Glueviz

--------------------

* Improved how we handle equal aspect ratio to not depend on
Matplotlib. [1894]

* Avoid showing a warning when closing an empty tab. [1890]

* Fix bug that caused component arithmetic to not work if
Numpy was imported in user's config.py file. [1887]

* Added the ability to define custom layer artist makers to
override default layer artists in viewers. [1850]

* Fix Plot.ly exporter for categorical components and histogram
viewer. [1886]

* Fix issues with reading very large FITS files on some systems. [1884]

* Added documentation about plugins. [1837]

* Better isolate code related to pixel selection tool in image
viewer that depended on Qt. [1763]

* Improve handling of units in FITS files. [1723]

* Added documentation about creating viewers for glue using the
new state-based infrastructure. [1740]

* Make it possible to pass the initial state of a viewer to an
application's ``new_data_viewer`` method. [1877]

* Ensure that glue can be imported if QtPy is installed but PyQt
and PySide aren't. [1865, 1836]

* Fix unit display for coordinates from WCS headers that don't have
CTYPE but have CUNIT. [1856]

* Enable tab completion on Data objects. [1874]

* Automatically select datasets in link editor if there are only two. [1837]

* Change 'Export Session' dialog to offer to save with relative paths to data
by default instead of absolute paths. [1803]

* Added a new method ``screenshot`` on ``GlueApplication`` to save a
screenshot of the current view. [1808]

* Show the active subset in the toolbar. [1797]

* Refactored the viewer class base classes [1746]:

- ``glue.core.application_base.ViewerBase`` has been removed in favor of
``glue.viewers.common.viewer.BaseViewer`` and
``glue.viewers.common.viewer.Viewer``.

- ``glue.viewers.common.viewer.Viewer`` is now where the base logic is defined
for using state classes in viewers (instead of
``glue.viewers.common.qt.DataViewerWithState``).

- ``glue.viewers.common.qt.DataViewerWithState`` is now deprecated.

* Make it so that the modest image only resamples the data when the
mouse is no longer pressed - this avoids too many refreshes when
panning/zooming. [1866]

* Make it possible to unglue multiple links in one go. [1809]

* Make it so that adding a subset to a viewer no longer adds the
associated data, since in some cases the viewer can handle the
subset size, but not the full data. [1807]

* Defined a new abstract base class for all datasets, ``BaseData``,
and a base class ``BaseCartesianData``,
which can be used to implement interfaces to datasets that may be
remote or may not be stored as regular cartesian data. [1768]

* Add a new method ``Data.compute_statistic`` which can be used
to find scalar and array statistics on the data, and use for
the profile viewer and the state limits helpers. [1737]

* Add a new method ``Data.compute_histogram`` which can be used
to find histograms of specific components, with or without
subsets applied. [1739]

* Removed ``Data.get_pixel_component_ids`` and ``Data.get_world_component_ids``
in favor of ``Data.pixel_component_ids`` and ``Data.world_component_ids``.
[1784]

* Deprecated ``Data.visible_components`` and ``Data.primary_components``. [1788]

* Speed up histogram calculations by using the fast-histogram package instead of
np.histogram. [1806]

* In the case of categorical attributes, ``Data[name]`` now returns a
``categorical_ndarray`` object rather than the indices of the categories. You
can access the indices with ``Data[name].codes`` and the unique categories
with ``Data[name].categories``. [1784]

* Compute profiles and histograms asynchronously when dataset is large
to avoid holding up the UI, and compute profiles in chunks to avoid
excessive memory usage. [1736, 1764]

* Improved naming of components when merging datasets. [1249]

* Fixed an issue that caused residual references to viewers
after they were closed if they were accessed through the
IPython console. [1770]

* Don't show layer edit options if layer is not visible. [1805]

* Make the Matplotlib viewer code that doesn't depend on Qt accessible
to non-Qt frontends. [1841]

* Avoid repeated coordinate components in merged datasets. [1792]

* Fix bug that caused new subset to be created when dragging an existing
subset in an image viewer. [1793]

* Better preserve data types when exporting data/subsets to FITS
and HDF5 formats. [1800]

--------------------

* Fix bug that caused .svg icons to not be correctly installed. [1882]

* Fix bug that occurred in certain cases when using the state attribute limit
helper with a state class that did not have a log attribute. [1842]

* Fix HDF5 reader for string columns. [1840]

* Fix visual bug in link editor in advanced mode when resizing window.

