Graphical Python Programming part 2: Write Your Own Screensaver - page 2
See the complete program on page 4
Colors in PyGTK, you may remember from the last article, can be specified either as color names or as Red, Green and Blue hues between 0 and 65535. You can vary your red, green and blue shades gradually, just the same way you did with the line positions. First initialize them:
r = random.randint(0, 65535) g = random.randint(0, 65535) b = random.randint(0, 65535) colorjump = 2048
Then inside the loop:
r = clip(r + random.randint(-colorjump, colorjump), 0, 65535) g = clip(g + random.randint(-colorjump, colorjump), 0, 65535) b = clip(b + random.randint(-colorjump, colorjump), 0, 65535) xgc.set_rgb_fg_color(gtk.gdk.Color(r, g, b))
If I also increase the number of steps in the loop to 500, I get something that looks like Figure 4.
Not bad! But wouldn't it be more fun if it just kept running and changing colors forever, like a screensaver?
Other Stories on LinuxPlanet
That gets a little trickier. Up to now, all the work has been done in the program's expose handler. But while the expose handler is running, the program can't be doing anything else -- like watching for clicks on the Quit button. It might not even have time to draw the screen. So you can't put a long loop, let alone one that will run forever, in handle_expose.
What's the solution? It's called an idle handler.
Solid state disks (SSDs) made a splash in consumer technology, and now the technology has its eyes on the enterprise storage market. Download this eBook to see what SSDs can do for your infrastructure and review the pros and cons of this potentially game-changing storage technology.
- 1Linux Top 3: CoreOS, Oracle Enterprise Linux 7 and Ubuntu 14.10
- 2Linux Top 3: Debian Dumps SPARC, Ubuntu Takes Over Linux 3.13 and the Core Infrastructure Initiative
- 3Linux Top 3: Fedora, Ubuntu and Gluster Lose Community Leaders
- 4Red Hat Enterprise Linux 7 Finally Hits the Big Time
- 5Linux Top 3: Tails 1.0, OpenMandriva Lx 2014.0 and Debian 7.5