update thread lines

app/src/main/java/app/fedilab/android/helper/RecyclerViewThreadLines.kt

@@ -43,6 +43,7 @@ class RecyclerViewThreadLines(context: Context, private val lineInfoList: List<L
 
     override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
         val position = parent.getChildAdapterPosition(view)
+        if (position < 0) return
         val level = lineInfoList[position].level
         val startMargin = margin * level + margin * fontScale
         if (parent.layoutDirection == View.LAYOUT_DIRECTION_LTR) outRect.left = startMargin else outRect.right = startMargin
@@ -53,6 +54,7 @@ class RecyclerViewThreadLines(context: Context, private val lineInfoList: List<L
         for (i in 0 until childCount) {
             val view = parent.getChildAt(i)
             val position = parent.getChildAdapterPosition(view)
+            if (position < 0) return
             val lineInfo = lineInfoList[position]
             val level = lineInfo.level
 
@@ -64,11 +66,11 @@ class RecyclerViewThreadLines(context: Context, private val lineInfoList: List<L
                 paint.color = if (j > 0) lineColors[j - 1] else Color.GRAY
 
                 // draw lines for below statuses
-                if (j != level && j >= lineInfo.fullLinesStart && j <= lineInfo.fullLinesEnd)
+                if (j != level && lineInfo.lines.contains(j))
                     c.drawLine(lineStart, lineTop, lineStart, view.bottom.toFloat(), paint)
 
                 // draw vertical line for current statuses
-                if (j == level && i != 0) {
+                if (j == level && position != 0) {
                     // top the line starts at the middle of the above status
                     if (i > 0) lineTop -= parent.getChildAt(i - 1).height / 2 - 1 // '- 1' is to prevent overlapping with above horizontal line
 
@@ -76,12 +78,8 @@ class RecyclerViewThreadLines(context: Context, private val lineInfoList: List<L
                     var lineBottom = view.bottom.toFloat() - view.height / 2
 
                     // if below status has a full line for current level, extend the line to the bottom
-                    if (i < lineInfoList.lastIndex - 1) {
-                        val nextLineInfo = lineInfoList[i + 1]
-                        if (level >= nextLineInfo.fullLinesStart && level <= nextLineInfo.fullLinesEnd) {
-                            lineBottom = view.bottom.toFloat()
-                        }
-                    }
+                    if (position < lineInfoList.lastIndex && lineInfoList[position + 1].lines.contains(level) && j != maxLevel)
+                        lineBottom = view.bottom.toFloat()
 
                     // if level is max, use a dashed line
                     if (j == maxLevel) paint.pathEffect = dashPathEffect
@@ -99,7 +97,7 @@ class RecyclerViewThreadLines(context: Context, private val lineInfoList: List<L
         }
     }
 
-    data class LineInfo(var level: Int, var end: Boolean, var fullLinesStart: Int, var fullLinesEnd: Int)
+    data class LineInfo(var level: Int, var lines: List<Int>)
 
     private val Int.dpToPx: Float
         get() = this * Resources.getSystem().displayMetrics.density
@@ -112,43 +110,33 @@ class RecyclerViewThreadLines(context: Context, private val lineInfoList: List<L
     }
 }
 
-fun getThreadDecorationInfo(fediContext: StatusContext, selectedStatusId: String): MutableList<LineInfo> {
+fun getThreadDecorationInfo(statusContext: StatusContext): MutableList<LineInfo> {
     val lineInfoList = mutableListOf<LineInfo>()
-    repeat(fediContext.ancestors.size) { lineInfoList.add(LineInfo(0, true, 0, 0)) }
-    lineInfoList.add(LineInfo(0, fediContext.descendants.isNotEmpty(), 0, 0))
-    val descendantsLineInfoList = List(fediContext.descendants.size) { LineInfo(0, false, 0, 0) }
-    for (i in fediContext.descendants.indices) {
-        fediContext.descendants[i].let { status ->
+    repeat(statusContext.ancestors.size) { lineInfoList.add(LineInfo(0, listOf(0))) }
+    lineInfoList.add(LineInfo(0, listOf(0)))
+    val descendantsLineInfoList = List(statusContext.descendants.size) { LineInfo(0, listOf()) }
+    for (i in statusContext.descendants.indices) {
+        statusContext.descendants[i].let { status ->
             var level = 0
             if (status.in_reply_to_id != null) {
-                if (status.in_reply_to_id == selectedStatusId)
-                    level = 1
-                else {
-                    var replyToId: String? = status.in_reply_to_id
-                    while (replyToId != null && level < RecyclerViewThreadLines.threadLineColors.size) {
-                        level += 1
-                        replyToId = fediContext.descendants.firstOrNull { it.id == replyToId }?.in_reply_to_id
-                    }
+                var replyToId: String? = status.in_reply_to_id
+                while (replyToId != null && level < RecyclerViewThreadLines.threadLineColors.size) {
+                    level += 1
+                    replyToId = statusContext.descendants.firstOrNull { it.id == replyToId }?.in_reply_to_id
                 }
             }
             descendantsLineInfoList[i].level = level
-            val firstReply = fediContext.descendants.firstOrNull { it.in_reply_to_id == status.id }
-            if (firstReply == null) descendantsLineInfoList[i].end = true
         }
     }
-    for (i in descendantsLineInfoList.indices) {
-        var fullLinesStart = descendantsLineInfoList[i].level
-        var fullLinesEnd = descendantsLineInfoList[i].level
-        var fullLinesEndSet = false
-        for (j in i + 1 until descendantsLineInfoList.lastIndex) {
-            if (!fullLinesEndSet && descendantsLineInfoList[j].level < descendantsLineInfoList[i].level) {
-                fullLinesEnd = descendantsLineInfoList[j].level
-                fullLinesEndSet = true
-            }
-            fullLinesStart = descendantsLineInfoList[j].level.coerceAtMost(fullLinesStart)
+    for (i in descendantsLineInfoList.indices.reversed()) {
+        val lines: MutableList<Int> = mutableListOf()
+        val lineInfo = descendantsLineInfoList[i]
+        lines.add(lineInfo.level)
+        if (i < descendantsLineInfoList.lastIndex) {
+            val belowLineInfo = descendantsLineInfoList[i + 1]
+            lines.addAll(belowLineInfo.lines.filter { it < lineInfo.level })
         }
-        descendantsLineInfoList[i].fullLinesStart = fullLinesStart
-        descendantsLineInfoList[i].fullLinesEnd = fullLinesEnd
+        descendantsLineInfoList[i].lines = lines
     }
 
     lineInfoList.addAll(descendantsLineInfoList)

app/src/main/java/app/fedilab/android/ui/fragment/timeline/FragmentMastodonContext.java

@@ -251,7 +251,7 @@ public class FragmentMastodonContext extends Fragment {
                 binding.recyclerView.removeItemDecorationAt(i);
             }
         }
-        List<LineInfo> threadDecorationInfo = getThreadDecorationInfo(context, focusedStatus.id);
+        List<LineInfo> threadDecorationInfo = getThreadDecorationInfo(context);
         binding.recyclerView.addItemDecoration(new RecyclerViewThreadLines(requireContext(), threadDecorationInfo));
         binding.swipeContainer.setRefreshing(false);
         binding.recyclerView.scrollToPosition(statusPosition);