SHM and damage - Otter Shell

SHM pools

Two pool types share the same acquire API:

Pool	Use
`DoubleShmPool`	Interactive surfaces (bar, launcher, settings)
`SingleShmPool`	Static content (wallpaper). `forceReleaseAll()` for rare redraws

self.shm_pool = try otter_wayland.DoubleShmPool.init(.{
    .wl_shm = wl_shm,
    .width = 800,
    .height = 600,
    .scale = 2,
    .name = "my-surface",
});
self.shm_pool.?.bindListeners(); // after struct is at final address

if (self.shm_pool.?.acquire()) |acquired| {
    var surface = render.Surface.fromPixelsScaledWithStride(
        acquired.pixels,
        pool.physicalWidth(),
        pool.physicalHeight(),
        acquired.stride_pixels,
        scale,
    );
    wl_surface.attach(acquired.wl_buffer, 0, 0);
    wl_surface.damageBuffer(0, 0, pool.physicalWidth(), pool.physicalHeight());
    wl_surface.commit();
}

Row stride is 256-byte aligned. Use acquired.stride_pixels when wrapping pixels. resizeWithScale requires all buffers to be free.

DamageTracker

Accumulates dirty rectangles for partial redraws. Overflow falls back to full-surface damage.

var tracker = otter_wayland.DamageTracker.init(width, height);
tracker.addRect(dirty);
const rects = tracker.rects();
const full = tracker.needsFullRedraw();

Pass rects to otter-render quad_renderer and wl_surface.damageBuffer.

Renderer helper

createRenderer ties pool acquire, UiState.rasterize, and commit into one path for simple apps. Most apps still manage pools explicitly for custom damage.

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