Generate documentation with Sphinx

6 files changed, 552 insertions, 0 deletions

diff --git a/doc/cpp/Doxyfile b/doc/cpp/Doxyfile
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index 0000000..2bb0f9f
--- /dev/null
+++ b/doc/cpp/Doxyfile
@@ -0,0 +1,40 @@
+PROJECT_NAME           = Pugl
+PROJECT_BRIEF          = "A minimal portable API for embeddable GUIs"
+
+QUIET                  = YES
+WARN_AS_ERROR          = NO
+WARN_IF_UNDOCUMENTED   = NO
+WARN_NO_PARAMDOC       = NO
+
+JAVADOC_AUTOBRIEF      = YES
+
+CASE_SENSE_NAMES       = YES
+EXCLUDE_SYMBOLS        = pugl::detail
+EXTRACT_LOCAL_CLASSES  = NO
+EXTRACT_PRIVATE        = NO
+HIDE_IN_BODY_DOCS      = YES
+HIDE_UNDOC_CLASSES     = YES
+HIDE_UNDOC_MEMBERS     = YES
+REFERENCES_LINK_SOURCE = NO
+
+GENERATE_HTML          = NO
+GENERATE_LATEX         = NO
+GENERATE_XML           = YES
+XML_PROGRAMLISTING     = NO
+SHOW_FILES             = NO
+
+MACRO_EXPANSION        = YES
+PREDEFINED             = PUGL_API PUGL_DISABLE_DEPRECATED PUGL_CONST_FUNC=
+
+INPUT                  = ../../include/pugl/cairo.h \
+                         ../../include/pugl/gl.h \
+                         ../../include/pugl/pugl.h \
+                         ../../include/pugl/stub.h \
+                         ../../include/pugl/vulkan.h \
+                         ../../bindings/cxx/include/pugl/cairo.hpp \
+                         ../../bindings/cxx/include/pugl/gl.hpp \
+                         ../../bindings/cxx/include/pugl/pugl.hpp \
+                         ../../bindings/cxx/include/pugl/stub.hpp \
+                         ../../bindings/cxx/include/pugl/vulkan.hpp
+
+OUTPUT_DIRECTORY       = .
diff --git a/doc/cpp/c-reference.rst b/doc/cpp/c-reference.rst
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+++ b/doc/cpp/c-reference.rst
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+###############
+C API Reference
+###############
+
+This section contains the generated documentation for all symbols in the public
+C API.
+It is included here because some C++ wrapper definitions refer to the underlying C symbols,
+but direct use of the C API should not be necessary in C++ applications.
+
+.. toctree::
+
+   api/status
+   api/world
+   api/view
+   api/events
+
+   api/cairo
+   api/gl
+   api/stub
+   api/vulkan
diff --git a/doc/cpp/cpp-reference.rst b/doc/cpp/cpp-reference.rst
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index 0000000..96c523c
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+++ b/doc/cpp/cpp-reference.rst
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+#################
+C++ API Reference
+#################
+
+This section contains the generated documentation for all symbols in the public
+C++ API.
+
+.. toctree::
+
+   api/statusxx
+   api/worldxx
+   api/viewxx
+   api/eventsxx
+
+   api/cairoxx
+   api/glxx
+   api/stubxx
+   api/vulkanxx
diff --git a/doc/cpp/index.rst b/doc/cpp/index.rst
new file mode 100644
index 0000000..c3d330e
--- /dev/null
+++ b/doc/cpp/index.rst
@@ -0,0 +1,7 @@
+.. toctree::
+
+   pugl
+   deployment
+   overview
+   cpp-reference
+   c-reference
diff --git a/doc/cpp/overview.rst b/doc/cpp/overview.rst
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index 0000000..5fffe37
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+++ b/doc/cpp/overview.rst
@@ -0,0 +1,423 @@
+.. default-domain:: cpp
+.. highlight:: cpp
+.. namespace:: pugl
+
+Pugl is a C library,
+but the bindings documented here provide a more idiomatic and type-safe API for C++.
+If you would rather use C,
+refer instead to the `C API documentation <../../c/singlehtml/index.html>`_.
