Humor4u

All of the videos have been posted from the various sessions I was in this year. Here they are, along with links to the slides. What's new in Android A presentation with  +Dan Sandler  that provides a quick overview of some of the larger features and new APIs in the L Developer Preview release and other new bits in the recent Androidosphere. There's also a really good deep-dive into Notifications, since Dan's the non-local expert on the subject. Slides (PDF) Material science This session, presented with  +Adam Powell , provides an overview of the engineering side of the Material design system. Many of the other sessions at Google I/O this year discussed the design side; this presentation covers the technical details of the APIs and the capabilities exposed by the framework for Android developers. Slides (PDF) Material witness I was happy to be joined once again by former Android developer and UI Toolkit team lead  +Romain Guy  for this talk on some of the new Ma...

Since we just released Android 4.3 yesterday, I thought I'd wax poetic about one of the features I worked on in the release: Overlays. Android devs Come out to play: Use the new ViewOverlay. There are many ways to get custom graphics (drawables) to appear in a view. You can set a background drawable if that's what you want, or you can use an ImageView, or you can create a custom View subclass and override onDraw(). Or if you want to draw them over the children in a layout, you can override the layout and override dispatchDraw() to draw them after all of the children (after a call to super.dispatchDraw()). But sometimes you just want something simpler: ViewOverlay . Here's how it works: You call View.getOverlay() , which returns a ViewOverlay object. Then you call add(Drawable) on that overlay object... and that's it. You can also call remove(Drawable) to get rid of the drawable or clear() to get rid of everything in the overlay, but that's the entire API. The only o...

Romain Guy and I gave two talks at Google I/O yesterday which are now live on YouTube: Android Graphics Performance: http://www.youtube.com/watch?v=vQZFaec9NpA Slides for Android Graphics Performance are posted on Romain's blog . A Moving Experience: http://www.youtube.com/watch?v=ihzZrS69i_s A Moving Experience Slides: Keynote PDF PDF with speaker notes The code from the animation demos will be posted soon, probably in conjunction with future DevBytes episodes.

Simple uses of ValueAnimator, ObjectAnimator, and interpolators to control how a shape is moved around on the screen. Code:  http://developer.android.com/shareables/devbytes/Bouncer.zip Video:  https://www.youtube.com/watch?v=vCTcmPIKgpM

This example shows how to speed up bitmap loading and reduce garbage collection by reusing existing bitmaps. Note that the reused bitmap must be mutable and of the same size and configuration as the bitmap you load into it. Not sure if this is clear from the video, although it is documented in the API. Code: http://developer.android.com/shareables/devbytes/BitmapAllocation.zip Video: http://www.youtube.com/watch?v=rsQet4nBVi8

This example shows how the use of BitmapOptions affects the resulting size of a loaded bitmap. Sub-sampling can speed up load times and reduce the need for large bitmaps in memory if your target bitmap size is much smaller, although it's good to understand that you can't get specific Bitmap sizes, but rather power-of-two reductions in sizes. Code: http://developer.android.com/shareables/devbytes/BitmapScaling.zip Video: http://www.youtube.com/watch?v=12cB7gnL6po

The Android team has just rolled out the first four shows in a new series called DevBytes, which is intended to be very short, focused tutorials on specific developer topics. A quick explanation, maybe a demo, and a few lines of code to walk through and it's done. Taking a break from work? Want to learn something new? Or just wonder how a specific piece of technology works on the platform? Tune into one of the DevBytes episodes to get a quick deep dive into that exact topic (well, assuming we've done a show on that topic. Maybe we could interest you in one of the shows that we've actually filmed yet instead?) The first few of these feature ... me! (Surprise, surprise!) I'll be doing many of these tutorials over time, especially in the areas of animation, graphics, and UI development, starting with this first set: ViewAnimations : This show covers the basics of creating and running pre-3.0 Animations on View objects. PropertyAnimations : This show parallels the ViewAnima...

(This tip and anecdote is specifically about Android, but the same technique applies to every platform I've ever worked on , which at this point is quite a few. In fact, it's a technique that Romain and I have stressed in our book and in most graphics/GUI talks that we've given over the years, such as this one from Devoxx in 2008 ) . I was debugging an application recently (names withheld to protect the completely and utterly guilty) and discovered that the source of a serious performance bottleneck was simply the size of the bitmaps involved. The application's job is to display lots of pictures, so using bitmaps is a given. And the size of the bitmaps being loaded and displayed is signficant, so there were going to be issues around memory and performance anyway. But it was the way in which the application was treating the source and destination sizes that was at the root of the problem. In particular, the application was loading each image into a bitmap of size X x Y...

