Safe Haskell	None
Language	GHC2024

NanoUI.Runner

Contents

Drawing Lock
Redraw Decision
Session loop

Description

The event loop the backends share: event waiting and frame pacing, click counting, the redraw decision, quit handling, and the drawing lock. A backend supplies a SessionDriver for event translation and presentation.

Synopsis

newtype DrawingLock = DrawingLock (IORef Bool)
newDrawingLock :: IO DrawingLock
tryWithDrawingLock :: DrawingLock -> IO a -> IO (Maybe a)
shouldRedrawFrame :: Context -> Input -> Input -> Bool -> Bool -> Bool -> IO Bool
data SessionDriver ev = SessionDriver {
- sdPollEvents :: IO [ev]
- sdWaitEvents :: Int -> IO [ev]
- sdApplyEvent :: Input -> ev -> Input
- sdIsButtonEdge :: ev -> Bool
- sdIsHardQuit :: ev -> Bool
- sdIsSessionQuit :: ev -> Bool
- sdSyncDisplay :: Context -> Input -> IO (Context, Input)
- sdDebug :: DebugSamplerRef
- sdContinuous :: !Bool
- sdPacingMs :: !Int
- sdPresentPaces :: IO Bool
- sdAlignSec :: Double
- sdShouldDraw :: Context -> Input -> Input -> Bool -> Bool -> IO Bool
- sdDraw :: Context -> Input -> Bool -> IO (Bool, Input)
- sdOnCursor :: Context -> Input -> IO ()
- sdShouldQuit :: Input -> Bool
}
runSessionLoop :: SessionDriver ev -> Context -> Input -> IO ()

Drawing Lock

newtype DrawingLock Source #

Concurrency lock for drawing vs async callbacks (e.g. resize watchers).

Constructors

DrawingLock (IORef Bool)

newDrawingLock :: IO DrawingLock Source #

Create a new unacquired drawing lock.

tryWithDrawingLock :: DrawingLock -> IO a -> IO (Maybe a) Source #

Attempt to execute an action under the drawing lock without blocking.

Redraw Decision

shouldRedrawFrame Source #

Arguments

:: Context
-> Input	Previous input
-> Input	Current input
-> Bool	Was animating on previous frame?
-> Bool	Continuous redraw requested?
-> Bool	Debug live refresh requested?
-> IO Bool

Centralized decision predicate: should the host backend redraw this frame?

Session loop

data SessionDriver ev Source #

What a backend provides to runSessionLoop.

Constructors

SessionDriver

Fields

sdPollEvents :: IO [ev]
Non-blocking poll for pending backend events.
sdWaitEvents :: Int -> IO [ev]
Wait for events with a timeout in milliseconds (-1 indicates blocking wait).
sdApplyEvent :: Input -> ev -> Input
Fold an event into the Input state.
sdIsButtonEdge :: ev -> Bool
Predicate identifying click/press boundaries where the event stream should be split.
sdIsHardQuit :: ev -> Bool
Predicate for immediate OS/SIGINT hard-quit signals (e.g. Ctrl+C).
sdIsSessionQuit :: ev -> Bool
Predicate for window close requests.
sdSyncDisplay :: Context -> Input -> IO (Context, Input)
Backend-specific display synchronization (window dimensions, DPI scale).
sdDebug :: DebugSamplerRef
The session's debug sampler: loop timing, skips, and the 4 Hz readout refresh.
sdContinuous :: !Bool
Redraw every pass without waiting for events.
sdPacingMs :: !Int
Event wait in milliseconds while something animates or a text field is being edited.
sdPresentPaces :: IO Bool
Whether the last present waited for the display (vsync), so a running animation can loop without waiting and still be frame-locked.
sdAlignSec :: Double
Frame pacing period in seconds for the timed-out wait path. Frame starts are wound onto a uniform grid of this period so animation cadence matches the host, instead of drifting with the event waiter's timer granularity.
sdShouldDraw :: Context -> Input -> Input -> Bool -> Bool -> IO Bool
Decision predicate: (ctx, prevInp, curInp, wasAnimating, debugDue) -> should this frame be rendered? Usually shouldRedrawFrame.
sdDraw :: Context -> Input -> Bool -> IO (Bool, Input)
Render frame: (ctx, curInp, forceFull) -> (dirtyAfterRender, syncedInput).
sdOnCursor :: Context -> Input -> IO ()
Sync the host cursor icon after every pass.
sdShouldQuit :: Input -> Bool
Application-level quit predicate.

runSessionLoop :: SessionDriver ev -> Context -> Input -> IO () Source #

Run an event-driven session loop until a termination event or user quit condition.