Module device_scale 

Global device-pixel-ratio (DPI) scale factor.

All layout values (margin, padding, min_size, max_size) are stored in logical (device-independent) units. Layout algorithms call device_scale once per frame (or per layout pass) and multiply logical values by the factor to obtain physical pixel values.

Typical usage

// At startup / when the window moves to a different monitor:
agg_gui::device_scale::set_device_scale(window.scale_factor());

// Inside a layout algorithm:
let physical_margin = child.margin().scale(device_scale());

Thread safety

GUI layout always runs on the main thread. The value is stored in a thread-local Cell so reads are zero-cost (no atomic, no lock). On WASM there is only one thread, so this works correctly there too.

Functions

device_scale

Return the current device scale factor (default 1.0).

set_device_scale

Set the device scale factor.