Notes on Wearable development

• Apparently, DataItem is persistent but doesn't work like database. When you send 2 DataItem objects to a same node via same Uri, the second one will replace the first one instead of update field by field. I thought it would work like update statement of database ;(
• If you send multiple DataItem to wearable while it's out of your handheld's range, the DataApi.DataListener you register on wearable side will only get called ONCE for the last DataItem you sent.

Java Enum's mystery

Today, I accidentally took a look at toMillis(long d) method of Java's TimeUnit class:

https://android.googlesource.com/platform/libcore/+/refs/heads/master/luni/src/main/java/java/util/concurrent/TimeUnit.java

And I was like: "such class, very confusing, much questions, wow" lol

Why this class has toMillis(long d) method, and its enum elements have that method as well?
Why this class's toMillis(long d) has only this line in its implementation?

throw new AbstractMethodError();

It was so confusing because normally I mostly only use enum as cases for switch statements, so I tried to research for a while then I occurred this thread: http://stackoverflow.com/questions/18392885/java-definition-of-methods-and-variables-inside-enums-constant.

Still confusing but somehow I came to this conclusion:

• Basically we can use Enum as a class to hold constants of a certain type that has certain desired methods OR we can call it "constant method" (I doubt about the latter?!)
• TimeUnit's toMillis(long d) method basically just throws an exception (AbstractMethodError), and its elements (SECONDS, MINUTES...) have type is TimeUnit, so they just override TimeUnit's toMillis(long d) method (@Override is omitted in this class, I guess the author did it intentionally because he didn't call super method in any overridden methods, and that was the point made this class so confusing at first to me). Then when we call TimeUnit.SECONDS.toMillis(10), SECONDS's toMillis(long d) will be called but it doesn't throw any exceptions because super method wasn't called.

That's it!

The method looks so well-designed but kind of confusing at first.

Now I see it's a really good practice to use Java's Enum.

Show unused resources in Android Studio

Today when I was reading about how to decrease size of an APK file, I discovered a functionality that I have been looking for in Android Studio, it's how to show unused resources. This functionality becomes extremely helpful when you want to optimize your APK file before release, and I believe the smaller your APK file the more download your app will get.

Enough rambling, this is how you get it:

Analyze -> Inspect code...

Then in  Inspection windows (View -> Tool Windows -> Inspection), under Android Lint, you will find an entry named "Unused resources", click on it and you would get something like:

Oh, just one more note, I'm using Android Studio Beta 0.8.11 (Updated from Canary Channel)
Yeah, that's it.

Happy coding ;)

ImageView.setImageBitmap and other ImageView's set image methods

Have you ever stumbled in a case that you use ImageView.setImageResource(R.drawable.your_image) and your image is displayed totally fine in all devices, then you want to make your ImageView more dynamic by put your image into a server, then use something (like Volley, UniversalImageLoader...) to load the image as a Bitmap, then use ImageView.setImageBitmap(your_bitmap) to display your image but it's displayed fine in all devices anymore?!

I got myself into that case today, after using ImageView.setImageBitmap(), my image is displayed too big in some devices and too small in some others. It took me an hour debugging and reading the ImaveView's source code and still couldn't figure out why but reminded me about Android's DisplayMetrics.
As we are developing Android and iOS versions parallel, both share the same resources, and I put all Android's image resources into drawable-xhdpi (as you may know, Android's xhdpi and iOS's retina have the same density), so when I use ImageView.setImageResource(), it displays my images pretty well on all current popular devices (exclude tablets), but why not ImageView.setImageBitmap()?!

The reason is ImageView.setImageResource() cares about device's density, but setImageBitmap() doens't seem to, I think it probably uses some default settings. So to fix it, just use Bitmap.setDensity() with an appropriate density from DensityMetrics. For example, in my case, I would use:

 bitmap.setDensity(DisplayMetrics.DENSITY_XHIGH);

That's it ;-)
Happy coding, guys!

A custom TextView that can shrink its text size to fit in a single line

9GAG - TV's iPhone app like animation on Android

I'm always a huge fan of http://9gag.com, and recently, they released a version of http://9gag.tv for iPhone with very cool animation. When I saw it, it aroused my curious, so I tried to implement it on Android, and here is what I've got :)

You can grab the source code here: https://github.com/mrleolink/9GAGTVAnimation

A side note: This is just a simple implementation I have made in a few hours, I tried to reuse views for cards bust just in a very simple way. I believe that this sample can be improved to hook with a custom Adapter to create a completed widget for Android, but I don't have enough of time at the moment, so if any of you have time to implement it, feel free to give me a pull request.

