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Add Sphinx-based Developer Guide documentation

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# Makefile for Sphinx documentation
#
# You can set these variables from the command line.
SPHINXOPTS =
SPHINXBUILD = sphinx-build
PAPER =
BUILDDIR = _build
# Internal variables.
PAPEROPT_a4 = -D latex_paper_size=a4
PAPEROPT_letter = -D latex_paper_size=letter
ALLSPHINXOPTS = -d $(BUILDDIR)/doctrees $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
# the i18n builder cannot share the environment and doctrees with the others
I18NSPHINXOPTS = $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
.PHONY: help clean html dirhtml singlehtml pickle json htmlhelp qthelp devhelp epub latex latexpdf text man changes linkcheck doctest gettext
help:
@echo "Please use \`make <target>' where <target> is one of"
@echo " html to make standalone HTML files"
@echo " dirhtml to make HTML files named index.html in directories"
@echo " singlehtml to make a single large HTML file"
@echo " pickle to make pickle files"
@echo " json to make JSON files"
@echo " htmlhelp to make HTML files and a HTML help project"
@echo " qthelp to make HTML files and a qthelp project"
@echo " devhelp to make HTML files and a Devhelp project"
@echo " epub to make an epub"
@echo " latex to make LaTeX files, you can set PAPER=a4 or PAPER=letter"
@echo " latexpdf to make LaTeX files and run them through pdflatex"
@echo " text to make text files"
@echo " man to make manual pages"
@echo " texinfo to make Texinfo files"
@echo " info to make Texinfo files and run them through makeinfo"
@echo " gettext to make PO message catalogs"
@echo " changes to make an overview of all changed/added/deprecated items"
@echo " linkcheck to check all external links for integrity"
@echo " doctest to run all doctests embedded in the documentation (if enabled)"
clean:
-rm -rf $(BUILDDIR)/*
html:
$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
@echo
@echo "Build finished. The HTML pages are in $(BUILDDIR)/html."
dirhtml:
$(SPHINXBUILD) -b dirhtml $(ALLSPHINXOPTS) $(BUILDDIR)/dirhtml
@echo
@echo "Build finished. The HTML pages are in $(BUILDDIR)/dirhtml."
singlehtml:
$(SPHINXBUILD) -b singlehtml $(ALLSPHINXOPTS) $(BUILDDIR)/singlehtml
@echo
@echo "Build finished. The HTML page is in $(BUILDDIR)/singlehtml."
pickle:
$(SPHINXBUILD) -b pickle $(ALLSPHINXOPTS) $(BUILDDIR)/pickle
@echo
@echo "Build finished; now you can process the pickle files."
json:
$(SPHINXBUILD) -b json $(ALLSPHINXOPTS) $(BUILDDIR)/json
@echo
@echo "Build finished; now you can process the JSON files."
htmlhelp:
$(SPHINXBUILD) -b htmlhelp $(ALLSPHINXOPTS) $(BUILDDIR)/htmlhelp
@echo
@echo "Build finished; now you can run HTML Help Workshop with the" \
".hhp project file in $(BUILDDIR)/htmlhelp."
qthelp:
$(SPHINXBUILD) -b qthelp $(ALLSPHINXOPTS) $(BUILDDIR)/qthelp
@echo
@echo "Build finished; now you can run "qcollectiongenerator" with the" \
".qhcp project file in $(BUILDDIR)/qthelp, like this:"
@echo "# qcollectiongenerator $(BUILDDIR)/qthelp/PyOtherSide.qhcp"
@echo "To view the help file:"
@echo "# assistant -collectionFile $(BUILDDIR)/qthelp/PyOtherSide.qhc"
devhelp:
$(SPHINXBUILD) -b devhelp $(ALLSPHINXOPTS) $(BUILDDIR)/devhelp
@echo
@echo "Build finished."
@echo "To view the help file:"
@echo "# mkdir -p $$HOME/.local/share/devhelp/PyOtherSide"
@echo "# ln -s $(BUILDDIR)/devhelp $$HOME/.local/share/devhelp/PyOtherSide"
@echo "# devhelp"
epub:
$(SPHINXBUILD) -b epub $(ALLSPHINXOPTS) $(BUILDDIR)/epub
@echo
@echo "Build finished. The epub file is in $(BUILDDIR)/epub."
latex:
$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
@echo
@echo "Build finished; the LaTeX files are in $(BUILDDIR)/latex."