* Fixed a bug that caused custom data importers to no longer work. [1813]

* Fixed a bug that caused ROIs to not be erased after selection if the
active subset was not in the list of layers for the viewer. [1801]

* Always returned to last used folder when opening/saving files. [1794]

* Show correct dataset when using control-click to select to add
arithmetic attributes or rename/reorder components. [1802]

* Improve performance when updating links and changing attributes
on subsets. [1716]

* Fix errors that happened when clicking on the 'Export Data' and
'Define arithmetic attributes' buttons when no data was present,
and fixed Qt errors that happened if the data collection changed
after the 'Export Data' dialog was opened. [1795]

* Fixed parsing of AVM meta-data from images. [1732]

* Fixed compatibility with Matplotlib 3.0. [1875]

--------------------

* Fixed a bug that caused the expression for derived attributes to
not immediately be updated in the list of derived attributes. [1708]

* Fixed a bug that caused combo boxes with Data objects to not update
when a data label was changed. [1704]

* Fixed a bug related to callback functions when restoring sessions.
[1695]

* Fixed a bug that meant that setting Data.coords after adding
components didn't work as expected. [1196]

* Fixed bugs related to components with only NaN or Inf values.
[1712]

* Fixed a bug that caused an error when the zoom or pan tools were
active and the viewer was closed. [1712]

* Fixed a Qt-related segmentation fault that occurred during the
testing process and may also affect users. [1703]

* Show image layer attribute in list of layers. [1706]

* Fixed a bug that caused scatter plots to not revert to fixed color
mode after being in linear color mode. [1705]

--------------------

* Fixed a bug that caused the EditSubsetMode toolbar to not change
when EditSubsetMode.mode was changed programatically. [1684]

* Fixed unintuitive behavior of single-pixel selection tool - now
moving the crosshairs requires clicking and dragging. [1684]

* Fixed bug that caused crosshairs to not be hidden when a layer was
set to not be visible [1684]

* Fixed a bug that caused viewers to be closed without warning when
pressing delete. [1684]

--------------------

* Fixed resetting and opening of sessions which caused Glue to quit. [1681]

* Fixed serialization of Data.meta when non-serializable keys or values
are present. [1681]

--------------------

* Added new perceptually uniform Matplotlib colormaps. [1679]

* Fixed a bug that caused vectors to not correctly be flipped when
flipping the x/y limits of the plot. [1677]

* Added a CSV and HDF5 data/subset exporter. [1676]

* Started adding helpful information dialogs that can be
hidden. [1669]

* Make it possible to have a 'None' entry in the ComponentIDComboHelper. [1661]

* Added a new metadata/header viewer for datasets/subsets. [1659]

* Re-write spectrum viewer into a generic profile viewer that uses
subsets to define the areas in which to compute profiles rather
than custom ROIs. [1635]

* Added support for PySide2 and remove support for PyQt4 and
PySide. [1662]

* Remove support for Matplotlib 1.5. [1662]

* Renamed ``qt4_to_mpl_color`` to ``qt_to_mpl_color`` and
``mpl_to_qt4_color`` to ``mpl_to_qt_color``. [1662]

* Improve performance when changing visual attributes of subsets.
[1617]

* Removed ``glue.core.qt.data_combo_helper`` (we now recommend using
the GUI framework-independent equivalent in
``glue.core.data_combo_helper``). [1625]

* Removed ``glue.viewers.common.qt.attribute_limits_helper`` in favor
of ``glue.core.state_objects``. [1625]

* Removed unused function ``glue.utils.misc.defer``. [1625]

* Added a new ``FloodFillSubsetState`` class to represent and
calculate subsets made by a flood-fill algorithm. [1616]

* Added the ability to easily create viewer tools with dropdown
menus. [1634]

* Remove the ``MatplotlibViewerToolbar`` class as it is now no
longer needed - instead you can just list the matplotlib tools
directly in the ``tools`` attribute of the viewer. [1634]

