<AWT Dev> [13] JDK-8218917: KeyEvent.getModifiers() returns inconsistent values for ALT keys

Thu Mar 21 10:34:14 UTC 2019

Hi Krishna,

> But, currently, with my fix, the code will behave exactly as in Java 1.8.

Nope, it still sends VK_ALT_GRAPH pressed event for the right Alt.

http://bugs.openjdk.java.net/browse/JDK-8151136
According to the issue above AltGr support was backported to 9.

On Wed, Mar 20, 2019 at 2:18 PM Krishna Addepalli
<krishna.addepalli at oracle.com> wrote:
>
> Hi Sergey Malenkov,
>
> We can debate on how to treat the ALTGR_KEY, and can choose to include the behaviour as a system flag.
> But, currently, with my fix, the code will behave exactly as in Java 1.8. Even there, when I pressed ALTGR key, after holding ALT key, I observed a KeyEvent 0 being sent.
>
> I would suggest to re-look at my fix which fixes the current problem at hand, and perhaps we can move this discussion under a new bug.
>
> Thanks,
> Krishna
>
> On 18-Mar-2019, at 8:02 PM, Sergey Malenkov <malenkov at gmail.com> wrote:
>
> Hi Sergey,
>
> ALT_GRAPH_DOWN_MASK is not the only mask missing in JavaDoc. What is
> about META_DOWN_MASK? What if the developer, who does not care about
> ALT_GRAPH, forget about META too? Guess how your example will work on
> Mac. What is about the WORA slogan?
>
> I believe that the example in the javadoc is not entirely correct.
> This is just a very simple example, related to the English locale on
> Windows (and possibly on Linux). It should not be used in
> multi-platform code.
>
>
>
> On Sun, Mar 17, 2019 at 1:26 AM Sergey Bylokhov
> <Sergey.Bylokhov at oracle.com> wrote:
>
>
> On 16/03/2019 03:58, Sergey Malenkov wrote:
>
> Your example is synthetic and shows a problem in the one specific
> case. I think if you introduce new mask, you have to use it in your
> example too. If you add ALT_GRAPH_DOWN_MASK to 'offmask' your example
> will not work (that's how processed all shortcuts in Swing and IDEA).
> If you add it to 'onmask' the KeyEvent(new Button(), 0, 0,
> ALT_GRAPH_DOWN_MASK, 0) will not work.
>
>
> Your example is good as well, but it shows the opposite, if
> ALT_GRAPH_DOWN_MASK was used as "onmask" or as "offmask" then it means
> that this example tries to take care about altGr and it only
> properly works after the fix. And if the code is unaware about the altGr
> flag as in previous example it will be ignored.
>
> Am I right that to support your specific case you have to find and fix
> all Alt-based shortcuts in Swing, we should fix all Alt-based
> shortcuts in all keymaps in our IDEs and we should notify all our
> users that they have to fix all Alt-based shortcuts in their custom
> keymaps? The brilliant example of backward compatibility!
>
>
> I do not remember all changes which were integrated since initially it was done
> ~4 years ago. But Swing was updated by some changes after that, for example:
> https://bugs.openjdk.java.net/browse/JDK-8194873
>
>
> So if the client will follow the spec below it should work as before, isn't it?:
> https://docs.oracle.com/en/java/javase/11/docs/api/java.desktop/java/awt/event/InputEvent.html#getModifiersEx()
>
>
> If a developer use this method as described his code will be broken
> too, because good and attentive developer definitely added
> ALT_GRAPH_DOWN_MASK to 'offmask'.
>
>
> If the user wants to ignore all combinations with "Alternate Character Key"
> then, as you pointed in the start of this thread, he should ignore both
> "alt" since on macOS both alt keys are "Alternate Character Key".
>
>
> On Sat, Mar 16, 2019 at 1:27 AM Sergey Bylokhov
> <Sergey.Bylokhov at oracle.com> wrote:
>
>
> On 15/03/2019 05:54, Sergey Malenkov wrote:
>
> We have a major issue about unexpected AltGr in the keyboard layout
> that should not have AltGr at all:
> https://urldefense.proofpoint.com/v2/url?u=http-3A__youtrack.jetbrains.com_issue_IDEA-2D206348&d=DwIFaQ&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=QF7AertWDY_M4hfHg_4S-iyX-aP0wtLYwZFgs0zfX_k&m=j-gQEy4UDmzd3Sa5zjEYskUw4CoYUZ9gDurLkGu1YOo&s=HcCKCq8FPyOoJEvT4qk59DJqCAiRB-BvECy_VCAdpqI&e=
> Why you decided to support AltGr for every keyboard layout? It really
> breaks backward compatibility!
