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@jsbain jsbain/iosurface.py
Created Oct 24, 2018

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iosurface.py
from objc_util import *
from ctypes import *
from contextlib import contextmanager
import ui
import numpy as np
''' define ctypes signatures'''
IOSurfaceCreate=c.IOSurfaceCreate
IOSurfaceCreate.argtypes=[c_void_p]
IOSurfaceCreate.restype=c_void_p
IOSurfaceGetBaseAddress=c.IOSurfaceGetBaseAddress
IOSurfaceGetBaseAddress.argtypes=[c_void_p]
IOSurfaceGetBaseAddress.restype=c_void_p
IOSurfaceGetBytesPerRow=c.IOSurfaceGetBytesPerRow
IOSurfaceGetBytesPerRow.argtypes=[c_void_p]
IOSurfaceGetBytesPerRow.restype=c_size_t
IOSurfaceGetPlaneCount=c.IOSurfaceGetPlaneCount
IOSurfaceGetPlaneCount.argtypes=[c_void_p]
IOSurfaceGetPlaneCount.restype=c_size_t
IOSurfaceLock=c.IOSurfaceLock
IOSurfaceLock.argtypes=[c_void_p, c_uint32, POINTER(c_uint32) ]
IOSurfaceLock.restype=c_int
IOSurfaceUnlock=c.IOSurfaceUnlock
IOSurfaceUnlock.argtypes=[c_void_p, c_uint32, POINTER(c_uint32) ]
IOSurfaceUnlock.restype=c_int
IOSurfaceGetPixelFormat=c.IOSurfaceGetPixelFormat
IOSurfaceGetPixelFormat.argtypes=[c_void_p]
IOSurfaceGetPixelFormat.restype=c_int32
kCVPixelFormat_32RGBA=int.from_bytes(b'RGBA', byteorder='big')
class IOSurfaceWrapper(object):
'''Wraps an IOSurface, exposing a numpy array and view.
.array=numpy array (hxwx4 channels)
.view = ui.View with display layer boind to .array contents
.Lock() context manager for updating array. use .Lock(True) to update, and .Lock(False) to delay redraw, with .redraw() to manually force render
s.Lock context manager must wrap all updates to array.
i.e:
# redraw when context manager exits:
with s.Lock(redraw=True):
s.arrray[...] #manipulate data
#delayed redraw,
with s.Lock(redraw=False):
s.arrray[...] #manipulate data
with s.Lock(redraw=False):
s.arrray[...] #manipulate data
s.redraw()
'''
def __init__(self, width=1024, height=768):
bpp=4 #bytes per pixel, one per color plus alpha
properties=ns(
{ObjCInstance(c_void_p.in_dll(c,'kIOSurfaceWidth')):width,
ObjCInstance(c_void_p.in_dll(c,'kIOSurfaceHeight')):height,
ObjCInstance(c_void_p.in_dll(c,'kIOSurfaceBytesPerElement')):bpp,
ObjCInstance(c_void_p.in_dll(c, 'kIOSurfacePixelFormat')) : kCVPixelFormat_32RGBA
})
self.height=height
self.width=width
self.surf=IOSurfaceCreate(ns(properties))
self.planecount = IOSurfaceGetPlaneCount(self.surf);
self.base = IOSurfaceGetBaseAddress(self.surf);
self.stride = IOSurfaceGetBytesPerRow(self.surf);
stridewidth=self.stride//bpp
data=cast(self.base, POINTER(c_uint8*bpp*(stridewidth)*(self.height)) ).contents
a=np.ctypeslib.as_array(data)
#handle the 'extra' columns.
self.array=a[0:self.height,0:self.width,:]
self.array[:,:,:]=255 #set to white, opaque
self.setupview()
@contextmanager
def Lock(self, redraw = True):
try:
IOSurfaceLock(self.surf, 0, None)
self.base = IOSurfaceGetBaseAddress(self.surf);
yield
finally:
IOSurfaceUnlock(self.surf, 0, None)
if redraw:
self.redraw()
def setupview(self):
self.view=ui.View(frame=(0,0,self.width,self.height))
self._layer=self.view.objc_instance.layer()
self._layer.contentsOpaque=0 #1 may be faster, if alpha channel not needed
self._layer.contentsFlipped=0 #set to 1 if needed
#bind IOSurface to the layer
self._layer.setContents_(c_void_p(self.surf))
@on_main_thread
def redraw(self):
self._layer.setContentsChanged()
def __del__(self):
self._layer.contents=None
del self.array
from objc_util import c, c_void_p
CFRelease=c.CFRelease
CFRelease.argtypes=[c_void_p]
CFRelease.restype=None
CFRelease(self.surf)
if __name__=='__main__':
s=IOSurfaceWrapper(256,256)
v=ui.View(frame=(0,0,s.width,s.height))
iv=ui.ImageView(frame=(0,0,s.width,s.height))
iv.image=ui.Image.named('test:Lenna')
v.add_subview(iv)
v.add_subview(s.view)
v.present('sheet')
#pre-allocate, because rand is slow
I=np.random.randint(255,size=(50,50,4))
N=200 #numframes
import time
t=time.perf_counter()
for i in range(N):
with s.Lock():
#blit I into place
x=np.random.randint(s.width-50)
y=np.random.randint(s.height-50)
s.array[y:(y+50),x:(x+50),0:4]=I
print('fps:',N/(time.perf_counter()-t))
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