Android Canvas's clipping functions doensn't work?

I was working on an Android's custom view to show a volume bar with an overlay gradient, it looks somewhat like to this:

My approach was calculate small volume bars's RectF then use Canvas's clipRect to clip the canvas, then draw the gradient and gray part on it. Everything worked well with Nexus 5 and Galaxy S2 LTE, but not with a NTTdocomo Android phone (all of them were 4.0 up).

At first I thought the divider between volume bars was too small but after double checked, it wasn't the reason. Then it took me 2 hours for many checks (Android API Samples) and searches, it's only because of something called Hardware Acceleration, as written in the developer page:

Hardware acceleration is enabled by default if your Target API level is >=14

 So, Hardware Acceleration must be enabled by default on all of my devices, then I tried to turn it off by putting this line into the Activity which contains my custom view:

android:hardwareAccelerated="false"

And it worked!!!

So all the blames should go to the Hardware Acceleration, but why did it still work with Hardware Acceleration ON on two other devices ?!
It's a question that I haven't but need to figure out later!

P/S: The more I work with Android, the more I see this sentence of a random guy on StackOverflow is very true:

Everything is so random with Android!

Hope this help someone out there to not waste 2 hours at work like I did lol, happy coding guys!

UPDATE: I just found this today (20140728) http://developer.android.com/guide/topics/graphics/hardware-accel.html. There is a table about Unsupported Drawing Operations, so you guys can take a look then enable/disable hardware acceleration to match your needs.

Android - LinearGradient comprehension

Today I read about Property Animation, and I got into following snippet somehow.

TextView tv = (TextView) rootView.findViewById(R.id.textview);
tv.setText("I'm Leo");
tv.setWidth(150);
tv.setBackgroundColor(Color.BLACK);
LinearGradient linearGradient = new LinearGradient(0, 0, 150, 0,
        new int[]{
                Color.BLACK,
                Color.WHITE,
                Color.BLACK
        },
        new float[]{
                0,
                0.5f,
                1
        },
        Shader.TileMode.CLAMP);   
tv.getPaint().setShader(linearGradient);

At first, I couldn't figure out how does LinearGradient really work, especially the part position, why when:

new float[]{
        0,
        0.5f,
        1
},

is used, it gives a result like above picture?!

After an hour of trial-and-error, I realized that:
- The first number 0 means where the first Color.BLACK begins
- The second one, 0.5f means 50% of the width (0 to 150), so the Color.WHITE begins at where X = 75 (relatively with the TextView). And the TextView turns from Color.BLACK(X=0) to Color.WHITE(X=75)  within the part from X=0 to X=75
- Same things happen between the second one and the third one, TextView turns from Color.WHITE(X=75) to Color.BLACK(X=150) within the part from X=75 to X=150

Well, that's how the gradient is rendered as a great above picture, and if you work some more to integrate LinearGradient with Property Animation, you will get a great effect ;)

Alternative to Intent.FLAG_ACTIVITY_CLEAR_TASK

I want to use Intent.FLAG_ACTIVITY_CLEAR_TASK to start my app from a notification on Android's status bar like it's restarted, but as you may know, Intent.FLAG_ACTIVITY_CLEAR_TASK requires Android API 11, so I found an alternative for it. Basically, just replace:

intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
PendingIntent contentIntent = PendingIntent.getActivity(this, REQUEST_CODE, intent, PendingIntent.FLAG_UPDATE_CURRENT);

with

ComponentName cn = intent.getComponent();
Intent restartIntent = IntentCompat.makeRestartActivityTask(cn);
PendingIntent contentIntent = PendingIntent.getActivity(this, REQUEST_CODE, restartIntent, PendingIntent.FLAG_UPDATE_CURRENT);

And it works as expected ;)

A hack to catch soft keyboard show/hide event on Android

Today at work, I got this problem: catching event when soft keyboard comes up/down (or show/hide) ?!

At first, I thought it would be easy to resolve, but after a while of googling, I realized that there is no official event or listener in Android API for that, but I did find some workarounds like:
http://stackoverflow.com/questions/4312319/howto-capture-the-virtual-keyboard-show-hide-event-in-android
http://stackoverflow.com/questions/3793093/android-edittext-soft-keyboard-show-hide-event

Well, there are some workarounds that were already posted but they are incomplete (some work on 4.0.4 but not 2.3, some don't work all the time), but at least they are still useful, they gave me an idea to make this "complete" workaround (well, at least it works like a charm in my case for now, I tested on both Android 2.3 and 4.0.4), so I would like to share it here, hope it helps someone out there ;)

Usage: just use following LinearLayout overridden class as the main layout(and of course, use "match_parent" for its layout_width and layout_height) of the activity where you want to catch soft keyboard show/hide events, then setOnSoftKeyboardVisibilityChangeListener for your main layout. Finally, you need this line in your <activity> tag (in manifest.xml) where SoftKeyboardHandledLinearLayout is used:

android:windowSoftInputMode="adjustResize"

Take a look at following code to get a better idea of how to implement this hack.

WRAP_CONTENT doesn't work with ViewPager?!

Lately, I have been working on an Android project, and when I was making a tutorial activity for it, I got into a problem with ViewPager.

I wanted to use ViewPager and ViewPagerIndicator to show content of the tutorial activity, the ViewPager had a rounded corner background, and each page of it contains an ImageView which is a part of the tutorial. And the problem is although I set layout_width for the ViewPager as wrap_content but it always acts like match_parent?!

After googling for a while, I saw some guys got into the same problem, for example: http://stackoverflow.com/questions/8394681/android-i-am-unable-to-have-viewpager-wrap-content. They proposed some solutions but none of them matches my need, but this anwser gave me an idea.

Because the rounded corner background and all image on pages of the ViewPager have the same size, and as the answer says, it's possible to set a fixed size for the ViewPager, so the solution for my case is just set size of the ViewPager as size of the rounded corner background.

Check out following gist to get a clearer idea about it.

Create a flexible link to open Google Play or your own App from web browser in Android

Today I learnt a completely new thing as the title says it all, so I want to note it here for later uses.
So how to do?

In manifest.xml:

        <activity 
            android:label="@string/activity_label"
            android:name="com.your.package.ActivityName">
            <intent-filter>
                 <data
                      android:host="your-domain-or-whatever.com"
                      android:scheme="your-own-scheme" />
                 <action android:name="android.intent.action.VIEW" />
                 <category android:name="android.intent.category.BROWSABLE" />
                 <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity> 

And your link should look like:

<a href="intent://your-domain-or-whatever.com/?param1=value1&amp;param2=value2#Intent;scheme=your-own-scheme;package=com.your.app.package;end">OPEN APP OR GOOGLE PLAY</a>

The last thing is catching parameters in your com.your.package.ActivityName. In onCreate of the Activity:

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.your_activity_layout);
  Uri mUri = getIntent().getData();
  String value1 = mUri.getQueryParameter("param1");
  String value2 = mUri.getQueryParameter("param2");
 }

That's all, bye xD!
P/S: Oh yeah, I just found this one too: https://developers.google.com/chrome/mobile/docs/intents, check it out!

Fancier Vim

Wow, it's been a while I haven't blogged anything, I know!

I have just been busy with learning Japanese, it's a hard language to learn, but it's even harder when I need to learn it under pressure...
Well, that does suck, but at least I'm still alive :)

Lately, I tried to get used to Vim and I think I fell in love with it. And today, I spent my whole precious Saturday to get to know it more, and this is a result:

Basically, above result is just combination of:

• Vim 7.3 on Ubuntu 13.04
• Eclim 2.2.7 (Vim plugin)
• Powerline (Vim plugin) (Instruction for Ubuntu)

It's not really cool yet, but it's late now, I need to sleep and continue learning Japanese tomorrow :(

Not really cool yet, but it's late now, I need to sleep :D
さようなら!

My Vim configuration

Recently, I got used to Vim, and it's really cooooooooool and it looks way so professional :D
I think I will keep it as my favorite text editors ;)

Anyway, I would like to save and share my Vim configuration here and it will be updated as  soon as I found something new ;)


Copy following configuration into your ~/.vimrc or ~/.exrc (well, I'm really not sure which one will be loaded by Vim :D)

"[Basic]
syntax on                               "turn syntax on
set number                              "show line number
set autoindent                          "turn auto indent on
set tabstop=4                           "set tab = 4 spaces
set shiftwidth=4                        "set tab when use > or < = 4 spaces
set colorcolumn=81                      "show margin line
set cursorline                          "hightlight current line

"[OmniCompletion]
autocmd FileType python set omnifunc=pythoncomplete#Complete
autocmd FileType javascript set omnifunc=javascriptcomplete#CompleteJS
autocmd FileType html set omnifunc=htmlcomplete#CompleteTags
autocmd FileType css set omnifunc=csscomplete#CompleteCSS
autocmd FileType xml set omnifunc=xmlcomplete#CompleteTags
autocmd FileType php set omnifunc=phpcomplete#CompletePHP
autocmd FileType c set omnifunc=ccomplete#Complete
autocmd FileType perl set omnifunc=perlcomplete#Complete
"change ^x^o to ^space
inoremap   pumvisible() \|\| &omnifunc == '' ?
\ "\C-n>" :
\ "\C-x>\C-o>=pumvisible() ?" .
\ "\"\\c-n>\\c-p>\\c-n>\" :" .
\ "\" \\bs>\\C-n>\"\"
imap  

Some useful GIT commands

View unpushed commits

git log --branches --not --remotes

Make git command line colorful

git config --global --add color.ui true 

Create simple infinite carousel in Android with ViewPager

At first I thought it's easy, someone must have implemented it already, but after searching for it on Google, I got no luck, nobody has done and shared it on the Net, so I decided to make it myself.

I read some posts like:

• http://stackoverflow.com/questions/11647021/how-to-create-create-a-carousel-pattern

• http://www.androidpatterns.com/uap_pattern/carousel

So I implemented it as you can see in below video:

 

The main idea is:

• Use ViewPager as the main view with pages are Fragment, then use ViewPager.setPageMargin(int) to set margin as a negative number, so the next and previous pages of the selected page will be showed up.
• Override the layout which is the root view of Fragments to create scale animation.
• Make a little hack in FragmentPagerAdapter so we can fling infinitely to both directions of the ViewPager.

For more information, you guys can get the source code here: https://github.com/mrleolink/SimpleInfiniteCarousel. I tried to comment as much as possible in source code, so I hope you understand my idea.

By the way, I don't think it's the best solution to implement the carousel pattern, so if you have any idea or there's something you don't understand about what I code, just drop me a line :)

[SmartSVN] How to host files on Google Code (javascript, css, html, ...) and get a permanent, non-redirecting and bandwidth-generous hotlink

Hell yeah, finally I've found a "safe" place to put my stuffs for my site (like html, javascript, css... files), it's Google Code :D

Well, first of all, I just want to let you know I got the know-how from this site: http://www.ubuntudz.com/2010/10/how-to-host-files-on-google-javascript.html, and I recommend you to read it before start with this post.

Currently, I'm using Windows 8 and already have SmartSVN installed, that means I don't have SVN command. It took me a while to figure out how to change mime-type before commit by SmartSVN, so I would like to note it here just in case I forget how to do it :D
OK, let's go :)


Step1: Add your file to stage

Step 2: Right click on the file -> Properties -> Edit Properties...

Step3: Choose existed property (svn:eol-style) -> click Edit -> Edit like the following screenshot (remember to change "Curren Value" to: text/css for ".css" file, text/html for ".htm" and ".html" files, text/javascript for ".js" files...

Step4: OK -> OK -> Commit file.

[Windows 8] Input method still remains after removing it?

Well, I've upgraded to Windows 8 recently, I tried to install Vietnamese input language method, but then I didn't feel like familiar to it, so I decided to remove it, well, everything was okay at that point.
After that, when I was working, I noticed that there's still Vietnamese input language method when I click on "ENG" button on task bar, that's weird, right? Afterwards, I searched and tried many ways (I even asked on a big forum: http://superuser.com/questions/522696/how-can-i-remove-an-input-method-completely-in-windows-8) to remove it but couldn't help... until this post:

http://answers.microsoft.com/en-us/windows/forum/windows_8-desktop/language-setting-question-display-lang-input-lang/4a057ad5-2965-4257-bc0f-5e1ab1411a63


Summary:

- Just add Vietnamese (or the language which you want to remove), then remove it again!

Hope it can help you out :)


 ---------------------
[UPDATE -20130612]
 ---------------------
 
Oh yeah, as I commented below, the above solution doesn't work, but today, finally, I got rid of it.
Actually, I almost surrendered and I have been having to stand it until today. I was starting learning Japanese, so I added Japanese Input Method to Language Bar and I got 3 entries English, Vietnamese, Japanese. The problem is using Windows+Space to switch between those 3 entries is really annoying, so I had to work my ass off on this problem once more time. And lucky me, I found this thread:

http://answers.microsoft.com/en-us/windows/forum/windows_8-desktop/remove-english-us-keyboard/16f81314-8c4f-4315-baf0-c6518449d8ae

After reading it, I took a look at my startup programs and did some "trial and error", logging in/out several times. Finally, I found out that "Unikey"  (a Vietnamese Input Method software that I was using) is the root cause of the problem, whenever it's started, it adds a Vietnamese entry to Language Bar - that sucks!

Well, I had been using Unikey for years, but at that time, I had to give it up! But then fortunately, after googling, I found another app which can do the same awesome job but DOES'T add anything to Language Bar, and it's:

http://www.trankynam.com/gotv/

I had been using that app on my Android phone, but didn't know it's also available on many other platforms, of course, includes Windows.

So... finally, after a very long time, my problem is solved completely xD

And one more thing, just a thought... that guy, TranKyNam is awesome indeed, he has a few other apps than gotv that I haven't had chances to try, but they looks cool also. I will definitely remember his name xD

Use adb wifi without rooting for Android phones

Well, if your phone is rooted already, it's very easy to use adb without USB cables. Just go to Google Play then search for "adb wifi", you'll see several apps which can help you with your rooted phone.
But if for some reasons, you don't want or mustn't root your phone (because of the warranty or the phone is not yours...), and you hate debugging your app with the cable plugged in your phone, well, there's still a workaround for you (but it still requires to use the USB cable once or twice)

Steps:

• Connect your Android phone with your  computer by the USB cable, and make sure you have adb and required drivers for you phone installed on your computer. Then type (this command tells adb daemon to listen over Wifi - port 5555):

adb tcpip 5555

• Okay, now you can plug out your USB cable and throw it away (just kidding, you'll might need it in case you restart your phone or you pull out the battery...). Now you have to find your phone IP, go to Setting -> Wi-Fi -> Select the Wi-Fi network your phone is using, then you'll see the IP address. Now on your computer, you have to connect adb to your phone, for example, IP address of my phone is 192.168.0.101, I'll do it by this command:

adb connect 192.168.0.101:5555

• Then you'll see message "connected to 192.168.0.101:5555", now your phone is connected to adb wirelessly. If you want to use adb over USB again, connect your phone to your computer then type in cmd or Terminal:

adb usb

That's all, good luck!

A note about .gitignore

First of all, take a look at this page: http://gitready.com/beginner/2009/01/19/ignoring-files.html
And I'm not copying its content lol, well, this is just a note about what I've done successfully with .gitignore to ignore some folders in my project.

Steps:

• Enter to root directory of your project, then "vi .gitignore" and enter something like:(I suppose you haven't had .gitignore in your project):

bin/ # ignore all folders which are named "bin"
.settings/ # ignore all folders which are named ".settings" 

• If there's nothing in your "bin" folders as well as ".settings" folders, your job here is done, everything you will put in those folders will not be tracked by Git. But if there's something in those folders which means Git are tracking it already, so you have to let Git know that you don't want to tracking it by these commands:

git rm --cached -r Your_Path/bin/
git rm --cached -r Your_Path/.settings/
git commit -m "Ignore folder bin and .settings"
git push origin your_branch

P/S: You may doubt about removing cache then commit & push, and yeah, I did, but don't worry. Doing so just removes cache not actual files in your folders (actually I have no idea about where is cache too, but I guess it's cache of git lol), and committing & pushing just delete those folders on remote server, not on your local repository.
In short, making a ".gitignore" just tells your Git program on your computer knows that don't list changes of files in those folders when you type "git status",  and removing cache & committing & pushing just delete those folders on remote repository.