Demo/sgi/video/DisplayVideoIn.py

   1 # Live video input from display class.
   2
   3 import gl
   4 import GL
   5
   6 # The live video input class.
   7 # Only instantiate this if have_video is true!
   8
   9 class DisplayVideoIn:
  10
  11         # Initialize an instance.  Arguments:
  12         # vw, vh: size of the video window data to be captured.
  13         # position defaults to 0, 0 but can be set later
  14         def __init__(self, pktmax, vw, vh, type):
  15                 self.pktmax = pktmax
  16                 self.realwidth, self.realheight = vw, vh
  17                 if type <> 'rgb':
  18                         raise 'Incorrent video data type', type
  19                 self.type = type
  20                 self.width = vw
  21                 self.height = vh
  22                 #
  23                 # Open dummy window
  24                 #
  25                 gl.foreground()
  26                 gl.noport()
  27                 self.wid = gl.winopen('DisplayVideoIn')
  28
  29                 self.x0 = 0
  30                 self.x1 = self.x0 + self.width - 1
  31                 self.y0 = 0
  32                 self.y1 = self.y0 + self.height - 1
  33                 # Compute # full lines per packet
  34                 self.lpp = pktmax / self.linewidth()
  35                 if self.lpp <= 0:
  36                         raise 'No lines in packet', self.linewidth()
  37                 self.pktsize = self.lpp*self.linewidth()
  38                 self.data = None
  39                 self.old_data = None
  40                 self.dataoffset = 0
  41                 self.lpos = 0
  42                 self.hints = 0
  43
  44         # Change the size of the video being displayed.
  45
  46         def resizevideo(self, vw, vh):
  47                 self.width = vw
  48                 self.height = vh
  49                 self.x1 = self.x0 + self.width - 1
  50                 self.y1 = self.y0 + self.height - 1
  51
  52         def positionvideo(self, x, y):
  53                 self.x0 = x
  54                 self.y0 = y
  55                 self.x1 = self.x0 + self.width - 1
  56                 self.y1 = self.y0 + self.height - 1
  57
  58         # Remove an instance.
  59         # This turns off continuous capture.
  60
  61         def close(self):
  62                 gl.winclose(self.wid)
  63
  64         # Get the length in bytes of a video line
  65         def linewidth(self):
  66                 return self.width*4
  67
  68         # Get the next video packet.
  69         # This returns (lpos, data) where:
  70         # - lpos is the line position
  71         # - data is a piece of data
  72         # The dimensions of data are:
  73         # - pixel depth = 1 byte
  74         # - scan line width = self.width (the vw argument to __init__())
  75         # - number of scan lines = self.lpp (PKTMAX / vw)
  76
  77         def getnextpacket(self):
  78                 if not self.data or self.dataoffset >= len(self.data):
  79                         self.old_data = self.data
  80                         self.data = gl.readdisplay(self.x0, self.y0, \
  81                                   self.x1, self.y1, self.hints)
  82                         self.dataoffset = 0
  83                         self.lpos = 0
  84                 data = self.data[self.dataoffset:self.dataoffset+self.pktsize]
  85                 while self.old_data and \
  86                           self.dataoffset+self.pktsize < len(self.data):
  87                         odata = self.old_data[self.dataoffset: \
  88                                   self.dataoffset+self.pktsize]
  89                         if odata <> data:
  90                                 break
  91                         print 'skip', self.lpos
  92                         self.lpos = self.lpos + self.lpp
  93                         self.dataoffset = self.dataoffset + self.pktsize
  94                         data = self.data[self.dataoffset:\
  95                                   self.dataoffset+self.pktsize]
  96                 lpos = self.lpos
  97                 self.dataoffset = self.dataoffset + self.pktsize
  98                 self.lpos = self.lpos + self.lpp
  99                 return lpos, data