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diff --git a/silx/gui/plot/items/marker.py b/silx/gui/plot/items/marker.py
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+++ b/silx/gui/plot/items/marker.py
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+# coding: utf-8
+# /*##########################################################################
+#
+# Copyright (c) 2017 European Synchrotron Radiation Facility
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+#
+# ###########################################################################*/
+"""This module provides markers item of the :class:`Plot`.
+"""
+
+__authors__ = ["T. Vincent"]
+__license__ = "MIT"
+__date__ = "06/03/2017"
+
+
+import logging
+
+from .core import Item, DraggableMixIn, ColorMixIn, SymbolMixIn
+
+
+_logger = logging.getLogger(__name__)
+
+
+class _BaseMarker(Item, DraggableMixIn, ColorMixIn):
+    """Base class for markers"""
+
+    _DEFAULT_COLOR = (0., 0., 0., 1.)
+    """Default color of the markers"""
+
+    def __init__(self):
+        Item.__init__(self)
+        DraggableMixIn.__init__(self)
+        ColorMixIn.__init__(self)
+
+        self._text = ''
+        self._x = None
+        self._y = None
+        self._constraint = self._defaultConstraint
+
+    def _addBackendRenderer(self, backend):
+        """Update backend renderer"""
+        # TODO not very nice way to do it, but simple
+        symbol = self.getSymbol() if isinstance(self, Marker) else None
+
+        return backend.addMarker(
+            x=self.getXPosition(),
+            y=self.getYPosition(),
+            legend=self.getLegend(),
+            text=self.getText(),
+            color=self.getColor(),
+            selectable=self.isSelectable(),
+            draggable=self.isDraggable(),
+            symbol=symbol,
+            constraint=self.getConstraint(),
+            overlay=self.isOverlay())
+
+    def isOverlay(self):
+        """Return true if marker is drawn as an overlay.
+
+        A marker is an overlay if it is draggable.
+
+        :rtype: bool
+        """
+        return self.isDraggable()
+
+    def getText(self):
+        """Returns marker text.
+
+        :rtype: str
+        """
+        return self._text
+
+    def setText(self, text):
+        """Set the text of the marker.
+
+        :param str text: The text to use
+        """
+        text = str(text)
+        if text != self._text:
+            self._text = text
+            self._updated()
+
+    def getXPosition(self):
+        """Returns the X position of the marker line in data coordinates
+
+        :rtype: float or None
+        """
+        return self._x
+
+    def getYPosition(self):
+        """Returns the Y position of the marker line in data coordinates
+
+        :rtype: float or None
+        """
+        return self._y
+
+    def getPosition(self):
+        """Returns the (x, y) position of the marker in data coordinates
+
+        :rtype: 2-tuple of float or None
+        """
+        return self._x, self._y
+
+    def setPosition(self, x, y):
+        """Set marker position in data coordinates
+
+        Constraint are applied if any.
+
+        :param float x: X coordinates in data frame
+        :param float y: Y coordinates in data frame
+        """
+        x, y = self.getConstraint()(x, y)
+        x, y = float(x), float(y)
+        if x != self._x or y != self._y:
+            self._x, self._y = x, y
+            self._updated()
+
+    def getConstraint(self):
+        """Returns the dragging constraint of this item"""
+        return self._constraint
+
+    def _setConstraint(self, constraint):  # TODO support update
+        """Set the constraint.
+
+        This is private for now as update is not handled.
+
+        :param callable constraint:
+        :param constraint: A function filtering item displacement by
+                           dragging operations or None for no filter.
+                           This function is called each time the item is
+                           moved.
+                           This is only used if isDraggable returns True.
+        :type constraint: None or a callable that takes the coordinates of
+                          the current cursor position in the plot as input
+                          and that returns the filtered coordinates.
+        """
+        if constraint is None:
+            constraint = self._defaultConstraint
+        assert callable(constraint)
+        self._constraint = constraint
+
+    @staticmethod
+    def _defaultConstraint(*args):
+        """Default constraint not doing anything"""
+        return args
+
+
+class Marker(_BaseMarker, SymbolMixIn):
+    """Description of a marker"""
+
+    _DEFAULT_SYMBOL = '+'
+    """Default symbol of the marker"""
+
+    def __init__(self):
+        _BaseMarker.__init__(self)
+        SymbolMixIn.__init__(self)
+
+        self._x = 0.
+        self._y = 0.
+
+    def _setConstraint(self, constraint):
+        """Set the constraint function of the marker drag.
+
+        It also supports 'horizontal' and 'vertical' str as constraint.
+
+        :param constraint: The constraint of the dragging of this marker
+        :type: constraint: callable or str
+        """
+        if constraint == 'horizontal':
+            constraint = self._horizontalConstraint
+        elif constraint == 'vertical':
+            constraint = self._verticalConstraint
+
+        super(Marker, self)._setConstraint(constraint)
+
+    def _horizontalConstraint(self, _, y):
+        return self.getXPosition(), y
+
+    def _verticalConstraint(self, x, _):
+        return x, self.getYPosition()
+
+
+class XMarker(_BaseMarker):
+    """Description of a marker"""
+
+    def __init__(self):
+        _BaseMarker.__init__(self)
+        self._x = 0.
+
+    def setPosition(self, x, y):
+        """Set marker line position in data coordinates
+
+        Constraint are applied if any.
+
+        :param float x: X coordinates in data frame
+        :param float y: Y coordinates in data frame
+        """
+        x, _ = self.getConstraint()(x, y)
+        x = float(x)
+        if x != self._x:
+            self._x = x
+            self._updated()
+
+
+class YMarker(_BaseMarker):
+    """Description of a marker"""
+
+    def __init__(self):
+        _BaseMarker.__init__(self)
+        self._y = 0.
+
+    def setPosition(self, x, y):
+        """Set marker line position in data coordinates
+
+        Constraint are applied if any.
+
+        :param float x: X coordinates in data frame
+        :param float y: Y coordinates in data frame
+        """
+        _, y = self.getConstraint()(x, y)
+        y = float(y)
+        if y != self._y:
+            self._y = y
+            self._updated()