python - 字体大小更改后 QTextEdit 中的 ZoomIn 没有影响

Question

此代码运行一个带有工具栏和 QTextEdit 区域的小窗口。

如果您突出显示“bananas”并更改字体大小，则使用工具栏按钮或 CTRL + 鼠标滚轮进行缩放只会调整“apples”的大小。有人知道为什么吗？

from PySide import QtGui, QtCore

class MainWindow(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.textEdit = Editor(self)
        self.toolBar  = QtGui.QToolBar(self)
        self.addToolBar(self.toolBar)
        self.setCentralWidget(self.textEdit)
        self.textEdit.setHtml('<font color=blue>apples bananas</font>')

        # Zoom
        self.actionZoomIn  = QtGui.QAction('Zoom In',  self)
        self.actionZoomOut = QtGui.QAction('Zoom Out', self)
        self.toolBar.addAction(self.actionZoomIn)
        self.toolBar.addAction(self.actionZoomOut)
        self.actionZoomIn.triggered.connect(self.onZoomInClicked)
        self.actionZoomOut.triggered.connect(self.onZoomOutClicked)

        # Font Size
        self.comboSize = QtGui.QComboBox(self.toolBar)
        self.toolBar.addWidget(self.comboSize)
        self.comboSize.addItem('0')
        self.comboSize.addItem('10')
        self.comboSize.addItem('18')
        self.comboSize.addItem('30')
        self.comboSize.addItem('48')
        self.comboSize.setCurrentIndex(1)
        self.comboSize.activated[str].connect(self.textSize)

    def textSize(self, pointSize):
        pointSize = int(pointSize)
        if pointSize > 0:
            fmt = QtGui.QTextCharFormat()
            fmt.setFontPointSize(pointSize)
            self.mergeFormatOnWordOrSelection(fmt)

    def mergeFormatOnWordOrSelection(self, format):
        cursor = self.textEdit.textCursor()
        if not cursor.hasSelection():
            cursor.select(QtGui.QTextCursor.WordUnderCursor)

        cursor.mergeCharFormat(format)
        self.textEdit.mergeCurrentCharFormat(format)

    def onZoomInClicked(self):
        self.textEdit.zoom(+1)

    def onZoomOutClicked(self):
        self.textEdit.zoom(-1)

class Editor(QtGui.QTextEdit):
    def __init__(self, parent=None):
        super(Editor, self).__init__(parent)
        self.zoomValue = 0

    def zoom(self, delta):
        zoomIncrement = 3

        if delta < 0:
            zoomIncrement = 0 - zoomIncrement

        self.zoomIn(zoomIncrement)
        self.zoomValue = self.zoomValue + zoomIncrement

        print "self.zoomValue", self.zoomValue

    def wheelEvent(self, event):
        if (event.modifiers() & QtCore.Qt.ControlModifier):
            self.zoom(event.delta())

if __name__ == '__main__':
    app = QtGui.QApplication([])
    window = MainWindow()
    window.resize(400, 180)
    window.show()
    app.exec_()

Answer 1

QTextEdit.zoomIn/Out 的默认实现只是更改文本编辑的基本字体的 pointSize。

示例中用于更改字体大小的方法将所选单词包装在 span 标记中，并使用内联 css 将 font-size 属性设置为固定值.这意味着当文本编辑随后被缩放时，只有未更改的文本会受到影响。

使用相对字体大小可以解决这个问题。然而，它看起来只是 css properties 的一个有限子集。受支持，因此只能设置不精确的值，如 small、large 等。

这可以通过进行以下更改在示例中实现:

    # Font Size
    self.comboSize = QtGui.QComboBox(self.toolBar)
    self.toolBar.addWidget(self.comboSize)
    self.comboSize.addItem('small')
    self.comboSize.addItem('medium')
    self.comboSize.addItem('large')
    self.comboSize.addItem('x-large')
    self.comboSize.addItem('xx-large')
    self.comboSize.setCurrentIndex(1)
    self.comboSize.activated[int].connect(self.textSize)

def textSize(self, size):
    fmt = QtGui.QTextCharFormat()
    fmt.setProperty(QtGui.QTextFormat.FontSizeAdjustment, size - 1)
    self.mergeFormatOnWordOrSelection(fmt)