How to develop a soft keyboard for Android

Question

I would like to play around with some ideas and develop a soft keyboard for Android to replace the default one    Is there any general information about soft keyboard development for Android out there  Any best practices or guidelines  Can I do with my keyboard application pretty much anything I could do with a normal Android application  Can I do HTTP connections to synchronize keyboard data with a cloud DB and other phones I have  Can I open other windows screens from a key press  e g  to display a custom input interface different to a normal QWERTY one  If that doesn t work  can I use a pop-up dialog instead

User · Answer

first of all you should define an  xml file and make keyboard UI in it    lt  xml version  1 0  encoding  utf-8   gt   lt Keyboard xmlns android  http   schemas android com apk res android  android keyWidth  12 50 p  android keyHeight  7 p  gt   lt  -- android horizontalGap  0 50 p  android verticalGap  0 50 p  NOTE When we add a horizontalGap in pixels  this interferes with keyWidth in percentages adding up to 100  NOTE When we have a horizontalGap  on Keyboard level  of 0  this make the horizontalGap  on Key level  to move from after the key to before the key     I consider this a bug   -- gt   lt Row gt       lt Key android codes  -5  android keyLabel  remove   android keyEdgeFlags  left    gt       lt Key android codes  48     android keyLabel  0    gt       lt Key android codes  55006  android keyLabel  clear    gt   lt  Row gt   lt Row gt       lt Key android codes  49     android keyLabel  1   android keyEdgeFlags  left    gt       lt Key android codes  50     android keyLabel  2    gt       lt Key android codes  51     android keyLabel  3    gt   lt  Row gt   lt Row gt       lt Key android codes  52     android keyLabel  4   android keyEdgeFlags  left    gt       lt Key android codes  53     android keyLabel  5    gt       lt Key android codes  54     android keyLabel  6    gt   lt  Row gt    lt Row gt       lt Key android codes  55     android keyLabel  7   android keyEdgeFlags  left    gt       lt Key android codes  56     android keyLabel  8    gt       lt Key android codes  57     android keyLabel  9    gt   lt  Row gt      In this example you have 4 rows and in each row you have 3 keys  also you can put an icon in each key you want     Then you should add xml tag in your activity UI like this      lt android inputmethodservice KeyboardView         android id    id keyboardview1          android layout width  wrap content          android layout height  wrap content          android background   color white          android focusable  true          android focusableInTouchMode  true          android visibility  visible    gt    Also in your  java activity file you should define the keyboard and assign it to a EditText     CustomKeyboard mCustomKeyboard1   new CustomKeyboard this              R id keyboardview1  R xml horizontal keyboard       mCustomKeyboard1 registerEditText R id inputSearch     This code asign inputSearch  which is a EditText  to your keyboard     import android app Activity  import android inputmethodservice Keyboard  import android inputmethodservice KeyboardView  import android inputmethodservice KeyboardView OnKeyboardActionListener  import android text Editable  import android text InputType  import android view MotionEvent  import android view View  import android view View OnClickListener  import android view View OnFocusChangeListener  import android view View OnTouchListener  import android view WindowManager  import android view inputmethod InputMethodManager  import android widget EditText    public class CustomKeyboard        A link to the KeyboardView that is used to render this CustomKeyboard     private KeyboardView mKeyboardView      A link to the activity that hosts the   link  mKeyboardView      private Activity mHostActivity       The key  code  handler     private OnKeyboardActionListener mOnKeyboardActionListener   new OnKeyboardActionListener          public final static int CodeDelete   -5     Keyboard KEYCODE DELETE     public final static int CodeCancel   -3     Keyboard KEYCODE CANCEL     public final static int CodePrev   55000      public final static int CodeAllLeft   55001      public final static int CodeLeft   55002      public final static int CodeRight   55003      public final static int CodeAllRight   55004      public final static int CodeNext   55005      public final static int CodeClear   55006        Override     public void onKey int primaryCode  int   keyCodes               NOTE We can say   lt Key android codes  49 50       gt   in the xml            file  all codes come in keyCodes  the first in this list in            primaryCode            Get the EditText and its Editable         View focusCurrent   mHostActivity getWindow   getCurrentFocus            if  focusCurrent    null                    focusCurrent getClass      EditText class              return          EditText edittext    EditText  focusCurrent          Editable editable   edittext getText            int start   edittext getSelectionStart               Apply the key to the edittext         if  primaryCode    CodeCancel                hideCustomKeyboard              else if  primaryCode    CodeDelete                if  editable    null  amp  amp  start  gt  0                  editable delete start - 1  start             else if  primaryCode    CodeClear                if  editable    null                  editable clear              else if  primaryCode    CodeLeft                if  start  gt  0                  edittext setSelection start - 1             else if  primaryCode    CodeRight                if  start  lt  edittext length                    