Bharathi Subramanian

Just in case, if you touchscreen failed, here is few key sequencs:

input keyevent 82 -- Menu (also help to unlock the screen)

input keyevent 4 -- Back

One more nice write-up from Dianne Hackborn about the Scheduling of task in Android System.

Recently Android Core Developer Dianne Hackborn explained about some of myth and reality of the GPU usage in Android Graphics System. I also in the assumption that, GPU is the only way to increase the rendering speed. But this explanation shows, that is not 100% correct :-)

• Android has always used some hardware accelerated drawing. Since before 1.0 all window compositing to the display has been done with hardware.

• This means that many of the animations you see have always been hardware accelerated: menus being shown, sliding the notification shade, transitions between activities, pop-ups and dialogs showing and hiding, etc.

• Android did historically use software to render the contents of each window. For example in a UI like

• Looking at drawing inside of a window, you don’t necessarily need to do this in hardware to achieve full 60fps rendering. This depends very much on the number of pixels in your display and the speed of your CPU. For example, Nexus S has no trouble doing 60fps rendering of all the normal stuff you see in the Android UI like scrolling lists on its 800x480 screen. The original Droid however struggled with a similar screen resolution.

• "Full" hardware accelerated drawing within a window was added in Android 3.0. The implementation in Android 4.0 is not any more full than in 3.0. Starting with 3.0, if you set the flag in your app saying that hardware accelerated drawing is allowed, then all drawing to the application’s windows will be done with the GPU. The main change in this regard in Android 4.0 is that now apps that are explicitly targeting 4.0 or higher will have acceleration enabled by default rather than having to put android:handwareAccelerated="true" in their manifest. (And the reason this isn’t just turned on for all existing applications is that some types of drawing operations can’t be supported well in hardware and it also impacts the behavior when an application asks to have a part of its UI updated. Forcing hardware accelerated drawing upon existing apps will break a significant number of them, from subtly to significantly.)

• Hardware accelerated drawing is not all full of win. For example on the PVR drivers of devices like the Nexus S and Galaxy Nexus, simply starting to use OpenGL in a process eats about 8MB of RAM. Given that our process overhead is about 2MB, this is pretty huge. That RAM takes away from other things, such as the number of background processes that can be kept running, potentially slowing down things like app switching.

• Because of the overhead of OpenGL, one may very well not want to use it for drawing. For example some of the work we are doing to make Android 4.0 run well on the Nexus S has involved turning off hardware accelerated drawing in parts of the UI so we don’t lose 8MB of RAM in the system process, another 8MB in the phone process, another 8MB in the system UI process, etc. Trust me, you won’t notice -- there is just no benefit on that device in using OpenGL to draw something like the status bar, even with fancy animations going on in there.

• Hardware accelerated drawing is not a magical silver bullet to butter-smooth UI. There are many different efforts that have been going on towards this, such as improved scheduling of foreground vs. background threads in 1.6, rewriting the input system in 2.3, strict mode, concurrent garbage collection, loaders, etc. If you want to achieve 60fps, you have 20 milliseconds to handle each frame. This is not a lot of time. Just touching the flash storage system in the thread that is running the UI can in some cases introduce a delay that puts you out of that timing window, especially if you are writing to storage.

• A recent example of the kinds of interesting things that impact UI smoothness: we noticed that ICS on Nexus S was actually less smooth when scrolling through lists than it was on Gingerbread. It turned out that the reason for this was due to subtle changes in timing, so that sometimes in ICS as the app was retrieving touch events and drawing the screen, it would go to get the next event slightly before it was ready, causing it to visibly miss a frame while tracking the finger even though it was drawing the screen at a solid 60fps.

• When people have historically compared web browser scrolling between Android and iOS, most of the differences they are seeing are not due to hardware accelerated drawing. Originally Android went a different route for its web page rendering and made different compromises: the web page is turned in to a display list, which is continually rendered to the screen, instead of using tiles. This has the benefit that scrolling and zooming never have artifacts of tiles that haven’t yet been drawn. Its downside is that as the graphics on the web page get more complicated to draw the frame rate goes down. As of Android 3.0, the browser now uses tiles, so it can maintain a consistent frame rate as you scroll or zoom, with the negative of having artifacts when newly needed tiles can’t be rendered quickly enough. The tiles themselves are rendered in software, which I believe is the case for iOS as well. (And this tile-based approach could be used prior to 3.0 without hardware accelerated drawing; as mentioned previously, the Nexus S CPU can easily draw the tiles to the window at 60fps.)

