CesiumGS/cesium

MOUSE_MOVE fires outside of canvas in Firefox

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#12,373 opened on Dec 13, 2024

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JTCgood first issueonrampingtype - bug

Description

What happened?

Inconsistent behavior of ScreenSpaceEventHandler with MOUSE_MOVE event between Firefox and Chrome.

In Chrome when the mouse moves out of the canvas and over another element the MOUSE_MOVE events stop. In Firefox the MOUSE_MOVE events continue and can have coordinates outside the range of the canvas.

My expectation is that the MOUSE_MOVE event is only triggered while the pointer is moving over the canvas element, and is not fired when the pointer is outside of the canvas.

https://github.com/user-attachments/assets/f4259184-29e5-4175-971b-58578d1c65da

Reproduction steps

  1. Open the below sandcastle in Chrome.
  2. Open the Console tab
  3. Move the mouse over the Cesium viewer and then over the red element
  4. Note that the console logs stop when the pointer moves over the red element
  5. Open sandcastle in Firefox
  6. Open the Console tab
  7. Move the mouse over the Cesium viewer and then over the red element
  8. Note that the console logs continue while over the red element, and the y value is negative.

Sandcastle example

https://sandcastle.cesium.com/#c=dVFta8IwEP4roftSQVLGvmktGyJsMHHg5qfCiMlNg+mlJJeKDP/7mlYnOBdIyHP3vFyItOiJNRr24NiEIezZFLwOFV91tbRMZIenFkloBFcmg3GJstNtBSpzLVxKB4DLWkiYNYD03JPSPoR7CQhcCmyEj04nD+6BXrAO9CRJW0y/AnYXlla2gar1GbDvElm3Yro1wI3d/LY5oHqzXkdR9I284/C/od4PNfD54mM5+5wvVrMoSIZJ7ulgoDjHPOqqto5YcCblPCOoaiMIfLYOcgfEpfd90llwZwN5reAyKWO1UErjZsQeHFTjS30t5G7jbEA1cqC6xrHv5tl5jFzphmk1KZOTcZkU8/a9rN2O0RYcxBN7HGGetZLTAy7qP19Y3OYZK+Ksi9bNiEOkbe+L177IOc+zFt5WkrVmLa6dfwA

Environment

Browser:

  • Chrome 131.0.6778.140
  • Firefox 133.0.3 CesiumJS Version: 1.124 Operating System: Windows 11 Enterprise 22631.4602

Contributor guide

Tech stack
javascript
Domain
frontend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
basic JavaScriptevent handling
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
The issue is a cross browser difference where Firefox continues to fire MOUSE MOVE events when the mouse leaves the canvas, unlike Chrome. To fix, investigate the ScreenSpaceEventHandler implementation. Look at how mouse events are bound and check if Firefox requires explicit checks on event target or use of pointer events. The code likely resides in Source/Scene/ScreenSpaceEventHandler.js or similar. Consider using pointer events or checking if the pointer is within canvas bounds before dispatching.