fix(macOS): correct right and middle mouse drag handling

[mkrusen]

Description

Fixes macOS right and middle mouse drag handling in the CoreGraphics mouse backend.

I encountered an issue while using Sunshine as a macOS host with Moonlight as the client where a normal right-click worked, but holding the right mouse button while moving the mouse did not behave correctly.

The macOS backend tracks mouse button state with index 0 as left, 1 as right, and 2 as middle. However, event_type_for_current_buttons() mapped the right button to kCGEventOtherMouseDragged and the middle button to kCGEventRightMouseDragged.

This change corrects those mappings so that:

• the right mouse button generates kCGEventRightMouseDragged
• the middle mouse button generates kCGEventOtherMouseDragged

It also adds selection of the currently held mouse button for relative and absolute mouse movement. Previously these movement events always passed kCGMouseButtonLeft to post_mouse(), even when the right or middle button was being held.

I tested the change using Sunshine on macOS with Moonlight as the client. Before the change, right-click worked but right-click-and-hold with mouse movement did not work correctly.

Screenshot

Issues Fixed or Closed

Roadmap Issues

Type of Change

• feat: New feature (non-breaking change which adds functionality)
• fix: Bug fix (non-breaking change which fixes an issue)
• docs: Documentation only changes
• style: Changes that do not affect the meaning of the code (white-space, formatting, missing semicolons, etc.)
• refactor: Code change that neither fixes a bug nor adds a feature
• perf: Code change that improves performance
• test: Adding missing tests or correcting existing tests
• build: Changes that affect the build system or external dependencies
• ci: Changes to CI configuration files and scripts
• chore: Other changes that don't modify src or test files
• revert: Reverts a previous commit
• BREAKING CHANGE: Introduces a breaking change (can be combined with any type above)

Checklist

• Code follows the style guidelines of this project
• Code has been self-reviewed
• Code has been commented, particularly in hard-to-understand areas
• Code docstring/documentation-blocks for new or existing methods/components have been added or updated
• Unit tests have been added or updated for any new or modified functionality

AI Usage

See our AI usage policy.

• None: No AI tools were used in creating this PR
• Light: AI provided minor assistance (formatting, simple suggestions)
• Moderate: AI helped with code generation or debugging specific parts
• Heavy: AI generated most or all of the code changes

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.47%. Comparing base (85cc60d) to head (955d27b).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/platform/macos/macos_backend.cpp	66.66%	4 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## master #95 +/- ##
==========================================
- Coverage 75.47% 75.47% -0.01% 
==========================================
Files 34 34 Lines 8131 8133 +2 Branches 3044 3044 ==========================================
+ Hits 6137 6138 +1 - Misses 1660 1715 +55 + Partials 334 280 -54 

Flag	Coverage Δ
FreeBSD	51.72% <ø> (ø)
Linux-Clang	57.48% <ø> (ø)
Linux-GCC	68.19% <ø> (ø)
Windows-MSVC	88.42% <ø> (-0.16%)	⬇️
Windows-MinGW-UCRT64	65.17% <ø> (ø)
macOS	51.42% <66.66%> (+0.17%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/platform/macos/macos_backend.cpp	41.82% <66.66%> (+2.74%)	⬆️

... and 11 files with indirect coverage changes

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud