Add an option to emulate US layout

Add an option to emulate US layout

Under some layouts (e.g. ru and cz), ASCII keysyms are not so
accessible as US layout.  In that case, people want to switch to the
US layout automatically, while other people don't want that switch.

This patch adds a user option "use_us_layout" to emulate US layout
when certain engine is active.

BUG=https://bugzilla.redhat.com/show_bug.cgi?id=760108

Committed: 6c88539

[Peng, 2013-02-20 05:51:18]

https://codereview.appspot.com/7368043/diff/1/src/engine.c
File src/engine.c (right):

https://codereview.appspot.com/7368043/diff/1/src/engine.c#newcode645
src/engine.c:645: IBusM17NEngineClass *klass = (IBusM17NEngineClass *)
G_OBJECT_GET_CLASS (m17n);
more than 80 chars

https://codereview.appspot.com/7368043/diff/1/src/engine.c#newcode646
src/engine.c:646: IBusKeymap *keymap = ibus_keymap_get ("us");
Maybe we could keep a ref in IBusEngine for better performance.

https://codereview.appspot.com/7368043/diff/1/src/engine.c#newcode671
src/engine.c:671: ibus_engine_forward_key_event (engine, keyval, keycode,
modifiers);
Do we really need forward key event back to application?
How about send char back directly via commit_text?

[Daiki Ueno, 2013-02-20 07:33:13]

Thanks for the review.  Updated CL.

https://codereview.appspot.com/7368043/diff/1/src/engine.c
File src/engine.c (right):

https://codereview.appspot.com/7368043/diff/1/src/engine.c#newcode645
src/engine.c:645: IBusM17NEngineClass *klass = (IBusM17NEngineClass *)
G_OBJECT_GET_CLASS (m17n);
On 2013/02/20 05:51:18, Peng wrote:
> more than 80 chars

Done.

https://codereview.appspot.com/7368043/diff/1/src/engine.c#newcode646
src/engine.c:646: IBusKeymap *keymap = ibus_keymap_get ("us");
On 2013/02/20 05:51:18, Peng wrote:
> Maybe we could keep a ref in IBusEngine for better performance.

Done.

https://codereview.appspot.com/7368043/diff/1/src/engine.c#newcode671
src/engine.c:671: ibus_engine_forward_key_event (engine, keyval, keycode,
modifiers);
On 2013/02/20 05:51:18, Peng wrote:
> Do we really need forward key event back to application?
> How about send char back directly via commit_text?

I heard that firefox seems to handle commit_text and key events differently on
some Web applications:
https://github.com/ueno/ibus-skk/issues/52

But fixed to use commit_text anyway.

[Peng, 2013-02-20 12:21:06]

lgtm

[Daiki Ueno, 2013-02-25 06:25:01]

On 2013/02/20 12:21:06, Peng wrote:
> lgtm

It seems that Mike had a concern about this, wait for his comment before commit.

[maiku.fabian, 2013-02-25 16:21:26]

I hope I have understood the problem I was experiencing, I was
quite confused for a while ...

First I test with this only:

commit 2b915cb54122e2010db1182f4f1007b9f7cda5aa
Author: Mike FABIAN <maiku.fabian@gmail.com>
Date:   Wed Feb 20 11:16:43 2013 +0900

    Use default keyboard layout by default

After this patch is applied but Ueno San’s patch is not yet applied,
the following test works.

1) select German keyboard layout in the gnome-panel
2) check that it works, type the key to the right of ‘l’, one
   should get ‘ö’, type RightAlt+e, one should get ‘€’.
3) switch to any ibus-m17n engine, for example latn-post.
4) type the ‘ö’ and the ‘€’ again, both still work.
   And one can type something like ‘a/’ to get ‘å’, i.e.
   latn-post also works. 

Now, after applying Ueno San’s patch as well and doing the same test
1) - 3) still behave the same but at point 4) one gets:

4) the ‘ö’ can be typed but the ‘€’ cannot be typed, instead of ‘€’ one
   gets ‘e’.

That happens even if the option ‘use-us-layout’ is ‘false’ for latn-post!

If ‘use-us-layout’ is ‘true’, that behaviour would be reasonable,
but if ‘use-us-layout’ is ‘false’, I think it is nicer if
the ‘€’ is just passed through as is.

This can be achieved by adding the following patch on top of Ueno San’s patch:

diff --git a/src/engine.c b/src/engine.c
index 622c299..edcb2e9 100644
--- a/src/engine.c
+++ b/src/engine.c
@@ -656,9 +656,7 @@ ibus_m17n_engine_process_key_event (IBusEngine     *engine,
     if (modifiers & IBUS_RELEASE_MASK)
         return FALSE;
 
-    /* If keyval is already translated by IBUS_MOD5_MASK.  Try to
-       obtain the untranslated keyval from the US keymap. */
-    if (klass->use_us_layout || (modifiers & IBUS_MOD5_MASK) != 0) {
+    if (klass->use_us_layout) {
         keyval = ibus_keymap_lookup_keysym (m17n->keymap, keycode,
                                             modifiers & ~IBUS_MOD5_MASK);
     }

With that extra patch, one can still type the characters RightAlt+<something>
for the engines which have ‘use-us-layout’ set to ‘false’, only
for the layouts with ‘use-us-layout’ set to ‘true’ the base character
is inserted.

[Daiki Ueno, 2013-02-26 02:49:26]

On 2013/02/25 16:21:26, maiku.fabian wrote:
> Now, after applying Ueno San’s patch as well and doing the same test
> 1) - 3) still behave the same but at point 4) one gets:
> 
> 4) the ‘ö’ can be typed but the ‘€’ cannot be typed, instead of ‘€’ one
>    gets ‘e’.

Yes, you are right; the patch breaks AltGr handling.  Thanks for catching this.
Could you try patch set 3?

[maiku.fabian, 2013-02-26 15:52:11]

> Could you try patch set 3?

Patch set 3 works fine for me. Thank you very much!