From 392a0c5a4d19da8f06b3ccab8b9d7fdcd558e64d Mon Sep 17 00:00:00 2001
From: Brian Jordan <brian@laptop.org>
Date: Fri, 27 Jun 2008 18:17:45 +0000
Subject: Initial commit

---
(limited to 'olpcgames/pausescreen.py')

diff --git a/olpcgames/pausescreen.py b/olpcgames/pausescreen.py
new file mode 100755
index 0000000..113a0ea
--- /dev/null
+++ b/olpcgames/pausescreen.py
@@ -0,0 +1,116 @@
+"""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
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