Android keymaps

注：下文中的qwerty.kl不再有效，应使用Generic.kl或者Vendor_<vendorID>_Product_<productID>.kl，推荐使用Vendor_<vendorID>_Product_<productID>.kl，这样不会因为改错造成Generic.kl的混乱从而影响到其他外接键盘的使用。

I recently bought a Bluetooth keyboard to use on Android; unfortunately some keys weren't recognised at all and others weren't quite mapped as I'd like. This is fairly easy to fix as an end user, as long as you have a rooted device (adb remount must succeed). Here's a quick howto, since I couldn't find one.

It shouldn't need saying, but you do this at your own risk. You can easily break your device's response to keys, and possibly make your device unbootable too if the file is invalid.

It's pretty much as described under Keymaps and Keyboard Input in the porting documentation. What we're going to do is edit one file: /system/usr/keylayout/qwerty.kl. This file maps scancodes to Android keycodes. For example: key 30 A means scancode 30 (decimal) maps toKEYCODE_A (29), the A key. As the porting docs say, a separate Key Character Map file deals with what characters, if any (e.g. "a", "A", "#"), should be generated given the keycode and the state of the modifiers (Shift, Fn/Sym, etc). A different KCM can be loaded for Bluetooth keyboards depending on their device name, but at least by default, the same key layout file (including your changes) is used for Bluetooth and the built-in keyboard (if any).

So, first we need to fetch your current key layout, and it's a good idea to keep backups (both on the device and locally).

adb pull /system/usr/keylayout/qwerty.kl qwerty.klcp qwerty.kl qwerty-orig.kladb shell cp /system/usr/keylayout/qwerty.kl /sdcard/qwerty-orig.kl

Now, edit qwerty.kl as you like. It should look initially look similar to this Nexus One example. You might find it helpful at this point to see what scancodes your keyboard is sending. There really ought to be a tool for this in Dev Tools or Spare Parts, but it seems there isn't. I've made a dirt-simple app to show you KeyEvent.toString(), which was the work of 5 minutes and could certainly be improved.

My particular keyboard is a white roll-up 87-key variety, that you can still find on eBay. It has F-keys doubling as media keys: if you get this model, be aware that the Fn key is really F-lock (toggles the state rather than acting as a modifier). Here is my layout file in case it's helpful. This layout mostly follows the principle of least surprise, except that the button with "Home" printed on it is Call, to mirror "End" being Hangup. F1 with F-lock on (Home symbol) is the Android "Home" keycode (goes to the home screen).

Now copy the layout back onto the device:

adb remountadb push qwerty.kl /system/usr/keylayout/qwerty.kl

(If the remount fails, you probably don't have a rooted device.) It seems you need to reboot for the changes to take effect, so go ahead and do that, and your keys should then behave as you've specified. :-)

附：bluetooth-keyboard-layout.txt内容如下

key 1     BACKkey 41    GRAVE# lower leftkey 86    BACKSLASH# print screenkey 99    CAMERA            WAKE# home upper rightkey 102   CALL              WAKE_DROPPED# menu lower leftkey 125   MENU# menu upper rightkey 126   MENU# menu icon upper right cornerkey 127   DPAD_CENTER# fn F1key 172   HOME              WAKE# fn F4key 156   STAR# fn F5key 164   MEDIA_PLAY_PAUSE  WAKE# fn F6key 163   MEDIA_NEXT        WAKE# fn F7key 165   MEDIA_PREVIOUS    WAKE# fn F8key 166   MEDIA_STOP# fn F11key 113   MUTE# fn F12 mediakey 171   FOCUS# pause breakkey 119   NOTIFICATION# ins lower rightkey 110   DPAD_CENTER# del lower rightkey 111   DELkey 399   GRAVEkey 2     1key 3     2key 4     3key 5     4key 6     5key 7     6key 8     7key 9     8key 10    9key 11    0key 158   BACK              WAKE_DROPPEDkey 230   SOFT_RIGHT        WAKEkey 60    SOFT_RIGHT        WAKEkey 107   ENDCALL           WAKE_DROPPEDkey 62    ENDCALL           WAKE_DROPPEDkey 229   MENU              WAKE_DROPPEDkey 139   MENU              WAKE_DROPPEDkey 59    MENU              WAKE_DROPPED#key 127   SEARCH            WAKE_DROPPEDkey 217   SEARCH            WAKE_DROPPEDkey 228   POUNDkey 227   STARkey 231   CALL              WAKE_DROPPEDkey 61    CALL              WAKE_DROPPEDkey 232   DPAD_CENTER       WAKE_DROPPEDkey 108   DPAD_DOWN         WAKE_DROPPEDkey 103   DPAD_UP           WAKE_DROPPED#key 102   HOME              WAKEkey 105   DPAD_LEFT         WAKE_DROPPEDkey 106   DPAD_RIGHT        WAKE_DROPPEDkey 115   VOLUME_UPkey 114   VOLUME_DOWNkey 116   POWER             WAKEkey 212   CAMERAkey 16    Qkey 17    Wkey 18    Ekey 19    Rkey 20    Tkey 21    Ykey 22    Ukey 23    Ikey 24    Okey 25    Pkey 26    LEFT_BRACKETkey 27    RIGHT_BRACKETkey 43    BACKSLASHkey 30    Akey 31    Skey 32    Dkey 33    Fkey 34    Gkey 35    Hkey 36    Jkey 37    Kkey 38    Lkey 39    SEMICOLONkey 40    APOSTROPHEkey 14    DEL        key 44    Zkey 45    Xkey 46    Ckey 47    Vkey 48    Bkey 49    Nkey 50    Mkey 51    COMMAkey 52    PERIODkey 53    SLASHkey 28    ENTER        key 56    ALT_LEFTkey 100   ALT_RIGHTkey 42    SHIFT_LEFTkey 54    SHIFT_RIGHTkey 15    TABkey 57    SPACEkey 150   EXPLORERkey 155   ENVELOPE        key 12    MINUSkey 13    EQUALSkey 215   AT

From: http://chris.boyle.name/blog/2010/08/android-keymaps/