WheelScrollGuard

Location: qml/components/control/util/WheelScrollGuard.qml

WheelScrollGuard routes wheel deltas to an intended inner flickable and optionally consumes the event.

Purpose

• Prevent nested scroll bleed between inner and outer scroll surfaces.
• Convert wheel delta input into bounded contentY updates.

API

• targetFlickable (must expose contentY, contentHeight, height)
• consumeInside (default true)
• fallbackStep (default Theme.gap20)
• wheelRouted(wheelEvent, delta, previousContentY, nextContentY) signal

Usage

import LVRS 1.0 as LV

LV.WheelScrollGuard {
    anchors.fill: parent
    targetFlickable: innerFlick
    consumeInside: true
}

How It Works

• Uses internal EventListener trigger wheel.
• Routes events only when pointer point lies within target flickable bounds.
• Delta source priority: pixelDelta.y -> angleDelta.y converted by fallbackStep.
• Applies bounded contentY updates (0..maxContentY) and emits wheelRouted.

Advanced Example: Passive Routing Mode

import LVRS 1.0 as LV

LV.WheelScrollGuard {
    targetFlickable: editorFlick
    consumeInside: false
}

This mode routes wheel delta but does not force event acceptance.

FAQ

Q. Why does wheel scroll still affect outer container?
A. Check consumeInside. When false, event propagation is intentionally allowed.

Q. Why no movement even though wheel events fire?
A. Verify target exposes valid contentHeight, height, and currently has scrollable overflow.

Validation Checklist

• pointer-inside detection maps correctly under nested transforms,
• delta conversion behaves consistently across mouse and touchpad,
• bounded scrolling prevents overshoot past content limits.