feat(android): replace math engine with RaTeX

android/build.gradle

@@ -47,25 +47,6 @@ android {
     }
   }
 
-  packaging {
-    jniLibs {
-      // Android test APK builds merge native libraries from this module and
-      // react-android. AndroidMath also ships libc++_shared.so, so keep a
-      // single copy to avoid duplicate native library failures in Detox and
-      // other instrumentation builds. Remove this workaround after migrating
-      // away from AndroidMath if the new math backend does not package it.
-      pickFirsts += ["**/libc++_shared.so"]
-    }
-
-    resources {
-      // AndroidMath pulls in appcompat/lifecycle dependencies that can bring
-      // both coroutines-core and coroutines-android into androidTest packaging.
-      // They ship the same ProGuard metadata file, so keep one copy to avoid
-      // mergeDebugAndroidTestJavaResource failures. Revisit with AndroidMath.
-      pickFirsts += ["META-INF/com.android.tools/proguard/coroutines.pro"]
-    }
-  }
-
   lintOptions {
     disable "GradleCompatible"
   }
@@ -91,7 +72,6 @@ android {
 repositories {
   mavenCentral()
   google()
-  maven { url 'https://jitpack.io' }
 }
 
 def kotlin_version = getExtOrDefault("kotlinVersion")
@@ -103,9 +83,7 @@ dependencies {
   implementation "androidx.profileinstaller:profileinstaller:1.3.1"
   // LaTeX math rendering (optional — set enrichedMarkdown.enableMath=false in gradle.properties to exclude)
   if (enableMath) {
-    implementation("com.github.gregcockroft:AndroidMath:v1.1.0") {
-      exclude group: 'com.google.guava', module: 'guava'
-    }
+    implementation("io.github.erweixin:ratex-android:0.1.10")
   }
 }
 

android/consumer-rules.pro

@@ -14,7 +14,6 @@
 -keep class com.swmansion.enriched.markdown.views.MathContainerView { *; }
 -keep class com.swmansion.enriched.markdown.renderer.MathInlineRenderer { *; }
 
-# AndroidMath and its FreeType dependency use JNI to instantiate Java objects from native code.
+# RaTeX uses JNI to instantiate Java objects from native code.
 # R8 cannot trace these lookups and will strip or rename the referenced classes.
--keep class com.agog.mathdisplay.** { *; }
--keep class com.pvporbit.freetype.** { *; }
+-keep class io.ratex.** { *; }

android/src/main/java/com/swmansion/enriched/markdown/EnrichedMarkdown.kt

@@ -460,7 +460,8 @@ class EnrichedMarkdown
             .newInstance(context, style) as View
         resolvedClass.getMethod("applyLatex", String::class.java).invoke(view, segment.latex)
         view
-      } catch (_: Exception) {
+      } catch (e: Exception) {
+        Log.e(TAG, "Failed to create math view", e)
         View(context)
       }
     }

android/src/main/java/com/swmansion/enriched/markdown/MeasurementStore.kt

@@ -388,7 +388,7 @@ object MeasurementStore {
         for (i in mathSegmentIndices.indices) {
           val metrics = mathResults[i]
           mathHeightByIndex[mathSegmentIndices[i]] =
-            (metrics.ascent + metrics.descent).toInt() + (style.mathStyle.padding * 2)
+            ceil(metrics.ascent + metrics.descent).toInt() + (style.mathStyle.padding * 2)
         }
       }
 
@@ -607,7 +607,7 @@ object MeasurementStore {
     }
     return try {
       val mathMeasureHelperClass = Class.forName("com.swmansion.enriched.markdown.spans.MathMeasureHelper")
-      val method = mathMeasureHelperClass.getMethod("measureOnMainThread", Context::class.java, List::class.java)
+      val method = mathMeasureHelperClass.getMethod("measure", Context::class.java, List::class.java)
       @Suppress("UNCHECKED_CAST")
       method.invoke(null, context, requests) as List<MathMetrics>
     } catch (_: Exception) {

android/src/main/java/com/swmansion/enriched/markdown/utils/text/extensions/SpannableExtensions.kt

