[Labs] Prefer lower root spaces in bottom space bar

Change-Id: I884f52bb29d7279350e1101fdc9fd995461534e0

library/ui-strings/src/main/res/values/strings_sc.xml

@@ -146,6 +146,8 @@
 
     <string name="settings_enable_space_pager">Swipe chat list to switch space</string>
     <string name="settings_enable_space_pager_summary">Allow to switch between root spaces by swiping horizontally in the chat list</string>
+    <string name="settings_space_pager_prefer_space_1">Prefer lower root space</string>
+    <string name="settings_space_pager_prefer_space_1_summary">Prioritize showing spaces in the bottom space bar that you have moved to the top of your root space list</string>
 
     <string name="settings_notif_only_alert_once">Only alert once</string>
     <string name="settings_notif_only_alert_once_summary">Omit alert sounds for new messages if there is already an open notification for that chat</string>

vector/src/main/java/im/vector/app/features/home/room/list/home/spacebar/SpaceBarController.kt

@@ -25,11 +25,13 @@ import com.airbnb.epoxy.Carousel
 import com.airbnb.epoxy.Carousel.SnapHelperFactory
 import com.airbnb.epoxy.EpoxyController
 import com.airbnb.epoxy.EpoxyModel
+import com.airbnb.epoxy.ModelProp
 import com.airbnb.epoxy.ModelView
 import com.github.rubensousa.gravitysnaphelper.GravitySnapHelper
 import im.vector.app.core.resources.StringProvider
 import im.vector.app.features.home.AvatarRenderer
 import im.vector.app.features.home.room.list.UnreadCounterBadgeView
+import im.vector.app.features.settings.VectorPreferences
 import org.matrix.android.sdk.api.session.room.model.RoomSummary
 import org.matrix.android.sdk.api.util.toMatrixItem
 import javax.inject.Inject
@@ -39,6 +41,7 @@ import kotlin.math.min
 class SpaceBarController @Inject constructor(
         val stringProvider: StringProvider,
         private val avatarRenderer: AvatarRenderer,
+        private val vectorPreferences: VectorPreferences,
 ) : EpoxyController() {
 
     private var data: SpaceBarData = SpaceBarData()
@@ -61,6 +64,7 @@ class SpaceBarController @Inject constructor(
 
     private fun addSpaces(host: SpaceBarController, spaces: List<RoomSummary?>, selectedSpace: RoomSummary?) {
         spaceBarCarousel {
+            enableSnap(host.vectorPreferences.preferSpecificSpacePagerSpace())
             id("spaces_carousel")
             padding(
                     Carousel.Padding(
@@ -146,12 +150,21 @@ class SpaceBarController @Inject constructor(
             // Scroll to an element such that the new selection is roughly in the middle
             val firstVisible = lm.findFirstCompletelyVisibleItemPosition()
             val visibleRange = lm.findLastCompletelyVisibleItemPosition() - firstVisible + 1
-            val overshoot = visibleRange/2
+            if (vectorPreferences.preferSpecificSpacePagerSpace()) { // scroll to smallest space possible
-            val currentMiddle = firstVisible + overshoot
+                effectivePosition = when {
-            if (currentMiddle < position) {
+                    position < 1 -> 0 // show home only if it is selected
-                effectivePosition = position + overshoot
+                    firstVisible < 1 && position <= visibleRange -> 1 + visibleRange // hide home
-            } else if (currentMiddle > position) {
+                    position > firstVisible + visibleRange -> position // make selection visible by scrolling right
-                effectivePosition = position - overshoot
+                    else -> max(1, position - visibleRange) // make selection visible by scrolling left, as right as possible without scrolling to home
+                }
+            } else { // center current space
+                val overshoot = visibleRange / 2
+                val currentMiddle = firstVisible + overshoot
+                if (currentMiddle < position) {
+                    effectivePosition = position + overshoot
+                } else if (currentMiddle > position) {
+                    effectivePosition = position - overshoot
+                }
             }
             // List limits
             effectivePosition = max(0, min(effectivePosition, lm.itemCount-1))
@@ -168,16 +181,19 @@ private inline fun <T> SpaceBarCarouselModelBuilder.withModelsFrom(
 }
 
