Q:

How to replace properly certain matches on QScintilla widget?

I got this little mcve code:
import sys
import re

from PyQt5 import QtGui, QtWidgets, QtCore
from PyQt5.QtCore import Qt
from PyQt5.Qsci import QsciScintilla
from PyQt5 import Qsci

class FloatSlider(QtWidgets.QWidget):

    value_changed = QtCore.pyqtSignal(float)

    def __init__(self, value=0.0, parent=None):
        super().__init__(parent)

        self.slider = QtWidgets.QSlider(Qt.Horizontal)
        self.label = QtWidgets.QLabel()
        self.label.setAlignment(Qt.AlignCenter)

        self.adjust(value)

        layout = QtWidgets.QHBoxLayout()
        layout.addWidget(self.slider)
        layout.addWidget(self.label)

        self.slider.valueChanged.connect(self.on_value_changed)
        self.setLayout(layout)
        self.setWindowTitle("Adjust number")

    def adjust(self, value):
        width = 100  # TODO: Adjust it properly depending on input value
        self.slider.setRange(value - width, value + width)
        self.slider.setSingleStep(1)
        self.slider.setValue(value)
        self.label.setText(str(float(value)))

    def on_value_changed(self, value):
        # vmax, vmin = self.slider.minimum(), self.slider.maximum()
        # value = 2 * value / (vmax - vmin)
        self.label.setText(str(float(value)))
        self.value_changed.emit(value)

class SimpleEditor(QsciScintilla):

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

        self.slider = FloatSlider(value=0.0)
        self.slider.value_changed.connect(self.float_value_changed)

        font = QtGui.QFont()
        font.setFamily('Courier')
        font.setFixedPitch(True)
        font.setPointSize(10)
        self.setFont(font)
        self.setMarginsFont(font)
        fontmetrics = QtGui.QFontMetrics(font)
        self.setMarginsFont(font)
        self.setMarginWidth(0, fontmetrics.width("00000") + 6)
        self.setMarginLineNumbers(0, True)
        self.setMarginsBackgroundColor(QtGui.QColor("#cccccc"))
        self.setBraceMatching(QsciScintilla.SloppyBraceMatch)
        self.setCaretLineVisible(True)
        self.setCaretLineBackgroundColor(QtGui.QColor("#E8E8FF"))

        if language:
            self.lexer = getattr(Qsci, 'QsciLexer' + language)()
            self.setLexer(self.lexer)

        self.SendScintilla(QsciScintilla.SCI_FOLDALL, True)
        self.setAutoCompletionThreshold(1)
        self.setAutoCompletionSource(QsciScintilla.AcsAPIs)
        self.setFolding(QsciScintilla.BoxedTreeFoldStyle)

        # Signals/Slots
        self.cursorPositionChanged.connect(self.on_cursor_position_changed)
        self.copyAvailable.connect(self.on_copy_available)
        self.indicatorClicked.connect(self.on_indicator_clicked)
        self.indicatorReleased.connect(self.on_indicator_released)
        self.linesChanged.connect(self.on_lines_changed)
        self.marginClicked.connect(self.on_margin_clicked)
        self.modificationAttempted.connect(self.on_modification_attempted)
        self.modificationChanged.connect(self.on_modification_changed)
        self.selectionChanged.connect(self.on_selection_changed)
        self.textChanged.connect(self.on_text_changed)
        self.userListActivated.connect(self.on_user_list_activated)

    def float_value_changed(self, v):
        print(v)

    def on_cursor_position_changed(self, line, index):
        text = self.text(line)
        for match in re.finditer('(?:^|(?<=\W))\d+(?:\.\d+)?(?=$|\W)', text):
            start, end = match.span()
            if start <= index <= end:
                pos = self.positionFromLineIndex(line, start)
                x = self.SendScintilla(
                    QsciScintilla.SCI_POINTXFROMPOSITION, 0, pos)
                y = self.SendScintilla(
                    QsciScintilla.SCI_POINTYFROMPOSITION, 0, pos)
                point = self.mapToGlobal(QtCore.QPoint(x, y))
                num = float(match.group())
                message = 'number: %s' % num

                self.slider.setWindowTitle('line: {0}'.format(line))
                self.slider.adjust(num)
                self.slider.move(point + QtCore.QPoint(0, 20))
                self.slider.show()

                break

    def on_copy_available(self, yes):
        print('-' * 80)
        print("on_copy_available")

    def on_indicator_clicked(self, line, index, state):
        print("on_indicator_clicked")

    def on_indicator_released(self, line, index, state):
        print("on_indicator_released")

    def on_lines_changed(self):
        print("on_lines_changed")

    def on_margin_clicked(self, margin, line, state):
        print("on_margin_clicked")

    def on_modification_attempted(self):
        print("on_modification_attempted")

    def on_modification_changed(self):
        print("on_modification_changed")

    def on_selection_changed(self):
        print("on_selection_changed")

    def on_text_changed(self):
        print("on_text_changed")

    def on_user_list_activated(self, id, text):
        print("on_user_list_activated")

def show_requirements():
    print(sys.version)
    print(QtCore.QT_VERSION_STR)
    print(QtCore.PYQT_VERSION_STR)

if __name__ == "__main__":
    show_requirements()

    app = QtWidgets.QApplication(sys.argv)

    ex = QtWidgets.QWidget()
    hlayout = QtWidgets.QHBoxLayout()
    ed = SimpleEditor("JavaScript")

    hlayout.addWidget(ed)

    ed.setText("""#ifdef GL_ES
precision mediump float;
#endif

#extension GL_OES_standard_derivatives : enable

uniform float time;
uniform vec2 mouse;
uniform vec2 resolution;

void main( void ) {

    vec2 st = ( gl_FragCoord.xy / resolution.xy );
    vec2 lefbot = step(vec2(0.1), st);
    float pct = lefbot.x*lefbot.y;
    vec2 rigtop = step(vec2(0.1), 1.-st);
    pct *= rigtop.x*rigtop.y;
    vec3 color = vec3(pct);

    gl_FragColor = vec4( color, 1.0 );""")

    ex.setLayout(hlayout)
    ex.show()
    ex.resize(800, 600)

    sys.exit(app.exec_())

There are several issues I don't know how to address:

My slider widget is changing the widget width every time I change values, I tried addStrecht(1) but it didn't work as I intended as there was too much empty space between widgets (ie: layout arrangement -> slider|strecht|label)
Once I type a numeric value on the QScintilla widget the FloatSlider widget will appear and that's definitely something I don't want. I'd like it to appear only when I press such numeric value with the left mouse button or any other combination (ie: ctrl+left_mouse)
I don't know how to replace properly the QScintilla text (regex match) on realtime. Ideally only the QScintilla matched text should be modified, for instance, I don't want to replace the whole text because the visual effect would be quite creepy

It didn't feel like opening 3 different questions for these little doubts was ok so I've decided to gather them in the same thread. Hopefully that's ok

A:

Use setFixedWidth to avoid either the slider or label changing width on every change
You shouldn't use on_cursor_position_changed event, instead just use mouseReleaseEvent
A good way to replace certain matches at certain position would be instead using setText using insertAt and SCI_DELETERANGE methods. For more information check QScintilla docs