@echo "Run \`make' in that directory to run these through (pdf)latex" \
"(use \`make latexpdf' here to do that automatically)."
latexpdf:
$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
@echo "Running LaTeX files through pdflatex..."
$(MAKE) -C $(BUILDDIR)/latex all-pdf
@echo "pdflatex finished; the PDF files are in $(BUILDDIR)/latex."
text:
$(SPHINXBUILD) -b text $(ALLSPHINXOPTS) $(BUILDDIR)/text
@echo
@echo "Build finished. The text files are in $(BUILDDIR)/text."
man:
$(SPHINXBUILD) -b man $(ALLSPHINXOPTS) $(BUILDDIR)/man
@echo
@echo "Build finished. The manual pages are in $(BUILDDIR)/man."
texinfo:
$(SPHINXBUILD) -b texinfo $(ALLSPHINXOPTS) $(BUILDDIR)/texinfo
@echo
@echo "Build finished. The Texinfo files are in $(BUILDDIR)/texinfo."
@echo "Run \`make' in that directory to run these through makeinfo" \
"(use \`make info' here to do that automatically)."
info:
$(SPHINXBUILD) -b texinfo $(ALLSPHINXOPTS) $(BUILDDIR)/texinfo
@echo "Running Texinfo files through makeinfo..."
make -C $(BUILDDIR)/texinfo info
@echo "makeinfo finished; the Info files are in $(BUILDDIR)/texinfo."
gettext:
$(SPHINXBUILD) -b gettext $(I18NSPHINXOPTS) $(BUILDDIR)/locale
@echo
@echo "Build finished. The message catalogs are in $(BUILDDIR)/locale."
changes:
$(SPHINXBUILD) -b changes $(ALLSPHINXOPTS) $(BUILDDIR)/changes
@echo
@echo "The overview file is in $(BUILDDIR)/changes."
linkcheck:
$(SPHINXBUILD) -b linkcheck $(ALLSPHINXOPTS) $(BUILDDIR)/linkcheck
@echo
@echo "Link check complete; look for any errors in the above output " \
"or in $(BUILDDIR)/linkcheck/output.txt."
doctest:
$(SPHINXBUILD) -b doctest $(ALLSPHINXOPTS) $(BUILDDIR)/doctest
@echo "Testing of doctests in the sources finished, look at the " \
"results in $(BUILDDIR)/doctest/output.txt."

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# -*- coding: utf-8 -*-
#
# PyOtherSide documentation build configuration file, created by
# sphinx-quickstart on Wed Feb 5 22:01:34 2014.
#
# This file is execfile()d with the current directory set to its containing dir.
#
# Note that not all possible configuration values are present in this
# autogenerated file.
#
# All configuration values have a default; values that are commented out
# serve to show the default.
import sys, os
# If extensions (or modules to document with autodoc) are in another directory,
# add these directories to sys.path here. If the directory is relative to the
# documentation root, use os.path.abspath to make it absolute, like shown here.
#sys.path.insert(0, os.path.abspath('.'))
# -- General configuration -----------------------------------------------------
# If your documentation needs a minimal Sphinx version, state it here.
#needs_sphinx = '1.0'
# Add any Sphinx extension module names here, as strings. They can be extensions
# coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
extensions = []
# Add any paths that contain templates here, relative to this directory.
templates_path = ['_templates']
# The suffix of source filenames.
source_suffix = '.rst'
# The encoding of source files.
#source_encoding = 'utf-8-sig'
# The master toctree document.
master_doc = 'index'
# General information about the project.
project = u'PyOtherSide'
copyright = u'2014, Thomas Perl'
# The version info for the project you're documenting, acts as replacement for
# |version| and |release|, also used in various other places throughout the
# built documents.
#
# The short X.Y version.
version = '0.2.0'
# The full version, including alpha/beta/rc tags.
release = '0.2.0'
# The language for content autogenerated by Sphinx. Refer to documentation
# for a list of supported languages.
#language = None
# There are two options for replacing |today|: either, you set today to some
# non-false value, then it is used:
#today = ''
# Else, today_fmt is used as the format for a strftime call.
#today_fmt = '%B %d, %Y'
# List of patterns, relative to source directory, that match files and
# directories to ignore when looking for source files.
exclude_patterns = ['_build']
# The reST default role (used for this markup: `text`) to use for all documents.
#default_role = None
# If true, '()' will be appended to :func: etc. cross-reference text.
#add_function_parentheses = True
# If true, the current module name will be prepended to all description
# unit titles (such as .. function::).
#add_module_names = True
# If true, sectionauthor and moduleauthor directives will be shown in the
# output. They are ignored by default.
#show_authors = False
# The name of the Pygments (syntax highlighting) style to use.
pygments_style = 'sphinx'
# A list of ignored prefixes for module index sorting.
#modindex_common_prefix = []
# -- Options for HTML output ---------------------------------------------------
# The theme to use for HTML and HTML Help pages. See the documentation for
# a list of builtin themes.
html_theme = 'default'
# Theme options are theme-specific and customize the look and feel of a theme
# further. For a list of options available for each theme, see the
# documentation.
#html_theme_options = {}
# Add any paths that contain custom themes here, relative to this directory.
#html_theme_path = []
# The name for this set of Sphinx documents. If None, it defaults to
# "<project> v<release> documentation".
#html_title = None
# A shorter title for the navigation bar. Default is the same as html_title.
#html_short_title = None
# The name of an image file (relative to this directory) to place at the top
# of the sidebar.
#html_logo = None
# The name of an image file (within the static path) to use as favicon of the
# docs. This file should be a Windows icon file (.ico) being 16x16 or 32x32
# pixels large.
#html_favicon = None
# Add any paths that contain custom static files (such as style sheets) here,
# relative to this directory. They are copied after the builtin static files,
# so a file named "default.css" will overwrite the builtin "default.css".
html_static_path = ['_static']
# If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
# using the given strftime format.
#html_last_updated_fmt = '%b %d, %Y'
# If true, SmartyPants will be used to convert quotes and dashes to
# typographically correct entities.
#html_use_smartypants = True
# Custom sidebar templates, maps document names to template names.
#html_sidebars = {}
# Additional templates that should be rendered to pages, maps page names to
# template names.
#html_additional_pages = {}
# If false, no module index is generated.
#html_domain_indices = True
# If false, no index is generated.
#html_use_index = True
# If true, the index is split into individual pages for each letter.
#html_split_index = False
# If true, links to the reST sources are added to the pages.
#html_show_sourcelink = True
# If true, "Created using Sphinx" is shown in the HTML footer. Default is True.
#html_show_sphinx = True
# If true, "(C) Copyright ..." is shown in the HTML footer. Default is True.
#html_show_copyright = True
# If true, an OpenSearch description file will be output, and all pages will
# contain a <link> tag referring to it. The value of this option must be the
# base URL from which the finished HTML is served.
#html_use_opensearch = ''
# This is the file name suffix for HTML files (e.g. ".xhtml").
#html_file_suffix = None
# Output file base name for HTML help builder.
htmlhelp_basename = 'PyOtherSidedoc'
# -- Options for LaTeX output --------------------------------------------------
latex_elements = {
# The paper size ('letterpaper' or 'a4paper').
#'papersize': 'letterpaper',
# The font size ('10pt', '11pt' or '12pt').
#'pointsize': '10pt',
# Additional stuff for the LaTeX preamble.
#'preamble': '',
}
# Grouping the document tree into LaTeX files. List of tuples
# (source start file, target name, title, author, documentclass [howto/manual]).
latex_documents = [
('index', 'PyOtherSide.tex', u'PyOtherSide Documentation',
u'Thomas Perl', 'manual'),
]
