As I mentioned before, getting zoom to work was pretty easy. Implementing panning/dragging was the hard part. The major issues I encountered and subsequently fixed were the following:

1. Panning continues indefinitely in all directions.
2. When you zoom and then pan, stop, and then start again, the view jerks to a new position instead of panning from the existing position.
3. Excessive panning towards the left and top can be constrained, but panning towards the right and bottom is not so easily constrained.

Once I fixed all the problems, I figured that it would be nice to document it for future reference, and I also think it would be a useful resource for others who have the same problem. Now a little disclaimer before I go any further: I’m not an Android expert and I’m really not that great with graphics; I just started it learning to program for Android this semester for one of my Masters electives. So there might be a better way of doing all this, and if there is, please let me know! Also, if you want to skip all the explanations and just see the code, you can skip to the last page.

Let’s start with the simple stuff first, that is implementing pinch-zoom. To implement pinch-zoom, we make use of the ScaleGestureDetector class. This class helps you detect the pinch-zoom event. Using it is pretty simple:

public class ZoomView extends View {

    private static float MIN_ZOOM = 1f;
    private static float MAX_ZOOM = 5f;

    private float scaleFactor = 1.f;
    private ScaleGestureDetector detector;

    public ZoomView(Context context) {
        super(context);
        detector = new ScaleGestureDetector(getContext(), new ScaleListener());
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        detector.onTouchEvent(event);
        return true;
    }

    @Override
    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        canvas.save();
        canvas.scale(scaleFactor, scaleFactor);

        // ...
        // your canvas-drawing code
        // ...

        canvas.restore();
    }

    private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
        @Override
        public boolean onScale(ScaleGestureDetector detector) {
            scaleFactor *= detector.getScaleFactor();
            scaleFactor = Math.max(MIN_ZOOM, Math.min(scaleFactor, MAX_ZOOM));
            invalidate();
            return true;
        }
    }
}

Your view class has four private members: MIN_ZOOM, MAX_ZOOM, detector, and scaleFactor. The first two are static constants that define the maximum and minimum zoom allowed. The third is of type ScaleGestureDetector and does all the heavy lifting as far as zooming is concerned. The fourth member holds the scaling factor i.e., a number that represents the amount of “zoom”.

Now what does this do?

In the constructor, you initialize the detector. The constructor to ScaleGestureDetector takes two parameters: the current context, and a listener. Our listener is defined inside the class ScaleListener which extends the abstract class ScaleGestureDetector.SimpleOnScaleGestureListener. Inside the onScale method, we get the current scale factor from the detector. We then check to see if it is greater or smaller than our upper and lower bounds. If so, we make sure that it we limit the value to be between those bounds. We then call invalidate() which forces the canvas to redraw itself.

The actual scaling happens inside the onDraw method. There, we save the canvas, set its scaling factor (which is the one we got from the detector), draw anything we need to draw, and then restore the canvas. What happens now is that anything you draw on the canvas is now scaled by the scaling factor. This is what gives you the “zoom” effect.

Also, I must bid farewell to a dear and old friend: my webserver enterprise. I set up my webserver almost 10 years ago (running FreeBSD of course), and she has been serving me faithfully for all this time. Over the years I’ve dealt with all kinds of disasters and I’ve been able to keep her running. However, after this latest disaster I’ve realized that I just don’t have the time to maintain and administer a server anymore; it’s hard to do with a full-time job and with a full-load at school (did I mention that I am doing my Masters?). Therefore, I’ve moved my site over to dreamhost. The cool thing is that they also offer shell access too, which in my opinion is absolutely indispensable. It took me a little while to migrate my WordPress installation over (I had to work out a few kinks), but now it looks like everything is running smoothly.

On that note, I’m looking forward to less server-administration and more blogging!

Helpful folks on XDA Developers have posted the datasheet to the eMMC and another kind soul (damnoregonian) was able to get the value of the CSD register (the register that seems to control the behavior of the MMC): d00f00320f5903fffffffdff924040c8.

