package app

import (

"time"

"github.com/gogpu/ui/widget"

)

// FrameStats holds timing information for a single frame.

//

// This is useful for performance monitoring and debugging.

// FrameStats is passed to the [FrameCallback] after each call to

// [App.Frame] or [Window.Frame].

type FrameStats struct {

// FrameStart is the time when Frame() was called.

FrameStart time.Time

// LayoutDuration is how long the layout pass took.

// Zero if layout was not performed this frame.

LayoutDuration time.Duration

// DrawDuration is how long the draw pass took.

DrawDuration time.Duration

// TotalDuration is the total time spent in Frame().

TotalDuration time.Duration

// LayoutPerformed indicates whether layout was recalculated this frame.

LayoutPerformed bool

// DrawSkipped indicates that the draw pass was skipped because no

// widgets in the tree needed re-rendering. When true, the host

// application can reuse the previous frame's GPU framebuffer output.

//

// This is the primary retained-mode optimization: idle UIs skip

// rendering entirely, consuming zero CPU for the draw phase.

DrawSkipped bool

// DrawStats provides per-widget statistics from the draw traversal.

//

// When DrawSkipped is true, DrawStats is zero-valued (no traversal

// was performed). When DrawSkipped is false, DrawStats shows how many

// widgets were drawn, how many were dirty vs clean, and how many were

// skipped due to invisibility.

//

// This is primarily useful for performance monitoring and for

// validating that the retained-mode dirty-tracking system is

// working correctly.

DrawStats widget.DrawStats

}

// FrameCallback is called after each frame completes with timing statistics.

//

// This is useful for frame time monitoring and adaptive rendering.

// The callback is invoked synchronously at the end of each Frame() call.

type FrameCallback func(stats FrameStats)

// SetFrameCallback sets a callback that is invoked after each Frame call

// with timing statistics.

//

// Set to nil to disable statistics tracking. The callback is called

// synchronously on the same goroutine as Frame().

func (a *App) SetFrameCallback(cb FrameCallback) {

if a.window == nil {

return

}

a.window.frameCallback = cb

}