fix(Android): recalculating layout after changing html styles

android/src/main/java/com/swmansion/enriched/EnrichedTextInputView.kt

@@ -30,8 +30,12 @@ import com.swmansion.enriched.events.MentionHandler
 import com.swmansion.enriched.events.OnInputBlurEvent
 import com.swmansion.enriched.events.OnInputFocusEvent
 import com.swmansion.enriched.events.OnRequestHtmlResultEvent
+import com.swmansion.enriched.spans.EnrichedH1Span
+import com.swmansion.enriched.spans.EnrichedH2Span
+import com.swmansion.enriched.spans.EnrichedH3Span
 import com.swmansion.enriched.spans.EnrichedImageSpan
 import com.swmansion.enriched.spans.EnrichedSpans
+import com.swmansion.enriched.spans.interfaces.EnrichedSpan
 import com.swmansion.enriched.styles.InlineStyles
 import com.swmansion.enriched.styles.ListStyles
 import com.swmansion.enriched.styles.ParagraphStyles
@@ -60,6 +64,13 @@ class EnrichedTextInputView : AppCompatEditText {
 
   val mentionHandler: MentionHandler? = MentionHandler(this)
   var htmlStyle: HtmlStyle = HtmlStyle(this, null)
+    set(value) {
+        if (field != value) {
+            val prev = field
+            field = value
+            reApplyHtmlStyleForSpans(prev, value)
+        }
+    }
   var spanWatcher: EnrichedSpanWatcher? = null
   var layoutManager: EnrichedTextInputViewLayoutManager = EnrichedTextInputViewLayoutManager(this)
 
@@ -336,6 +347,7 @@ class EnrichedTextInputView : AppCompatEditText {
     // This ensured that newly created spans will take the new font size into account
     htmlStyle.invalidateStyles()
     layoutManager.invalidateLayout()
+    forceScrollToSelection()
   }
 
   fun setFontFamily(family: String?) {
@@ -592,6 +604,72 @@ class EnrichedTextInputView : AppCompatEditText {
     }
   }
 
+    private fun forceScrollToSelection() {
+      val textLayout = layout ?: return
+      val cursorOffset = selectionStart
+      if (cursorOffset <= 0) return
+
+      val selectedLineIndex = textLayout.getLineForOffset(cursorOffset)
+      val selectedLineTop = textLayout.getLineTop(selectedLineIndex)
+      val selectedLineBottom = textLayout.getLineBottom(selectedLineIndex)
+      val visibleTextHeight = height - paddingTop - paddingBottom
+
+      if (visibleTextHeight <= 0) return
+
+      val visibleTop = scrollY
+      val visibleBottom = scrollY + visibleTextHeight
+      var targetScrollY = scrollY
+
+      if (selectedLineTop < visibleTop) {
+        targetScrollY = selectedLineTop
+      } else if (selectedLineBottom > visibleBottom) {
+        targetScrollY = selectedLineBottom - visibleTextHeight
+      }
+
+      val maxScrollY = (textLayout.height - visibleTextHeight).coerceAtLeast(0)
+      targetScrollY = targetScrollY.coerceIn(0, maxScrollY)
+      scrollTo(scrollX, targetScrollY)
+    }
+
+  private fun reApplyHtmlStyleForSpans(previousHtmlStyle: HtmlStyle, nextHtmlStyle: HtmlStyle) {
+    val shouldRemoveBoldSpanFromH1Span = !previousHtmlStyle.h1Bold && nextHtmlStyle.h1Bold
+    val shouldRemoveBoldSpanFromH2Span = !previousHtmlStyle.h2Bold && nextHtmlStyle.h2Bold
+    val shouldRemoveBoldSpanFromH3Span = !previousHtmlStyle.h3Bold && nextHtmlStyle.h3Bold
+
+    val spannable = text as? Spannable ?: return
+    if (spannable.isEmpty()) return
+
+    var shouldEmitStateChange = false
+
+    runAsATransaction {
+      val spans = spannable.getSpans(0, spannable.length, EnrichedSpan::class.java)
+      for (span in spans) {
+        if (!span.dependsOnHtmlStyle) continue
+
+        val start = spannable.getSpanStart(span)
+        val end = spannable.getSpanEnd(span)
+        val flags = spannable.getSpanFlags(span)
+
+        if (start == -1 || end == -1) continue
+
+        if ((span is EnrichedH1Span && shouldRemoveBoldSpanFromH1Span) || (span is EnrichedH2Span && shouldRemoveBoldSpanFromH2Span) || (span is EnrichedH3Span && shouldRemoveBoldSpanFromH3Span)) {
+          val isRemoved = removeStyle(EnrichedSpans.BOLD, start, end)
+          if (isRemoved) shouldEmitStateChange = true
+        }
+
+        spannable.removeSpan(span)
+        val newSpan = span.rebuildWithStyle(htmlStyle)
+        spannable.setSpan(newSpan, start, end, flags)
+      }
+
+      if (shouldEmitStateChange) {
+        selection?.validateStyles()
+      }
+    }
+    layoutManager.invalidateLayout()
+    forceScrollToSelection()
+  }
+
   override fun onAttachedToWindow() {
     super.onAttachedToWindow()
 