WP_GRP_SIZE[36:32] and WP_GRP_ENABLE[31:31] seem to be the bits that control the write-protect (per the datasheet). Currently these seem to be set to the default values per the data sheet (11111b and 1b). Clearing the bits should (theoretically) turn off the write protection. The value to do that would be d00f00320f5903fffffffde0124040c8. The CSD node is R/O and so you cannot echo to it directly. The only way to do it would be to write a kernel module/driver that writes to the register. Apparently the kernel exports a function called mmc_send_csd, and so one should be able to write to this register.

I’m tempted to write a kernel module that does just that. But since working at Intel I haven’t written any kernel drivers. Also while I did write drivers at Intel, I pretty much made modifications to what others before me had written, and so I never wrote one from scratch. I’m going to see if I can start on something this weekend… wish I was still in college… I had a lot more time then!

If this works (and that’s a big if), there’s still the issue of restores being done while the phone is in operation. That could cause a lot of inconsistency. So this might be a partial solution.

Either way, I’m sure someone will come up with a way to root the phone. But if there’s nothing by next Friday, I’m going to return the phone.

UPDATE

Someone posted updated specs. It looks like those bits are read-only. Bummer. Also, this from T-Mobile’s website:

Bellevue, Wash. — Oct. 7, 2010

As pioneers in Android-powered mobile devices, T-Mobile and HTC strive to support innovation. The T-Mobile G2 is a powerful and highly customizable Android-powered smartphone, which customers can personalize and make their own, from the look of their home screen to adding their favorite applications and more.

The HTC software implementation on the G2 stores some components in read-only memory as a security measure to prevent key operating system software from becoming corrupted and rendering the device inoperable. There is a small subset of highly technical users who may want to modify and re-engineer their devices at the code level, known as “rooting,” but a side effect of HTC’s security measure is that these modifications are temporary and cannot be saved to permanent memory. As a result the original code is restored.

Well, T-Mobile. How about you provide us technical users a way to root our devices? What you’re doing is stupid. You’re going against everything Android stands for. If I can’t root it, I think I will return my phone and get a Vibrant instead. I would have expected this from Apple or Verizon. But not from you. Very disappointing.

• 3.7 inch WVGA capacitive touch screen
• 5 megapixel camera with auto-focus and flash
• Qualcomm MSM7230 800MHz processor
• 4GB ROM
• 512MB RAM
• GPS/aGPS
• WiFi
• Bluetooth
• Android 2.2
• Runs on T-Mobile’s 4G/HSPA+ network
• Slide-out keyboard

I was a little concerned about the 800Mhz clock-speed, but after doing some research it turns out that the phone more than makes up for it with better hardware acceleration. Either way, it’s not like I can’t overclock it .

For having a slideout keyboard, the phone is actually not very bulky. It also looks very slick and clean (no where near as bulky as the G1). I’ve been using the on-screen keyboard on the MyTouch for little over a year now and I have to say that I haven’t gotten used to it (I missed the physical keyboard on the G1). Even after a year of using it, my typing is still error-prone and not as fast. That’s why I was pretty excited about the slide-out keyboard on the G2. I tried typing on it and it doesn’t feel too bad. The keys seem to be slightly more widely spaced than is comfortable and so there might to be opportunities for fat-fingering. But I think it’s a matter of getting used to it.

I haven’t turned on the thing yet and so I don’t have any pictures of it turned on. I’m going to wait until they have some GhostArmor for it. Until then I’m keeping it safe in its box and I will be using my MyTouch. Apparently the G2 runs stock Android 2.2, so it shouldn’t be any different from any other devices that run stock Android 2.2 (like the Nexus One). Without further ado, here are some pictures (you can click on them to get a larger version):

The G2 in its box

The G2 and its box, side-by-side

Front of G2 - I

Front of G2 - II

Back of G2 - I

Back of G2 - II

G2 with keyboard exposed - I

G2 with keyboard exposed - II

Note: The white patches on the keyboard are not a defects; they are air bubbles under the protective plastic-cover

G2 and accessories - I (L-R: charger, USB cable, Stereo headset)

G2 and accessories - II (L-R: USB cable, Stereo headset, charger)

Download ShapeWriter APK

vivin@serenity ~/Projects/code
$ scp -r vivin@www.vivin.net:~/code/agnostic .
Password:
ps: Process environment requires procfs(5)
Initializing new SSH agent...

vivin@serenity ~/Projects/code
$

I fixed the procfs problem by adding the following to my /etc/fstab:

proc                    /proc           procfs  rw              0       0
linproc                 /compat/linux/proc      linprocfs       rw      0       0

and then running:

vivin@enterprise ~
$ sudo mount /compat/linux/proc

vivin@enterprise ~
$ sudo mount /proc

So I try to scp again and I get:

vivin@serenity ~/Projects/code
$ scp -r vivin@www.vivin.net:~/code/agnostic .
Password:
Initializing new SSH agent...

vivin@serenity ~/Projects/code
$

WTF? Then I remembered making some changes to my .bashrc to be able to commit to github:

function start_agent {
  echo "Initializing new SSH agent..."
  /usr/bin/ssh-agent | sed 's/^echo/#echo/' > "${SSH_ENV}"
  echo succeeded
  chmod 600 "${SSH_ENV}"
  . "${SSH_ENV}" > /dev/null
  /usr/bin/ssh-add;
}

# Source SSH settings, if applicable
if [ -f "${SSH_ENV}" ]; then
  . "${SSH_ENV}" > /dev/null
  #ps ${SSH_AGENT_PID} doesn't work under cywgin
  ps -ef | grep ${SSH_AGENT_PID} | grep ssh-agent$ > /dev/null || {
    start_agent;
  }
else
  start_agent;
fi

I pulled all that out of my .bashrc and made a separate shell script for it. After I did that, scp started working again. I had no idea that calling scp would actually run .bashrc

I was having a conversation with Sheehan over twitter and I made a comment that “Chrome OS is doing the kiosk thing all over again”. I guess that’s true to an extent. ChromeOS will be running on approved hardware with an SSD. You’re probably not going to be able to install anything on the machine and everything seems to be a webapp. What this means is that all your data is online. To be honest, I don’t find very much use for that, but then again, I’m not part of the target market. I think this might be useful for people who are on-the-go and who need access to their data from anywhere in the world (well, anywhere in the world with an internet connection). I use my machine for a variety of things; mainly development. Since I also like to tinker with it from time to time, I’m always installing stuff on it. Google will need a very strong marketing campaign so that consumers understand exactly what they’re getting. They won’t be able to install applications (maybe webapps?) and they won’t be able to save arbitrary files to the machine. I wonder what this means for the online experience. What if they’re trying to download some sort of file? Where would they save it? Would Google provide online storage for the users? It’s a major paradigm shift. Like I mentioned before, your machine turns into a kiosk or a thin-client. Maybe some people won’t mind using one, but I view my machine as something much more and so I don’t think I will be satisfied.

ChromeOS .vmx file for the .vmdk

.encoding = "UTF-8"
displayName = "Chrome OS"
guestOS = "other"
memsize = "512"

ethernet0.present= "true"
ethernet0.startConnected = "true"
ethernet0.virtualDev = "e1000"
ethernet0.connectionType = "nat"
ethernet0.addressType = "generated"
ethernet0.generatedAddress = "00:0c:29:cd:8d:e6"
ethernet0.generatedAddressOffset = "0"

usb.present = "true"

sound.present = "false"
sound.autodetect = "true"
sound.virtualDev = "es1371"
sound.fileName = "-1"
sound.startConnected = "true"

ide0:0.present = "true"
ide0:0.fileName="chrome-os-0.4.22.8-gdgt.vmdk"
ide0:0.deviceType = "disk"
ide0:0.mode = "persistent"
ide0:0.redo = ""
ide0:0.writeThrough = "false"
ide0:0.startConnected = "false"

virtualHW.version = "3"
config.version = "8"

floppy0.present = "false"

I’m no longer seeding the torrent. I suggest downloading the vmdk from gdgt (sign-up required, but just make a fake profile – no verification is performed) and using this vmx file with it.

