How to highlight a word from the text in qtextedit in pyqt5 python?

Question

I'm creating a text editor in pyqt5 python. and I want to add the find feature like any other text/code editor. After entering a word or words in a find line edit; that word will be highlighted in TextEdit! how can do it in pyqt5 python [not in pyqt4 or any other programming language] my code:

class Ui_nms_pad(QMainWindow):
    def __init__(self):
        super(Ui_nms_pad, self).__init__() 
        uic.loadUi('Nms_pad.ui', self)
        self.Find_Button.clicked.connect(self.Find_word())
    def Find_word(self):
        words = self.Find_lineEdit.text
        {highlight words in text edit}

Answer 1

I hope the code below will serve your purpose.

    def Find_word(self):
        self.findDialog = QtWidgets.QDialog(self)

        label = QtWidgets.QLabel("Find Word:")
        self.lineEdit = QtWidgets.QLineEdit()
        self.lineEdit.setText(self.lastSearchText)
        label.setBuddy(self.lineEdit)

        self.findButton = QtWidgets.QPushButton("Find Next")
        self.findButton.setDefault(True)
        self.findButton.clicked.connect(self.searchText)

        buttonBox = QtWidgets.QDialogButtonBox(QtCore.Qt.Vertical)
        buttonBox.addButton(self.findButton, QtWidgets.QDialogButtonBox.ActionRole)

        topLeftLayout = QtWidgets.QHBoxLayout()
        topLeftLayout.addWidget(label)
        topLeftLayout.addWidget(self.lineEdit)

        leftLayout = QtWidgets.QVBoxLayout()
        leftLayout.addLayout(topLeftLayout)

        mainLayout = QtWidgets.QGridLayout()
        mainLayout.setSizeConstraint(QtWidgets.QLayout.SetFixedSize)
        mainLayout.addLayout(leftLayout, 0, 0)
        mainLayout.addWidget(buttonBox, 0, 1)
        mainLayout.setRowStretch(2, 1)
        self.findDialog.setLayout(mainLayout)

        self.findDialog.setWindowTitle("Find")
        self.findDialog.show()

    def searchText(self):
        cursor = self.text.textCursor()
        findIndex = cursor.anchor()
        text = self.lineEdit.text()
        content = self.text.toPlainText()
        length = len(text)

        self.lastSearchText = text
        index = content.find(text, findIndex)

        if -1 == index:
            errorDialog = QtWidgets.QMessageBox(self)
            errorDialog.addButton("Cancel", QtWidgets.QMessageBox.ActionRole)

            errorDialog.setWindowTitle("Find")
            errorDialog.setText("Not Found\"%s\"." % text)
            errorDialog.setIcon(QtWidgets.QMessageBox.Critical)
            errorDialog.exec_()
        else:
            start = index

            cursor = self.text.textCursor()
            cursor.clearSelection()
            cursor.movePosition(QtGui.QTextCursor.Start, QtGui.QTextCursor.MoveAnchor)
            cursor.movePosition(QtGui.QTextCursor.Right, QtGui.QTextCursor.MoveAnchor, start + length)
            cursor.movePosition(QtGui.QTextCursor.Left, QtGui.QTextCursor.KeepAnchor, length)
            cursor.selectedText()
            self.text.setTextCursor(cursor)

Answer 2

QTextEdit features find() which automatically highlights the first occurrance of the text match and returns a bool if the text has been found.
Without any argument, besides the search string, the search is done starting from the current text cursor position up to the end of the document. In the following example, the search is "wrapped" by moving the cursor to the beginning of the document in case no match has been found; this is obviously only for demonstration purposes (if this is the preferred search mode, you can just move the cursor in the first place, before starting the search).

    def find_word(self):
        words = self.find_lineEdit.text()
        if not self.textEdit.find(words):
            # no match found, move the cursor to the beginning of the
            # document and start the search once again
            cursor = self.textEdit.textCursor()
            cursor.setPosition(0)
            self.textEdit.setTextCursor(cursor)
            self.textEdit.find(words)

Answer 3

from PyQt5.QtWidgets import QMainWindow, QTextEdit, QWidget, QLineEdit, QVBoxLayout, QApplication
from PyQt5.QtGui import QTextCharFormat, QBrush
from PyQt5.QtCore import Qt
import sys

class MainWindow(QMainWindow):

    def __init__(self, parent=None):
        super().__init__(parent)

        self.extraSelections = []
        self.lineEdit = QLineEdit(placeholderText="search")
        self.textEdit = QTextEdit("""Lorem Ipsum is simply dummy text of the printing
                                                        and typesetting industry.
                                                        Lorem Ipsum has been the industry's standard
                                                        dummy text ever since the 1500s, when an
                                                        unknown printer took a galley of type and
                                                        scrambled it to make a type specimen book.
                                                        It has survived not only five centuries,
                                                        but also the leap into electronic typesetting,
                                                        remaining essentially unchanged.
                                                        It was popularised in the 1960s with the release of
                                                        Letraset sheets containing Lorem Ipsum passages,
                                                        and more recently with desktop publishing software
                                                        like Aldus PageMaker including versions of Lorem Ipsum.""")
        
        w = QWidget()
        v  = QVBoxLayout()
        v.addWidget(self.lineEdit)
        v.addWidget(self.textEdit)
        w.setLayout(v)
        self.setCentralWidget(w)

        self.lineEdit.returnPressed.connect(self.find_word)

    def appendExtraSelection(self, tc):
        
            ex = QTextEdit.ExtraSelection()            
            ex.cursor = tc
            ex.format.setForeground(QBrush(Qt.blue))
            ex.format.setBackground(QBrush(Qt.yellow))
            self.extraSelections.append(ex)
 
            
    def find_word(self):
        
        self.extraSelections.clear()    
        doc = self.textEdit.document()
        self.find_recursion(0)
        self.textEdit.setExtraSelections(self.extraSelections)
            
    def find_recursion(self, pos):

        doc = self.textEdit.document()
        tc = doc.find(self.lineEdit.text(), pos)
        if not tc.isNull():
            self.appendExtraSelection(tc)
            self.find_recursion(tc.selectionEnd())


     
    
        
def main():

    app = QApplication([])
    w = MainWindow()
    w.show()
    sys.exit(app.exec())

if __name__ == "__main__":
    main()

1. To use find function of QTextDocument.
2. To set QTextEdit.ExtraSelection for highlighting text.
3. To use find function as recursion to search for all target texts.