Import Upstream version 0.5.0+dfsg

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diff --git a/silx/gui/plot/_utils/ticklayout.py b/silx/gui/plot/_utils/ticklayout.py
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+# coding: utf-8
+# /*##########################################################################
+#
+# Copyright (c) 2014-2017 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 implements labels layout on graph axes."""
+
+from __future__ import absolute_import, division, unicode_literals
+
+__authors__ = ["T. Vincent"]
+__license__ = "MIT"
+__date__ = "18/10/2016"
+
+
+import math
+
+
+# utils #######################################################################
+
+def numberOfDigits(tickSpacing):
+    """Returns the number of digits to display for text label.
+
+    :param float tickSpacing: Step between ticks in data space.
+    :return: Number of digits to show for labels.
+    :rtype: int
+    """
+    nfrac = int(-math.floor(math.log10(tickSpacing)))
+    if nfrac < 0:
+        nfrac = 0
+    return nfrac
+
+
+# Nice Numbers ################################################################
+
+def _niceNum(value, isRound=False):
+    expvalue = math.floor(math.log10(value))
+    frac = value/pow(10., expvalue)
+    if isRound:
+        if frac < 1.5:
+            nicefrac = 1.
+        elif frac < 3.:
+            nicefrac = 2.
+        elif frac < 7.:
+            nicefrac = 5.
+        else:
+            nicefrac = 10.
+    else:
+        if frac <= 1.:
+            nicefrac = 1.
+        elif frac <= 2.:
+            nicefrac = 2.
+        elif frac <= 5.:
+            nicefrac = 5.
+        else:
+            nicefrac = 10.
+    return nicefrac * pow(10., expvalue)
+
+
+def niceNumbers(vMin, vMax, nTicks=5):
+    """Returns tick positions.
+
+    This function implements graph labels layout using nice numbers
+    by Paul Heckbert from "Graphics Gems", Academic Press, 1990.
+    See `C code <http://tog.acm.org/resources/GraphicsGems/gems/Label.c>`_.
+
+    :param float vMin: The min value on the axis
+    :param float vMax: The max value on the axis
+    :param int nTicks: The number of ticks to position
+    :returns: min, max, increment value of tick positions and
+              number of fractional digit to show
+    :rtype: tuple
+    """
+    vrange = _niceNum(vMax - vMin, False)
+    spacing = _niceNum(vrange / nTicks, True)
+    graphmin = math.floor(vMin / spacing) * spacing
+    graphmax = math.ceil(vMax / spacing) * spacing
+    nfrac = numberOfDigits(spacing)
+    return graphmin, graphmax, spacing, nfrac
+
+
+def _frange(start, stop, step):
+    """range for float (including stop)."""
+    assert step >= 0.
+    while start <= stop:
+        yield start
+        start += step
+
+
+def ticks(vMin, vMax, nbTicks=5):
+    """Returns tick positions and labels using nice numbers algorithm.
+
+    This enforces ticks to be within [vMin, vMax] range.
+    It returns at least 2 ticks.
+
+    :param float vMin: The min value on the axis
+    :param float vMax: The max value on the axis
+    :param int nbTicks: The number of ticks to position
+    :returns: tick positions and corresponding text labels
+    :rtype: 2-tuple: list of float, list of string
+    """
+    start, end, step, nfrac = niceNumbers(vMin, vMax, nbTicks)
+    positions = [t for t in _frange(start, end, step) if vMin <= t <= vMax]
+
+    # Makes sure there is at least 2 ticks
+    if len(positions) < 2:
+        positions = [vMin, vMax]
+        nfrac = numberOfDigits(vMax - vMin)
+
+    # Generate labels
+    format_ = '%g' if nfrac == 0 else '%.{}f'.format(nfrac)
+    labels = [format_ % tick for tick in positions]
+    return positions, labels
+
+
+def niceNumbersAdaptative(vMin, vMax, axisLength, tickDensity):
+    """Returns tick positions using :func:`niceNumbers` and a
+    density of ticks.
+
+    axisLength and tickDensity are based on the same unit (e.g., pixel).
+
+    :param float vMin: The min value on the axis
+    :param float vMax: The max value on the axis
+    :param float axisLength: The length of the axis.
+    :param float tickDensity: The density of ticks along the axis.
+    :returns: min, max, increment value of tick positions and
+              number of fractional digit to show
+    :rtype: tuple
+    """
+    # At least 2 ticks
+    nticks = max(2, int(round(tickDensity * axisLength)))
+    tickmin, tickmax, step, nfrac = niceNumbers(vMin, vMax, nticks)
+
+    return tickmin, tickmax, step, nfrac
+
+
+# Nice Numbers for log scale ##################################################
+
+def niceNumbersForLog10(minLog, maxLog, nTicks=5):
+    """Return tick positions for logarithmic scale
+
+    :param float minLog: log10 of the min value on the axis
+    :param float maxLog: log10 of the max value on the axis
+    :param int nTicks: The number of ticks to position
+    :returns: log10 of min, max, increment value of tick positions and
+              number of fractional digit to show
+    :rtype: tuple of int
+    """
+    graphminlog = math.floor(minLog)
+    graphmaxlog = math.ceil(maxLog)
+    rangelog = graphmaxlog - graphminlog
+
+    if rangelog <= nTicks:
+        spacing = 1.
+    else:
+        spacing = math.floor(rangelog / nTicks)
+
+        graphminlog = math.floor(graphminlog / spacing) * spacing
+        graphmaxlog = math.ceil(graphmaxlog / spacing) * spacing
+
+    nfrac = numberOfDigits(spacing)
+
+    return int(graphminlog), int(graphmaxlog), int(spacing), nfrac
+
+
+def niceNumbersAdaptativeForLog10(vMin, vMax, axisLength, tickDensity):
+    """Returns tick positions using :func:`niceNumbers` and a
+    density of ticks.
+
+    axisLength and tickDensity are based on the same unit (e.g., pixel).
+
+    :param float vMin: The min value on the axis
+    :param float vMax: The max value on the axis
+    :param float axisLength: The length of the axis.
+    :param float tickDensity: The density of ticks along the axis.
+    :returns: log10 of min, max, increment value of tick positions and
+              number of fractional digit to show
+    :rtype: tuple
+    """
+    # At least 2 ticks
+    nticks = max(2, int(round(tickDensity * axisLength)))
+    tickmin, tickmax, step, nfrac = niceNumbersForLog10(vMin, vMax, nticks)
+
+    return tickmin, tickmax, step, nfrac
+
+
+def computeLogSubTicks(ticks, lowBound, highBound):
+    """Return the sub ticks for the log scale for all given ticks if subtick
+    is in [lowBound, highBound]
+
+    :param ticks: log10 of the ticks
+    :param lowBound: the lower boundary of ticks
+    :param highBound: the higher boundary of ticks
+    :return: all the sub ticks contained in ticks (log10)
+    """
+    if len(ticks) < 1:
+        return []
+
+    res = []
+    for logPos in ticks:
+        dataOrigPos = logPos
+        for index in range(2, 10):
+            dataPos = dataOrigPos * index
+            if lowBound <= dataPos <= highBound:
+                res.append(dataPos)
+    return res