path: root/silx/gui/plot/_utils/panzoom.py

# coding: utf-8
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"""Functions to apply pan and zoom on a Plot"""

__authors__ = ["T. Vincent", "V. Valls"]
__license__ = "MIT"
__date__ = "08/08/2017"


import math
import numpy


# Float 32 info ###############################################################
# Using min/max value below limits of float32
# so operation with such value (e.g., max - min) do not overflow

FLOAT32_SAFE_MIN = -1e37
FLOAT32_MINPOS = numpy.finfo(numpy.float32).tiny
FLOAT32_SAFE_MAX = 1e37
# TODO double support


def scale1DRange(min_, max_, center, scale, isLog):
    """Scale a 1D range given a scale factor and an center point.

    Keeps the values in a smaller range than float32.

    :param float min_: The current min value of the range.
    :param float max_: The current max value of the range.
    :param float center: The center of the zoom (i.e., invariant point).
    :param float scale: The scale to use for zoom
    :param bool isLog: Whether using log scale or not.
    :return: The zoomed range.
    :rtype: tuple of 2 floats: (min, max)
    """
    if isLog:
        # Min and center can be < 0 when
        # autoscale is off and switch to log scale
        # max_ < 0 should not happen
        min_ = numpy.log10(min_) if min_ > 0. else FLOAT32_MINPOS
        center = numpy.log10(center) if center > 0. else FLOAT32_MINPOS
        max_ = numpy.log10(max_) if max_ > 0. else FLOAT32_MINPOS

    if min_ == max_:
        return min_, max_

    offset = (center - min_) / (max_ - min_)
    range_ = (max_ - min_) / scale
    newMin = center - offset * range_
    newMax = center + (1. - offset) * range_

    if isLog:
        # No overflow as exponent is log10 of a float32
        newMin = pow(10., newMin)
        newMax = pow(10., newMax)
        newMin = numpy.clip(newMin, FLOAT32_MINPOS, FLOAT32_SAFE_MAX)
        newMax = numpy.clip(newMax, FLOAT32_MINPOS, FLOAT32_SAFE_MAX)
    else:
        newMin = numpy.clip(newMin, FLOAT32_SAFE_MIN, FLOAT32_SAFE_MAX)
        newMax = numpy.clip(newMax, FLOAT32_SAFE_MIN, FLOAT32_SAFE_MAX)
    return newMin, newMax


def applyZoomToPlot(plot, scaleF, center=None):
    """Zoom in/out plot given a scale and a center point.

    :param plot: The plot on which to apply zoom.
    :param float scaleF: Scale factor of zoom.
    :param center: (x, y) coords in pixel coordinates of the zoom center.
    :type center: 2-tuple of float
    """
    xMin, xMax = plot.getXAxis().getLimits()
    yMin, yMax = plot.getYAxis().getLimits()

    if center is None:
        left, top, width, height = plot.getPlotBoundsInPixels()
        cx, cy = left + width // 2, top + height // 2
    else:
        cx, cy = center

    dataCenterPos = plot.pixelToData(cx, cy)
    assert dataCenterPos is not None

    xMin, xMax = scale1DRange(xMin, xMax, dataCenterPos[0], scaleF,
                              plot.getXAxis()._isLogarithmic())

    yMin, yMax = scale1DRange(yMin, yMax, dataCenterPos[1], scaleF,
                              plot.getYAxis()._isLogarithmic())

    dataPos = plot.pixelToData(cx, cy, axis="right")
    assert dataPos is not None
    y2Center = dataPos[1]
    y2Min, y2Max = plot.getYAxis(axis="right").getLimits()
    y2Min, y2Max = scale1DRange(y2Min, y2Max, y2Center, scaleF,
                                plot.getYAxis()._isLogarithmic())

    plot.setLimits(xMin, xMax, yMin, yMax, y2Min, y2Max)


def applyPan(min_, max_, panFactor, isLog10):
    """Returns a new range with applied panning.

    Moves the range according to panFactor.
    If isLog10 is True, converts to log10 before moving.

    :param float min_: Min value of the data range to pan.
    :param float max_: Max value of the data range to pan.
                       Must be >= min.
    :param float panFactor: Signed proportion of the range to use for pan.
    :param bool isLog10: True if log10 scale, False if linear scale.
    :return: New min and max value with pan applied.
    :rtype: 2-tuple of float.
    """
    if isLog10 and min_ > 0.:
        # Negative range and log scale can happen with matplotlib
        logMin, logMax = math.log10(min_), math.log10(max_)
        logOffset = panFactor * (logMax - logMin)
        newMin = pow(10., logMin + logOffset)
        newMax = pow(10., logMax + logOffset)

        # Takes care of out-of-range values
        if newMin > 0. and newMax < float('inf'):
            min_, max_ = newMin, newMax

    else:
        offset = panFactor * (max_ - min_)
        newMin, newMax = min_ + offset, max_ + offset

