget(author, 1, 0)        grid.addWidget(authorEdit, 1, 1)        grid.addWidget(review, 2, 0)        grid.addWidget(reviewEdit, 2, 1, 5, 1)        self.setLayout(grid)        self.setGeometry(300, 300, 450, 450)        self.setWindowTitle('网格布局--文本审阅窗口')        self.show()        passdef main4():    app = QApplication(sys.argv)    example4 = Example4()    sys.exit(app.exec_())if __name__ == '__main__':    main4()

效果图:

要点提示

1.addWidget的原型

void QGridLayout::addLayout(QLayout *layout, int row, int column, Qt::Alignment alignment = Qt::Alignment())Places the layout at position (row, column) in the grid. The top-left position is (0, 0).The alignment is specified by alignment. The default alignment is 0, which means that the widget fills the entire cell.A non-zero alignment indicates that the layout should not grow to fill the available space but should be sized according to sizeHint().layout becomes a child of the grid layout

第二个参数是行号，第三个坐标是列号。默认左上角为(0, 0)。

2.addWidget的第二种:

void QGridLayout::addWidget(QWidget *widget, int fromRow, int fromColumn, int rowSpan, int columnSpan, Qt::Alignment alignment = Qt::Alignment())This is an overloaded function.This version adds the given widget to the cell grid, spanning multiple rows/columns. The cell will start at fromRow, fromColumn spanning rowSpan rows and columnSpan columns. The widget will have the given alignment.If rowSpan and/or columnSpan is -1, then the widget will extend to the bottom and/or right edge, respectively.