Smooth Automatic Scrolling for Webtoon (#777)

(cherry picked from commit 82f0e5bc01e93baa1cd81f9c898d15d51e3faa1b)

app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderActivity.kt

@@ -807,12 +807,22 @@ class ReaderActivity : BaseActivity() {
                         repeatOnLifecycle(Lifecycle.State.STARTED) {
                             val interval = parsed.seconds
                             while (true) {
-                                delay(interval)
-                                viewer.let { v ->
-                                    when (v) {
-                                        is PagerViewer -> v.moveToNext()
-                                        is WebtoonViewer -> v.scrollDown()
+                                if (!binding.readerMenu.isVisible) {
+                                    viewer.let { v ->
+                                        when (v) {
+                                            is PagerViewer -> v.moveToNext()
+                                            is WebtoonViewer -> {
+                                                if (readerPreferences.smoothAutoScroll().get()) {
+                                                    v.linearScroll(interval)
+                                                } else {
+                                                    v.scrollDown()
+                                                }
+                                            }
+                                        }
                                     }
+                                    delay(interval)
+                                } else {
+                                    delay(100)
                                 }
                             }
                         }

app/src/main/java/eu/kanade/tachiyomi/ui/reader/setting/ReaderPreferences.kt

@@ -133,6 +133,8 @@ class ReaderPreferences(
 
     fun autoscrollInterval() = preferenceStore.getFloat("eh_util_autoscroll_interval", 3f)
 
+    fun smoothAutoScroll() = preferenceStore.getBoolean("smooth_auto_scroll", true)
+
     fun preserveReadingPosition() = preferenceStore.getBoolean("eh_preserve_reading_position", false)
 
     fun preloadSize() = preferenceStore.getInt("eh_preload_size", 10)

app/src/main/java/eu/kanade/tachiyomi/ui/reader/setting/ReaderReadingModeSettings.kt

@@ -134,6 +134,7 @@ class ReaderReadingModeSettings @JvmOverloads constructor(context: Context, attr
         // SY -->
         binding.webtoonPrefsGroup.zoomOutWebtoon.bindToPreference(readerPreferences.webtoonEnableZoomOut())
         binding.webtoonPrefsGroup.cropBordersContinuousVertical.bindToPreference(readerPreferences.cropBordersContinuousVertical())
+        binding.webtoonPrefsGroup.smoothScrollWebtoon.bindToPreference(readerPreferences.smoothAutoScroll())
         binding.webtoonPrefsGroup.pageTransitionsWebtoon.bindToPreference(readerPreferences.pageTransitionsWebtoon())
         // SY <--
     }

app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonViewer.kt

@@ -6,6 +6,7 @@ import android.view.MotionEvent
 import android.view.View
 import android.view.ViewGroup
 import android.view.ViewGroup.LayoutParams.MATCH_PARENT
+import android.view.animation.LinearInterpolator
 import androidx.core.app.ActivityCompat
 import androidx.core.view.isGone
 import androidx.core.view.isVisible
@@ -29,6 +30,7 @@ import uy.kohesive.injekt.api.get
 import uy.kohesive.injekt.injectLazy
 import kotlin.math.max
 import kotlin.math.min
+import kotlin.time.Duration
 
 /**
  * Implementation of a [BaseViewer] to display pages with a [RecyclerView].
@@ -300,6 +302,13 @@ class WebtoonViewer(val activity: ReaderActivity, val isContinuous: Boolean = tr
         }
     }
 
+    /**
+     * Scrolls one screen over a period of time
+     */
+    fun linearScroll(duration: Duration) {
+        recycler.smoothScrollBy(0, activity.resources.displayMetrics.heightPixels, LinearInterpolator(), duration.inWholeMilliseconds.toInt())
+    }
+
     /**
      * Scrolls down by [scrollDistance].
      */

app/src/main/res/layout/reader_webtoon_settings.xml

@@ -46,6 +46,15 @@
         android:text="@string/pref_crop_borders"
         android:textColor="?android:attr/textColorSecondary" />
 
+    <com.google.android.material.materialswitch.MaterialSwitch
+        android:id="@+id/smooth_scroll_webtoon"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:paddingHorizontal="16dp"
+        android:paddingVertical="16dp"
+        android:textColor="?android:attr/textColorSecondary"
+        android:text="@string/pref_smooth_scroll"/>
+
     <com.google.android.material.materialswitch.MaterialSwitch
         android:id="@+id/page_transitions_webtoon"
         android:layout_width="match_parent"

i18n/src/main/res/values/strings_sy.xml

@@ -253,6 +253,7 @@
     <string name="pref_left_handed_vertical_seekbar_summary">Switches which side the seekbar is on</string>
     <string name="pref_force_horz_seekbar">Force horizontal seekbar</string>
     <string name="pref_force_horz_seekbar_summary">Removes vertical seekbar entirely in favour of horizontal</string>
+    <string name="pref_smooth_scroll">Smooth Auto Scroll</string>
 
     <!-- Reader -->
     <!-- Reader Actions -->