On Mon, 26 Sep 2022 17:36:04 GMT, Nikita Provotorov <d...@openjdk.org> wrote:
> Hi there! > JetBrains has faced with a bug on Apple M2 MacBooks when tapping (_not_ > pressing) with two fingers on a trackpad generates wrong mouse modifiers > (which are returned by > [MouseEvent.getModifiersEx](https://docs.oracle.com/en/java/javase/17/docs/api/java.desktop/java/awt/event/InputEvent.html#getModifiersEx())). > > <s>As far as I see, OpenJDK bug tracker still doesn't contain such a bug and > I don't have rights to create a new one, so the PR doesn't refer any id</s> > UPD: fixed. Here is the bug link from the JetBrains own tracker: > [JBR-4765](https://youtrack.jetbrains.com/issue/JBR-4765/Cannot-invoke-context-menu-by-two-fingers-tapping-on-MacBook-with-M2-chip). > > The bug is 100% reproducible on M2 MacBooks (at least under macOS 12.5). It's > also reproducible on M1 MacBooks, but much more rarely (about 10-15% of > reproducibility). > > ## Steps to reproduce > 1. Enable `System Preferences` -> `Trackpad` -> `Tap to click` > 2. Tap with two fingers in the following app: > > import javax.swing.*; > import java.awt.event.MouseAdapter; > import java.awt.event.MouseEvent; > > class MouseWindow { > final JFrame frame; > > MouseWindow() { > frame = new JFrame(); > frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); > > frame.setTitle("Mouse window"); > > frame.addMouseListener(new MouseAdapter() { > @Override > public void mousePressed(MouseEvent e) { > System.out.println(e); > } > }); > > frame.pack(); > > frame.setSize(300, 300); > > frame.setVisible(true); > } > > public static void main(String[] args) { > SwingUtilities.invokeLater(MouseWindow::new); > } > } > > > ### Expected > Printed mouse event has `modifiersEx` is `4096` (which is > `InputEvent.BUTTON3_DOWN_MASK`) > > ### Actual > Printed mouse event has `modifiersEx` is `4352` (which is > `InputEvent.BUTTON3_DOWN_MASK | InputEvent.META_DOWN_MASK`) > > ## Evaluation > The following happens when a native mouse event reaches Java: > 1. `NSEvent.nsToJavaModifiers(0)` called inside > [CPlatformResponder.handleMouseEvent():81](https://github.com/openjdk/jdk/blob/5ae6bc23e857535532b59aae674e2b917bbf7284/src/java.desktop/macosx/classes/sun/lwawt/macosx/CPlatformResponder.java#L81) > returns `0`. Earlier it always returned `4096` > (`InputEvent.BUTTON3_DOWN_MASK`) but not in the cases of M2 tapping. For a > trackpad press (not a tap) it still returns `4096`; > 2. So, the `0` modifier comes into MouseEvent constructor which then [goes > into > MouseEvent.setOldModifiers()](https://github.com/openjdk/jdk/blob/5ae6bc23e857535532b59aae674e2b917bbf7284/src/java.desktop/share/classes/java/awt/event/MouseEvent.java#L800) > which [initializes the field MouseEvent.modifiers to the value > 4](https://github.com/openjdk/jdk/blob/5ae6bc23e857535532b59aae674e2b917bbf7284/src/java.desktop/share/classes/java/awt/event/MouseEvent.java#L1159) > (it's `InputEvent.BUTTON3_MASK`); > 3. Next, this constructed `MouseEvent` object is pushed into EDT queue. > 4. Next, when a EDT thread pulls the event from the queue and starts to > process it, it goes into `java.awt.LightweightDispatcher.retargetMouseEvent` > and [creates a new MouseEvent based on the pulled > one](https://github.com/openjdk/jdk/blob/5ae6bc23e857535532b59aae674e2b917bbf7284/src/java.desktop/share/classes/java/awt/Container.java#L4920) > with the new value of the modifiers == `getModifiersEx() | getModifiers()`. > From the p.2 we know, that `MouseEvent.modifiers` of the pulled event is `4`, > so `getModifiersEx() | getModifiers()` is evaluated to `4`. > 5. Next, the constructor of the new MouseEvent [goes into > setNewModifiers()](https://github.com/openjdk/jdk/blob/5ae6bc23e857535532b59aae674e2b917bbf7284/src/java.desktop/share/classes/java/awt/event/MouseEvent.java#L795) > (instead of `setOldModifiers` as in p.2) and initializes its own field > modifiers to the value `4356` (`InputEvent.BUTTON3_MASK | > InputEvent.BUTTON3_DOWN_MASK | InputEvent.META_DOWN_MASK`, see > [setNewModifiers():1099](https://github.com/openjdk/jdk/blob/5ae6bc23e857535532b59aae674e2b917bbf7284/src/java.desktop/share/classes/java/awt/event/MouseEvent.java#L1099), > > [setNewModifiers():1129](https://github.com/openjdk/jdk/blob/5ae6bc23e857535532b59aae674e2b917bbf7284/src/java.desktop/share/classes/java/awt/event/MouseEvent.java#L1129)). > 6. Thus, an app receives the instance of MouseEvent with `getModifiers()` == > `4` and `getModifiersEx()` == `4352` so it thinks there is a `Command` > keystroke. > > ## Fixing > Let's set manually inside `CPlatformResponder.handleMouseEvent` a mouse > modifier which corresponds to the pressed button. > > ## What about a regression test > I've failed to write a regression test using Robot because it somehow forces > the correct mouse modifiers (`NSEvent.nsToJavaModifiers()` correctly returns > `InputEvent.BUTTON3_DOWN_MASK`), so I wrote a test that directly invokes > `CPlatformResponder.handleMouseEvent` via reflection. This pull request has now been integrated. Changeset: 2da079c6 Author: Nikita Provotorov <nikita.provoto...@jetbrains.com> Committer: Alexey Ushakov <a...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/2da079c64e880835c9c0eb36f5e63a7752ebb328 Stats: 365 lines in 2 files changed: 365 ins; 0 del; 0 mod 8294426: Two fingers tap generates wrong mouse modifiers on M2 MacBooks Reviewed-by: prr ------------- PR: https://git.openjdk.org/jdk/pull/10429
