From fb3889c6021013b6dc028cae0f4392bc0bcf0eae Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Jaakko=20Kera=CC=88nen?= jaakko.keranen@iki.fi

Date: Mon, 17 Jan 2022 07:12:35 +0200

Subject: [PATCH 1/1] macOS: Scroll glitch prevention (Monterey 12.1)

src/macos.m | 39 ++++++++++++++++++++++++++++++++++++++-

1 file changed, 38 insertions(+), 1 deletion(-)

diff --git a/src/macos.m b/src/macos.m

index 911f5e3a..4ad267c1 100644

--- a/src/macos.m

+++ b/src/macos.m

@@ -429,12 +429,48 @@ static void trackSwipe_(NSEvent *event) {

#endif

static int swipeDir_ = 0;

+static int preventTapGlitch_ = 0;

static iBool processScrollWheelEvent_(NSEvent *event) {

 const iBool isPerPixel = (event.hasPreciseScrollingDeltas != 0);

 const iBool isInertia  = (event.momentumPhase & (NSEventPhaseBegan | NSEventPhaseChanged)) != 0;

 const iBool isEnded    = event.scrollingDeltaX == 0.0f && event.scrollingDeltaY == 0.0f && !isInertia;

 const iWindow *win     = &get_MainWindow()->base;

• if (isPerPixel) {

•    /* On macOS 12.1, stopping ongoing inertia scroll with a tap seems to sometimes produce
  

•       spurious large scroll events. */
  

•    switch (preventTapGlitch_) {
  

•        case 0:
  

•            if (isInertia && event.momentumPhase == NSEventPhaseChanged) {
  

•                preventTapGlitch_++;
  

•            }
  

•            else {
  

•                preventTapGlitch_ = 0;
  

•            }
  

•            break;
  

•        case 1:
  

•            if (event.scrollingDeltaY == 0 && event.momentumPhase == NSEventPhaseEnded) {
  

•                preventTapGlitch_++;
  

•            }
  

•            break;
  

•        case 2:
  

•            if (event.scrollingDeltaY == 0 && event.momentumPhase == 0 && isEnded) {
  

•                preventTapGlitch_++;
  

•            }
  

•            else {
  

•                preventTapGlitch_ = 0;
  

•            }
  

•            break;
  

•        case 3:
  

•            if (event.scrollingDeltaY != 0 && event.momentumPhase == 0 && !isInertia) {
  

•                preventTapGlitch_ = 0;
  

•                // printf("SPURIOUS\n"); fflush(stdout);
  

•                return iTrue;
  

•            }
  

•            preventTapGlitch_ = 0;
  

•            break;
  

•    }
  

• }

 /* Post corresponding MOUSEWHEEL events. */

 SDL_MouseWheelEvent e = { .type = SDL_MOUSEWHEEL };

 e.timestamp = SDL_GetTicks();

@@ -464,7 +500,8 @@ static iBool processScrollWheelEvent_(NSEvent *event) {

     e.x = -event.scrollingDeltaX;

     e.y = iSign(event.scrollingDeltaY);

 }

-// printf("#### dx:%d dy:%d phase:%ld end:%d\n", e.x, e.y, (long) event.momentumPhase, isEnded); fflush(stdout);

• // printf("#### [%d] dx:%d dy:%d phase:%ld inertia:%d end:%d\n", preventTapGlitch_, e.x, e.y, (long) event.momentumPhase,

• // isInertia, isEnded); fflush(stdout);

 SDL_PushEvent((SDL_Event *) &e);

#if 0

     /* On macOS, we handle both trackpad and mouse events. We expect SDL to identify

--

2.25.1