android/src/main/java/com/swmansion/enriched/spans/EnrichedBlockQuoteSpan.kt

@@ -11,6 +11,8 @@ import com.swmansion.enriched.styles.HtmlStyle
 
 // https://android.googlesource.com/platform/frameworks/base/+/refs/heads/main/core/java/android/text/style/QuoteSpan.java
 class EnrichedBlockQuoteSpan(private val htmlStyle: HtmlStyle) : MetricAffectingSpan(), LeadingMarginSpan, EnrichedBlockSpan {
+  override val dependsOnHtmlStyle: Boolean = true
+
   override fun updateMeasureState(p0: TextPaint) {
     // Do nothing, but inform layout that this span affects text metrics
   }
@@ -35,4 +37,8 @@ class EnrichedBlockQuoteSpan(private val htmlStyle: HtmlStyle) : MetricAffecting
       textPaint?.color = color
     }
   }
+
+  override fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedBlockQuoteSpan {
+    return EnrichedBlockQuoteSpan(htmlStyle)
+  }
 }

android/src/main/java/com/swmansion/enriched/spans/EnrichedBoldSpan.kt

@@ -2,9 +2,15 @@ package com.swmansion.enriched.spans
 
 import android.graphics.Typeface
 import android.text.style.StyleSpan
+import com.swmansion.enriched.spans.interfaces.EnrichedBlockSpan
 import com.swmansion.enriched.spans.interfaces.EnrichedInlineSpan
 import com.swmansion.enriched.styles.HtmlStyle
 
 @Suppress("UNUSED_PARAMETER")
 class EnrichedBoldSpan(htmlStyle: HtmlStyle) : StyleSpan(Typeface.BOLD), EnrichedInlineSpan {
+  override val dependsOnHtmlStyle: Boolean = false
+
+  override fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedBoldSpan {
+    return EnrichedBoldSpan(htmlStyle)
+  }
 }

android/src/main/java/com/swmansion/enriched/spans/EnrichedCodeBlockSpan.kt

@@ -13,6 +13,8 @@ import com.swmansion.enriched.spans.interfaces.EnrichedBlockSpan
 import com.swmansion.enriched.styles.HtmlStyle
 
 class EnrichedCodeBlockSpan(private val htmlStyle: HtmlStyle) : MetricAffectingSpan(), LineBackgroundSpan, EnrichedBlockSpan {
+  override val dependsOnHtmlStyle: Boolean = true
+
   override fun updateDrawState(paint: TextPaint) {
     paint.typeface = Typeface.MONOSPACE
     paint.color = htmlStyle.codeBlockColor
@@ -74,4 +76,8 @@ class EnrichedCodeBlockSpan(private val htmlStyle: HtmlStyle) : MetricAffectingS
     canvas.drawPath(path, p)
     p.color = previousColor
   }
+
+  override fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedCodeBlockSpan {
+    return EnrichedCodeBlockSpan(htmlStyle)
+  }
 }

android/src/main/java/com/swmansion/enriched/spans/EnrichedH1Span.kt

@@ -7,11 +7,17 @@ import com.swmansion.enriched.spans.interfaces.EnrichedHeadingSpan
 import com.swmansion.enriched.styles.HtmlStyle
 
 class EnrichedH1Span(private val style: HtmlStyle) : AbsoluteSizeSpan(style.h1FontSize), EnrichedHeadingSpan {
+  override val dependsOnHtmlStyle: Boolean = true
+
   override fun updateDrawState(tp: TextPaint) {
     super.updateDrawState(tp)
     val bold = style.h1Bold
     if (bold) {
       tp.typeface = Typeface.create(tp.typeface, Typeface.BOLD)
     }
   }
+
+  override fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedH1Span {
+    return EnrichedH1Span(htmlStyle)
+  }
 }

android/src/main/java/com/swmansion/enriched/spans/EnrichedH2Span.kt

@@ -7,11 +7,17 @@ import com.swmansion.enriched.spans.interfaces.EnrichedHeadingSpan
 import com.swmansion.enriched.styles.HtmlStyle
 
