silx.gui.plot.PlotWidget: Added yaxis arcsinh support with matplotlib backend

src/silx/gui/plot/PlotWindow.py

@@ -183,6 +183,12 @@ def __init__(
         self.yAxisLogarithmicAction.setVisible(logScale)
         self.addAction(self.yAxisLogarithmicAction)
 
+        self.yAxisArcsinhAction = self.group.addAction(
+            actions.control.YAxisArcsinhAction(self, parent=self)
+        )
+        self.yAxisArcsinhAction.setVisible(logScale)
+        self.addAction(self.yAxisArcsinhAction)
+
         self.gridAction = self.group.addAction(
             actions.control.GridAction(self, gridMode="both", parent=self)
         )

src/silx/gui/plot/actions/control.py

@@ -282,6 +282,35 @@ def _actionTriggered(self, checked=False):
         scale = self.axis.LOGARITHMIC if checked else self.axis.LINEAR
         self.axis.setScale(scale)
 
+
+class YAxisArcsinhAction(PlotAction):
+    """QAction controlling Y axis arcsinh scale on a :class:`.PlotWidget`.
+
+    :param plot: :class:`.PlotWidget` instance on which to operate
+    :param parent: See :class:`QAction`
+    """
+
+    def __init__(self, plot, parent=None):
+        super().__init__(
+            plot,
+            icon="plot-yasinh",
+            text="Arcsinh scale",
+            tooltip="Arcsinh y-axis when checked",
+            triggered=self._actionTriggered,
+            checkable=True,
+            parent=parent,
+        )
+        self.axis = plot.getYAxis()
+        self.setChecked(self.axis.getScale() == self.axis.ARCSINH)
+        self.axis.sigScaleChanged.connect(self._setCheckedIfArcsinhScale)
+
+    def _setCheckedIfArcsinhScale(self, scale):
+        self.setChecked(scale == self.axis.ARCSINH)
+
+    def _actionTriggered(self, checked=False):
+        scale = self.axis.ARCSINH if checked else self.axis.LINEAR
+        self.axis.setScale(scale)
+
 
 class GridAction(PlotAction):
     """QAction controlling grid mode on a :class:`.PlotWidget`.

src/silx/gui/plot/backends/BackendMatplotlib.py

@@ -1321,6 +1321,17 @@ def setYAxisLogarithmic(self, flag):
         self.ax.set_yscale("linear")
         self.ax.yaxis.set_major_formatter(DefaultTickFormatter())
 
+    def setYAxisArcsinh(self, flag):
+        if flag:
+            self.ax2.set_yscale("asinh")
+            self.ax.set_yscale("asinh")
+            return
+
+        self.ax2.set_yscale("linear")
+        self.ax2.yaxis.set_major_formatter(DefaultTickFormatter())
+        self.ax.set_yscale("linear")
+        self.ax.yaxis.set_major_formatter(DefaultTickFormatter())
+
     def setYAxisInverted(self, flag):
         if self.ax.yaxis_inverted() != bool(flag):
             self.ax.invert_yaxis()

src/silx/gui/plot/backends/BackendOpenGL.py

@@ -1596,6 +1596,9 @@ def setYAxisLogarithmic(self, flag):
             self._plotFrame.yAxis.isLog = flag
             self._plotFrame.y2Axis.isLog = flag
 
+    def setYAxisArcsinh(self, flag):
+        ...
+
     def setYAxisInverted(self, flag):
         if flag != self._plotFrame.isYAxisInverted:
             self._plotFrame.isYAxisInverted = flag

src/silx/gui/plot/items/axis.py

@@ -63,7 +63,10 @@ class Axis(qt.QObject):
     LOGARITHMIC = "log"
     """Constant defining a logarithmic scale"""
 
-    _SCALES = {LINEAR, LOGARITHMIC}
+    ARCSINH = "arcsinh"
+    """Constant defining an arcsinh scale"""
+
+    _SCALES = {LINEAR, LOGARITHMIC, ARCSINH}
 
     sigInvertedChanged = qt.Signal(bool)
     """Signal emitted when axis orientation has changed"""
@@ -242,7 +245,6 @@ def setScale(self, scale):
         for item in plot.getItems():
             item._updated()
         plot._invalidateDataRange()
-
         if scale == self.LOGARITHMIC:
             self._internalSetLogarithmic(True)
             if vmin <= 0:
@@ -254,6 +256,8 @@ def setScale(self, scale):
                         self.setLimits(dataRange[0], vmax)
                     else:
                         self.setLimits(*dataRange)
+        elif scale == self.ARCSINH:
+            self._internalSetArcsinh(True)
         elif scale == self.LINEAR:
             self._internalSetLogarithmic(False)
         else:
@@ -451,6 +455,9 @@ def _internalSetLimits(self, ymin, ymax):
     def _internalSetLogarithmic(self, flag):
         self._getBackend().setYAxisLogarithmic(flag)
 
+    def _internalSetArcsinh(self, flag):
+        self._getBackend().setYAxisArcsinh(flag)
+
     def setInverted(self, flag=True):
         """Set the axis orientation.