The videos and slides are now posted for the presentations that I did with Romain Guy at Google I/O a couple of weeks ago. What's New in Android : A developer's overview of some of the new features available in Android 4.1 Jelly Bean, including a deep dive into the enhanced Notifications capabilities (this part by Daniel Sandler, one of the engineers responsible). For Butter or Worse : A very geeky look into how hardware accelerated rendering works on Android, what we did to make things smoother and faster in the latest release, and what Android developers can do to make their applications faster and smoother as well. These videos were posted within a day of the talks, but the slides took a bit longer (possibly explained by the rush up to IO followed by everyone collapsing in fatuge when it was over). There are tons of other great talks from the conference that are posted as well, both in the Google Developers channel on YouTube and (with slides) on the IO site itself . Enjo...

The animation support added in Android 3.0 and enhanced since then is useful, allowing a flexible system of property animation to animate literally anything you want. Like a store going out of business: if it ain't nailed down, it's up for grabs. But that doesn't mean we're done yet; there are many things that we'd like to do to keep improving the animation system and making Android animations easier to write and more powerful. One of those things is curved motion. Right now, if you animate something between a start and end point, it will move in a straight line between those values. For example, a translation animation, where the object moves from one (x, y) location to another, will move in a straight line beween those points. You can (and should) use non-linear timing for these animations, and the animation framework uses ease-in/ease-out timing by default. But the actual spacial movement is linear; there is no way for you to specify a curved path for an object...

I'm starting to prepare presentations for the ~8 hours of talks that Romain and I are giving at Devoxx in a couple of weeks. "Preparing" generally entails mostly worrying, followed by a mad rush of writing slides and code at night, on the long flight, after beers, between talks, and sometimes during the talks. It's a busy time of year. I realized that the organizers of Devoxx had recently released all of the recorded talks from last year into the wild (read: they're free on parleys.com ), so it seemed worth linking to them in case anyone wanted to see what we had to say last time around. I'll give a plug for the conference and the Parleys site here. If there were an ad banner, it'd go here. Not because I'm paid (I would make a poor ad salesman, apparently), but because I think that both the conference and the parleys site rock. The organizers do a great job of putting it all together, and the recordings and presentation of the talks on parleys.com...

Here's a simple app that I wrote recently to see how background processing affects frame rate. There's nothing too complicated going on in the app, but it seemed worth publishing to show how to do various things in Android, such as: Using a single ValueAnimator (3.0+ API) to animate several objects independently Manipulating the transform of Canvas to move/rotate objects Using the GPU to provide faster rendering (3.0+ capability) Tracking the current frames per second performance Here's a video of the running application, captured using HDMI on a 3.1 tablet. You can see how the More, Less, and GPU controls affect what's going on in the app. Note that it starts out with no GPU acceleration and bogs down when we have lots of flakes on the screen. Then see how the frame rate improves once the GPU box is checked. The app is accelerated by default; non-GPU rendering is performed by setting a software layer on the view, which forces rendering to happen in software to a bitmap...

I've given some talks about Android graphics recently, and the same questions keep coming up: What is Renderscript appropriate for? Is it a replacement for OpenGL rendering? How do I access Renderscript from NDK code? When do I choose between the different rendering options? Can I have a free tablet? It seemed to me that a brief article might help. In particular, I wanted to write something that lays out the various rendering options that Android provides and describes how we envision developers using them (and how we use them ourselves in the applications that we ship) so that you might better understand how and when to use them in your applications. Of course you're not bound to what we think; if you come up with new ways to use what the platform provides, all the better. But we can at least provide a little guidance to help you navigate the myriad of options. Hopefully this article will help answer the questions above. Except for the last question about the free tablet - I c...

Here are slides for two of the approximately 871 talks that Romain Guy and I gave at Devoxx last month (and again at the SF Android User Group meeting a couple of days ago). Videos of all of the Devoxx sessions are already posted on the excellent Parleys site for a small subscription fee, and should be made freely available sometime in the next few months. You probably want to check out those videos for the complete details. But in case you were at the talks, are sick of listening to us speak, or simply want to peruse the slideware, here you go... Android Graphics and Animation Android UI Development: Tips, Tricks and Techniques