Implementing the Mouse Lock API in Firefox

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Revision as of 15:27, 24 November 2011 by NorthWind87 (talk | contribs) (High-Level Mouse Lock Implementation Tasks)
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This is a working document for the implementation of the Mouse Lock API spec in Mozilla by students in David Humphrey's Mozilla Development class at Seneca College.

Please add, edit, correct, expand, etc. as necessary. This page should contain any links or other info we need.


While the project is primarily meant for students in DPS909/OSD600, feel free to join us if you want to work on things.

  • David Humphrey (lead developer, professor, @humphd)
  • Hasan Kamal-Al-Deen (tardy student, @NorthWind87)
  • Matthew Schranz (Student, OSD600, @mjschranz)
  • Yevgeniy Ivanchenko (Student, OSD600)
  • Chris Gosselin (Student, OSD600)
  • Anurag Bhatnagar (Student, DPS909, @anuragbh)
  • Raymond Hung (Wannabe Developer, Student, @Raymond_Hung)
  • Ausley Johnson(Student, OSD600)
  • Jesse Silver (Student, OSD600)
  • Ching Wei Tseng(Student, DPS909)
  • Michelle Mendoza (Student, DPS909)
  • Archana Sahota (Student, DPS909)
  • Greg Krilov (Student, DPS909)
  • Roman Hotin (Student, DPS909)
  • Sergiu Ecob (Student, OSD600)
  • Jordan Raffoul (Student)
  • Hyungryul Chun (Student, DPS909)
  • James Boelen (Masked Crusader, @jamesboelen)
  • Jacky Siu (Student, OSD600)
  • Abhishek Bhatnagar (Student, @abhishekToronto)
  • Diogo Golovanevsky Monteiro (@diogogmt)
  • Simon de Almeida(Student) (@simon661)
  • Stanley Tsang (Student, DPS909)
  • Denise Rigato (Student, DPS909)
  • Qian (Ken) Xu (Student, DPS909)
  • Moussa Tabcharani (Student, DPS909)
  • Keyan Ren (Student, OSD600)
  • <your name here>


Development work will be done using a combination of the following:


Getting Started

  1. Clone our repo and build a debug version locally
  2. Get a account and CC yourself on the bug.
  3. Set a Watch on this page and the Q/A page so you know when things change.
  4. Break the spec down into an itemized list of things we need to do, tests we need to write, features we have to add, edge cases we have to worry about, demos we need to build, etc. Put the info into this page. We need to know everything we'll have to write and schedule when we'll do each bit.
  5. Blog about your work on this implementation
  6. Add questions/answers to Mouse Lock Implementation FAQ

High-Level Mouse Lock Implementation Tasks

This list is incomplete, and needs more detail added as the following bits are completed.

  1. No mouse cursor is displayed when the mouse is locked - rhung
  2. MouseLockable DOM Implementation, navigator.pointer (Notes on MouseLock DOM Implementation Nov 13, 2011) - humph
    1. void lock (in Element target, optional in VoidCallback successCallback, optional in VoidCallback failureCallback);
      1. Callback implementation
    2. void unlock ();
      1. Needs to reset the mouse position back to the original position
    3. bool islocked (); - humph
  3. Mouse Lock Platform Implementations
    1. Windows: SetCursorPos(x, y)
    2. OS X CGWarpMouseCursorPosition(CGPointMake(x, y))
    3. Linux (GTK) gdk_display_warp_pointer (display, screen, x, y), add to ???
    4. Mobile?
  4. Investigate whether we can get movement information directly from OS - northWind
  5. mouselocklost event DOM Implementation - diogogmt
  6. Extend MouseEvent DOM implementation with movementX, movementY - humph, JSilver999
    1. Stack Trace for nsDOMMouseEvent::nsDOMMouseEvent ctor (created on mouse move)
    2. Stack Trace for nsDOMMouseEvent::GetScreenX
    3. Where to store the state info (e.g., previous position) between mouse events?
  7. The browser must exit the mouse lock state if the user agent, window, or tab loses focus - diogogmt
  8. Fixup NULLs being returned from lock() C++ implementation, should be NS*
  9. The ESC key should exit mouse lock - diogogmt
  10. Mouse lock should only work when in Full Screen Mode - diogogmt, rhung
  11. Suppress non-user generated events in mouse lock mode - rhung
  12. Refactor nsIDOMNavigator changes for pointer attribute to be in separate interface
  13. Do we need to add a user pref to enable/disable mouse lock?
  14. Do we need to do conditional compilation for mouse lock?
  15. When mouse lock is enabled clientX, clientY, screenX, and screenY must hold constant values as if the mouse did not move at all once mouse lock was entered.
  16. Freeze mouse pointer in centre of window when mouse lock is enabled (e.g., moving the mouse causes an event, but forces the mouse to go back to the original position). - JSilver999
  17. Proper IDL documentation for navigator.pointer (see example in, MouseLockable and its methods, MouseLockLost event, etc.
  18. Write a JavaScript library to somehow combine element.mozRequestFullScreen() and navigator.pointer.lock(). It would be good to hide the complexities of doing fullscreen then locking in a single API call.
  19. Mouse lock specification fix requests
  20. Convert Rescue Fox to use Mouse Lock, see
  21. Convert to use Mouse Lock
  22. Tests, tests, tests. We need tests for all aspects of the spec. List tests we need below:
    1. Check the mouse cursor during mouse lock and after mouse lock. (Needs content scripts?)
    2. Check that after unlock mouse is reset to original positions.
    3. Test to make sure that mouse lock only occurs when an element is in full screen mode (not F11 or done via the menus). This includes:
      1. Pressing the ESC key
      2. Switching focus to another window
    4. Tests for mouselocklost event
    5. <test cases go here...>
  1. Create a tutorial on how to use Mouse Lock, with code examples
  2. Add demo pages to gh-pages branch
  3. User agents may prompt for confirmation before locking, this preference may be saved as a content setting (Mentioned in class by humphd, setting would be in about:config ) mjschranz