From 75048c473b65a4ac2ed16a86de8c0f589f584816 Mon Sep 17 00:00:00 2001
From: 2xB <31772910+2xB@users.noreply.github.com>
Date: Mon, 16 Nov 2020 20:54:46 +0100
Subject: [PATCH] TickSliderItem: Use Tick.removeAllowed (#1441)

* Fix: TickSliderItem ignores Tick.removeAllowed

This prohibits removing ticks from a `TickSliderItem` if they were set to `tick.removeAllowed=False`.

Test code:
```python3
import pyqtgraph as pg
from pyqtgraph.Qt import QtCore
import numpy as np

app = pg.mkQApp()

class CustomWidget(pg.GraphicsView):
    def __init__(self, parent=None, *args, **kargs):
        pg.GraphicsView.__init__(self, parent, useOpenGL=False, background=None)
        self.item = pg.TickSliderItem(*args, **kargs)

        for pos in (0, 0.5, 1):
            tick = self.item.addTick(pos)
            tick.removeAllowed = False # Possibility 1

        # Possibility 2
        for tick, value in self.item.listTicks():
            tick.removeAllowed = False

        self.setCentralItem(self.item)
        self.setFixedHeight(31)

w = CustomWidget()
w.show()

app.exec_()
```

* Make 'removeAllowed' regular property of 'Tick'

Co-authored-by: 2xB <2xB@users.noreply.github.com>
---
 pyqtgraph/graphicsItems/GradientEditorItem.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pyqtgraph/graphicsItems/GradientEditorItem.py b/pyqtgraph/graphicsItems/GradientEditorItem.py
index d00f804f..40e88947 100644
--- a/pyqtgraph/graphicsItems/GradientEditorItem.py
+++ b/pyqtgraph/graphicsItems/GradientEditorItem.py
@@ -210,7 +210,7 @@ class TickSliderItem(GraphicsWidget):
         self.sigTicksChangeFinished.emit(self)
     
     def tickClicked(self, tick, ev):
-        if ev.button() == QtCore.Qt.RightButton:
+        if ev.button() == QtCore.Qt.RightButton and tick.removeAllowed:
             self.removeTick(tick)
     
     def widgetLength(self):
@@ -766,7 +766,6 @@ class GradientEditorItem(TickSliderItem):
             color = self.getColor(x)
         t = TickSliderItem.addTick(self, x, color=color, movable=movable, finish=finish)
         t.colorChangeAllowed = True
-        t.removeAllowed = True
         
         return t
         
@@ -872,6 +871,7 @@ class Tick(QtGui.QGraphicsWidget):  ## NOTE: Making this a subclass of GraphicsO
         self.pen = fn.mkPen(pen)
         self.hoverPen = fn.mkPen(255,255,0)
         self.currentPen = self.pen
+        self.removeAllowed = True
         self.pg = QtGui.QPainterPath(QtCore.QPointF(0,0))
         self.pg.lineTo(QtCore.QPointF(-scale/3**0.5, scale))
         self.pg.lineTo(QtCore.QPointF(scale/3**0.5, scale))