        # Takes care of out-of-range values
        if newMin > - float('inf') and newMax < float('inf'):
            min_, max_ = newMin, newMax
    return min_, max_


class _Unset(object):
    """To be able to have distinction between None and unset"""
    pass


class ViewConstraints(object):
    """
    Store constraints applied on the view box and compute the resulting view box.
    """

    def __init__(self):
        self._min = [None, None]
        self._max = [None, None]
        self._minRange = [None, None]
        self._maxRange = [None, None]

    def update(self, xMin=_Unset, xMax=_Unset,
               yMin=_Unset, yMax=_Unset,
               minXRange=_Unset, maxXRange=_Unset,
               minYRange=_Unset, maxYRange=_Unset):
        """
        Update the constraints managed by the object

        The constraints are the same as the ones provided by PyQtGraph.

        :param float xMin: Minimum allowed x-axis value.
            (default do not change the stat, None remove the constraint)
        :param float xMax: Maximum allowed x-axis value.
            (default do not change the stat, None remove the constraint)
        :param float yMin: Minimum allowed y-axis value.
            (default do not change the stat, None remove the constraint)
        :param float yMax: Maximum allowed y-axis value.
            (default do not change the stat, None remove the constraint)
        :param float minXRange: Minimum allowed left-to-right span across the
            view (default do not change the stat, None remove the constraint)
        :param float maxXRange: Maximum allowed left-to-right span across the
            view (default do not change the stat, None remove the constraint)
        :param float minYRange: Minimum allowed top-to-bottom span across the
            view (default do not change the stat, None remove the constraint)
        :param float maxYRange: Maximum allowed top-to-bottom span across the
            view (default do not change the stat, None remove the constraint)
        :return: True if the constraints was changed
        """
        updated = False

        minRange = [minXRange, minYRange]
        maxRange = [maxXRange, maxYRange]
        minPos = [xMin, yMin]
        maxPos = [xMax, yMax]

        for axis in range(2):

            value = minPos[axis]
            if value is not _Unset and value != self._min[axis]:
                self._min[axis] = value
                updated = True

            value = maxPos[axis]
            if value is not _Unset and value != self._max[axis]:
                self._max[axis] = value
                updated = True

            value = minRange[axis]
            if value is not _Unset and value != self._minRange[axis]:
                self._minRange[axis] = value
                updated = True

            value = maxRange[axis]
            if value is not _Unset and value != self._maxRange[axis]:
                self._maxRange[axis] = value
                updated = True

        # Sanity checks

        for axis in range(2):
            if self._maxRange[axis] is not None and self._min[axis] is not None and self._max[axis] is not None:
                # max range cannot be larger than bounds
                diff = self._max[axis] - self._min[axis]
                self._maxRange[axis] = min(self._maxRange[axis], diff)
                updated = True

        return updated

    def normalize(self, xMin, xMax, yMin, yMax, allow_scaling=True):
        """Normalize a view range defined by x and y corners using predefined
        containts.

        :param float xMin: Min position of the x-axis
        :param float xMax: Max position of the x-axis
        :param float yMin: Min position of the y-axis
        :param float yMax: Max position of the y-axis
        :param bool allow_scaling: Allow or not to apply scaling for the
            normalization. Used according to the interaction mode.
        :return: A normalized tuple of (xMin, xMax, yMin, yMax)
        """
        viewRange = [[xMin, xMax], [yMin, yMax]]

        for axis in range(2):
            # clamp xRange and yRange
            if allow_scaling:
                diff = viewRange[axis][1] - viewRange[axis][0]
                delta = None
                if self._maxRange[axis] is not None and diff > self._maxRange[axis]:
                    delta = self._maxRange[axis] - diff
                elif self._minRange[axis] is not None and diff < self._minRange[axis]:
                    delta = self._minRange[axis] - diff
                if delta is not None:
                    viewRange[axis][0] -= delta * 0.5
                    viewRange[axis][1] += delta * 0.5

            # clamp min and max positions
            outMin = self._min[axis] is not None and viewRange[axis][0] < self._min[axis]
            outMax = self._max[axis] is not None and viewRange[axis][1] > self._max[axis]

            if outMin and outMax:
                if allow_scaling:
                    # we can clamp both sides
                    viewRange[axis][0] = self._min[axis]
                    viewRange[axis][1] = self._max[axis]
                else:
                    # center the result
                    delta = viewRange[axis][1] - viewRange[axis][0]
                    mid = self._min[axis] + self._max[axis] - self._min[axis]
                    viewRange[axis][0] = mid - delta
                    viewRange[axis][1] = mid + delta
            elif outMin:
                delta = self._min[axis] - viewRange[axis][0]
                viewRange[axis][0] += delta
                viewRange[axis][1] += delta
            elif outMax:
                delta = self._max[axis] - viewRange[axis][1]
                viewRange[axis][0] += delta
                viewRange[axis][1] += delta

        return viewRange[0][0], viewRange[0][1], viewRange[1][0], viewRange[1][1]