 class EnrichedH2Span(private val htmlStyle: HtmlStyle) : AbsoluteSizeSpan(htmlStyle.h2FontSize), EnrichedHeadingSpan {
+  override val dependsOnHtmlStyle: Boolean = true
+
   override fun updateDrawState(tp: TextPaint) {
     super.updateDrawState(tp)
     val bold = htmlStyle.h2Bold
     if (bold) {
       tp.typeface = Typeface.create(tp.typeface, Typeface.BOLD)
     }
   }
+
+  override fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedH2Span {
+    return EnrichedH2Span(htmlStyle)
+  }
 }

android/src/main/java/com/swmansion/enriched/spans/EnrichedH3Span.kt

@@ -7,11 +7,17 @@ import com.swmansion.enriched.spans.interfaces.EnrichedHeadingSpan
 import com.swmansion.enriched.styles.HtmlStyle
 
 class EnrichedH3Span(private val htmlStyle: HtmlStyle) : AbsoluteSizeSpan(htmlStyle.h3FontSize), EnrichedHeadingSpan {
+  override val dependsOnHtmlStyle: Boolean = true
+
   override fun updateDrawState(tp: TextPaint) {
     super.updateDrawState(tp)
     val bold = htmlStyle.h3Bold
     if (bold) {
       tp.typeface = Typeface.create(tp.typeface, Typeface.BOLD)
     }
   }
+
+  override fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedH3Span {
+    return EnrichedH3Span(htmlStyle)
+  }
 }

android/src/main/java/com/swmansion/enriched/spans/EnrichedImageSpan.kt

@@ -18,9 +18,12 @@ import com.swmansion.enriched.utils.AsyncDrawable
 import androidx.core.graphics.drawable.toDrawable
 import com.swmansion.enriched.R
 import com.swmansion.enriched.spans.utils.ForceRedrawSpan
+import com.swmansion.enriched.styles.HtmlStyle
 import com.swmansion.enriched.utils.ResourceManager
 
 class EnrichedImageSpan : ImageSpan, EnrichedInlineSpan {
+  override val dependsOnHtmlStyle: Boolean = false
+
   private var width: Int = 0
   private var height: Int = 0
 
@@ -119,6 +122,8 @@ class EnrichedImageSpan : ImageSpan, EnrichedInlineSpan {
     return height
   }
 
+  override fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedImageSpan = this
+
   companion object {
     fun createEnrichedImageSpan(src: String, width: Int, height: Int): EnrichedImageSpan {
       var imgDrawable = prepareDrawableForImage(src)

android/src/main/java/com/swmansion/enriched/spans/EnrichedInlineCodeSpan.kt

@@ -7,6 +7,8 @@ import com.swmansion.enriched.spans.interfaces.EnrichedInlineSpan
 import com.swmansion.enriched.styles.HtmlStyle
 
 class EnrichedInlineCodeSpan(private val htmlStyle: HtmlStyle) : MetricAffectingSpan(), EnrichedInlineSpan {
+  override val dependsOnHtmlStyle: Boolean = true
+
   override fun updateDrawState(textPaint: TextPaint) {
     val typeface = Typeface.create(Typeface.MONOSPACE, Typeface.NORMAL)
     textPaint.typeface = typeface
@@ -18,4 +20,8 @@ class EnrichedInlineCodeSpan(private val htmlStyle: HtmlStyle) : MetricAffecting
     val typeface = Typeface.create(Typeface.MONOSPACE, Typeface.NORMAL)
     textPaint.typeface = typeface
   }
+
+  override fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedInlineCodeSpan {
+    return EnrichedInlineCodeSpan(htmlStyle)
+  }
 }

android/src/main/java/com/swmansion/enriched/spans/EnrichedItalicSpan.kt

@@ -7,4 +7,9 @@ import com.swmansion.enriched.styles.HtmlStyle
 
 @Suppress("UNUSED_PARAMETER")
 class EnrichedItalicSpan(private val htmlStyle: HtmlStyle) : StyleSpan(Typeface.ITALIC), EnrichedInlineSpan {
+  override val dependsOnHtmlStyle: Boolean = false
+
+  override fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedItalicSpan {
+    return EnrichedItalicSpan(htmlStyle)
+  }
 }

android/src/main/java/com/swmansion/enriched/spans/EnrichedLinkSpan.kt

@@ -7,6 +7,8 @@ import com.swmansion.enriched.spans.interfaces.EnrichedInlineSpan
 import com.swmansion.enriched.styles.HtmlStyle
 
 class EnrichedLinkSpan(private val url: String, private val htmlStyle: HtmlStyle) : ClickableSpan(), EnrichedInlineSpan {
+  override val dependsOnHtmlStyle: Boolean = true
+
   override fun onClick(view: View) {
     // Do nothing, links inside the input are not clickable.
     // We are using `ClickableSpan` to allow the text to be styled as a link.
@@ -21,4 +23,8 @@ class EnrichedLinkSpan(private val url: String, private val htmlStyle: HtmlStyle
   fun getUrl(): String {
     return url
   }
+
+  override fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedLinkSpan {
+    return EnrichedLinkSpan(url, htmlStyle)
+  }
 }