openssl s_client -connect localhost:995

Everything seemed fine. Furthermore, this problem seemed to be limited to both my FreeBSD servers. My Linux box seemed to be running fine. I tried a bunch of things. I restarted both machines, restarted the network interfaces, made sure firewalls weren’t running, reset my router… nothing seemed to work. Every time I tested the connection to the machines (using this awesome tool here), the connections would time out. What was even stranger was that a netstat showed connections to be in a SYN_RCVD state, which meant that the box had accepted the connection. It’s just that the response wasn’t getting out. Eventually I was so desperate that I decided to reinstall FreeBSD on one of the machines. I also posted to a BSD forum asking for help. I figured that next evening I could probably fix it after work.

Well, next morning I still felt terrible, but it wasn’t so bad. My throat wasn’t hurting as much and I didn’t have that much of a headache so I was able to work from home. Oh, and the installation had completed. I set everything up quickly and gave it a whirl. Nope. Same problem. Yeah, I was getting pretty frustrated and annoyed at this point. I went so far as to contemplate wiping my beloved FreeBSD off both machines and putting Linux on there. I updated my post at the forum and I checked on it periodically throughout the day as I kept working. Finally, a kind soul popped in to help me out. He helped me troubleshoot using tcpdump and I was able to confirm that the machine was responding to the incoming connection, but it wasn’t going out. Finally, he asked me to check the routing information. I’m not that well-versed with that so I didn’t see the problem until he pointed it out. The routing information was all wrong!

See, I have two network interfaces on the box. One for my internal network, and one pointing to the outside world. The one pointing to the outside world is statically configured, whereas the one for my internal network picks up its configuration from my AirPort Extreme router. What was happening was that dhclient was overwriting the route information. So when the machine tried to respond back, it saw its default route as the internal router, and not my modem! I had to update my dhclient.conf and force the router address to the correct one:

backoff-cutoff 2;
initial-interval 1;
retry 10;
select-timeout 0;
timeout 30;

interface "vr0" {
   supersede routers 209.x.y.54;
   supersede host-name "enterprise";
   supersede domain-name "xxxx.xxx";
   request subnet-mask,
           domain-name-servers;

   require subnet-mask,
           domain-name-servers;
}

The important line here is the one that says supersede routers 209.x.y.54; (I’ve hidden the actual numbers from teh hax0rs). This tells the dhclient to override the router information that it gets from the DHCP server. Once I did this, everything started working again. My thanks to jggimi at DaemonForums!

[Errno 5] Input/output error

This is often due to a faulty CD/DVD disk or drive, or a faulty hard disk. It may help to clean the CD/DVD, to burn the CD/DVD at a lower speed, to clean the CD/DVD drive lens (cleaning kits are often available from electronics suppliers), to check whether the hard disk is old and in need of replacement, or to move the system to a cooler environment.

Fun stuff. So then, I burnt myself another copy of the install CD, making sure to burn this one at the lowest speed (1x) and then verifying the image. I also made sure that the MD5 sums on the ISO matched the one on the Ubuntu website. This time when I booted up, the install proceeded along further before dying at 78% with the same error. I restarted the installation multiple times only to see it fail at the same point. I started wondering if it was a problem with the hard-drive. Since the drive is SMART enabled, I decided to run some tests on it. From the LiveCD, I started up the terminal and installed smartmontools through apt-get (sudo apt-get install smartmontools). I then got some errors about unfulfilled dependencies and postfix (strange), but smartmontools seem to be installed so I didn’t think much of it. I followed the instructions at this site and tested my hard-drive. I even ran the long test which took about two hours to complete. The tests passed. At this point I was at my wit’s end. It wasn’t the image, the CD, or the hard-drive. It had to be a hardware problem. Was it the drive itself?

Finally I figured it out. It was mostly due to blind luck/intuition that I was able to figure it out. I vaguely remembered trying to install FreeBSD a few years ago and running into a problem with ACPI. So when the LiveCD booted up, I hit F6 and checked the first three options (acpi=off, noapic, nolapic). This time, the installation went without a hitch and now I’m able to dual-boot between Windows 7 and Ubuntu 9.04!