Surface: correct scroll-event semantics (scrolling was far too fast)#9
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ghostty_surface_mouse_scroll's last argument is a scroll-mods bitmask (bit 0 = precision, bits 1-3 = momentum phase; ghostty src/input/mouse.zig), but scrollWheel passed the keyboard-modifier bitmask and never set precision. Ghostty therefore treated trackpad pixel deltas as discrete wheel ticks and multiplied each by the cell height -- one line per pixel of finger travel, ~30x too fast -- and holding shift while scrolling happened to flip the precision bit. Mirror ghostty's own AppKit surface view: hasPreciseScrollingDeltas sets the precision flag (deltas are pixels, with ghostty's 2x feel multiplier), discrete wheel ticks pass through unscaled, and momentumPhase is forwarded so inertial scrolling decays properly. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01RHWv6ccUfu4nK3yiGB4ocZ
arach
approved these changes
Jul 12, 2026
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Another one from running Termini in Belfry (see #3, #8): scrolling in the macOS surface is drastically too fast, because
scrollWheelpasses the wrong thing inghostty_surface_mouse_scroll's flags argument.The bug. That argument is a scroll-mods bitmask — bit 0 is the precision flag, bits 1–3 the momentum phase (
src/input/mouse.zigin ghostty) — butscrollWheelpasses the keyboard modifier bitmask and never sets precision. Two consequences:scrollingDeltaX/YwithhasPreciseScrollingDeltas) are pixel values, but without the precision bit ghostty interprets them as discrete wheel ticks and multiplies each by the cell height — so one pixel of finger travel scrolls a whole line, roughly cell-height× too fast (~30× at typical font sizes).The fix mirrors ghostty's own
SurfaceView_AppKit.swiftscrollWheel:hasPreciseScrollingDeltassets the precision flag and deltas pass as pixels (with the same 2× feel multiplier ghostty uses), discrete wheel ticks pass through unscaled, andNSEvent.momentumPhaseis mapped ontoghostty_input_mouse_momentum_eso inertial flick-scrolling decays properly instead of replaying raw deltas.The iOS surface's pan-gesture path already sets the precision bit correctly and is untouched.
Verified by feel in Belfry (trackpad, mouse wheel, and momentum flicks) against Ghostty.app as the reference;
swift buildclean.🤖 Generated with Claude Code
https://claude.ai/code/session_01RHWv6ccUfu4nK3yiGB4ocZ