android/src/main/java/com/swmansion/enriched/spans/EnrichedMentionSpan.kt

@@ -8,6 +8,8 @@ import com.swmansion.enriched.styles.HtmlStyle
 
 class EnrichedMentionSpan(private val text: String, private val indicator: String, private val attributes: Map<String, String>, private val htmlStyle: HtmlStyle) :
   ClickableSpan(), EnrichedInlineSpan {
+  override val dependsOnHtmlStyle: Boolean = true
+
   override fun onClick(view: View) {
     // Do nothing. Mentions inside the input are not clickable.
     // We are using `ClickableSpan` to allow the text to be styled as a clickable element.
@@ -33,4 +35,8 @@ class EnrichedMentionSpan(private val text: String, private val indicator: Strin
   fun getIndicator(): String {
     return indicator
   }
+
+  override fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedMentionSpan {
+    return EnrichedMentionSpan(text, indicator, attributes, htmlStyle)
+  }
 }

android/src/main/java/com/swmansion/enriched/spans/EnrichedOrderedListSpan.kt

@@ -11,6 +11,8 @@ import com.swmansion.enriched.spans.interfaces.EnrichedParagraphSpan
 import com.swmansion.enriched.styles.HtmlStyle
 
 class EnrichedOrderedListSpan(private var index: Int, private val htmlStyle: HtmlStyle) : MetricAffectingSpan(), LeadingMarginSpan, EnrichedParagraphSpan {
+  override val dependsOnHtmlStyle: Boolean = true
+
   override fun updateMeasureState(p0: TextPaint) {
     // Do nothing, but inform layout that this span affects text metrics
   }
@@ -78,4 +80,8 @@ class EnrichedOrderedListSpan(private var index: Int, private val htmlStyle: Htm
   fun setIndex(i: Int) {
     index = i
   }
+
+  override fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedOrderedListSpan {
+    return EnrichedOrderedListSpan(index, htmlStyle)
+  }
 }

android/src/main/java/com/swmansion/enriched/spans/EnrichedStrikeThroughSpan.kt

@@ -6,4 +6,9 @@ import com.swmansion.enriched.styles.HtmlStyle
 
 @Suppress("UNUSED_PARAMETER")
 class EnrichedStrikeThroughSpan(private val htmlStyle: HtmlStyle) : StrikethroughSpan(), EnrichedInlineSpan {
+  override val dependsOnHtmlStyle: Boolean = false
+
+  override fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedStrikeThroughSpan {
+    return EnrichedStrikeThroughSpan(htmlStyle)
+  }
 }

android/src/main/java/com/swmansion/enriched/spans/EnrichedUnderlineSpan.kt

@@ -6,4 +6,9 @@ import com.swmansion.enriched.styles.HtmlStyle
 
 @Suppress("UNUSED_PARAMETER")
 class EnrichedUnderlineSpan(private val htmlStyle: HtmlStyle) : UnderlineSpan(), EnrichedInlineSpan {
+  override val dependsOnHtmlStyle: Boolean = false
+
+  override fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedUnderlineSpan {
+    return EnrichedUnderlineSpan(htmlStyle)
+  }
 }

android/src/main/java/com/swmansion/enriched/spans/EnrichedUnorderedListSpan.kt

@@ -12,6 +12,8 @@ import com.swmansion.enriched.styles.HtmlStyle
 
 // https://android.googlesource.com/platform/frameworks/base/+/refs/heads/main/core/java/android/text/style/BulletSpan.java
 class EnrichedUnorderedListSpan(private val htmlStyle: HtmlStyle) : MetricAffectingSpan(), LeadingMarginSpan, EnrichedParagraphSpan {
+  override val dependsOnHtmlStyle: Boolean = true
+
   override fun updateMeasureState(p0: TextPaint) {
     // Do nothing, but inform layout that this span affects text metrics
   }
@@ -56,4 +58,8 @@ class EnrichedUnorderedListSpan(private val htmlStyle: HtmlStyle) : MetricAffect
       paint.style = style
     }
   }
+
+  override fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedUnorderedListSpan {
+    return EnrichedUnorderedListSpan(htmlStyle)
+  }
 }

android/src/main/java/com/swmansion/enriched/spans/interfaces/EnrichedSpan.kt

@@ -1,4 +1,8 @@
 package com.swmansion.enriched.spans.interfaces
 
+import com.swmansion.enriched.styles.HtmlStyle
+
 interface EnrichedSpan {
+  val dependsOnHtmlStyle: Boolean
+  fun rebuildWithStyle(htmlStyle: HtmlStyle): EnrichedSpan
 }