fix(linux): fix touch misalignment for wlgrab on scaled outputs

[herboh]

Description

PR #4607 added logical dimension tracking and scalar_tpcoords scaling support for the kmsgrab (KMS/DRM) capture backend, but my configuration (niri, multimonitor, scaled hidpi output) was still mapping input to the wrong portion of the desktop.

This PR tries to mirror the pattern used in kmsgrab.cpp to wlgrab.cpp:

• Adds env_logical_width / env_logical_height statics to the wl namespace
• Sets logical_width, logical_height, env_logical_width, env_logical_height on the display object during wlr_t::init()

Additionally, the touch and pen passthrough functions in input.cpp are updated to normalize coordinates relative to the streamed monitor rather than the full desktop.

Screenshot

Issues Fixed or Closed

• Partially fixes Touch input is wrong on multi-monitor configurations on Linux #2166 for wlgrab

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

• 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

[ReenigneArcher]

@juliosanz could you review please?

[juliosanz]

KMS still works just fine like it did in PR #4607. Changes made are in wlgrab.cpp and, indeed, mirror those made to kmsgrab.cpp.

At first glance, these changes should absolutely make things work right in wlroots. I don't have an installation at hand to try it myself, though. @Dregu pointed out some issues my PR had in wlroots, perhaps they can test it better.

[herboh]

Follow up commit to address the Sonar issues with duplication in input.cpp.

• added a helper function for touch and pen to use for monitor normalization
• removed wlgrab.cpp globals to instead compute local dimensions during wlgrab init
• renamed variables wlgrab.cpp to avoid shadowing a class field

No functional changes, just to better match the guidelines.

[ReenigneArcher]

Follow up commit to address the Sonar issues with duplication in input.cpp.

* added a helper function for touch and pen to use for monitor normalization

* removed `wlgrab.cpp` globals to instead compute local dimensions during wlgrab init

* renamed variables `wlgrab.cpp` to avoid shadowing a class field

No functional changes, just to better match the guidelines.

Thank you! Really appreciate when we can get some of this code cleaned up!

[codecov]

Bundle Report

Bundle size has no change ✅

[ReenigneArcher]

There's some issues building the docs:

Generating code for file src/home/docs/checkouts/readthedocs.org/user_builds/sunshinestream/checkouts/4665/src/input.cpp:907: error: argument 'input' of command @param is not found in the argument list of input::monitor_touch_port(const input::touch_port_t &touch_port, std::pair< float, float > &coords)
--
/home/docs/checkouts/readthedocs.org/user_builds/sunshinestream/checkouts/4665/src/input.cpp:907: error: argument 'packet' of command @param is not found in the argument list of input::monitor_touch_port(const input::touch_port_t &touch_port, std::pair< float, float > &coords)
/home/docs/checkouts/readthedocs.org/user_builds/sunshinestream/checkouts/4665/src/input.cpp:907: error: The following parameters of input::monitor_touch_port(const input::touch_port_t &touch_port, std::pair< float, float > &coords) are not documented:
parameter 'touch_port'
parameter 'coords'

[sonarqubecloud]

Quality Gate failed

Failed conditions
19.6% Duplication on New Code (required ≤ 2%)
2 Duplicated Blocks on New Code (required ≤ 0)

See analysis details on SonarQube Cloud

[ReenigneArcher]

Suggested change

	void passthrough(std::shared_ptr<input_t> &input, PSS_TOUCH_PACKET packet) {
	/**
	* @brief Called to pass a touch message to the platform backend.
	* @param input The input context pointer.
	* @param packet The touch packet.
	*/
	void passthrough(std::shared_ptr<input_t> &input, PSS_TOUCH_PACKET packet) {

I think the docs were accidentally removed from this function?

[Dregu]

perhaps they can test it better

Well I don't use touch, but at least the things I do use, mouse on scaled wlr and kms, still seem to work fine 👍🏻