# The name of an image file (relative to this directory) to place at the top of
# the title page.
#latex_logo = None
# For "manual" documents, if this is true, then toplevel headings are parts,
# not chapters.
#latex_use_parts = False
# If true, show page references after internal links.
#latex_show_pagerefs = False
# If true, show URL addresses after external links.
#latex_show_urls = False
# Documents to append as an appendix to all manuals.
#latex_appendices = []
# If false, no module index is generated.
#latex_domain_indices = True
# -- Options for manual page output --------------------------------------------
# One entry per manual page. List of tuples
# (source start file, name, description, authors, manual section).
man_pages = [
('index', 'pyotherside', u'PyOtherSide Documentation',
[u'Thomas Perl'], 1)
]
# If true, show URL addresses after external links.
#man_show_urls = False
# -- Options for Texinfo output ------------------------------------------------
# Grouping the document tree into Texinfo files. List of tuples
# (source start file, target name, title, author,
# dir menu entry, description, category)
texinfo_documents = [
('index', 'PyOtherSide', u'PyOtherSide Documentation',
u'Thomas Perl', 'PyOtherSide', 'One line description of project.',
'Miscellaneous'),
]
# Documents to append as an appendix to all manuals.
#texinfo_appendices = []
# If false, no module index is generated.
#texinfo_domain_indices = True
# How to display URL addresses: 'footnote', 'no', or 'inline'.
#texinfo_show_urls = 'footnote'

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PyOtherSide Developer Guide
===========================
*PyOtherSide* is a Qt 5 QML Plugin that provides access to a Python 3
interpreter from QML. It was designed with mobile devices in mind, where
high-framerate touch interfaces are common, and where the user usually
interfaces only with one application at a time via a touchscreen. As such, it
is important to never block the UI thread, so that the user can always continue
to use the interface, even when the backend is processing, downloading or
calculating something in the background.
At its core, PyOtherSide is basically a simple layer that converts Qt (QML)
objects to Python objects and vice versa, with focus on asynchronous events
and continuation-passing style function calls.
While PyOtherSide historically also worked with Python 2.x and Qt 4.x, its
focus now lies on Python 3.x and Qt 5. Python 3 has been out for several years,
and offers some nice language features and clean-ups, while Qt 5 supports most
mobile platforms well, and has an improved QML engine and a faster renderer (Qt
Scene Graph) compared to Qt 4.
QML API
=======
This section describes the QML API exposed by the *PyOtherSide* QML Plugin.
The current QML API version of PyOtherSide is 1.0. When new features are
introduced, the API version will be bumped and documented here.
Import Versions
---------------
**io.thp.pyotherside 1.0** (since: 0.1.0)
Initial API release.
QML ``Python`` Element
----------------------
The ``Python`` element exposes a Python interpreter in a QML file. In
PyOtherSide 1.0, if multiple Python elements are instantiated, they will share
the same underlying Python interpreter, so Python module-global state will be
shared between all Python elements.
To use the ``Python`` element in a QML file, you have to import the plugin using:
.. code-block:: javascript
import io.thp.pyotherside 1.0
Signals
```````
**received(var data)**
Default event handler for ``pyotherside.send()``
if no other event handler was set.
**error(string traceback)**
Error handler for errors from Python.
Methods
```````
To configure event handlers for events from Python, you can use
the ``setHandler(event, callback)`` method:
**setHandler(string event, callable callback)**
Set the handler for events sent with ``pyotherside.send()``.
Importing modules is then done by optionally adding an import
path and then importing the module asynchronously:
**addImportPath(string path)**
Add a local filesystem path to Python's ``sys.path``.
**importModule(string name, callable callback)**
Import a Python module.
Once modules are imported, Python function can be called on the
imported modules using:
**call(string func, args=[], function callback(result) {})**
Call the Python function ``func`` with ``args`` asynchronously.
If ``args`` is omitted, ``func`` will be called without arguments.
If ``callback`` is a callable, it will be called with the Python
function result as single argument when the call has succeeded.
For some of these methods, there also exist synchronous variants, but it is
highly recommended to use the asynchronous variants instead to avoid blocking
the QML UI thread:
**var evaluate(string expr)**
Evaluate a Python expression synchronously.
**bool importModule_sync(string name)**
Import a Python module. Returns ``true`` on success, ``false`` otherwise.
