From 4a03c76b436bf0fe27b33039b12f034b85b27341 Mon Sep 17 00:00:00 2001
From: Jaakko Keränen <jaakko.keranen@iki.fi>
Date: Thu, 6 Aug 2020 08:20:24 +0300
Subject: macOS: Smooth inertia scrolling with trackpad

Requires a slightly tweaked SDL 2, though, when it comes to handling the scroll events.
---
 src/main.c              | 3 +++
 src/ui/documentwidget.c | 5 +++++
 src/ui/macos.m          | 7 ++++++-
 3 files changed, 14 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/main.c b/src/main.c
index f6ff045d..a8f97d52 100644
--- a/src/main.c
+++ b/src/main.c
@@ -7,7 +7,10 @@
 
 #include "app.h"
 
+extern void enableWheel_MacOS(void);
+
 int main(int argc, char **argv) {
+    enableWheel_MacOS();
 #if defined (iPlatformMsys)
     /* MSYS runtime takes care of WinMain. */
     SDL_SetMainReady();
diff --git a/src/ui/documentwidget.c b/src/ui/documentwidget.c
index 48eb482f..6d3e7a9c 100644
--- a/src/ui/documentwidget.c
+++ b/src/ui/documentwidget.c
@@ -864,11 +864,16 @@ static iBool processEvent_DocumentWidget_(iDocumentWidget *d, const SDL_Event *e
         }
     }
     else if (ev->type == SDL_MOUSEWHEEL) {
+#if defined (iPlatformApple)
+        /* Momentum scrolling. */
+        scroll_DocumentWidget_(d, -ev->wheel.y * get_Window()->pixelRatio);
+#else
         if (keyMods_Sym(SDL_GetModState()) == KMOD_PRIMARY) {
             changeTextSize_DocumentWidget_(d, ev->wheel.y > 0 ? 10 : -10);
             return iTrue;
         }
         scroll_DocumentWidget_(d, -3 * ev->wheel.y * lineHeight_Text(default_FontId));
+#endif
         return iTrue;
     }
     else if (ev->type == SDL_MOUSEMOTION) {
diff --git a/src/ui/macos.m b/src/ui/macos.m
index b50fbf38..46d2bfa1 100644
--- a/src/ui/macos.m
+++ b/src/ui/macos.m
@@ -98,7 +98,7 @@ enum iTouchBarVariant {
 //- (NSTouchBar *)makeTouchBar;
 /* SDL needs to do its own thing. */
 - (BOOL)application:(NSApplication *)theApplication openFile:(NSString *)filename;
-- (void)applicationDidFinishLaunching:(NSNotification *)notificatiosn;
+- (void)applicationDidFinishLaunching:(NSNotification *)notifications;
 @end
 
 @implementation MyDelegate
@@ -333,6 +333,11 @@ enum iTouchBarVariant {
 
 @end
 
+void enableWheel_MacOS(void) {
+    [[NSUserDefaults standardUserDefaults] setBool: YES
+                                            forKey: @"AppleMomentumScrollSupported"];
+}
+
 void setupApplication_MacOS(void) {
     NSApplication *app = [NSApplication sharedApplication];
     /* Our delegate will override SDL's delegate. */
-- 
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