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""" Implements a fast replacement for calling DrawLines with an array as an
argument. It uses weave, so you'll need that installed.
Copyright: Space Telescope Science Institute
License: BSD Style
Designed by: Enthought, Inc.
Author: Eric Jones eric@enthought.com
I wrote this because I was seeing very bad performance for DrawLines when
called with a large number of points -- 5000-30000. Now, I have found the
performance is sometimes OK, and sometimes very poor. Drawing to a
MemoryDC seems to be worse than drawing to the screen. My first cut of the
routine just called PolyLine directly, but I got lousy performance for this
also. After noticing the slowdown as the array length grew was much worse
than linear, I tried the following "chunking" algorithm. It is much more
efficient (sometimes by 2 orders of magnitude, but usually only a factor
of 3). There is a slight drawback in that it will draw end caps for each
chunk of the array which is not strictly correct. I don't imagine this is
a major issue, but remains an open issue.
"""
import weave
from RandomArray import *
from Numeric import *
from wxPython.wx import *
"""
const int n_pts = _Nline[0];
const int bunch_size = 100;
const int bunches = n_pts / bunch_size;
const int left_over = n_pts % bunch_size;
for (int i = 0; i < bunches; i++)
{
Polyline(hdc,(POINT*)p_data,bunch_size);
p_data += bunch_size*2; //*2 for two longs per point
}
Polyline(hdc,(POINT*)p_data,left_over);
"""
def polyline(dc,line,xoffset=0,yoffset=0):
#------------------------------------------------------------------------
# Make sure the array is the correct size/shape
#------------------------------------------------------------------------
shp = line.shape
assert(len(shp)==2 and shp[1] == 2)
#------------------------------------------------------------------------
# Offset data if necessary
#------------------------------------------------------------------------
if xoffset or yoffset:
line = line + array((xoffset,yoffset),line.typecode())
#------------------------------------------------------------------------
# Define the win32 version of the function
#------------------------------------------------------------------------
if sys.platform == 'win32':
# win32 requires int type for lines.
if (line.typecode() != Int or not line.iscontiguous()):
line = line.astype(Int)
code = """
HDC hdc = (HDC) dc->GetHDC();
Polyline(hdc,(POINT*)line,Nline[0]);
"""
else:
if (line.typecode() != UInt16 or
not line.iscontiguous()):
line = line.astype(UInt16)
code = """
GdkWindow* win = dc->m_window;
GdkGC* pen = dc->m_penGC;
gdk_draw_lines(win,pen,(GdkPoint*)line,Nline[0]);
"""
weave.inline(code,['dc','line'])
#------------------------------------------------------------------------
# Find the maximum and minimum points in the drawing list and add
# them to the bounding box.
#------------------------------------------------------------------------
max_pt = maximum.reduce(line,0)
min_pt = minimum.reduce(line,0)
dc.CalcBoundingBox(max_pt[0],max_pt[1])
dc.CalcBoundingBox(min_pt[0],min_pt[1])
#-----------------------------------------------------------------------------
# Define a new version of DrawLines that calls the optimized
# version for Numeric arrays when appropriate.
#-----------------------------------------------------------------------------
def NewDrawLines(dc,line):
"""
"""
if (type(line) is ArrayType):
polyline(dc,line)
else:
dc.DrawLines(line)
#-----------------------------------------------------------------------------
# And attach our new method to the wxPaintDC class
# !! We have disabled it and called polyline directly in this example
# !! to get timing comparison between the old and new way.
#-----------------------------------------------------------------------------
#wxPaintDC.DrawLines = NewDrawLines
if __name__ == '__main__':
from wxPython.wx import *
import time
class Canvas(wxWindow):
def __init__(self, parent, id = -1, size = wxDefaultSize):
wxWindow.__init__(self, parent, id, wxPoint(0, 0), size,
wxSUNKEN_BORDER | wxWANTS_CHARS)
self.calc_points()
EVT_PAINT(self, self.OnPaint)
EVT_SIZE(self, self.OnSize)
def calc_points(self):
w,h = self.GetSizeTuple()
#x = randint(0+50, w-50, self.point_count)
#y = randint(0+50, h-50, len(x))
x = arange(0,w,typecode=Int32)
y = h/2.*sin(x*2*pi/w)+h/2.
y = y.astype(Int32)
self.points = concatenate((x[:,NewAxis],y[:,NewAxis]),-1)
def OnSize(self,event):
self.calc_points()
self.Refresh()
def OnPaint(self,event):
w,h = self.GetSizeTuple()
print len(self.points)
dc = wxPaintDC(self)
dc.BeginDrawing()
# This first call is slow because your either compiling (very slow)
# or loading a DLL (kinda slow)
# Resize the window to get a more realistic timing.
pt_copy = self.points.copy()
t1 = time.clock()
offset = array((1,0))
mod = array((w,0))
x = pt_copy[:,0];
ang = 2*pi/w;
size = 1
red_pen = wxPen('red',size)
white_pen = wxPen('white',size)
blue_pen = wxPen('blue',size)
pens = iter([red_pen,white_pen,blue_pen])
phase = 10
for i in range(1500):
if phase > 2*pi:
phase = 0
try:
pen = pens.next()
except:
pens = iter([red_pen,white_pen,blue_pen])
pen = pens.next()
dc.SetPen(pen)
polyline(dc,pt_copy)
next_y = (h/2.*sin(x*ang-phase)+h/2.).astype(Int32)
pt_copy[:,1] = next_y
phase += ang
t2 = time.clock()
print 'Weave Polyline:', t2-t1
t1 = time.clock()
pt_copy = self.points.copy()
pens = iter([red_pen,white_pen,blue_pen])
phase = 10
for i in range(1500):
if phase > 2*pi:
phase = 0
try:
pen = pens.next()
except:
pens = iter([red_pen,white_pen,blue_pen])
pen = pens.next()
dc.SetPen(pen)
dc.DrawLines(pt_copy)
next_y = (h/2.*sin(x*ang-phase)+h/2.).astype(Int32)
pt_copy[:,1] = next_y
phase += ang
t2 = time.clock()
dc.SetPen(red_pen)
print 'wxPython DrawLines:', t2-t1
dc.EndDrawing()
class CanvasWindow(wxFrame):
def __init__(self, id=-1, title='Canvas',size=(500,500)):
parent = NULL
wxFrame.__init__(self, parent,id,title, size=size)
self.canvas = Canvas(self)
self.Show(1)
class MyApp(wxApp):
def OnInit(self):
frame = CanvasWindow(title="Speed Examples",size=(500,500))
frame.Show(true)
return true
app = MyApp(0)
app.MainLoop()
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