**var call_sync(string func, var args=[])**
Call a Python function. Returns the return value of the Python function.
Python API
==========
PyOtherSide uses a normal Python 3.x interpreter for running your Python code.
The ``pyotherside`` module
--------------------------
When a module is imported in PyOtherSide, it will have access to a special
module called ``pyotherside`` in addition to all Python Standard Library modules
and Python modules in ``sys.path``:
.. code-block:: python
import pyotherside
The module can be used to send events asynchronously (even from different threads)
to the QML layer, register a callback for doing clean-ups at application exit and
integrate with other QML-specific features of PyOtherSide.
Methods
```````
**pyotherside.send(event, *args)**
Send an asynchronous event with name ``event`` with optional arguments ``args`` to QML.
**pyotherside.atexit(callback)**
Register a ``callback`` to be called when the application is closing.
**pyotherside.set_image_provider(provider)**
Set the QML `image provider`_ (``image://python/``).
.. _constants:
Constants
`````````
These constants are used in the return value of a `image provider`_ function:
**pyotherside.format_mono**
Mono pixel format (``QImage::Format_Mono``).
**pyotherside.format_mono_lsb**
Mono pixel format, LSB alignment (``QImage::Format_MonoLSB``).
**pyotherside.format_rgb32**
32-bit RGB format (``QImage::Format_RGB32``).
**pyotherside.format_argb32**
32-bit ARGB format (``QImage::Format_ARGB32``).
**pyotherside.format_rgb16**
16-bit RGB format (``QImage::Format_RGB16``).
**pyotherside.format_rgb666**
18bpp RGB666 format (``QImage::Format_RGB666``).
**pyotherside.format_rgb555**
15bpp RGB555 format (``QImage::Format_RGB555``).
**pyotherside.format_rgb888**
24-bit RGB format (``QImage::Format_RGB888``).
**pyotherside.format_rgb444**
12bpp RGB format (``QImage::Format_RGB444``).
**pyotherside.format_data**
Encoded image file data (e.g. PNG/JPEG data).
Data Type Mapping
=================
PyOtherSide will automatically convert Python data types to Qt data types
(which in turn will be converted to QML data types by the QML engine).
The following data types are supported and can be used to pass data
between Python and QML (and vice versa):
+------------+------------+-----------------------------+
| Python | QML | Remarks |
+============+============+=============================+
| bool | bool | |
+------------+------------+-----------------------------+
| int | int | |
+------------+------------+-----------------------------+
| float | double | |
+------------+------------+-----------------------------+
| str | string | |
+------------+------------+-----------------------------+
| list | JS Array | |
+------------+------------+-----------------------------+
| tuple | JS Array | JS Arrays are converted to |
| | | lists, no tuples |
+------------+------------+-----------------------------+
| dict | JS Object | Keys must be strings |
+------------+------------+-----------------------------+
Trying to pass in other types than the ones listed here is undefined
behavior and will usually result in an error.
.. _image provider:
Image Provider
==============
A QML Image Provider can be registered from Python to load image
data (e.g. map tiles, diagrams, graphs or generated images) in
QML ``Image`` elements without resorting to saving/loading files.
An image provider has the following argument list and return values:
.. code-block:: python
def image_provider(image_id, requested_size):
...
return bytearray(pixels), (width, height), format
The parameters to the image provider functions are:
**image_id**
The ID of the image URL (``image://python/<image_id>``).
**requested_size**
The source size of the QML ``Image`` as tuple: ``(width, height)``.
``(-1, -1)`` if the source size is not set.
The image provider must return a tuple ``(data, size, format)``:
**data**
A ``bytearray`` object containing the pixel data for the
given size and the given format.
**size**
A tuple ``(width, height)`` describing the size of the
pixel data in pixels.
**format**
The pixel format of ``data`` (see `constants`_), or
``pyotherside.format_data`` if ``data`` contains an
encoded (PNG/JPEG) image instead of raw pixel data.
