Hi guys,
I'm here to share with you the script I created in order to achieve
the falling snow effect: I hope you enjoy it.
#!/usr/bin/python
# -*- coding: utf-8 -*-
"""Show of how to create a full-screen transparent window used to reproduce
the effect of objects falling over your desktop.
"""
from __future__ import division
import sys
from math import sin
from random import random
import cairo
import gobject
import gtk
from gtk import gdk
class OverlayWindow(object):
"""Full-screen transparent window.
"""
def __init__(self, symbol, color, nelem):
"""Constructor.
Other than create a window to draw things, we have to generate a list
of objects (3d-coordinates).
Keywords:
symbol symbol displayed on screen.
color color of the symbol.
nelem number of elements to display.
"""
self.symbol = symbol
self.color = map(lambda v: int(v, 16) / 255,
[color[:2], color[2:4], color[4:6]])
self.bin = [[3 * random() - 1.5, 2 * random() - 1, 2 * random()]
for _ in xrange(nelem)]
self.time = 0L
screen = gdk.screen_get_default()
# Create off-screen contexts.
width, height = screen.get_width(), screen.get_height()
ratio = width / height
self.surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
self.context = cairo.Context(self.surface)
self.context.scale(width * 0.5 / ratio, height / 2)
self.context.translate(ratio, 1)
# Create a full-screen window specifying we are entirely responsible
# for drawing the background of the widget.
win = gtk.Window()
win.set_app_paintable(True)
#win.fullscreen()
# Let's try to use a colormap supporting transparency
colormap = screen.get_rgba_colormap()
if colormap:
win.set_colormap(colormap)
win.connect('delete-event', gtk.main_quit)
win.connect('expose-event', self.expose_cb)
win.show()
gobject.timeout_add(66, self.refresh, win)
def expose_cb(self, widget, event):
"""Output the content of the ImageSurface on the window context.
"""
context = widget.window.cairo_create()
# clip the context in order to display only the exposed area
context.rectangle(event.area.x, event.area.y,
event.area.width, event.area.height)
context.clip()
# make the background transparent
context.set_operator(cairo.OPERATOR_SOURCE)
context.set_source_rgba(0, 0, 0, 0)
# paint the content of the off-screen surface
#context.set_source_surface(self.surface)
context.paint()
return False
def refresh(self, widget):
"""Draw things over the off-screen context, and queue a redraw.
"""
width, height = widget.window.get_size()
self.draw(self.context)
widget.queue_draw()
return True
def draw(self, context):
"""Draw the objects over the window.
The movement of each objects follows a sinusoidal behavior based on the
time variable.
Keywords:
context context used to draw.
"""
symbol = self.symbol
time = self.time
context.set_operator(cairo.OPERATOR_SOURCE)
context.set_source_rgba(0, 0, 0, 0)
context.paint()
context.set_operator(cairo.OPERATOR_OVER)
for (i, item) in enumerate(self.bin):
x, y, z = item
x1 = (x + .1 * sin(time + i / 10)) / z
y1 = y / z
font_size = .05 / z
x_bearing, y_bearing, width, height = \
context.text_extents(symbol)[:4]
context.move_to(x1 - width / 2 - x_bearing,
y1 - height / 2 - y_bearing)
r, g, b = map(lambda v: v / (z + 1), self.color)
context.set_source_rgb(r, g, b)
context.set_font_size(font_size)
context.save()
context.rotate(time + i / 10)
context.show_text(symbol)
context.restore()
y = -1 if y1 > 1 else y + 0.005
item[1] = y
self.time += 0.05
def main():
overlay = OverlayWindow('❄', '99CCFF', 200)
gtk.main()
if __name__ == '__main__':
main()
Regards,
Matteo
On Sun, Dec 27, 2009 at 8:10 PM, Matteo Landi wrote:
> Thanks for the hint.
>
> On Sun, Dec 27, 2009 at 6:41 PM, Liam R E Quin wrote:
>> On Sun, 2009-12-27 at 16:27 +0100, Matteo Landi wrote:
>>> Hi all,
>>> for fun I'm trying to reproduce snowflakes falling down on my
>>> fullscreen gtk app.
>>
>> I'd say look at "xsnow" if it's still around.
>>
>> Liam
>>
>>
>> --
>> Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
>> Pictures from old books: http://fromoldbooks.org/
>> Ankh: irc.sorcery.net irc.gnome.org www.advogato.org
