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authorBrian Jordan <brian@laptop.org>2008-06-27 18:17:45 (GMT)
committer Brian Jordan <brian@laptop.org>2008-06-27 18:22:14 (GMT)
commit392a0c5a4d19da8f06b3ccab8b9d7fdcd558e64d (patch)
tree7fefd02a04479932b4afe7ccd14b12de3c6294c6 /olpcgames/pausescreen.py
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+"""Display a "paused" version of the currently-displayed screen
+
+This code is largely cribbed from the Pippy activity's display code,
+but we try to be a little more generally usable than they are, as
+we have more involved activities using the code.
+
+We use svgsprite to render a graphic which is stored in the
+olpcgames data directory over a dimmed version of the current
+screen contents.
+
+_LAST_EVENT_TIME -- tracks the last time that we saw an event
+ come across the wire.
+"""
+import logging
+log = logging.getLogger( 'olpcgames.pausescreen' )
+import pygame
+from pygame import sprite
+
+_LAST_EVENT_TIME = 0
+
+def _set_last_event_time( time=None ):
+ """Set time as the last event time
+
+ time -- if None, pygame.time.get_ticks() is used
+
+ returns time set
+ """
+ global _LAST_EVENT_TIME
+ if time is None:
+ time = pygame.time.get_ticks()
+ _LAST_EVENT_TIME = time
+ return time
+
+def last_event_time( ):
+ """Return the duration since last event for pausing operations
+
+ returns time in seconds
+ """
+ global _LAST_EVENT_TIME
+ return (pygame.time.get_ticks() - _LAST_EVENT_TIME)/1000.
+
+
+def get_events( sleep_timeout = 10, pause=None, **args ):
+ """Retrieve the set of pending events or sleep
+
+ sleep_timeout -- dormant period before we invoke pause_screen
+ pause -- callable to produce visual notification of pausing, normally
+ by taking the current screen and modifying it in some way. Defaults
+ to pauseScreen in this module. If you return nothing from this
+ function then no restoration or display-flipping will occur
+ *args -- if present, passed to 'pause' to configuration operation (e.g.
+ to specify a different overlaySVG file)
+
+ returns set of pending events (potentially empty)
+ """
+ if not pause:
+ pause = pauseScreen
+ events = pygame.event.get( )
+ if not events:
+ log.info( 'No events in queue' )
+ old_screen = None
+ if last_event_time() > sleep_timeout:
+ # we've been waiting long enough, go to sleep visually
+ log.warn( 'Pausing activity after %s with function %s', sleep_timeout, pause )
+ old_screen = pause( )
+ if old_screen:
+ pygame.display.flip()
+ # now we wait until there *are* some events (efficiently)
+ # and retrieve any extra events that are waiting...
+ events = [ pygame.event.wait() ] + pygame.event.get()
+ log.warn( 'Activity restarted')
+ if old_screen:
+ restoreScreen( old_screen )
+ if events:
+ _set_last_event_time()
+ return events
+
+def pauseScreen( overlaySVG=None ):
+ """Display a "Paused" screen and suspend
+
+ This default implementation will not do anything to shut down your
+ simulation or other code running in other threads. It will merely block
+ this thread (the pygame thread) until an event shows up in the
+ eventwrap queue.
+
+ Returns a surface to pass to restoreScreen to continue...
+ """
+ from olpcgames import svgsprite
+ if not overlaySVG:
+ from olpcgames.data import sleeping_svg
+ overlaySVG = sleeping_svg.data
+ screen = pygame.display.get_surface()
+ old_screen = screen.copy() # save this for later.
+ pause_sprite = svgsprite.SVGSprite(
+ overlaySVG,
+ )
+ pause_sprite.rect.center = screen.get_rect().center
+ group = sprite.RenderUpdates( )
+ group.add( pause_sprite )
+
+ # dim the screen and display the 'paused' message in the center.
+ BLACK = (0,0,0)
+ WHITE = (255,255,255)
+ dimmed = screen.copy()
+ dimmed.set_alpha(128)
+ screen.fill(BLACK)
+ screen.blit(dimmed, (0,0))
+
+ group.draw( screen )
+ return old_screen
+
+def restoreScreen( old_screen ):
+ """Restore the original screen and return"""
+ screen = pygame.display.get_surface()
+ screen.blit(old_screen, (0,0))
+ return old_screen