* Improve hiding/showing of side-panels. No longer hide side-panels
when glue application goes out of focus. [1535]

* Use memory-mapping with contiguous arrays in HDF5 files, resulting
in improved performance for large files. [1628]

* Deselect tools when the viewer focus changes. [1584, 1608]

* Added support for whether symbols are shown filled or not. [1559]

* Improved link editor to include a graph of links. [1534]

* Improve mouse interaction with ROIs in image viewers, including
click-and-drag relocation. Allow for more customization of mouse/toolbar
modes. [1515]

* Add a toolbar item to save data. [1516, 1519, 1575]

* Give instructions for how to move selections in status tip. [1504]

* Improve the display of data cube slice labels to include only the
precision required given the separation of world coordinate values.
[1500, 1660]

* Removed the ability to edit the marker symbol in the style dialog
since this isn't recognized by any viewer anymore. [1560]

* Remove back/forward tools in Matplotlib viewer toolbars to
declutter. [1505]

* Added a new component manager that makes it possible to rename,
reorder, and remove components, as well as better manage derived
components, including editing previous equations. [1479]

* Added new messages ``DataReorderComponentMessage`` and
``DataRenameComponentMessage`` which can be subscribed to. [1479]

* Add support for the datetime64 dtype in Data objects, and adjust
Matplotlib viewers to correctly show this data. [1510]

* Make it possible to reorder components in ``Data`` using the new
``Data.reorder_components`` method. [1479]

* The default order of components has changed - coordinate components
will now always come first (rather than second). [1479]

* Added support for scatter density maps, which is useful when making
scatter plots of many points. [1461]

* Improve how ComponentIDComboHelper deals with non-primary components.
The .visible property has been removed, and a new .derived property
has been added (to show/hide derived components). Components are now
split up into sections in the combo boxes. [1476]

* Fixed a bug that caused ghost components to be added when creating a
derived component with data[...] = ... [1476]

* Fixed a bug that caused errors when removing items from a selection
property linked to a QComboBox. [1476]

* Added initial support for customizing keyboard shortcuts. [1475, 1514, 1524]

* Added support for using relative paths in session files. [1537]

* Remember last session filename and filter used. [1537]

* EditSubsetMode is now no longer a singleton class and is
instead instantiated at the Application/Session level. [1530]

* Improve performance of image viewer. [1558]

* Added new ``Projected3dROI`` and ``RoiSubsetState3d`` classes
to represent 3D selections made in the projection plane. [1522]

* Fixed saving of sessions with ``BinaryComponentLink``. [1533]

* Refactored/simplified handling of links between datasets and
fixed performance issues when adding/removing links or loading
data collections with many links. [1531, 1533]

* Significantly improve performance of link computations when the
links depend only on pixel or world coordinate components. [1585]

* Added the ability to customize the appearance of tick and axis
labels in Matplotlib plots. [1511]

* Added the ability to export Python scripts from the main
Matplotlib-based viewers. [1511]

* Added a new selection mode that always forces the creation of a new subset.
[1525]

* Added a mouse over pixel selection tool, which creates a one pixel subset
under the mouse cursor. [1619]

* Fixed an issue that caused sliders to not be correctly updated when
switching reference data in the image viewer. [1665]

* Fixed a bug that caused Data.meta to not be saved/restored from session
files. [1668]

* Fixed an issue that caused an IndexError when quitting glue in some
cases. [1657]

* Fixed a bug that caused matplotlibrc files to not be ignored. [1649]

* Fixed a non-deterministic error that happened when closing the
TableViewer. [7310]

* Fixed size of markers when value for size is out of vmin/vmax range. [1609]

* Fix a bug that caused viewer limits to be calculated incorrectly if
inf/-inf values were present in the data. [1614]

* Fixed a bug which caused the y-axis in the PV slice viewer to be
incorrect if the WCS could not be computed. [1615]

* Fixed a bug that caused the WCS of a PV slice to be incorrect if the
user has selected a custom order of the axes of a cube in the image
viewer. [1615]

* Fixed ticks on log x-axis in histogram viewer. [7310]

* Fixed a bug that led to poor performance when slicing through data cubes.
[1554]