From d3619e7acdb01e6f3841336b737ec90051905ca0 Mon Sep 17 00:00:00 2001
From: John Factotum <50942278+johnfactotum@users.noreply.github.com>
Date: Sat, 27 May 2023 02:30:36 +0800
Subject: [PATCH] Make touchscreen/touchpad gesture 1-to-1

For the reflowable renderer only. This breaks gestures for fixed-layout.

Fixes #862
---
 src/book-viewer.js   | 33 ++++++++++++++-------------------
 src/foliate-js       |  2 +-
 src/reader/reader.js |  9 +++++++++
 3 files changed, 24 insertions(+), 20 deletions(-)

diff --git a/src/book-viewer.js b/src/book-viewer.js
index a8dc17de..6a3e294c 100644
--- a/src/book-viewer.js
+++ b/src/book-viewer.js
@@ -253,7 +253,8 @@ GObject.registerClass({
                 .catch(e => console.error(e)),
         }))
 
-        // handle scroll and swipe events
+        // handle scroll events
+        let isDiscrete = true, dxLast, dyLast
         const scrollPageAsync = utils.debounce((dx, dy) => {
             if (Math.abs(dx) > Math.abs(dy)) {
                 if (dx > 0) return this.goRight()
@@ -266,30 +267,24 @@ GObject.registerClass({
         this.#webView.add_controller(utils.connect(new Gtk.EventControllerScroll({
             flags: Gtk.EventControllerScrollFlags.BOTH_AXES,
         }), {
+            'scroll-begin': () => isDiscrete = false,
             'scroll': (_, dx, dy) => {
                 if (this.#pinchFactor > 1) return false
                 if (this.viewSettings.scrolled) return false
-                scrollPageAsync(dx, dy)
-                return true
-            },
-        }))
-        this.add_controller(utils.connect(new Gtk.GestureSwipe({
-            propagation_phase: Gtk.PropagationPhase.CAPTURE,
-            touch_only: true,
-        }), {
-            'swipe': (_, vx, vy) => {
-                if (this.#pinchFactor > 1) return false
-                if (Math.max(Math.abs(vx), Math.abs(vy)) < 200) return false
-                if (this.viewSettings.scrolled) return false
-                if (Math.abs(vx) > Math.abs(vy)) {
-                    if (vx > 0) return this.goLeft()
-                    else if (vx < 0) return this.goRight()
-                } else {
-                    if (vy > 0) return this.prev()
-                    else if (vy < 0) return this.next()
+                if (isDiscrete) scrollPageAsync(dx, dy)
+                else {
+                    dxLast = dx
+                    dyLast = dy
+                    this.#exec('reader.scrollBy', [dx, dy])
                 }
                 return true
             },
+            'scroll-end': () => {
+                if (dxLast != null) this.#exec('reader.snap', [dxLast, dyLast])
+                isDiscrete = false
+                dxLast = null
+                dyLast = null
+            },
         }))
 
         const applyStyle = () => this.#applyStyle().catch(e => console.error(e))
diff --git a/src/foliate-js b/src/foliate-js
index a9681ee7..abcd87ed 160000
--- a/src/foliate-js
+++ b/src/foliate-js
@@ -1 +1 @@
-Subproject commit a9681ee7eb52e6c7ab665bf7cb3a892d524f3c4e
+Subproject commit abcd87ed9a9c45033bbb36170a3fda524751f3e5
diff --git a/src/reader/reader.js b/src/reader/reader.js
index 513d394d..0c37f9e3 100644
--- a/src/reader/reader.js
+++ b/src/reader/reader.js
@@ -351,6 +351,15 @@ class Reader {
             return null
         }
     }
+
+    // wrap these renderer methods
+    // because `FoliateWebView.exec()` can only pass one argument
+    scrollBy([x, y]) {
+        return this.view.renderer.scrollBy?.(x, y)
+    }
+    snap([x, y]) {
+        return this.view.renderer.snap?.(x, y)
+    }
 }
 
 globalThis.init = () => document.getElementById('file-input').click()