CODEWITHSUNDEEP
pythonpyqtpyqt5
mapf
mapf

Reputation: 2058

Is there a way to set the alignment of the QTextEdit.placeholderText() in PyQt5?

I know you can set the alignment of the text using setAlignment(), but that has no effect on the placeholder text. Maybe you would need to edit the styleSheet of the underlying documentin order to do it? Or is the document only relevant for the actual text but not the placeholder?

Here's an MWE to play around with:

import sys

from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import QDialog, QApplication, QGridLayout, QTextEdit


class Test(QDialog):
    def __init__(self):
        super().__init__()
        self.edit = QTextEdit()
        self.edit.setPlaceholderText(
            # '<html><body><p align="center">'
            'this is a placeholder'
            # '</p></body></html>'
        )
        self.edit.setAlignment(Qt.AlignHCenter)
        self.lay = QGridLayout(self)
        self.lay.addWidget(self.edit)
        self.setLayout(self.lay)


if __name__ == '__main__':
    app = QApplication(sys.argv)
    GUI = Test()
    GUI.show()
    sys.exit(app.exec_())

Upvotes: 1

Views: 1555

Answers (1)

musicamante
musicamante

Reputation: 48231

The placeholder cannot be directly customized, as it is directly painted by the QTextEdit using the default top alignment, so the only solution is to subclass, overwrite the paintEvent and paint the placeholder using your own alignment.

You might also add much more control by using a QTextDocument, which will allow you to use html and custom colors/alignment/etc.

html placeholder text

class HtmlPlaceholderTextEdit(QTextEdit):
    _placeholderText = ''
    def setPlaceholderText(self, text):
        if Qt.mightBeRichText(text):
            self._placeholderText = QTextDocument()
            try:
                color = self.palette().placeholderText().color()
            except:
                # for Qt < 5.12
                color = self.palette().windowText().color()
                color.setAlpha(128)
            # IMPORTANT: the default stylesheet _MUST_ be set *before*
            # adding any text, otherwise it won't be used.
            self._placeholderText.setDefaultStyleSheet(
                '''body {{color: rgba({}, {}, {}, {});}}
                '''.format(*color.getRgb()))
            self._placeholderText.setHtml(text)
        else:
            self._placeholderText = text
        self.update()

    def placeholderText(self):
        return self._placeholderText

    def paintEvent(self, event):
        super().paintEvent(event)
        if self.document().isEmpty() and self.placeholderText():
            qp = QPainter(self.viewport())
            margin = self.document().documentMargin()
            r = QRectF(self.viewport().rect()).adjusted(margin, margin, -margin, -margin)
            text = self.placeholderText()
            if isinstance(text, str):
                try:
                    color = self.palette().placeholderText().color()
                except:
                    # for Qt < 5.12
                    color = self.palette().windowText().color()
                    color.setAlpha(128)
                qp.setPen(color)
                qp.drawText(r, self.alignment() | Qt.TextWordWrap, text)
            else:
                text.setPageSize(self.document().pageSize())
                text.drawContents(qp, r)


class Test(QDialog):
    def __init__(self):
        super().__init__()
        self.edit = HtmlPlaceholderTextEdit()
        self.edit.setPlaceholderText(
            '<html><body><p align="center">'
            'this is a <font color="blue">placeholder</font>'
            '</p></body></html>'
        )
        # ...

Upvotes: 1

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