edittext setSelection start   1             else if  primaryCode    CodeAllLeft                edittext setSelection 0             else if  primaryCode    CodeAllRight                edittext setSelection edittext length               else if  primaryCode    CodePrev                View focusNew   edittext focusSearch View FOCUS BACKWARD               if  focusNew    null                  focusNew requestFocus              else if  primaryCode    CodeNext                View focusNew   edittext focusSearch View FOCUS FORWARD               if  focusNew    null                  focusNew requestFocus              else      insert character             editable insert start  Character toString  char  primaryCode                          Override     public void onPress int arg0                Override     public void onRelease int primaryCode                Override     public void onText CharSequence text                Override     public void swipeDown                 Override     public void swipeLeft                 Override     public void swipeRight                 Override     public void swipeUp                      Create a custom keyboard  that uses the KeyboardView  with resource id     lt var gt viewid lt  var gt   of the  lt var gt host lt  var gt  activity  and load the keyboard    layout from xml file  lt var gt layoutid lt  var gt   see   link Keyboard  for    description   Note that the  lt var gt host lt  var gt  activity must have a     lt var gt KeyboardView lt  var gt  in its layout  typically aligned with the bottom    of the activity   Note that the keyboard layout xml file may include key    codes for navigation  see the constants in this class for their values     Note that to enable EditText s to use this custom keyboard  call the      link  registerEditText int            param host               The hosting activity      param viewid               The id of the KeyboardView      param layoutid               The id of the xml file containing the keyboard layout      public CustomKeyboard Activity host  int viewid  int layoutid        mHostActivity   host      mKeyboardView    KeyboardView  mHostActivity findViewById viewid       mKeyboardView setKeyboard new Keyboard mHostActivity  layoutid        mKeyboardView setPreviewEnabled false      NOTE Do not show the preview                                                balloons     mKeyboardView setOnKeyboardActionListener mOnKeyboardActionListener          Hide the standard keyboard initially     mHostActivity getWindow   setSoftInputMode              WindowManager LayoutParams SOFT INPUT STATE ALWAYS HIDDEN          Returns whether the CustomKeyboard is visible     public boolean isCustomKeyboardVisible         return mKeyboardView getVisibility      View VISIBLE            Make the CustomKeyboard visible  and hide the system keyboard for view v      public void showCustomKeyboard View v        mKeyboardView setVisibility View VISIBLE       mKeyboardView setEnabled true       if  v    null            InputMethodManager  mHostActivity                  getSystemService Activity INPUT METHOD SERVICE                    hideSoftInputFromWindow v getWindowToken    0          Make the CustomKeyboard invisible     public void hideCustomKeyboard         mKeyboardView setVisibility View GONE       mKeyboardView setEnabled false             Register  lt var gt EditText lt var gt  with resource id  lt var gt resid lt  var gt   on the    hosting activity  for using this custom keyboard          param resid               The resource id of the EditText that registers to the custom               keyboard      public void registerEditText int resid           Find the EditText  resid      EditText edittext    EditText  mHostActivity findViewById resid          Make the custom keyboard appear     edittext setOnFocusChangeListener new OnFocusChangeListener                NOTE By setting the on focus listener  we can show the custom            keyboard when the edit box gets focus  but also hide it when the            edit box loses focus          Override         public void onFocusChange View v  boolean hasFocus                if  hasFocus                  showCustomKeyboard v               else                 hideCustomKeyboard                          edittext setOnClickListener new OnClickListener                NOTE By setting the on click listener  we can show the custom            keyboard again  by tapping on an edit box that already had focus             but that had the keyboard hidden            Override         public void onClick View v                showCustomKeyboard v                            Disable standard keyboard hard way        NOTE There is also an easy way          edittext setInputType InputType TYPE NULL    but you will not have a        cursor  and no  edittext setCursorVisible true   doesn t work       edittext setOnTouchListener new OnTouchListener              Override         public boolean onTouch View v  MotionEvent event                EditText edittext    EditText  v              int inType   edittext getInputType       Backup the input type             edittext setInputType InputType TYPE NULL      Disable standard                                                            keyboard             edittext onTouchEvent event      Call native handler             edittext setInputType inType      Restore input type             return true     Consume touch event                          Disable spell check  hex strings look like words to Android      edittext setInputType edittext getInputType                 InputType TYPE TEXT FLAG NO SUGGESTIONS            NOTE How can we change the background color of some keys  like the    shift ctrl alt      NOTE What does android keyEdgeFlags do mean

