<AWT Dev> [13] JDK-8218917: KeyEvent.getModifiers() returns inconsistent values for ALT keys
Sergey Malenkov
malenkov at gmail.com
Thu Mar 21 10:18:28 UTC 2019
Hi Sergey,
> I am not sure what does it meant "forget about Meta", if the code does not care
> about "altGr"/"meta/mouse_buttons" it should not use it as off/onnmask and as a result it should ignore it.
> BTW it is not missed in the JavaDoc:
> https://docs.oracle.com/en/java/javase/11/docs/api/java.desktop/java/awt/event/InputEvent.html#field.summary
That is I am talking about!
Consider opposite point of view. If the code care about these buttons,
your fix breaks the code, because Alt became AltGr unexpectedly.
> > I believe that the example in the javadoc is not entirely correct.
>
> Why it is incorrect?
Because on Mac it considers that Alt+F and Alt+Meta+F are equal.
And junior developer will be surprised.
> >
> > 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:
> >>>>> http://youtrack.jetbrains.com/issue/IDEA-206348
> >>>>> 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://sites.google.com/site/malenkov/java/141229
> >>>>>>>>>>
> >>>>>>>>>> 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 http://sites.google.com/site/malenkov/java/190312
> >>>>>>>>>>
> >>>>>>>>>> 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://help.ubuntu.com/community/ComposeKey
> >>>>>>>>>>>>
> >>>>>>>>>>>>> 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://developer.apple.com/library/archive/technotes/tn2450/_index.html
> >>>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>>> 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.
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> --
> >>>>>>>>>> Best regards, Sergey.
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> --
> >>>>>>>> Best regards, Sergey.
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>> --
> >>>>>>> Best regards,
> >>>>>>> Sergey A. Malenkov
> >>>>>>
> >>>>>
> >>>>>
> >>>>
> >>>>
> >>>> --
> >>>> Best regards, Sergey.
> >>>
> >>>
> >>>
> >>
> >>
> >> --
> >> Best regards, Sergey.
> >
> >
> >
>
>
> --
> Best regards, Sergey.
--
Best regards,
Sergey A. Malenkov
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