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Surface: correct scroll-event semantics (scrolling was far too fast) #9

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Merged
arach merged 1 commit into from
Jul 12, 2026
Merged

Surface: correct scroll-event semantics (scrolling was far too fast) #9

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77 changes: 77 additions & 0 deletions Package.resolved
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34 changes: 31 additions & 3 deletions Sources/Termini/TerminiSurfaceView.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -691,12 +691,40 @@ public final class SurfaceContainerView: NSView {
sendMouseMove(event)
}

// The last argument of ghostty_surface_mouse_scroll is NOT keyboard mods:
// bit 0 is the precision flag and bits 1–3 the momentum phase (ghostty
// src/input/mouse.zig). Passing the keyboard-modifier bitmask made ghostty
// treat trackpad *pixel* deltas as discrete wheel ticks, multiplying each
// by the cell height — one line scrolled per pixel of finger travel (and
// holding shift flipped the precision bit). Mirror ghostty's own AppKit
// surface view instead: precise deltas are pixels (with ghostty's 2x feel
// multiplier), discrete wheel ticks pass through unscaled, and the
// momentum phase is forwarded so inertial scrolling behaves.
public override func scrollWheel(with event: NSEvent) {
guard let surface else { return }
let mods = modsFromFlags(event.modifierFlags)
ghostty_surface_mouse_scroll(surface, event.scrollingDeltaX, event.scrollingDeltaY, ghostty_input_scroll_mods_t(mods.rawValue))
var x = event.scrollingDeltaX
var y = event.scrollingDeltaY
let precision = event.hasPreciseScrollingDeltas
if precision {
x *= 2
y *= 2
}
let momentum: ghostty_input_mouse_momentum_e
switch event.momentumPhase {
case .began: momentum = GHOSTTY_MOUSE_MOMENTUM_BEGAN
case .stationary: momentum = GHOSTTY_MOUSE_MOMENTUM_STATIONARY
case .changed: momentum = GHOSTTY_MOUSE_MOMENTUM_CHANGED
case .ended: momentum = GHOSTTY_MOUSE_MOMENTUM_ENDED
case .cancelled: momentum = GHOSTTY_MOUSE_MOMENTUM_CANCELLED
case .mayBegin: momentum = GHOSTTY_MOUSE_MOMENTUM_MAY_BEGIN
default: momentum = GHOSTTY_MOUSE_MOMENTUM_NONE
}
let scrollMods = ghostty_input_scroll_mods_t(
(precision ? 1 : 0) | (Int32(momentum.rawValue) << 1)
)
ghostty_surface_mouse_scroll(surface, x, y, scrollMods)
requestActiveRenderBurst(duration: 0.35)
logInput("scroll dx=\(event.scrollingDeltaX) dy=\(event.scrollingDeltaY) mods=0x\(String(mods.rawValue, radix: 16))")
logInput("scroll dx=\(x) dy=\(y) precision=\(precision) momentum=\(momentum.rawValue)")
}

private func sendMouse(_ event: NSEvent, state: ghostty_input_mouse_state_e) {
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