GuiShell/ui/lineNumberWidget.py

from PySide2.QtGui import *
from PySide2 import QtCore, QtGui, QtWidgets
from PySide2.QtCore import Qt


class Editor(QtWidgets.QPlainTextEdit):
    def __init__(self, parent=None):
        super().__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.setLineWrapMode(QtWidgets.QPlainTextEdit.LineWrapMode.NoWrap)
        self.setReadOnly(True)
        
    def goToLine(self, center_line):
        total_num_of_lines = self.document().lineCount()
        # 计算每行的高度
        line_height = self.fontMetrics().lineSpacing()
        # 获取文本控件可视窗口的高度
        viewport_height = self.viewport().height()
        # 每行所需滚动条的值
        scroll_per_line = (self.verticalScrollBar().pageStep() + self.verticalScrollBar().maximum())/total_num_of_lines
        
        scroll_value = (center_line - viewport_height/2/line_height) * scroll_per_line
        
        # 移动光标
        cursor = self.textCursor()
        cursor.movePosition(QtGui.QTextCursor.Start)
        for i in range(center_line - 1):
            cursor.movePosition(QtGui.QTextCursor.Down, QtGui.QTextCursor.MoveAnchor)
        self.setTextCursor(cursor)
        self.verticalScrollBar().setValue(0) 
        self.verticalScrollBar().setValue(scroll_value)  

                                                            
    def lineNumberAreaWidth(self):
        digits = 1
        count = max(1, self.blockCount())
        while count >= 10:
            count /= 10
            digits += 1
        space = 3 + self.fontMetrics().horizontalAdvance('9') * digits
        return space

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

    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 resizeEvent(self, event):
        super().resizeEvent(event)
        cr = self.contentsRect()
        self.lineNumberArea.setGeometry(QtCore.QRect(cr.left(), cr.top(), self.lineNumberAreaWidth(), cr.height()))

    def highlightCurrentLine(self):
        extraSelections = []

        selection = QtWidgets.QTextEdit.ExtraSelection()

        lineColor = QtGui.QColor(232,232,255)

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

        self.setExtraSelections(extraSelections)


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

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

    def paintEvent(self, event):
        painter = QtGui.QPainter(self)
        painter.fillRect(event.rect(), QtCore.Qt.lightGray)

        block = self.editor.firstVisibleBlock()
        blockNumber = block.blockNumber()
        top = self.editor.blockBoundingGeometry(block).translated(self.editor.contentOffset()).top()
        bottom = top + self.editor.blockBoundingRect(block).height()

        height = self.editor.fontMetrics().height()
        while block.isValid() and top <= event.rect().bottom():
            if block.isVisible() and bottom >= event.rect().top():
                number = str(blockNumber + 1)
                painter.setPen(QtCore.Qt.black)
                painter.drawText(0, top, self.width(), height, QtCore.Qt.AlignRight, number)

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