+
+The C++ bindings are very lightweight and do not require virtual functions,
+RTTI,
+exceptions,
+or linking to the C++ standard library.
+They are provided by the package ``puglxx-0`` which must be used in addition to the desired platform+backend package above.
+
+The core API (excluding backend-specific components) is declared in ``pugl.hpp``:
+
+.. code-block:: cpp
+
+   #include <pugl/pugl.hpp>
+
+The API revolves around two main objects: the `world` and the `view`.
+An application creates a world to manage top-level state,
+then creates one or more views to display.
+
+Creating a World
+================
+
+The world is the top-level object which represents an instance of Pugl.
+It handles the connection to the window system,
+and manages views and the event loop.
+
+An application typically has a single world,
+which is constructed once on startup and used to drive the main event loop.
+
+Construction
+------------
+
+A world must be created before any views, and it must outlive all of its views.
+The world constructor requires an argument to specify the application type:
+
+.. code-block:: cpp
+
+   pugl::World world{pugl::WorldType::program};
+
+For a plugin, specify :enumerator:`WorldType::module` instead.
+In some cases, it is necessary to pass additional flags.
+For example, Vulkan requires thread support:
+
+.. code-block:: cpp
+
+   pugl::World world{pugl::WorldType::program, pugl::WorldFlag::threads};
+
+It is a good idea to set a class name for your project with :func:`World::setClassName`.
+This allows the window system to distinguish different applications and,
+for example, users to set up rules to manage their windows nicely:
+
+.. code-block:: cpp
+
+   world.setClassName("MyAwesomeProject");
+
+Creating a View
+===============
+
+A `view` is a drawable region that receives events.
+You may think of it as a window,
+though it may be embedded and not represent a top-level system window. [#f1]_
+
+Pugl communicates with views by dispatching events.
+For flexibility, the event handler can be a different object than the view.
+This allows using :class:`View` along with a separate event handler class.
+Alternatively, a view class can inherit from :class:`View` and set itself as its event handler,
+for a more object-oriented style.
+
+This documentation will use the latter approach,
+so we will define a class for our view that contains everything needed:
+
+.. code-block:: cpp
+
+   class MyView : public pugl::View
+   {
+   public:
+     explicit MyView(pugl::World& world)
+         : pugl::View{world}
+     {
+       setEventHandler(*this);
+     }
+
+     pugl::Status onEvent(const pugl::ConfigureEvent& event) noexcept;
+     pugl::Status onEvent(const pugl::ExposeEvent& event) noexcept;
+
+     // With other handlers here as needed...
+
+     // Fallback handler for all other events
+     template<PuglEventType t, class Base>
+     pugl::Status onEvent(const pugl::Event<t, Base>&) noexcept
+     {
+          return pugl::Status::success;
+     }
+
+   private:
+     // Some data...
+   };
+
+Pugl will call an ``onEvent`` method of the event handler (the view in this case) for every event.
+
+Note that Pugl uses a static dispatching mechanism rather than virtual functions to minimize overhead.
+It is therefore necessary for the final class to define a handler for every event type.
+A terse way to do this without writing every implementation is to define a fallback handler as a template,
+as in the example above.
+Alternatively, you can define an explicit handler for each event that simply returns :enumerator:`Status::success`.
+This way, it will be a compile error if any event is not explicitly handled.
+
+Configuring the Frame
+---------------------
+
+Before display,
+the necessary :doc:`frame <api/frame>` and :doc:`window <api/window>` attributes should be set.
+These allow the window system (or plugin host) to arrange the view properly.
+
+Derived classes can configure themselves during construction,
+but we assume here that configuration is being done outside the view.
+For example:
+
+.. code-block:: cpp
+
+   const double defaultWidth = 1920.0;
+   const double defaultHeight = 1080.0;
+
+   view.setWindowTitle("My Window");
+   view.setDefaultSize(defaultWidth, defaultHeight);
+   view.setMinSize(defaultWidth / 4.0, defaultHeight / 4.0);
+   view.setAspectRatio(1, 1, 16, 9);
+
+There are also several :type:`hints <PuglViewHint>` for basic attributes that can be set:
+
+.. code-block:: cpp
+
+   view.setHint(pugl::ViewHint::resizable, true);
+   view.setHint(pugl::ViewHint::ignoreKeyRepeat, true);
+
+Embedding
+---------
+
+To embed the view in another window,
+you will need to somehow get the :type:`native view handle <pugl::NativeView>` for the parent,
+then set it with :func:`View::setParentWindow`.
