#6 PhaseOut Qwt
===============

Phasing out Qwt and Matplotlib Widgets from the Karabo GUI Client
*****************************************************************

The karabo graphical user interface (GUI) currently uses three different plotting
libraries, namely **Qwt**, **matplotlib** and **PyQtGraph**.
The library **Qwt** was not fulfilling the demands in the past with regard of
configuration storage, tailorable tools such as region of interest settings,
linked aux plots, etc. Moreover, it uses a C++ backend, which we consider
widely as technical debt in our future plans.
The library **matplotlib** is not the best choice for fast plotting and
interactive features.

For this reason, we implemented each existing **Qwt** plot widget using the
library **PyQtGraph** and tailored the features to the feedback we received so far.
The ``MultiCurve`` widget from **matplotlib** will get its graph counterpart
in Karabo 2.8.0 in March.

.. figure:: images/qwt.png
   :align: center
   :alt: example of Qwt widgets
   :figclass: align-center

   Old plotting widgets using the library ``Qwt``.


+----------------+--------------------+-------------+------------------------+
|                         **Widget Table**                                   |
+================+====================+=============+========================+
| Type           |        Qwt         | Matplotlib  | PyQtGraph              |
+----------------+--------------------+-------------+------------------------+
| Vector         | Plot               | -           | Vector Graph           |
+----------------+--------------------+-------------+------------------------+
| Vector         | XY-Plot            | -           | Vector X-Y Scatter     |
+----------------+--------------------+-------------+------------------------+
| Vector         | -                  | -           | VectorRoll Graph       |
+----------------+--------------------+-------------+------------------------+
| Vector         | -                  | -           | Vector Histogram Graph |
+----------------+--------------------+-------------+------------------------+
| Vector         | -                  | -           | Vector Bar Graph       |
+----------------+--------------------+-------------+------------------------+
| Vector         | -                  | -           | Vector Fill Graph      |
+----------------+--------------------+-------------+------------------------+
| Image          | Aligned Image View | -           | Detector Graph         |
+----------------+--------------------+-------------+------------------------+
| Image          | Image Element      | -           | WebCam Graph           |
+----------------+--------------------+-------------+------------------------+
| Image          | Image View         | -           | Image Graph            |
+----------------+--------------------+-------------+------------------------+
| Image          | Webcam Image       | -           | WebCam Graph           |
+----------------+--------------------+-------------+------------------------+
| Image          | Scientific Image   | -           | WebCam Graph           |
+----------------+--------------------+-------------+------------------------+
| Float/Bool/Int |        -           | XY-Plot     | Scatter Graph          |
+----------------+--------------------+-------------+------------------------+
| Float/Bool/Int |        -           | MultiCurve  | Development ...        |
+----------------+--------------------+-------------+------------------------+
| Float/Bool/Int | Trendline          | -           | Trend Graph            |
+----------------+--------------------+-------------+------------------------+
| States         | -                  | -           | State Graph            |
+----------------+--------------------+-------------+------------------------+
| Alarms         | -                  | -           | Alarm Graph            |
+----------------+--------------------+-------------+------------------------+


In order to move further, we will finally deprecate and remove the **Qwt**
and **matplotlib** widgets with Karabo **2.9.0**, which will be released **15.05.2020**.
We are aiming for an automatic procedure with a script working on the project
database content to replace the existing Qwt and matplotlib widgets with their
PyQtGraph counterpart.