go on http://sourceforge.net/projects/pythoncad/ we strongly use it :-)
>----Messaggio originale---- >Da: [email protected] >Data: 21/12/2009 5.05 >A: "chuong nguyen vien"<[email protected]> >Cc: <[email protected]> >Ogg: Re: [pygtk] How drawing, Drawable, ....work in pygtk ! > >chuong nguyen vien <[email protected]>: >> Hello, >> >> I have just played with pygtk a couple of day and everything seems ok but the drawing system. I dont know how it works basically and got confused, very confused ! >> >> I read somewhere on the internet it say that i have to follow a pattern to make it work, and the key to that pattern is : we need to implement the drawing code within the expose event handler. Why ? >> >> I tried to make some drawing code outside the expose event handler, and didnt write a expose event handler at all. It didnt work. It just appear a window without anything, or my drawing stuff didnt display. >> >> So basically, how the expose event and drawing in GTK work or relate to each other ? >> >> Thanks >> >> Chuong > >Here's the canvas- management class I wrote for the GPSD test client. You >may be able to use it as a model. Note how (a) all the actual drawing >is done in the expose event, (b) redrawing is implemented with the >queue_draw() method, (c) the canvas's actual size allocation >is picked up for later use in the on_size_allocate event. > >class SkyView(gtk.DrawingArea): > "Satellite skyview, encapsulates pygtk's draw-on-expose behavior." > # See <http://faq.pygtk.org/index.py? req=show&file=faq18.008.htp> > HORIZON_PAD = 20 # How much whitespace to leave around horizon > SAT_RADIUS = 5 # Diameter of satellite circle > GPS_PRNMAX = 32 # above this number are SBAS satellites > def __init__ (self): > gtk.DrawingArea.__init__(self) > self.set_size_request (400, 400) > self.gc = None # initialized in realize-event handler > self.width = 0 # updated in size-allocate handler > self. height = 0 # updated in size-allocate handler > self.connect('size- allocate', self.on_size_allocate) > self.connect('expose-event', self. on_expose_event) > self.connect('realize', self.on_realize) > self.pangolayout = self.create_pango_layout("") > self. satellites = [] > > def on_realize(self, widget): > self.gc = widget. window.new_gc() > self.gc.set_line_attributes(1, gtk.gdk.LINE_SOLID, > gtk.gdk.CAP_ROUND, gtk.gdk.JOIN_ROUND) > > def on_size_allocate(self, widget, allocation): > self.width = allocation.width > self.height = allocation.height > self. diameter = min(self.width, self.height) - SkyView.HORIZON_PAD > > def set_color(self, spec): > "Set foreground color for drawing." > self.gc.set_rgb_fg_color(gtk.gdk.color_parse(spec)) > > def draw_circle (self, widget, x, y, diam, filled=False): > "Draw a circle centered on the specified midpoint." > widget.window.draw_arc(self.gc, filled, > x - diam / 2, y - diam / 2, > diam, diam, 0, 360 * 64) > > def draw_square (self, widget, x, y, diam, filled=False): > "Draw a square centered on the specified midpoint." > widget.window.draw_rectangle(self.gc, filled, > x - diam / 2, y - diam / 2, > diam, diam) > > def draw_string(self, widget, x, y, letter): > "Draw a letter on the skyview." > self. pangolayout.set_text(letter) > # FIXME: When the layout object can report its size, use it > self.window.draw_layout(self.gc, x-5, y-10, self.pangolayout) > > def pol2cart(self, az, el): > "Polar to Cartesian coordinates within the horizon circle." > az *= (math.pi/180) # Degrees to radians > # Exact spherical projection would be like this: > # el = sin((90.0 - el) * DEG_2_RAD); > el = ((90.0 - el) / 90.0); > xout = int ((self.width / 2) + math.sin(az) * el * (self.diameter / 2)) > yout = int((self. height / 2) - math.cos(az) * el * (self.diameter / 2)) > return (xout, yout) > > def on_expose_event(self, widget, event): > self.set_color ("white") > widget.window.draw_rectangle(self.gc, True, 0,0, self.width, self.height) > # The zenith marker > self.set_color("gray") > self.draw_circle(widget, self.width / 2, self.height / 2, 6) > # The circle corresponding to 45 degrees elevation. > # There are two ways we could plot this. Projecting the sphere > # on the display plane, the circle would have a diameter of > # sin(45) ~ 0.7. But the naive linear mapping, just splitting > # the horizon diameter in half, seems to work better visually. > self.draw_circle(widget, self.width / 2, self.height / 2, > int(self.diameter * 0.5)) > self.set_color("black") > # The horizon circle > self. draw_circle(widget, self.width / 2, self.height / 2, > self.diameter) > # The compass-point letters > (x, y) = self. pol2cart(0, 0) > self.draw_string(widget, x, y+10, "N") > (x, y) = self.pol2cart(90, 0) > self.draw_string(widget, x-10, y, "E") > (x, y) = self.pol2cart(180, 0) > self.draw_string(widget, x, y-10, "S") > (x, y) = self.pol2cart(270, 0) > self.draw_string(widget, x+10, y, "W") > # The satellites > for sat in self.satellites: > (x, y) = self.pol2cart(sat.azimuth, sat.elevation) > if sat.ss < 10: > self.set_color("Black") > elif sat.ss < 30: > self.set_color("Red") > elif sat.ss < 35: > self.set_color("Yellow"); > elif sat.ss < 40: > self.set_color("Green3"); > else: > self.set_color("Green1"); > if sat.PRN > SkyView.GPS_PRNMAX: > self.draw_square(widget, > x- SkyView.SAT_RADIUS, y-SkyView.SAT_RADIUS, > 2 * SkyView.SAT_RADIUS + 1, sat.used); > else: > self. draw_circle(widget, > x-SkyView.SAT_RADIUS, y- SkyView.SAT_RADIUS, > 2 * SkyView.SAT_RADIUS + 1, sat.used); > self.set_color("Black") > self.draw_string (widget, x, y+10, str(sat.PRN)) > def redraw(self, satellites): > "Redraw the skyview." > self.satellites = satellites > self. queue_draw() > > >-- > <a href="http://www.catb.org/~esr/";>Eric S. Raymond</a> >_______________________________________________ >pygtk mailing list [email protected] >http://www.daa.com.au/mailman/listinfo/pygtk >Read the PyGTK FAQ: http://faq.pygtk.org/ > _______________________________________________ pygtk mailing list [email protected] http://www.daa.com.au/mailman/listinfo/pygtk Read the PyGTK FAQ: http://faq.pygtk.org/