>
>
> Even in your bug report the people complain that altGr key does not work, and
> the only problem here is that it does not assigned by default.
> But on the other side it is possible to set separate shortcuts
> to the "Alt + Alt Graph + Enter"and "Alt + Enter":
>
> I think the main client is Swing and pressed AltGr that looks like
> 'Alt+AltGr+' breaks all Alt-based shortcuts defined in
> javax.swing.plaf.basic.BasicLookAndFeel#initComponentDefaults and
> other places. Now, if you press "alt LEFT", the "moveColumnLeft"
> action is performed only for the left Alt. And this also breaks a
> backward compatibility.
>
>
> The term "all" is not so critical, there are only few such shortcuts, and it is
> a good thing that potentially we can set different shortcuts for each.
> This is a bug that these places were not updated, it is easy to fix since this
> is not exposed via public API.
> But we will get the same result if we will use the AltGr mask only.
>
> It is not backward compatible to use AltGr instead of right Alt in
> both cases. Instead of 'Alt+key' you will get 'AltGr+key' or
> 'Alt+AltGr+key', which are not bound to any action.
>
>
> It is compatible to the specification of InputEvent.getModifiersEx():
> KeyEvent event = new KeyEvent(new Button(), 0, 0,
>                                ALT_DOWN_MASK | ALT_GRAPH_DOWN_MASK, 0);
>    int onmask =  ALT_DOWN_MASK;
>    int offmask = CTRL_DOWN_MASK|SHIFT_DOWN_MASK;
>    if ((event.getModifiersEx() & (onmask | offmask)) == onmask) {
>      ...
>    }
>
> The code above works before and after the change for altGr.
> But it will stop working if we will use altGr only, and it will be hard to argue
> why the ALT flag is not set while alt key is pressed(since on some keyboards this key is
> marked as alt and on some other altGr).
>
> And as specially noted in the method above the code should not assume which
> flags(and how many) were set by the actions, if such assumptions exists in
> Swing itself they should be fixed as well.
>
>
> On Fri, Mar 15, 2019 at 9:27 AM Krishna Addepalli
> <krishna.addepalli at oracle.com> wrote:
>
>
> Hi Sergey Malenkov,
>
> 'Alt+AltGr+Right' does nothing, because we do not assign this shortcut yet
>
> In my personal experience, I did not find any instance, wherein a shortcut had left and right alt in it.
> Although it is not impossible, it seems weird to define such shortcuts.
> It would be helpful if you could point to some resources, wherein defining such shortcuts is acceptable.
>
> Thanks,
> Krishna
>
> On 14-Mar-2019, at 4:03 PM, Sergey Malenkov <malenkov at gmail.com> wrote:
>
> I strongly don't like two masks for one key. If you press VK_ALT,
> ALT_DOWN_MASK should be set. If you press VK_SHIFT then,
> SHIFT_DOWN_MASK should be added to indicate that both keys are
> pressed. And if you press VK_ALT_GRAPH, only ALT_GRAPH_DOWN_MASK
> should be added. Otherwise, you can't distinguish the following key
> strokes: 'AltGr+Right' and 'Alt+AltGr+Right'. But these keystrokes are
> different and should invoke different actions. For example,
> 'Alt+Right' moves cursor to the next word
> 'Alt+Shift+Right' moves cursor to the next word AND adds all skipped
> characters to selection
> 'Alt+AltGr+Right' does nothing, because we do not assign this shortcut yet
>
> On Thu, Mar 14, 2019 at 12:09 AM Sergey Bylokhov
> <Sergey.Bylokhov at oracle.com> wrote:
>
>
> On 13/03/2019 03:59, Sergey Malenkov wrote:
>
> I missed the "for ALT keys" in the bug title and thought that
> "KeyEvent.getModifiers() returns inconsistent values" was about
> incompatible behaviour on different platforms. In fact, JDK-8218917
> should be renamed to something like “The right Alt key on Mac should
> behave as Alt and must not break the left Alt key processing”.
>
>
> But the "right Alt" should behave like a "left alt" already, it should use both flags:
> the common alt(ALT_DOWN_MASK) and the altGr(ALT_GRAPH_DOWN_MASK).
>
> So if the client will follow the spec below it should work as before, isn't it?:
> https://docs.oracle.com/en/java/javase/11/docs/api/java.desktop/java/awt/event/InputEvent.html#getModifiersEx()
>
> On Wed, Mar 13, 2019 at 6:57 AM Sergey Bylokhov
