edit.py

import sys
from PySide2.QtGui import QPixmap, QImage, QIcon, QTextCursor, QColor, QTextFormat, QFont, QPainter
from PySide2.QtWidgets import QWidget, QPlainTextEdit, QApplication, QTextEdit
from PySide2.QtCore import Slot, Qt, QPoint, Signal, QEvent, QTimer, QSize, QRect
from layout import Ui_MainWindow, icon
from send_file import SendFileDialog

class LineNumberArea(QWidget):
    def __init__(self, browser):
        super(LineNumberArea, self).__init__(browser)
        self.browser = browser

    def sizeHint(self):
        return QSize(self.browser.lineNumberAreaWidth(), 0)

    def paintEvent(self, event):
        self.browser.lineNumberAreaPaintEvent(event)


class LinePlainTextEdit(QPlainTextEdit):
    def __init__(self, parent=None):
        super(LinePlainTextEdit, self).__init__(parent)
        self.lineNumberArea = LineNumberArea(self)
        self.blockCountChanged.connect(self.updateLineNumberAreaWidth)
        self.updateRequest.connect(self.updateLineNumberArea)
        self.cursorPositionChanged.connect(self.highlightCurrentLine)

        self.updateLineNumberAreaWidth(0)
        # self.highlightCurrentLine()

    def setFont(self, font):
        super(LinePlainTextEdit, self).setFont(font)
        self.lineNumberArea.setFont(font)
    
    def lineNumberAreaPaintEvent(self, event):
        painter = QPainter(self.lineNumberArea)
        painter.fillRect(event.rect(), QColor(45, 45, 45))
        block = self.firstVisibleBlock()
        blockNumber = block.blockNumber()
        top = round(self.blockBoundingGeometry(block).translated(self.contentOffset()).top())
        bottom = top + round(self.blockBoundingRect(block).height())
        a = self.blockCount()
        while block.isValid() and (top <= event.rect().bottom()):
            if block.isVisible() and (bottom >= event.rect().top()):
                number = str(blockNumber + 1)
                # painter.setPen(Qt.black)
                painter.setPen(QColor(145, 145, 145))
                painter.drawText(-3, top, self.lineNumberArea.width(), self.fontMetrics().height(),
                                Qt.AlignRight, number)

            block = block.next()
            top = bottom
            bottom = top + round(self.blockBoundingRect(block).height())
            blockNumber += 1

    def lineNumberAreaWidth(self):
        digits = 1
        max_ = max(1, self.blockCount())
        while max_ >= 10 :
            max_ /= 10
            digits += 1

        space = 10 + self.fontMetrics().horizontalAdvance(ord('9')) * digits
        return space

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

        cr = self.contentsRect()
        self.lineNumberArea.setGeometry(QRect(cr.left(), cr.top(), self.lineNumberAreaWidth(), cr.height()))

    def updateLineNumberAreaWidth(self, newBlockCount):
        self.setViewportMargins(self.lineNumberAreaWidth(), 0, 0, 0)

    def highlightCurrentLine(self):
        extraSelections = list()

        if not self.isReadOnly() :
            selection = QTextEdit.ExtraSelection()

            lineColor = QColor(Qt.yellow).lighter(160)

            selection.format.setBackground(lineColor)
            selection.format.setProperty(QTextFormat.FullWidthSelection, True)
            selection.cursor = self.textCursor()
            selection.cursor.clearSelection()
            extraSelections.append(selection)
        
        self.setExtraSelections(extraSelections)

    def updateLineNumberArea(self, rect, dy):
        if dy:
            self.lineNumberArea.scroll(0, dy)
        else:
            self.lineNumberArea.update(0, rect.y(), self.lineNumberArea.width(), rect.height())

        if rect.contains(self.viewport().rect()):
            self.updateLineNumberAreaWidth(0)
    


def main():
    app = QApplication(sys.argv)
    w = LinePlainTextEdit()
    w.show()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()