 @ModelView(autoLayout = ModelView.Size.MATCH_WIDTH_WRAP_HEIGHT)
-internal class SpaceBarCarousel(context: Context?) : Carousel(context) {
+class SpaceBarCarousel(context: Context?) : Carousel(context) {
+    private var mEnableSnap: Boolean = false
+    @ModelProp // Couldn't get ModelProp to work without explicit setter
+    fun setEnableSnap(value: Boolean) {
+        mEnableSnap = value
+    }
     override fun getSnapHelperFactory(): SnapHelperFactory? {
-        return null // SpaceBarSnapHelperFactory()
+        return if (mEnableSnap) SpaceBarSnapHelperFactory() else null
     }
 }
 
-/*
 internal class SpaceBarSnapHelperFactory: SnapHelperFactory() {
     override fun buildSnapHelper(context: Context?): SnapHelper {
-        return GravitySnapHelper(Gravity.CENTER)
+        return GravitySnapHelper(Gravity.START)
     }
 }
- */

vector/src/main/java/im/vector/app/features/settings/VectorPreferences.kt

@@ -252,6 +252,7 @@ class VectorPreferences @Inject constructor(
         private const val SETTINGS_JUMP_TO_BOTTOM_ON_SEND = "SETTINGS_JUMP_TO_BOTTOM_ON_SEND"
         private const val SETTINGS_SPACE_MEMBERS_IN_SPACE_ROOMS = "SETTINGS_SPACE_MEMBERS_IN_SPACE_ROOMS"
         private const val SETTINGS_ENABLE_SPACE_PAGER = "SETTINGS_ENABLE_SPACE_PAGER"
+        private const val SETTINGS_SPACE_PAGER_BAR_PREFER_SPACE = "SETTINGS_SPACE_PAGER_BAR_PREFER_SPACE"
         private const val SETTINGS_NOTIF_ONLY_ALERT_ONCE = "SETTINGS_NOTIF_ONLY_ALERT_ONCE"
         private const val SETTINGS_HIDE_CALL_BUTTONS = "SETTINGS_HIDE_CALL_BUTTONS"
         private const val SETTINGS_READ_RECEIPT_FOLLOWS_READ_MARKER = "SETTINGS_READ_RECEIPT_FOLLOWS_READ_MARKER"
@@ -1223,6 +1224,11 @@ class VectorPreferences @Inject constructor(
         return defaultPrefs.getBoolean(SETTINGS_ENABLE_SPACE_PAGER, false)
     }
 
+    // SC addition
+    fun preferSpecificSpacePagerSpace(): Boolean {
+        return defaultPrefs.getBoolean(SETTINGS_SPACE_PAGER_BAR_PREFER_SPACE, false)
+    }
+
     // SC addition
     fun onlyAlertOnce(): Boolean {
         return defaultPrefs.getBoolean(SETTINGS_NOTIF_ONLY_ALERT_ONCE, false)
@@ -1292,6 +1298,7 @@ class VectorPreferences @Inject constructor(
                 .putBoolean(SETTINGS_FOLLOW_SYSTEM_LOCALE, true)
                 .putBoolean(SETTINGS_ENABLE_MEMBER_NAME_CLICK, false)
                 .putBoolean(SETTINGS_CLEAR_HIGHLIGHT_ON_SCROLL, true)
+                .putBoolean(SETTINGS_SPACE_PAGER_BAR_PREFER_SPACE, true)
                 .apply()
     }
 

vector/src/main/res/xml/vector_settings_labs.xml

@@ -67,6 +67,13 @@
             android:title="@string/settings_enable_space_pager"
             android:summary="@string/settings_enable_space_pager_summary" />
 
+        <im.vector.app.core.preference.VectorSwitchPreference
+            android:defaultValue="false"
+            android:key="SETTINGS_SPACE_PAGER_BAR_PREFER_SPACE"
+            android:dependency="SETTINGS_ENABLE_SPACE_PAGER"
+            android:title="@string/settings_space_pager_prefer_space_1"
+            android:summary="@string/settings_space_pager_prefer_space_1_summary" />
+
         <im.vector.app.core.preference.VectorSwitchPreference
             android:defaultValue="false"
             android:key="SETTINGS_SHOW_OPEN_ANONYMOUS"