No longer mention cairo in the docs

Especially the installation docs

documentation/src/api_architecture.rst

@@ -87,9 +87,10 @@ These also are simple drawing commands. Some of them get ``x``, ``y`` and
 at the current coordinate origin. Often these commands create holes or
 hole patterns.
 
-Cairo
-.....
+Back end
+........
 
-Boxes.py uses cairo as graphics library. It is not fully encapsulated
+Boxes.py used to use cairo as graphics library. It now uses its own -
+pure Python - back end. It is not fully encapsulated
 within the drawing methods of the Boxes class. Although this is the
-long term goal. Boxes.ctx is the cairo context all drawing is made on.
+long term goal. Boxes.ctx is the context all drawing is made on.

documentation/src/api_generator.rst

@@ -9,7 +9,7 @@ Generators are sub classes of
 Most code is directly in this class. Sub class are supposed to over
 write the ``.__init__()`` and ``.render()`` method.
 
-The Boxes class keeps a cairo canvas object (self.ctx) that all
+The Boxes class keeps a canvas object (self.ctx) that all
 drawing is made on. In addition it keeps a couple of global settings
 used for various drawing operations. See the ``.__init__()`` method
 for the details. 

documentation/src/api_navigation.rst

@@ -1,7 +1,7 @@
 Navigation
 ----------
 
-The cairo library can both move the origin and the current point from
+The back end can both move the origin and the current point from
 which the next line is going to start. Boxes.py hides this by using
 Turtle Graphics commands that also move the origin to the end of the
 last line. Other drawing commands restore the current position after
@@ -35,7 +35,7 @@ It can be used with the following code pattern:
 
    # continue above the row
 
-Parts of the code still directly use the cairo primitives **Boxes.ctx.save()**
+Parts of the code still directly use the back end primitives **Boxes.ctx.save()**
 and **Boxes.ctx.restore()**. But this has several disadvantages and is
 discouraged. For one it requires matchiung calls. It also does not
 reset the starting point of the next line. This is "healed" by a

documentation/src/install.rst

@@ -9,11 +9,10 @@ installing or building binary formats.
 Requirements
 ------------
 
-Cairo
-.....
-Boxes.py is based on the cairo graphics library. It supports both the PyPi
-version :code:`cairocffi` and :code:`python-cairo` that might be shipped with
-your distribution.
+Affine
+........
+:code:`Affine` (package name may be :code:`python-affine` or
+:code:`python3-affine`) is used for vector calculation.
 
 Markdown
 ........

documentation/src/install/macos.rst

@@ -23,14 +23,15 @@ General
 2. Install cairio:
 
   .. code::
-      brew install cairo pkg-config
+
+      brew install pkg-config
 
 
 3. Install required Python modules:
 
    .. code::
 
-      pip3 install pycairo cairocffi Markdown lxml
+      pip3 install Markdown lxml affine
 
 4. Download Boxes.py via Git:
 

documentation/src/install/windows.rst

@@ -1,11 +1,6 @@
 Windows
 =======
 
-While there is no known reason why Boxes.py should not run on Windows
-there is no upstream experience with doing so. The tricky part is
-getting the cairo library installed and to run with the Python version
-used. Python version and the architecture (32 or 64 bit) must match.
-
 Getting the Inkscape plugins to run will likely need manual
 installation (see above). Note that Inkscape may come with its own
 Python. If you run into trouble or have better installation
@@ -32,47 +27,18 @@ Following steps are known to work under Windows 10 (64-bit):
        :alt: Screenshot of Python 3.7 (64-bit) installer with PATH checked
        :align: center
 
-3.  Go to https://www.lfd.uci.edu/~gohlke/pythonlibs/#cairocffi
-    and download :code:`cairocffi‑1.0.2‑cp37‑cp37m‑win_amd64.whl`
-
-    .. figure:: windows_browser_download_pycairo.png
-       :scale: 50%
-       :alt: Screenshot of download for Python wheel of pycairo
-       :align: center
-
-4.  Go to https://www.lfd.uci.edu/~gohlke/pythonlibs/#pycairo
-    and download `pycairo‑1.18.0‑cp37‑cp37m‑win_amd64.whl`
-
-    .. figure:: windows_browser_download_cairocffi.png
-       :scale: 50%
-       :alt: Screenshot of download for Python wheel of cairocffi
-       :align: center
-
-5.  Open the Command Prompt
-    (i.e. via the shortcut Windows + R and then typing "cmd"
-    and pressing Enter)
-6.  Change to the folder where the .whl files from step 3 and 4 are located
-    (e.g. with the command :code:`cd \Users\[USERNAME]\Downloads`
-    where `[USERNAME]` is your username and `Downloads` the folder where
-    the .whl files are located)
-7.  Run the command :code:`pip install cairocffi‑1.0.2‑cp37‑cp37m‑win_amd64.whl
-    pycairo‑1.18.0‑cp37‑cp37m‑win_amd64.whl Markdown lxml`
+3.  Run the command :code:`pip install Markdown lxml affine`
     (Note: If the command pip is not found, you probably forgot to add the
     Python installation to the PATH environment variable in step 2)
-
-    .. figure:: windows_cmd_pip_install_dependencies.png
-       :scale: 50%
-       :alt: Command Prompt with pip installing dependencies
-       :align: center
-
-8.  Download Boxes.py as ZIP archive from GitHub
+	       
+4.  Download Boxes.py as ZIP archive from GitHub
 
     .. figure:: windows_browser_download_boxespy.png
        :scale: 50%
        :alt: Screenshot of download from Boxes.py project on GitHub
        :align: center
 
-9.  Extract the ZIP archive
+5.  Extract the ZIP archive
     (e.g. via the built-in Windows feature or other tools like 7-Zip)
 
     .. figure:: windows_boxespy_zip_extract.png
@@ -80,9 +46,9 @@ Following steps are known to work under Windows 10 (64-bit):
        :alt: Screenshot of Windows tools to extract the ZIP archive
        :align: center
 
-10. Change into the folder for Boxes.py,
+6. Change into the folder for Boxes.py,
     e.g. with the command :code:`cd \Users\[USERNAME]\Downloads\boxes-master`
-11. Run the development server with the command
+7. Run the development server with the command
     :code:`python scripts\boxesserver`
     Note: You likely will be notified by your firewall that it blocked network
     access. If you want to use boxesserver you need to allow connections.
@@ -92,7 +58,7 @@ Following steps are known to work under Windows 10 (64-bit):
        :alt: Screenshot of command for running boxesserver and firewall notice
        :align: center
 
-12. Open the address http://localhost:8000/ in your browser and have fun :)
+8. Open the address http://localhost:8000/ in your browser and have fun :)
 
     .. figure:: windows_browser_boxespy.png
        :scale: 50%