Here is a Qt4 widget written in Python that allows for line numbers next to a
QTextEdit
. Similar to what is seen in a number of text editors such as gedit
and kate.
from PyQt4.Qt import QFrame, QWidget, QTextEdit, QHBoxLayout, QPainter
class LineTextWidget(QFrame):
class NumberBar(QWidget):
def __init__(self, *args):
QWidget.__init__(self, *args)
self.edit = None
# This is used to update the width of the control.
# It is the highest line that is currently visibile.
self.highest_line = 0
def setTextEdit(self, edit):
self.edit = edit
def update(self, *args):
'''
Updates the number bar to display the current set of numbers.
Also, adjusts the width of the number bar if necessary.
'''
# The + 4 is used to compensate for the current line being bold.
width = self.fontMetrics().width(str(self.highest_line)) + 4
if self.width() != width:
self.setFixedWidth(width)
QWidget.update(self, *args)
def paintEvent(self, event):
contents_y = self.edit.verticalScrollBar().value()
page_bottom = contents_y + self.edit.viewport().height()
font_metrics = self.fontMetrics()
current_block = self.edit.document().findBlock(self.edit.textCursor().position())
painter = QPainter(self)
line_count = 0
# Iterate over all text blocks in the document.
block = self.edit.document().begin()
while block.isValid():
line_count += 1
# The top left position of the block in the document
position = self.edit.document().documentLayout().blockBoundingRect(block).topLeft()
# Check if the position of the block is out side of the visible
# area.
if position.y() > page_bottom:
break
# We want the line number for the selected line to be bold.
bold = False
if block == current_block:
bold = True
font = painter.font()
font.setBold(True)
painter.setFont(font)
# Draw the line number right justified at the y position of the
# line. 3 is a magic padding number. drawText(x, y, text).
painter.drawText(self.width() - font_metrics.width(str(line_count)) - 3, round(position.y()) - contents_y + font_metrics.ascent(), str(line_count))
# Remove the bold style if it was set previously.
if bold:
font = painter.font()
font.setBold(False)
painter.setFont(font)
block = block.next()
self.highest_line = line_count
painter.end()
QWidget.paintEvent(self, event)
def __init__(self, *args):
QFrame.__init__(self, *args)
self.setFrameStyle(QFrame.StyledPanel | QFrame.Sunken)
self.edit = QTextEdit()
self.edit.setFrameStyle(QFrame.NoFrame)
self.edit.setAcceptRichText(False)
self.number_bar = self.NumberBar()
self.number_bar.setTextEdit(self.edit)
hbox = QHBoxLayout(self)
hbox.setSpacing(0)
hbox.setMargin(0)
hbox.addWidget(self.number_bar)
hbox.addWidget(self.edit)
self.edit.installEventFilter(self)
self.edit.viewport().installEventFilter(self)
def eventFilter(self, object, event):
# Update the line numbers for all events on the text edit and the viewport.
# This is easier than connecting all necessary singals.
if object in (self.edit, self.edit.viewport()):
self.number_bar.update()
return False
return QFrame.eventFilter(object, event)
def getTextEdit(self):
return self.edit