In order to register the image provider with PyOtherSide for use
as provider for ``image://python/`` URLs, the image provider function
needs to be passed to PyOtherSide:
.. code-block:: python
import pyotherside
def image_provider(image_id, requested_size):
...
pyotherside.set_image_provider(image_provider)
Because Python modules are usually imported asynchronously, the image
provider will only be registered once the module registering the image
provider is successfully imported. You have to make sure that setting
the ``source`` property on a QML ``Image`` element only happens *after*
the image provider has been set (e.g. by setting the ``source`` property
in the callback function passed to ``importModule``).
Cookbook
========
This section contains code examples and best practices for combining Python and
QML.
Importing modules and calling functions asynchronously
------------------------------------------------------
In this example, we import the Python Standard Library module ``os``
and - when the module is imported - call the ``os.getcwd()`` function on it.
The result of the ``os.getcwd()`` function is then printed to the console
and ``os.chdir()`` is called with a single argument (``'/'``) - again, after
the ``os.chdir()`` function has returned, a message will be printed.
In this example, importing modules and calling functions are both done in
an asynchronous way - the QML/GUI thread will not block while these functions
execute. In fact, the ``Component.onCompleted`` code block will probably
finish before the ``os`` module has been imported in Python.
.. code-block:: javascript
Python {
Component.onCompleted: {
importModule('os', function() {
call('os.getcwd', [], function (result) {
console.log('Working directory: ' + result);
call('os.chdir', ['/'], function (result) {
console.log('Working directory changed.');
}););
});
});
}
}
While this `continuation-passing style`_ might look a like a little pyramid
due all the nesting and indentation at first, it makes sure your application's
UI is always responsive. The user will be able to interact with the GUI (e.g.
scroll and move around in the UI) while the Python code can process requests.
.. _Continuation-passing style: https://en.wikipedia.org/wiki/Continuation-passing_style
Evaluating Python expressions in QML
````````````````````````````````````
The ``evaluate()`` method on the ``Python`` object can be used to evaluate a
simple Python expression and return its result as JavaScript object:
.. code-block:: javascript
Python {
Component.onCompleted: {
console.log('Squares: ' + evaluate('[x for x in range(10)]'));
}
}
Evaluating expressions is done synchronously, so make sure you only use it for
expressions that are not long-running calculations / operations.
Error handling in QML
---------------------
If an error happens in Python while calling functions, the traceback of the
error (or an error message in case the error happens in the PyOtherSide layer)
will be sent with the ``error`` signal of the ``Python`` element. During early
development, it's probably enough to just log the error to the console:
.. code-block:: javascript
Python {
// ...
onError: console.log('Error: ' + traceback)
}
Once your application grows, it might make sense to maybe show the error to the
user in a dialog box, message or notification in addition to or instead of using
``console.log()`` to print the error.
Handing asynchronous events from Python in QML
----------------------------------------------
Your Python code can send asynchronous events with optional data to the QML
layer using the ``pyotherside.send()`` function. You can call this function from
functions called from QML, but also from anywhere else - including threads that
you created in Python. The first parameter is mandatory, and must be a string
that identifies the event. Additional parameters are optional and can be of any
data type that PyOtherSide supports:
.. code-block:: python
import pyotherside
pyotherside.send('new-entries', 100, 123)
If you do not add a special handler on the ``Python`` object, such events would
be handled by the ``onReceived`` signal in QML - its ``data`` parameter contains
the event name and all arguments in a list:
.. code-block:: javascript
Python {
// ..
onReceived: console.log('Event: ' + data)
}
Usually, you want to install a handler for such events. If you have e.g. the
``'new-entries'`` event like shown above (with two numeric parameters that we
will call ``first`` and ``last`` for this example), you might want to define a
simple handler function that will process this event:
.. code-block:: javascript
Python {
// ..
Component.onCompleted: {
setHandler('new-entries', function (first, last) {
console.log('New entries from ' + first + ' to ' + last);
});
}
}
Once a handler for a given event is defined, the ``onReceived`` signal will not
be emitted anymore. If you need to unset a handler for a given event, you can
use ``setHandler('event', undefined)`` to do so.
In some cases, it might be useful to not install a handler function directly, but
turn the ``pyotherside.send()`` call into a new signal on the ``Python`` object.
As there is no easy way for PyOtherSide to determine the names of the arguments
of the event, you have to define and hook up these signals manually. The upside
of having to define the signals this way is that all signals will be nicely
documented in your QML file for future reference:
.. code-block:: javascript
Python {
signal updated()
signal newEntries(int first, int last)
signal entryRenamed(int index, string name)
Component.onCompleted: {
setHandler('updated', updated);
setHandler('new-entries', newEntries);
setHandler('entry-renamed', entryRenamed);
}
}
With this setup, you can now emit these signals from the ``Python`` object by
using ``pyotherside.send()`` in your Python code:
.. code-block:: python
pyotherside.send('updated')
pyotherside.send('new-entries', 20, 30)
pyotherside.send('entry-renamed', 11, 'Hello World')
Loading ``ListModel`` data from Python
--------------------------------------
Most of the time a PyOtherSide QML application will display some data stored
somewhere and retrieved or generated with Python. The easiest way to do this is
to return a list-of-dicts in your Python function:
**listmodel.py**
.. code-block:: python
def get_data():
return [
{'name': 'Alpha', 'team': 'red'},
{'name': 'Beta', 'team': 'blue'},
{'name': 'Gamma', 'team': 'green'},
{'name': 'Delta', 'team': 'yellow'},
{'name': 'Epsilon', 'team': 'orange'},
]
Of course, the function could do other things (such as doing web requests, querying
databases, etc..) - as long as it returns a list-olf-dicts, it will be fine (if you
are using a generator that yields dicts, just wrap the generator with ``list()``).
Using this function from QML is straightforward:
**listmodel.qml**
.. code-block:: javascript
import QtQuick 2.0
import io.thp.pyotherside 1.0
Rectangle {
color: 'black'
width: 400
height: 400
ListView {
anchors.fill: parent
model: ListModel {
id: listModel
}
delegate: Text {
// Both "name" and "team" are taken from the model
text: name
color: team
}
}
Python {
id: py
Component.onCompleted: {
// Add the directory of this .qml file to the search path
addImportPath(Qt.resolvedUrl('.').substr('file://'.length));
// Import the main module and load the data
importModule('listmodel', function () {
py.call('listmodel.get_data', [], function(result) {
// Load the received data into the list model
for (var i=0; i<result.length; i++) {
listModel.append(result[i]);
}
});
});
}
}
}
Instead of passing a list-of-dicts, it is of course also possible to send
new list items via ``pyotherside.send()``, one item at a time, and append
them to the list model that way.
Rendering RGBA image data in Python
-----------------------------------
.. image:: images/image_provider_example.png
This example uses the `image provider`_ feature of PyOtherSide to
render RGB image data in Python and display the rendered data in
QML using a normal QtQuick 2.0 ``Image`` element:
**imageprovider.py**
.. code-block:: python
import pyotherside
import math
def render(image_id, requested_size):
print('image_id: "{image_id}", size: {requested_size}'.format(**locals()))
# width and height will be -1 if not set in QML
if requested_size == (-1, -1):
requested_size = (300, 300)
width, height = requested_size
# center for circle
cx, cy = width/2, 10
pixels = []
for y in range(height):
for x in range(width):
pixels.extend(reversed([
255, # alpha
int(10 + 10 * ((x - y * 0.5) % 20)), # red
20 + 10 * (y % 20), # green
int(255 * abs(math.sin(0.3*math.sqrt((cx-x)**2 + (cy-y)**2)))) # blue
]))
return bytearray(pixels), (width, height), pyotherside.format_argb32
pyotherside.set_image_provider(render)
This module can now be imported in QML and used as ``source`` in the QML
``Image`` element:
**imageprovider.qml**
.. code-block:: javascript
import QtQuick 2.0
import io.thp.pyotherside 1.0
Image {
id: image
width: 300
height: 300
Python {
Component.onCompleted: {
// Add the directory of this .qml file to the search path
addImportPath(Qt.resolvedUrl('.').substr('file://'.length));
importModule('imageprovider', function () {
image.source = 'image://python/image-id-passed-from-qml';
});
}
onError: console.log('Python error: ' + traceback)
}
}
Search
======
* :ref:`search`