Struct Pool

struct Pool {
    gl: Option<Arc<Context>>,
    free: Vec<Target>,
    live: usize,
}

Size-keyed target pool. GL objects are created by the renderer when take finds nothing reusable and deleted here when the free list outgrows its budget. Ping-pong falls out of it: composite takes a second canvas-sized target, draws into it and returns the old canvas here, so the two keep swapping.

Fields

gl: Option<Arc<Context>>

The context, so put can actually free what it evicts. None in the pure-bookkeeping tests.

free: Vec<Target>

live: usize

Targets handed out and not yet returned.

Implementations

impl Pool

const MAX_FREE_PX: usize = 67_108_864usize

How many RGBA8 pixels the free list may hold (~256 MB: 8 × 4K, 30 × 1080p). Without a cap a preview resize walks through one target per pixel width and never frees any of them.

fn take(&mut self, w: u32, h: u32) -> Option<Target>

A free target of exactly this size, if there is one (callers create one otherwise).

fn created(&mut self)

Count a target the caller just created.

fn put(&mut self, t: Target)

Trait Implementations

impl Default for Pool

fn default() -> Pool

Returns the “default value” for a type.