1. Stefano Rivera
  2. pygame-pypy


marcus  committed 8b86177

Started the hello world tutorial

  • Participants
  • Parent commits 360c7b7
  • Branches pgreloaded

Comments (0)

Files changed (2)

File doc/tutorial/helloworld.rst

View file
  • Ignore whitespace
+Hello World
+Ahhh, the great tradition of saying "Hello World" in a programming
+language. To whet your appetite, we will do the same with a most simple
+application, which will display the typical Pygame logo. It is not
+important to understand anything at once, which will be used by the
+example. Nearly all parts used now are explained in later chapters, so
+do not hesitate, if the one or other explanation is missing.
+Pygame2 uses a strict seperation of modules to allow you to build and
+import only those parts needed for your specific needs. In contrast to
+Pygame, this forces you to write more import statements, but the benefit
+is that you can keep your dependencies small.
+Let's start with importing some basic SDL modules, which are necessary
+to display a small nice window and to do some basic drawing within that
+window. ::
+  import sys
+  import pygame2
+  import pygame2.examples
+  try:
+      import pygame2.sdl.constants as constants
+      import pygame2.sdl.image as image
+      import pygame2.sdl.event as event
+      import pygame2.sdl.video as video
+  except ImportError:
+      print ("No pygame2.sdl support")
+      sys.exit ()
+First of all, we import the :mod:`pygame2` core module, which allows us
+to use some basic things, such as :class:`pygame2.Color` and
+:class:`pygame2.Rect` objects. In nearly all graphics applications
+written with pygame2, you will need the core.
+Afterwards, we import the shipped examples. This is mainly done to have
+the logo around, which resides within the :mod:`pygame2.examples`
+package. In your own applications, it is unlikely that you will ever
+need to import them.
+Finally, we try to get the :mod:`pygame2.sdl` modules, which are
+necessary for displaying the window and image. As Pygame2 can be built
+without SDL support, we add a typical safety net to get out without too
+much noise, if SDL support is not given.
+Window Creation and Image Loading
+Any graphical application requires access to the screen, mostly in form
+of a window, which basically represents a portion of the screen, the
+application has access to and the application can manipulate. Mostly,
+that portion has a border and title bar around it, so the user can move
+it around on the screen and reorganize anything, so it fits his needs.
+Once we have imported all necessary parts, let's create a window to have
+access to the screen, so we can display the logo and thus represent it
+to the user. ::
+  video.init ()
+  imgresource = pygame2.examples.RESOURCES.get ("logo.bmp")
+  surface = image.load_bmp (imgresource)
+  screen = video.set_mode (surface.width + 10, surface.height + 10)
+  screen.fill (pygame2.Color (255, 255, 255))
+  screen.blit (surface, (5, 5))
+  screen.flip ()
+First, we initialize the :mod:`pygame2.sdl.video` internals, so we can
+have access to the screen and create windows on top of it. Afterwards,
+we get the logo from the :mod:`pygame2.examples` package and create a
+:class:`pygame2.sdl.video.Surface` from it, which can be easily shown
+later on and which allows us to determine the minimum window size we
+need to display it.
+Once done with that, :meth:`pygame2.sdl.video.set_mode` will create the
+window for us. We make the window slightly larger than the image size
+to have some small border around the image.
+If the window is first created, it will appear all black on the screen
+by default. We change that by filling the window (which is nothing else
+than a special :class:`pygame2.sdl.video.Surface`) with a white color
+now and afterwards copy (which is called *blitting*) our loaded image to
+the window. As you can see, we are using ``(5, 5)`` as second argument
+to :meth:`pygame2.sdl.video.Surface.blit`. This is the top-left (x, y)
+offset to start copying the image contents at.
+.. tip::
+   Try to experiment with different values instead of (5, 5), for
+   example (-10, 8) or (17, -12) to learn more about the blit offset and
+   its behaviour.
+Finally, we have to instruct the window to tell the operating system or
+window manager that it should update the area where the window is
+located using :meth:`pygame2.sdl.video.Surface.flip`. This will cause
+the image to be shown.
+Making the Application responsive
+We are nearly done by now. We have an image to display, we have a
+window, where the image should be displayed on, so we can execute the
+written code, not?
+Well, yes, but the only thing that will happen is that we will notice a
+short flickering before the application exits. Maybe we can even see
+the window with the logo for a short moment, but that's not what we
+want, do we?
+To keep the window on the screen and to make it responsive to user
+input, such as closing the window, react upon the mouse cursor or key
+presses, we have to add a so-called event loop. The event loop will deal
+with certain types of actions happening on the window or while the
+window is focused by the user and - as long as the event loop is
+running - will keep the window shown on the screen [#f1]_. ::
+  okay = True
+  while okay:
+      for ev in event.get ():
+          if ev.type == constants.QUIT:
+              okay = False
+          if ev.type == constants.KEYDOWN and ev.key == constants.K_ESCAPE:
+              okay = False
+  video.quit ()
+.. rubric:: Footnotes
+.. [#f1] *shown* is not entirely true, but let's go with that for now.

File doc/tutorial/index.rst

View file
  • Ignore whitespace
 .. toctree::
   :maxdepth: 2
+  helloworld
 Indices and tables