User · Answer

Create Custom Key Board for Own EditText  Download Entire Code       In this post i Created Simple Keyboard which contains Some special keys like    France keys   and it s supported Capital letters and small letters and Number keys  and some Symbols    package sra keyboard   import android app Activity  import android os Bundle  import android util Log  import android view MotionEvent  import android view View  import android view WindowManager  import android view View OnClickListener  import android view View OnFocusChangeListener  import android view View OnTouchListener  import android widget Button  import android widget EditText  import android widget RelativeLayout   public class Main extends Activity implements OnTouchListener  OnClickListener    OnFocusChangeListener    private EditText mEt  mEt1     Edit Text boxes  private Button mBSpace  mBdone  mBack  mBChange  mNum   private RelativeLayout mLayout  mKLayout   private boolean isEdit   false  isEdit1   false   private String mUpper    upper   mLower    lower    private int w  mWindowWidth   private String sL        a    b    c    d    e    f    g    h    i    j       k    l    m    n    o    p    q    r    s    t    u    v    w       x    y    z                                          private String cL        A    B    C    D    E    F    G    H    I    J       K    L    M    N    O    P    Q    R    S    T    U    V    W       X    Y    Z                                          private String nS                            3               amp     8                           -    9    0    1    4         5    7         2             6                         lt      gt            private Button mB     new Button 32      Override  public void onCreate Bundle savedInstanceState      super onCreate savedInstanceState     try      setContentView R layout main         adjusting key regarding window sizes    setKeys       setFrow       setSrow       setTrow       setForow       mEt    EditText  findViewById R id xEt      mEt setOnTouchListener this      mEt setOnFocusChangeListener this      mEt1    EditText  findViewById R id et1       mEt1 setOnTouchListener this      mEt1 setOnFocusChangeListener this      mEt setOnClickListener this      mEt1 setOnClickListener this      mLayout    RelativeLayout  findViewById R id xK1      mKLayout    RelativeLayout  findViewById R id xKeyBoard        catch  Exception e       Log w getClass   getName    e toString                Override  public boolean onTouch View v  MotionEvent event      if  v    mEt       hideDefaultKeyboard       enableKeyboard           if  v    mEt1       hideDefaultKeyboard       enableKeyboard           return true        Override  public void onClick View v       if  v    mBChange        if  mBChange getTag   equals mUpper         changeSmallLetters        changeSmallTags         else if  mBChange getTag   equals mLower         changeCapitalLetters        changeCapitalTags              else if  v    mBdone  amp  amp  v    mBack  amp  amp  v    mBChange  amp  amp  v    mNum       addText v        else if  v    mBdone        disableKeyboard         else if  v    mBack       isBack v       else if  v    mNum       String nTag    String  mNum getTag       if  nTag equals  num          changeSyNuLetters        changeSyNuTags        mBChange setVisibility Button INVISIBLE            if  nTag equals  ABC          changeCapitalLetters        changeCapitalTags                     Override  public void onFocusChange View v  boolean hasFocus      if  v    mEt  amp  amp  hasFocus    true       isEdit   true     isEdit1   false       else if  v    mEt1  amp  amp  hasFocus    