Added background color to the markers

- Drop the auto background

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

@@ -154,6 +154,9 @@ class ItemChangedType(enum.Enum):
     FONT = "fontChanged"
     """Item's text font changed flag."""
 
+    BACKGROUND_COLOR = "backgroundColorChanged"
+    """Item's text background color changed flag."""
+
 
 class Item(qt.QObject):
     """Description of an item of the plot"""

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

@@ -31,6 +31,7 @@
 
 
 import logging
+import numpy
 
 from ....utils.proxy import docstring
 from .core import (
@@ -44,6 +45,8 @@
 )
 from silx import config
 from silx.gui import qt
+from silx.gui import colors
+
 
 _logger = logging.getLogger(__name__)
 
@@ -75,28 +78,24 @@ def __init__(self):
 
         self._x = None
         self._y = None
+        self._bgColor: colors.RGBAColorType | numpy.ndarray | None = None
         self._constraint = self._defaultConstraint
         self.__isBeingDragged = False
 
     def _addRendererCall(self, backend, symbol=None, linestyle="-", linewidth=1):
         """Perform the update of the backend renderer"""
-        color = self.getColor()
-        intensity = color[0] * 0.299 + color[1] * 0.587 + color[2] * 0.114
-        bgColor = (
-            (1.0, 1.0, 1.0, 0.75) if intensity <= 0.5 else (0.0, 0.0, 0.0, 0.75)
-        )
         return backend.addMarker(
             x=self.getXPosition(),
             y=self.getYPosition(),
             text=self.getText(),
-            color=color,
+            color=self.getColor(),
             symbol=symbol,
             linestyle=linestyle,
             linewidth=linewidth,
             constraint=self.getConstraint(),
             yaxis=self.getYAxis(),
             font=self._font,  # Do not use getFont to spare creating a new QFont
-            bgcolor=bgColor,
+            bgcolor=self.getBackgroundColor(),
         )
 
     def _addBackendRenderer(self, backend):
@@ -147,6 +146,38 @@ def setFont(self, font: qt.QFont | None):
             self._font = None if font is None else qt.QFont(font)
             self._updated(ItemChangedType.FONT)
 
+    def getBackgroundColor(self) -> colors.RGBAColorType | numpy.ndarray | None:
+        """Returns the RGBA background color of the item
+
+        :rtype: 4-tuple of float in [0, 1] or array of colors
+        """
+        return self._bgColor
+
+    def setBackgroundColor(self, color, copy=True):
+        """Set item background  color
+
+        :param color: color(s) to be used
+        :type color: str ("#RRGGBB") or (npoints, 4) unsigned byte array or
+                     one of the predefined color names defined in colors.py
+        :param bool copy: True (Default) to get a copy,
+                         False to use internal representation (do not modify!)
+        """
+        if color is None:
+            pass
+        elif isinstance(color, (str, qt.QColor)):
+            color = colors.rgba(color)
+        else:
+            color = numpy.array(color, copy=copy)
+            # TODO more checks + improve color array support
+            if color.ndim == 1:  # Single RGBA color
+                color = colors.rgba(color)
+            else:  # Array of colors
+                assert color.ndim == 2
+
+        if self._bgColor != color:
+            self._bgColor = color
+            self._updated(ItemChangedType.BACKGROUND_COLOR)
+
     def getXPosition(self):
         """Returns the X position of the marker line in data coordinates