+If the parent is a Pugl view,
+the native handle can be accessed with :func:`View::nativeWindow`.
+For example:
+
+.. code-block:: cpp
+
+   view.setParentWindow(view, parent.getNativeWindow());
+
+Setting a Backend
+-----------------
+
+Before being realized, the view must have a backend set with :func:`View::setBackend`.
+
+The backend manages the graphics API that will be used for drawing.
+Pugl includes backends and supporting API for
+:doc:`Cairo <api/cairo>`, :doc:`OpenGL <api/gl>`, and :doc:`Vulkan <api/vulkan>`.
+
+Using Cairo
+^^^^^^^^^^^
+
+Cairo-specific API is declared in the ``cairo.hpp`` header:
+
+.. code-block:: cpp
+
+   #include <pugl/cairo.hpp>
+
+The Cairo backend is provided by :func:`cairoBackend()`:
+
+.. code-block:: cpp
+
+   view.setBackend(pugl::cairoBackend());
+
+No additional configuration is required for Cairo.
+To draw when handling an expose event,
+the `Cairo context <https://www.cairographics.org/manual/cairo-cairo-t.html>`_ can be accessed with :func:`View::context`:
+
+.. code-block:: cpp
+
+   cairo_t* cr = static_cast<cairo_t*>(view.context());
+
+Using OpenGL
+^^^^^^^^^^^^
+
+OpenGL-specific API is declared in the ``gl.hpp`` header:
+
+.. code-block:: cpp
+
+   #include <pugl/gl.hpp>
+
+The OpenGL backend is provided by :func:`glBackend()`:
+
+.. code-block:: cpp
+
+   view.setBackend(pugl::glBackend());
+
+Some hints must also be set so that the context can be set up correctly.
+For example, to use OpenGL 3.3 Core Profile:
+
+.. code-block:: cpp
+
+   view.setHint(pugl::ViewHint::useCompatProfile, false);
+   view.setHint(pugl::ViewHint::contextVersionMajor, 3);
+   view.setHint(pugl::ViewHint::contextVersionMinor, 3);
+
+If you need to perform some setup using the OpenGL API,
+there are two ways to do so.
+
+The OpenGL context is active when
+:type:`CreateEvent` and
+:type:`DestroyEvent`
+events are dispatched,
+so things like creating and destroying shaders and textures can be done then.
+
+Alternatively, if it is cumbersome to set up and tear down OpenGL in the event handler,
+:func:`enterContext` and :func:`leaveContext` can be used to manually activate the OpenGL context during application setup.
+Note, however, that unlike many other APIs, these functions must not be used for drawing.
+It is only valid to use the OpenGL API for configuration in a manually entered context,
+rendering will not work.
+For example:
+
+.. code-block:: cpp
+
+   pugl::enterContext(view);
+   myApp.setupOpenGL();
+   pugl::leaveContext(view);
+
+   while (!myApp.quit()) {
+     world.update(0.0);
+   }
+
+   pugl::enterContext(view);
+   myApp.teardownOpenGL();
+   pugl::leaveContext(view);
+
+Using Vulkan
+^^^^^^^^^^^^
+
+Vulkan-specific API is declared in the ``vulkan.hpp`` header.
+This header includes Vulkan headers,
+so if you are dynamically loading Vulkan at runtime,
+you should define ``VK_NO_PROTOTYPES`` before including it.
+
+.. code-block:: cpp
+
+   #define VK_NO_PROTOTYPES
+
+   #include <pugl/vulkan.hpp>
+
+The Vulkan backend is provided by :func:`vulkanBackend()`:
+
+.. code-block:: cpp
+
+   view.setBackend(pugl::vulkanBackend());
+
+Unlike OpenGL, almost all Vulkan configuration is done using the Vulkan API directly.
+Pugl only provides a portable mechanism to load the Vulkan library and get the functions used to load the rest of the Vulkan API.
