Innovative Interfaces with Clutter
Listing 3. Clutter Rotating a Video
import clutter import gst from clutter import cluttergst class HelloWorld: def __init__ (self): self.stage = clutter.Stage() self.stage.set_color(clutter.color_parse('Black')) self.stage.set_size(500, 400) self.stage.set_title('Clutter 3-D Video Player') # Setup video. video_tex = cluttergst.VideoTexture() self.pipeline = gst.Pipeline("mypipe") playbin = video_tex.get_playbin() movfile = "file:///home/user/Videos/Video.mov" playbin.set_property('uri', movfile) self.pipeline.add(playbin) video_tex.set_position(90,80) self.stage.add(video_tex) self.pipeline.set_state(gst.STATE_PLAYING) # Create timeline that lasts for 100 frames # at ten frames per second. timeline = clutter.Timeline(100, 10) # Set timeline to loop forever. timeline.set_loop(True) # Create an alpha. alpha = clutter.Alpha(timeline, clutter.smoothstep_dec_func) # Set up rotation. Rotation = clutter.BehaviourRotate( axis=clutter.Y_AXIS, direction=clutter.ROTATE_CW, angle_start=0, angle_end=360, alpha=alpha) Rotation.set_center(160, 160, 0) Rotation.apply(video_tex) # Start it all up. timeline.start() self.stage.show_all() clutter.main() # Run program. main = HelloWorld()
The Alpha Functions
At first, especially to those who've forgotten their Calculus and Algebra, the alpha functions may seem unpredictable or confusing. There is a large list of the number of available functions: exp_dec_func, exp_inc_func, ramp_dec_func, ramp_func, ramp_inc_func, sine_dec_func, sine_func, sine_half_func, sine_inc_func, smoothstep_dec_func, smoothstep_inc_func and square_func. Here's a brief explanation of each type:
Exponential functions: depending on whether you're using a decaying function or an increasing function, exponential functions make the animation speed up or slow down at an exponential rate.
Ramp functions: ramp functions animate at a constant speed. However, the full ramp function animates at both a negative and a positive constant speed by switching directions.
Sine functions: sine functions make the animation reverse. Like the graph of a sine function, the animation would speed up, slow down, change directions, speed up in the reverse direction, and then slow down again.
Smooth step functions: the smooth step function works logistically. It starts slowly, then quickly increases and finally slows down toward the end of the animation.
Square functions: square functions follow a step pattern, which results in quick changes between two constant animation speeds.
Hopefully, you've learned a good deal about how Clutter works, and you can start developing and programming using the Clutter API. Using just the features you've seen here, you'll be able to create any interface that uses text, buttons, images and video with Clutter. Of course, after learning the basics, the more advanced UI elements will become easier to understand and work with.
In the future, the Clutter developers will continue to improve and update the API, and many new improvements are expected in the Clutter 1.0 release. You can learn more about the Clutter development process from the Web site (see Resources). Clutter is going to power many innovative open-source applications in the future.
Alex Crits-Christoph has been working with Linux for some time now. He enjoys developing and designing open-source graphical user interfaces.
Practical Task Scheduling Deployment
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
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- Stunnel Security for Oracle
- The Firebird Project's Firebird Relational Database
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- SUSE LLC's SUSE Manager
- Managing Linux Using Puppet
- My +1 Sword of Productivity
- Non-Linux FOSS: Caffeine!
- Doing for User Space What We Did for Kernel Space
- Google's SwiftShader Released
- SuperTuxKart 0.9.2 Released
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide