Source code for layer_viewer.widgets.fraction_selection_bar

import pyqtgraph as pg
import os
from pyqtgraph.Qt import QtCore, QtGui
import pyqtgraph.Qt as Qt
import PyQt5
class FractionSelectionBar( QtGui.QWidget ):
    fractionChanged = QtCore.pyqtSignal(float)

    def __init__( self, initial_fraction=1., parent=None ):
        super(FractionSelectionBar, self).__init__( parent=parent )
        self._fraction = initial_fraction
        self._lmbDown = False

    def fraction( self ):
        return self._fraction

    def setFraction( self, value ):
        if value == self._fraction:
            return
        if(value < 0.):
            value = 0.
            warnings.warn("FractionSelectionBar.setFraction(): value has to be between 0. and 1. (was %s); setting to 0." % str(value))
        if(value > 1.):
            value = 1.
            warnings.warn("FractionSelectionBar.setFraction(): value has to be between 0. and 1. (was %s); setting to 1." % str(value))
        self._fraction = float(value)
        self.update()

    def mouseMoveEvent(self, event):
        if self._lmbDown:
            self.setFraction(self._fractionFromPosition( event.localPos() ))
            self.fractionChanged.emit(self._fraction)

    def mousePressEvent(self, event):
        if event.button() == QtCore.Qt.RightButton:
            return
        self._lmbDown = True
        self.setFraction(self._fractionFromPosition( event.localPos() ))
        self.fractionChanged.emit(self._fraction)

    def mouseReleaseEvent(self, event):
        self._lmbDown = False

    def paintEvent( self, ev ):
        painter = QtGui.QPainter(self)

        # calc bar offset
        y_offset =(self.height() - self._barHeight()) // 2
        ## prevent negative offset
        y_offset = 0 if y_offset < 0 else y_offset

        # frame around fraction indicator
        painter.setBrush(self.palette().dark())
        painter.save()
        ## no fill color
        b = painter.brush(); b.setStyle(QtCore.Qt.NoBrush); painter.setBrush(b)
        painter.drawRect(
            QtCore.QRect(QtCore.QPoint(0, y_offset),
                  QtCore.QSize(self._barWidth(), self._barHeight())))
        painter.restore()

        # fraction indicator
        painter.drawRect(
            QtCore.QRect(QtCore.QPoint(0, y_offset),
                  QtCore.QSize(self._barWidth()*self._fraction, self._barHeight())))

    def sizeHint( self ):
        return QtCore.QSize(100, 10)

    def minimumSizeHint( self ):
        return QtCore.QSize(1, 3)

    def _barWidth( self ):
        return self.width()-1

    def _barHeight( self ):
        return self.height()-1

    def _fractionFromPosition( self, pointf ):
        frac = float(pointf.x())/ self.width()
        # mouse has left the widget
        if frac < 0.:
            frac = 0.
        if frac > 1.:
            frac = 1.
        return frac