在PyQt中将标签字体大小与布局同步

Question

更改标签的字体大小以匹配通过信号/插槽包含的布局大小的具体方法是什么？

Answer 1

以下是QLabel从此处发布的解决方案衍生而来的解决方案：https : //forum.qt.io/topic/36088/automatically-scale-text-in-qlabels/5。

这包括resizeEvent方法的重新实现，其中QLabel根据的大小更新的字体大小contentRect。请注意，必须sizePolicy将Qlabel的设置Ignored为才能正常工作。

import sys
from PyQt4 import QtGui     

class myQLabel(QtGui.QLabel):
    def __init__(self, *args, **kargs):
        super(myQLabel, self).__init__(*args, **kargs)

        self.setSizePolicy(QtGui.QSizePolicy(QtGui.QSizePolicy.Ignored,
                                             QtGui.QSizePolicy.Ignored))  

        self.setMinSize(14)

    def setMinSize(self, minfs):        

        f = self.font()
        f.setPixelSize(minfs)
        br = QtGui.QFontMetrics(f).boundingRect(self.text())

        self.setMinimumSize(br.width(), br.height())

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

        if not self.text():
            return

        #--- fetch current parameters ----

        f = self.font()
        cr = self.contentsRect()

        #--- find the font size that fits the contentsRect ---

        fs = 1                    
        while True:

            f.setPixelSize(fs)
            br =  QtGui.QFontMetrics(f).boundingRect(self.text())

            if br.height() <= cr.height() and br.width() <= cr.width():
                fs += 1
            else:
                f.setPixelSize(max(fs - 1, 1)) # backtrack
                break  

        #--- update font size ---

        self.setFont(f)     


class myApplication(QtGui.QWidget):
    def __init__(self, parent=None):
        super(myApplication, self).__init__(parent)

        #---- Prepare a Layout ----

        grid = QtGui.QGridLayout()  

        for i in range(3):
            grid.addWidget(myQLabel('some text'), i, 0)  
            grid.setRowStretch(i, i+1)
            grid.setRowMinimumHeight(i, 25)

        self.setLayout(grid)
        self.resize(500, 300)


if __name__ == '__main__':

    app = QtGui.QApplication(sys.argv)

    instance = myApplication()  
    instance.show()    

    sys.exit(app.exec_())

结果是：

更新-resizeEvent的优化：

下面是该resizeEvent方法的优化版本，应该可以产生更好的性能。它大大减少了寻找字体大小最佳值所需的迭代次数。我还没有进行广泛的测试。

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

    if not self.text():
        return

    #--- fetch current parameters ----

    f = self.font()
    cr = self.contentsRect()

    #--- iterate to find the font size that fits the contentsRect ---

    dw = event.size().width() - event.oldSize().width()   # width change
    dh = event.size().height() - event.oldSize().height() # height change

    fs = max(f.pixelSize(), 1)        
    while True:

        f.setPixelSize(fs)
        br =  QtGui.QFontMetrics(f).boundingRect(self.text())

        if dw >= 0 and dh >= 0: # label is expanding

            if br.height() <= cr.height() and br.width() <= cr.width():
                fs += 1
            else:
                f.setPixelSize(max(fs - 1, 1)) # backtrack
                break                    

        else: # label is shrinking

            if br.height() > cr.height() or br.width() > cr.width():
                fs -= 1
            else:
                break

        if fs < 1: break

    #--- update font size ---           

    self.setFont(f)