• Hardware accleration does not magically make drawing performance problems disappear. There is still a limit to how much the GPU can do. A recent interesting example of this is tablets built with Tegra 2 -- that GPU can touch every pixel of a 1024x800 screen about 2.5 times at 60fps. Now consider the Android 3.0 tablet home screen where you are switching to the all apps list: you need to draw the background (1x all pixels), then the layer of shortcuts and widgets (let’s be nice and say this is .5x all pixels), then the black background of all apps (1x all pixels), and the icons and labels of all apps (.5x all pixels). We’ve already blown our per-pixel budget, and we haven’t even composited the separate windows to the final display yet. To get 60fps animation, Android 3.0 and later use a number of tricks. A big one is that it tries to put all windows into overlays instead of having to copy them to the framebuffer with the GPU. In the case here even with that we are still over-budget, but we have another trick: because the wallpaper on Android is in a separate window, we can make this window larger than the screen to hold the entire bitmap. Now, as you scroll, the movement of the background doesn’t require any drawing, just moving its window... and because this window is in an overlay, it doesn’t even need to be composited to the screen with the GPU.

• As device screen resolution goes up, achieving a 60fps UI is closely related to GPU speed and especially the GPU’s memory bus bandwidth. In fact, if you want to get an idea of the performance of a piece of hardware, always pay close attention to the memory bus bandwidth. There are plenty of times where the CPU (especially with those wonderful NEON instructions) can go a lot faster than the memory bus.

Related Links:

Skia (2D Graphics Library)

Few days back, we are trying to emulate the slow speed connection to test our iPhone Application behavior. Unlike Android Emulator, the iPhone Simulator does not have an in-build option to enforce the speed. Many suggest to go for iPhone device. But I felt, this is not something that, I am only under going and someone might be having some solution for it.

After few search, I found SpeedLimit, the Leopard preference pane to regulate the speed. It is very useful for iPhone testing and it has few default connection profiles like Dial-Up, Edge, ..

Today, Google Android Team released the source of the latest Ice Cream Sandwich OR Android 4.0. After Ginger bread, the source of HoneyComb is not released to public stating that, HoneyComb is a quick fix to Ginger Bread to work on Tablet. And Google assured that, ICS source will be released as an open source. Good to see Google did it.

The binary driver for different platforms supported by default in the source can found in the following link: http://code.google.com/intl/zh-CN/android/nexus/drivers.html

Google DevFest 2011 @ Singapore is announced. It will be on Sat 12th Nov 2011 @ Grand Hyatt, 10 Scotts Road, Singapore. This time major focus on following topics:

• Google Plus
• Android Market
• HTML5
• Google App Engine

Register Here

; John McCarthy Died on 24/10/2011
(print "Goodbye John McCarthy")

I am not a regular user of LISP. But due to the influence of my guide Prof TAG, occasionally used LISP with Emacs for processing the source code.

After Nokia took over the Trolltech, there are some doubt/hesitation among FOSS developer in contributing to Qt and this is started increasing after Nokia + Microsoft deal. On today, Nokia announced that, the Qt will continue to be an Open Source Project and there won't any difference in accessing the latest development of Qt in-between the Nokia developer and external developer. It is very good move.

Qt Project Announcement from Qt Labs

Qt Project Site

The sad part is, Nokia and Intel moving away from maemo, in favor of Tizen. So we need to wait and watch to know, in future, how Qt will used in Mobile platforms.

Today, Google released the next version of the Android Platform for developer access. In this release, the Android Team merged the UI part of the tablet and mobile to provide unified user experience. Some of the new features:

• Unified UI toolkit: A single set of UI components, styles, and capabilities for phones, tablets, and other devices.
• Rich communication and sharing: New social and calendar APIs, Android Beam for NFC-based instant sharing, Wi-Fi Direct support, Bluetooth Health Device Profile support.
• Deep interactivity and customization: Improved notifications, lockscreen with camera and music controls, and improved app management in the launcher.
• New graphics, camera, and media capabilities: Image and video effects, precise camera metering and face detection, new media codecs and containers.
• Interface and input: Hardware-accelerated 2D drawing, new grid-based layout, improved soft keyboard, spell-checker API, stylus input support, and better mouse support.
• Improved accessibility: New accessibility APIs and text-to-speech APIs for writing new engines.
• Enhancements for enterprise: Keychain and VPN APIs for managing credentials and connections, a new administrator policy for disabling the camera.

To install the new Ice Cream Sandwitch image, SDK Tooks and ADT Plug-in must upgraded to latest version. Just upgraded and installed the new SDK, complete change in the SDK Manager UI, Emulator supports in-built laptop camera, UI looking nice, more control for developer and lot of improvement in applications.

NOTE: By default, the USB debugging is disabled in the in emulator. You have enable this, to make it accessible thru ADB or from Eclipse IDE.

Hope, unlike Honeycomb, this version source code will be released as the old versions. Waiting ... :)

Good Bye DMR and Thanks for all your contributions and perticularly for the C and Unix.