true       isEdit   false     isEdit1   true             private void addText View v      if  isEdit    true       String b          b    String  v getTag       if  b    null           adding text in Edittext     mEt append b                if  isEdit1    true       String b          b    String  v getTag       if  b    null           adding text in Edittext     mEt1 append b                    private void isBack View v      if  isEdit    true       CharSequence cc   mEt getText       if  cc    null  amp  amp  cc length    gt  0               mEt setText           mEt append cc subSequence 0  cc length   - 1                       if  isEdit1    true       CharSequence cc   mEt1 getText       if  cc    null  amp  amp  cc length    gt  0               mEt1 setText           mEt1 append cc subSequence 0  cc length   - 1                       private void changeSmallLetters       mBChange setVisibility Button VISIBLE     for  int i   0  i  lt  sL length  i       mB i  setText sL i      mNum setTag  12         private void changeSmallTags       for  int i   0  i  lt  sL length  i       mB i  setTag sL i      mBChange setTag  lower      mNum setTag  num        private void changeCapitalLetters       mBChange setVisibility Button VISIBLE     for  int i   0  i  lt  cL length  i       mB i  setText cL i      mBChange setTag  upper      mNum setText  12           private void changeCapitalTags       for  int i   0  i  lt  cL length  i       mB i  setTag cL i      mNum setTag  num          private void changeSyNuLetters        for  int i   0  i  lt  nS length  i       mB i  setText nS i      mNum setText  ABC         private void changeSyNuTags       for  int i   0  i  lt  nS length  i       mB i  setTag nS i      mNum setTag  ABC            enabling customized keyboard  private void enableKeyboard        mLayout setVisibility RelativeLayout VISIBLE     mKLayout setVisibility RelativeLayout VISIBLE            Disable customized keyboard  private void disableKeyboard       mLayout setVisibility RelativeLayout INVISIBLE     mKLayout setVisibility RelativeLayout INVISIBLE         private void hideDefaultKeyboard       getWindow   setSoftInputMode      WindowManager LayoutParams SOFT INPUT STATE ALWAYS HIDDEN         private void setFrow       w    mWindowWidth   13     w   w - 15    mB 16  setWidth w     mB 22  setWidth w   3     mB 4  setWidth w     mB 17  setWidth w     mB 19  setWidth w     mB 24  setWidth w     mB 20  setWidth w     mB 8  setWidth w     mB 14  setWidth w     mB 15  setWidth w     mB 16  setHeight 50     mB 22  setHeight 50     mB 4  setHeight 50     mB 17  setHeight 50     mB 19  setHeight 50     mB 24  setHeight 50     mB 20  setHeight 50     mB 8  setHeight 50     mB 14  setHeight 50     mB 15  setHeight 50         private void setSrow       w    mWindowWidth   10     mB 0  setWidth w     mB 18  setWidth w     mB 3  setWidth w     mB 5  setWidth w     mB 6  setWidth w     mB 7  setWidth w     mB 26  setWidth w     mB 9  setWidth w     mB 10  setWidth w     mB 11  setWidth w     mB 26  setWidth w      mB 0  setHeight 50     mB 18  setHeight 50     mB 3  setHeight 50     mB 5  setHeight 50     mB 6  setHeight 50     mB 7  setHeight 50     mB 9  setHeight 50     mB 10  setHeight 50     mB 11  setHeight 50     mB 26  setHeight 50        private void setTrow       w    mWindowWidth   12     mB 25  setWidth w     mB 23  setWidth w     mB 2  setWidth w     mB 21  setWidth w     mB 1  setWidth w     mB 13  setWidth w     mB 12  setWidth w     mB 27  setWidth w     mB 28  setWidth w     mBack setWidth w      mB 25  setHeight 50     mB 23  setHeight 50     mB 2  setHeight 50     mB 21  setHeight 50     mB 