> <Sergey.Bylokhov at oracle.com> wrote:
>
>
> On 12/03/2019 12:28, Sergey Malenkov wrote:
>
> Hi Sergey,
>
> 1. macOS uses a regular Alt key as "Alternate Character Key". This is
> the reason why JDK Toolkit defines Ctrl+Alt to select a mnemonic,
> instead of simple Alt. See
> https://urldefense.proofpoint.com/v2/url?u=https-3A__sites.google.com_site_malenkov_java_141229&d=DwIFaQ&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=QF7AertWDY_M4hfHg_4S-iyX-aP0wtLYwZFgs0zfX_k&m=j-gQEy4UDmzd3Sa5zjEYskUw4CoYUZ9gDurLkGu1YOo&s=Y6PcJ4DGp2cSnTLEvtsIdt55_u0F8VqL5LSA7vBPbkw&e=
>
>
> Right, but introducing this flag for the "left alt" could cause even more
> issues, so this flag is set only for the right.
>
> 3. Regression was caused by adding AltGr to key processing on Mac. But
> I found more issues with inconsistent key processing on different
> platforms. See https://urldefense.proofpoint.com/v2/url?u=http-3A__sites.google.com_site_malenkov_java_190312&d=DwIFaQ&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=QF7AertWDY_M4hfHg_4S-iyX-aP0wtLYwZFgs0zfX_k&m=j-gQEy4UDmzd3Sa5zjEYskUw4CoYUZ9gDurLkGu1YOo&s=Y7GZdeTQvRyIBxAsCDtaB8PZo9_GRVYIZZvn2VfCzJc&e=
>
>
> Not sure that CAPS_LOCK is related.
>
>
>
> On Tue, Mar 12, 2019 at 4:17 AM Sergey Bylokhov
> <Sergey.Bylokhov at oracle.com> wrote:
>
>
> On 11/03/2019 17:37, Philip Race wrote:
>
> The debate is about AltGraph which an ancient MS-DOSism for
> asking for an ALTernate GRAPHics bitmap font - all pre-dates windows
> and I am sure has never been applicable to any MacOS.
>
>
> It also about the "right alt" which is also know as "AltGraph". I guess currently
> it is implemented as "right alt" on Linux/macOS/windows.
>
> BTW on linux it is also named as "Alternative Characters Key":
> https://urldefense.proofpoint.com/v2/url?u=https-3A__help.ubuntu.com_community_ComposeKey&d=DwIFaQ&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=QF7AertWDY_M4hfHg_4S-iyX-aP0wtLYwZFgs0zfX_k&m=j-gQEy4UDmzd3Sa5zjEYskUw4CoYUZ9gDurLkGu1YOo&s=DvJtvBcerkulT3S417Vu6hQyXy7e0bI1bX9fInefV-A&e=
>
> So someone needs to properly explain why we would claim a Mac keyboard
> is OK to generate a keycode it doesn't have and cause a slew of regressions
> in the process ...>
> If Mac doesn't distinguish these two, we should generate the same keycode for both.
>
>
> The macOS supports "right alt", otherwise it would not be possible to implement it in java:
> https://urldefense.proofpoint.com/v2/url?u=https-3A__developer.apple.com_library_archive_technotes_tn2450_-5Findex.html&d=DwIFaQ&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=QF7AertWDY_M4hfHg_4S-iyX-aP0wtLYwZFgs0zfX_k&m=j-gQEy4UDmzd3Sa5zjEYskUw4CoYUZ9gDurLkGu1YOo&s=hD5wMxSuL3iN_tqTn0Cd5ULhp_bGzQl3fFnQQdNXNuU&e=
>
>
> One could suppose there is a difference else why two keys, but what is the right
> thing to do here  that fixes all the problems. What exactly WAS the problem
> with what was there in the first place ? And if changing it is correct why is it
> causing regressions ?
>
>
> Regressions were caused by the bugs in the fix implementation, or am I missed something?
>
>
>
> -phil.
>
>
>
> On 3/12/19, 5:34 AM, Sergey Bylokhov wrote:
>
> Hi, Phil.
> On 11/03/2019 07:43, Philip Race wrote:
>
> The reasoning that AltGraph might be useful to someone is a bit weak
> and I don't think I'd want to support it via system property or build options.
>
> If its not a platform keyboard key, why do we need it ?
>
>
> The "AltGraph" key is also commonly referred to as "Right Alt", and
> it has been implemented on all platforms as a "Right Alt", it is convenient to
> distinguish the left/right alts.
>
>
>
> --
> Best regards, Sergey.
>
>
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> --
> Best regards, Sergey.
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> --
> Best regards, Sergey.
>
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>
>
> --
> Best regards,
> Sergey A. Malenkov
>
>
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> --
> Best regards, Sergey.
>
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> --
> Best regards, Sergey.
>
>
>
>
> --
> Best regards,
> Sergey A. Malenkov
>
>

-- 
Best regards,
Sergey A. Malenkov