Highlight rows after collapsing logs

app/src/main/java/se/ajpanton/notificationlog/ViewLogsFragment.kt

@@ -1,5 +1,10 @@
 package se.ajpanton.notificationlog
 
+import android.animation.Animator
+import android.animation.AnimatorListenerAdapter
+import android.animation.ArgbEvaluator
+import android.animation.ValueAnimator
+import android.graphics.Color
 import android.graphics.BitmapFactory
 import android.graphics.Paint
 import android.os.Bundle
@@ -26,6 +31,7 @@ import se.ajpanton.notificationlog.capture.NotificationCaptureService
 import java.text.DateFormat
 import java.util.Date
 import androidx.fragment.app.Fragment
+import androidx.core.content.ContextCompat
 import androidx.core.view.children
 import androidx.core.view.doOnPreDraw
 
@@ -124,10 +130,18 @@ class ViewLogsFragment : Fragment(R.layout.fragment_view_logs) {
             val contents = fieldValue(LogField.CONTENTS, row.entry, settings)
             val hasContents = LogField.CONTENTS in settings.visibleFields && !contents.isNullOrEmpty()
             val toggleExpanded = {
-                val collapseAnchor = if (expanded) captureCollapseAnchor(this@apply) else null
+                val collapsing = expanded
+                val collapseAnchor = if (collapsing) captureCollapseAnchor(this@apply) else null
                 if (!expandedIds.add(row.entry.id)) expandedIds.remove(row.entry.id)
                 renderExpanded(row.entry.id in expandedIds)
-                collapseAnchor?.let(::restoreCollapseAnchor)
+                if (collapsing) {
+                    val highlight = { highlightCollapsedRow(this@apply) }
+                    if (collapseAnchor != null) {
+                        restoreCollapseAnchor(collapseAnchor, highlight)
+                    } else {
+                        this@apply.doOnPreDraw { highlight() }
+                    }
+                }
                 Unit
             }
             val metadataCell = metadataCell(metadata, expanded, toggleExpanded, row.entry.id).apply {
@@ -355,7 +369,7 @@ class ViewLogsFragment : Fragment(R.layout.fragment_view_logs) {
         }
     }
 
-    private fun restoreCollapseAnchor(anchor: CollapseAnchor) {
+    private fun restoreCollapseAnchor(anchor: CollapseAnchor, afterRestore: () -> Unit) {
         val currentBinding = binding ?: return
         val scroll = currentBinding.logScroll
         val rows = currentBinding.logRows
@@ -368,6 +382,30 @@ class ViewLogsFragment : Fragment(R.layout.fragment_view_logs) {
             }
             val maximum = (scroll.getChildAt(0).height - scroll.height).coerceAtLeast(0)
             scroll.scrollTo(0, target.coerceIn(0, maximum))
+            afterRestore()
+        }
+    }
+
+    private fun highlightCollapsedRow(row: View) {
+        if (!row.isAttachedToWindow) return
+        val baseColor = ContextCompat.getColor(row.context, R.color.primary)
+        val startColor = Color.argb(
+            COLLAPSE_HIGHLIGHT_ALPHA,
+            Color.red(baseColor),
+            Color.green(baseColor),
+            Color.blue(baseColor),
+        )
+        val endColor = Color.argb(0, Color.red(baseColor), Color.green(baseColor), Color.blue(baseColor))
+        row.setBackgroundColor(startColor)
+        ValueAnimator.ofObject(ArgbEvaluator(), startColor, endColor).apply {
+            duration = COLLAPSE_HIGHLIGHT_DURATION_MILLIS
+            addUpdateListener { row.setBackgroundColor(it.animatedValue as Int) }
+            addListener(object : AnimatorListenerAdapter() {
+                override fun onAnimationEnd(animation: Animator) {
+                    row.background = null
+                }
+            })
+            start()
         }
     }
 
@@ -406,5 +444,7 @@ class ViewLogsFragment : Fragment(R.layout.fragment_view_logs) {
         const val ROW_SEPARATOR_MARGIN_DP = 4
         const val METADATA_INDENT_DP = 8
         const val MAXIMUM_METADATA_COLUMN_FRACTION = 0.45f
+        const val COLLAPSE_HIGHLIGHT_ALPHA = 52
+        const val COLLAPSE_HIGHLIGHT_DURATION_MILLIS = 450L
     }
 }