reduced_motion.rs

`crates/veilvoice-gui/src/reduced_motion.rs`

veilvoice-gui · 348 lines · read the source here · or on GitHub

Whether the operating system has been asked to reduce motion.

Why this exists rather than an egui call

egui does not surface the platform's accessibility preference, so it has to be read here. The website gets this for free -- CSS has prefers-reduced-motion and the browser answers it -- and it would be odd for the desktop app to be the one front-end that ignores the setting.

Read once, at startup

Every platform answers this through a subprocess, and a subprocess per frame would be indefensible in a paint loop. It is read once when the app starts and cached for the session. Someone who changes the setting while VeilVoice is open sees it on the next launch, which is the same behaviour most applications have.

Absolute paths, always

Command::new("defaults") is a search, and on Windows that search includes the current working directory -- which is precisely the defect (F-13) this project fixed in veilvoice-watch and veilvoice-guard. Every tool here is named by absolute path, and an unfound tool answers "I do not know" rather than falling back to a search.

When it cannot tell

Query::Unknown means the platform was not asked or did not answer, and the caller treats that as "no reduction requested" -- because defaulting to off would silently disable animation for everybody on a platform this cannot read, which is a worse failure than missing the preference for the few who set it. The settings panel only claims the system asked for reduced motion when it actually saw it say so.

In plain words

Asks the operating system whether you have said you would rather things did not animate.

Some people get motion sickness from moving interfaces, and every system has a setting for it. Honouring it is not decoration: an application that animates regardless is one those people cannot comfortably use.

When the answer cannot be determined, animation stays on, and the setting can be overridden by hand either way.

WHAT THIS FILE CONTAINS

348 lines defining 8 functions (2 public), 1 type and 0 constants. Everything below is read out of the source, so it cannot disagree with the code.

The types it owns.

enum Query line 80 · What the platform said.

What happens when it runs. These are the ways in: public, and nothing else in this file calls them, so they are what an outside caller reaches first.

Query::reduces line 93 · Whether to treat this as a request to reduce motion.
query line 113 · Ask the operating system.
reaches macos_query, unix_query, windows_query, no_window, tool, parse_user_preferences_mask

WHAT CALLS WHAT

The functions this file defines, and the calls between them. An edge means the callee's name appears, called, inside the caller's body. This is a syntactic reading, not a type-resolved one.

The same graph as Mermaid source

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flowchart TD
    n_no_window["no_window<br/>line 68"]
    n_reduces(["Query::reduces<br/>line 93"])
    n_tool["tool<br/>line 99"]
    n_query(["query<br/>line 113"])
    n_windows_query["windows_query<br/>line 137"]
    n_parse_user_preferences_mask["parse_user_preferences_mask<br/>line 167"]
    n_macos_query["macos_query<br/>line 191"]
    n_unix_query["unix_query<br/>line 216"]
    n_macos_query --> n_no_window
    n_macos_query --> n_tool
    n_query --> n_macos_query
    n_query --> n_unix_query
    n_query --> n_windows_query
    n_unix_query --> n_no_window
    n_unix_query --> n_tool
    n_windows_query --> n_no_window
    n_windows_query --> n_parse_user_preferences_mask
    n_windows_query --> n_tool
    click n_no_window href "https://github.com/tilas01/veilvoice/blob/main/crates/veilvoice-gui/src/reduced_motion.rs#L68" "open the source"
    click n_reduces href "https://github.com/tilas01/veilvoice/blob/main/crates/veilvoice-gui/src/reduced_motion.rs#L93" "open the source"
    click n_tool href "https://github.com/tilas01/veilvoice/blob/main/crates/veilvoice-gui/src/reduced_motion.rs#L99" "open the source"
    click n_query href "https://github.com/tilas01/veilvoice/blob/main/crates/veilvoice-gui/src/reduced_motion.rs#L113" "open the source"
    click n_windows_query href "https://github.com/tilas01/veilvoice/blob/main/crates/veilvoice-gui/src/reduced_motion.rs#L137" "open the source"
    click n_parse_user_preferences_mask href "https://github.com/tilas01/veilvoice/blob/main/crates/veilvoice-gui/src/reduced_motion.rs#L167" "open the source"
    click n_macos_query href "https://github.com/tilas01/veilvoice/blob/main/crates/veilvoice-gui/src/reduced_motion.rs#L191" "open the source"
    click n_unix_query href "https://github.com/tilas01/veilvoice/blob/main/crates/veilvoice-gui/src/reduced_motion.rs#L216" "open the source"
    classDef entry fill:#1f2335,stroke:#7aa2f7,color:#c0caf5
    class n_reduces,n_query entry
    classDef helper fill:#1f2335,stroke:#bb9af7,color:#c0caf5
    class n_no_window,n_tool,n_windows_query,n_parse_user_preferences_mask,n_macos_query,n_unix_query helper

This site loads no third-party script, so it cannot run Mermaid; the diagram above is the same nodes and edges drawn by the generator instead. GitHub renders the source below directly.

ITEMS

Item	Line	Documentation
`no_window` _fn	68	Spawn without a console window.
`Query` _{pub enum}	80	What the platform said.
`Query::reduces` _{pub fn}	93	Whether to treat this as a request to reduce motion.
`tool` _fn	99	Resolve a tool to an absolute path.
`query` _{pub fn}	113	Ask the operating system.
`windows_query` _fn	137	Windows: "Show animations in Windows" lives in the UserPreferencesMask under HKCU\Control Panel\Desktop.
`parse_user_preferences_mask` _fn	167	Pull the mask out of reg query output and read the animation bit.
`macos_query` _fn	191	macOS: the Accessibility "Reduce motion" switch.
`unix_query` _fn	216	Linux and the BSDs: GNOME's enable-animations, which the other major desktops have largely adopted as the common key.