+
+Loading Vulkan
+^^^^^^^^^^^^^^
+
+For maximum compatibility,
+it is best to not link to Vulkan at compile-time,
+but instead load the Vulkan API at run-time.
+To do so, first create a :class:`VulkanLoader`:
+
+.. code-block:: cpp
+
+   pugl::VulkanLoader loader{world};
+
+The loader manages the dynamically loaded Vulkan library,
+so it must be kept alive for as long as the application is using Vulkan.
+You can get the function used to load Vulkan functions with :func:`VulkanLoader::getInstanceProcAddrFunc`:
+
+.. code-block:: cpp
+
+   auto vkGetInstanceProcAddr = loader.getInstanceProcAddrFunc();
+
+It is best to use this function to load everything at run time,
+rather than link to the Vulkan library at run time.
+You can, for example, pass this to get the ``vkCreateInstance`` function using this,
+then use that to create your Vulkan instance.
+In practice, you will want to use some loader or wrapper API since there are many Vulkan functions.
+
+It is not necessary to use :class:`VulkanLoader`,
+you can, for example, use the ``DynamicLoader`` from ``vulkan.hpp`` in the Vulkan SDK instead.
+
+The details of using Vulkan are far beyond the scope of this documentation,
+but Pugl provides a portable function, :func:`createSurface`,
+to get the Vulkan surface for a view.
+Assuming you have somehow created your ``VkInstance``,
+you can get the surface for a view using :func:`createSurface`:
+
+.. code-block:: cpp
+
+   VkSurfaceKHR* surface = nullptr;
+   puglCreateSurface(loader.getDeviceProcAddrFunc(),
+                     view,
+                     vulkanInstance,
+                     nullptr,
+                     &surface);
+
+Pugl does not provide API that uses ``vulkan.hpp`` to avoid the onerous dependency,
+but if you are using it with exceptions and unique handles,
+it is straightforward to wrap the surface handle yourself.
+
+Showing the View
+----------------
+
+Once the view is configured, it can be "realized" with :func:`View::realize`.
+This creates a "real" system view, for example:
+
+.. code-block:: cpp
+
+   pugl::Status status = view.realize();
+   if (status != pugl::Status::success) {
+     std::cerr << "Error realizing view: " << pugl::strerror(status) << "\n";
+   }
+
+Note that realizing a view can fail for many reasons,
+so the return code should always be checked.
+This is generally the case for any function that interacts with the window system.
+Most functions also return a :enum:`Status`,
+but these checks are omitted for brevity in the rest of this documentation.
+
+A realized view is not initially visible,
+but can be shown with :func:`View::show`:
+
+.. code-block:: cpp
+
+   view.show();
+
+To create an initially visible view,
+it is also possible to simply call :func:`View::show()` right away.
+The view will be automatically realized if necessary.
+
+Handling Events
+===============
+
+Events are sent to a view when it has received user input,
+must be drawn, or in other situations that may need to be handled such as resizing.
+
+Events are sent to the ``onEvent`` method that takes the matching event type.
+The application must handle at least :type:`ConfigureEvent`
+and :type:`ExposeEvent` to draw anything,
+but there are many other :type:`event types <pugl::EventType>`.
+
+For example, basic event handling for our above class might look something like:
+
+.. code-block:: cpp
+
+   pugl::Status
+   MyView::onEvent(const pugl::ConfigureEvent& event) noexcept
+   {
+     return resize(event.width, event.height);
+   }
+
+   pugl::Status
+   MyView::onEvent(const pugl::ExposeEvent& event) noexcept
+   {
+     return drawMyAwesomeInterface(event.x, event.y, event.width, event.height);
+   }
+
+Drawing
+-------
+
+Note that Pugl uses a different drawing model than many libraries,
+particularly those designed for game-style main loops like `SDL <https://libsdl.org/>`_ and `GLFW <https://www.glfw.org/>`_.
+
+In that style of code, drawing is performed imperatively in the main loop,
+but with Pugl, the application must draw only while handling an expose event.
+This is because Pugl supports event-driven applications that only draw the damaged region when necessary,
+and handles exposure internally to provide optimized and consistent behavior across platforms.
+
+Driving the Event Loop
+======================
+
+Pugl does not contain any threads or other event loop "magic".
+For flexibility, the event loop is driven manually by repeatedly calling :func:`World::update`,
+which processes events from the window system and dispatches them to views when necessary.
+
+The exact use of :func:`World::update` depends on the application.
+Plugins typically call it with a ``timeout`` of 0 in a callback driven by the host.
+This avoids blocking the main loop,
+since other plugins and the host itself need to run as well.
+
+A program can use whatever timeout is appropriate:
+event-driven applications may wait forever by using a ``timeout`` of -1,
+while those that draw continuously may use a significant fraction of the frame period
+(with enough time left over to render).
+
+Redrawing
+---------
+
+Occasional redrawing can be requested by calling :func:`View::postRedisplay` or :func:`View::postRedisplayRect`.
+After these are called,
+a :type:`ExposeEvent` will be dispatched on the next call to :func:`World::update`.
+Note, however, that this will not wake up a blocked :func:`World::update` call on MacOS
+(which does not handle drawing via events).
+
+For continuous redrawing,
+call :func:`View::postRedisplay` while handling a :type:`UpdateEvent`.
+This event is sent just before views are redrawn,
+so it can be used as a hook to expand the update region right before the view is exposed.
+Anything else that needs to be done every frame can be handled similarly.
+
+.. _pkg-config: https://www.freedesktop.org/wiki/Software/pkg-config/
+
+.. rubric:: Footnotes
+
+.. [#f1] MacOS has a strong distinction between
+   `views <https://developer.apple.com/documentation/appkit/nsview>`_,
+   which may be nested, and
+   `windows <https://developer.apple.com/documentation/appkit/nswindow>`_,
+   which may not.
+   On Windows and X11, everything is a nestable window,
+   but top-level windows are configured differently.
diff --git a/doc/cpp/wscript b/doc/cpp/wscript
new file mode 100644
index 0000000..a7aefc1
--- /dev/null
+++ b/doc/cpp/wscript
@@ -0,0 +1,44 @@
+#!/usr/bin/env python
+
+def build(bld):
+    dox_to_sphinx = bld.path.find_node("../../scripts/dox_to_sphinx.py")
+    index_xml = bld.path.get_bld().make_node("xml/index.xml")
+
+    files = [
+        ("../../resources/pugl.svg", "sphinx/_static/pugl.svg"),
+        ("../_static/custom.css", "sphinx/_static/custom.css"),
+        ("../_templates/about.html", "sphinx/_templates/about.html"),
+        ("../deployment.rst", "sphinx/deployment.rst"),
+        ("../pugl.rst", "sphinx/pugl.rst"),
+        ("c-reference.rst", "sphinx/c-reference.rst"),
+        ("cpp-reference.rst", "sphinx/cpp-reference.rst"),
+        ("index.rst", "sphinx/index.rst"),
+        ("overview.rst", "sphinx/overview.rst"),
+    ]
+
+    # Run Doxygen to generate XML documentation
+    bld(features="doxygen", doxyfile="Doxyfile")
+
+    # Substitute variables to make Sphinx configuration file
+    bld(features="subst",
+        source="../conf.py.in",
+        target="sphinx/conf.py",
+        PUGL_VERSION=bld.env.PUGL_VERSION)
+
+    # Copy static documentation files to Sphinx build directory
+    for f in files:
+        bld(features="subst", is_copy=True, source=f[0], target=f[1])
+
+    # Generate Sphinx markup from Doxygen XML
+    bld.add_group()
+    bld(rule="${PYTHON} " + dox_to_sphinx.abspath() + " -l cpp -f ${SRC} ${TGT}",
+        source=index_xml,
+        target="sphinx/api/")
+
+    # Run Sphinx to generate HTML documentation
+    doc_dir = bld.env.DOCDIR + "/pugl-%s/" % bld.env.PUGL_MAJOR_VERSION
+    bld(features="sphinx",
+        sphinx_source=bld.path.get_bld().make_node("sphinx"),
+        sphinx_output_format="singlehtml",
+        sphinx_options=["-E", "-q"],
+        install_path=doc_dir + "cpp/singlehtml/")