1  setHeight 50     mB 13  setHeight 50     mB 12  setHeight 50     mB 27  setHeight 50     mB 28  setHeight 50     mBack setHeight 50         private void setForow       w    mWindowWidth   10     mBSpace setWidth w   4     mBSpace setHeight 50     mB 29  setWidth w     mB 29  setHeight 50      mB 30  setWidth w     mB 30  setHeight 50      mB 31  setHeight 50     mB 31  setWidth w     mBdone setWidth w    w   1      mBdone setHeight 50         private void setKeys       mWindowWidth   getWindowManager   getDefaultDisplay   getWidth       getting      window      height      getting ids from xml files   mB 0     Button  findViewById R id xA     mB 1     Button  findViewById R id xB     mB 2     Button  findViewById R id xC     mB 3     Button  findViewById R id xD     mB 4     Button  findViewById R id xE     mB 5     Button  findViewById R id xF     mB 6     Button  findViewById R id xG     mB 7     Button  findViewById R id xH     mB 8     Button  findViewById R id xI     mB 9     Button  findViewById R id xJ     mB 10     Button  findViewById R id xK     mB 11     Button  findViewById R id xL     mB 12     Button  findViewById R id xM     mB 13     Button  findViewById R id xN     mB 14     Button  findViewById R id xO     mB 15     Button  findViewById R id xP     mB 16     Button  findViewById R id xQ     mB 17     Button  findViewById R id xR     mB 18     Button  findViewById R id xS     mB 19     Button  findViewById R id xT     mB 20     Button  findViewById R id xU     mB 21     Button  findViewById R id xV     mB 22     Button  findViewById R id xW     mB 23     Button  findViewById R id xX     mB 24     Button  findViewById R id xY     mB 25     Button  findViewById R id xZ     mB 26     Button  findViewById R id xS1     mB 27     Button  findViewById R id xS2     mB 28     Button  findViewById R id xS3     mB 29     Button  findViewById R id xS4     mB 30     Button  findViewById R id xS5     mB 31     Button  findViewById R id xS6     mBSpace    Button  findViewById R id xSpace     mBdone    Button  findViewById R id xDone     mBChange    Button  findViewById R id xChange     mBack    Button  findViewById R id xBack     mNum    Button  findViewById R id xNum     for  int i   0  i  lt  mB length  i       mB i  setOnClickListener this     mBSpace setOnClickListener this     mBdone setOnClickListener this     mBack setOnClickListener this     mBChange setOnClickListener this     mNum setOnClickListener this

User · Answer

A good place to start is the sample application provided on the developer docs    Guidelines would be to just make it as usable as possible  Take a look at the others available on the market to see what you should be aiming for Yes  services can do most things  including internet  provided you have asked for those permissions You can open activities and do anything you like n those if you run into a problem with doing some things in the keyboard  For example HTC s keyboard has a button to open the settings activity  and another to open a dialog to change languages    Take a look at other IME s to see what you should be aiming for  Some  like the official one  are open source

User · Answer

Some tips    Read this tutorial  Creating an Input Method clone this repo  LatinIME   About your questions   An inputMethod is basically an Android Service  so yes  you can do HTTP and all the stuff you can do in a Service   You can open Activities and dialogs from the InputMethod  Once again  it s just a Service   I ve been developing an IME  so ask again if you run into an issue

[android] How to develop a soft keyboard for Android?

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