@@ -37,7 +37,7 @@ fun SpannableString.replaceMathSpansWithPlaceholders(context: Context) {
       }
 
     val mathMeasureHelperClass = Class.forName("com.swmansion.enriched.markdown.spans.MathMeasureHelper")
-    val measureMethod = mathMeasureHelperClass.getMethod("measureOnMainThread", Context::class.java, List::class.java)
+    val measureMethod = mathMeasureHelperClass.getMethod("measure", Context::class.java, List::class.java)
 
     @Suppress("UNCHECKED_CAST")
     val results = measureMethod.invoke(null, context, requests) as? List<MathMetrics> ?: return

android/src/math/java/com/swmansion/enriched/markdown/renderer/MathInlineRenderer.kt

@@ -5,6 +5,7 @@ import android.text.SpannableStringBuilder
 import com.swmansion.enriched.markdown.parser.MarkdownASTNode
 import com.swmansion.enriched.markdown.spans.MathInlineSpan
 import com.swmansion.enriched.markdown.utils.text.span.SPAN_FLAGS_EXCLUSIVE_EXCLUSIVE
+import io.ratex.RaTeXFontLoader
 
 class MathInlineRenderer(
   private val config: RendererConfig,
@@ -17,6 +18,8 @@ class MathInlineRenderer(
     onLinkLongPress: ((String) -> Unit)?,
     factory: RendererFactory,
   ) {
+    RaTeXFontLoader.ensureLoaded(context)
+
     val latex = extractLatex(node)
     if (latex.isEmpty()) return
 

android/src/math/java/com/swmansion/enriched/markdown/spans/MathInlineSpan.kt

@@ -5,9 +5,10 @@ import android.graphics.Bitmap
 import android.graphics.Canvas
 import android.graphics.Paint
 import android.text.style.ReplacementSpan
-import android.view.View.MeasureSpec
-import com.agog.mathdisplay.MTMathView
-import kotlin.math.roundToInt
+import io.ratex.RaTeXEngine
+import io.ratex.RaTeXFontLoader
+import io.ratex.RaTeXRenderer
+import kotlin.math.ceil
 
 class MathInlineSpan(
   private val context: Context,
@@ -26,28 +27,21 @@ class MathInlineSpan(
     if (renderFailed) return
 
     try {
-      val mathView =
-        MTMathView(context).apply {
-          labelMode = MTMathView.MTMathViewMode.KMTMathViewModeText
-          textAlignment = MTMathView.MTTextAlignment.KMTTextAlignmentLeft
-          this.fontSize = this@MathInlineSpan.fontSize
-          this.textColor = this@MathInlineSpan.textColor
-          this.latex = this@MathInlineSpan.latex
-        }
+      val displayList = RaTeXEngine.parseBlocking(latex, displayMode = false, color = textColor)
+      val renderer = RaTeXRenderer(displayList, fontSize) { RaTeXFontLoader.getTypeface(it) }
 
-      val spec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)
-      mathView.measure(spec, spec)
+      cachedWidth = renderer.widthPx.toInt().coerceAtLeast(1)
+      mathAscent = renderer.heightPx
+      mathDescent = renderer.depthPx
 
-      val width = mathView.measuredWidth.coerceAtLeast(1)
-      val height = mathView.measuredHeight.coerceAtLeast(1)
+      val bitmap =
+        Bitmap.createBitmap(
+          cachedWidth,
+          ceil(renderer.totalHeightPx).toInt().coerceAtLeast(1),
+          Bitmap.Config.ARGB_8888,
+        )
 
-      cachedWidth = width
-      calculateMetrics(mathView, height)
-
-      mathView.layout(0, 0, width, height)
-
-      val bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888)
-      mathView.draw(Canvas(bitmap))
+      renderer.draw(Canvas(bitmap))
       cachedBitmap = bitmap
     } catch (_: Exception) {
       renderFailed = true
@@ -58,25 +52,6 @@ class MathInlineSpan(
     }
   }
 
-  private fun calculateMetrics(
-    view: MTMathView,
-    height: Int,
-  ) {
-    try {
-      val dl = DISPLAY_LIST_FIELD?.get(view)
-      if (dl != null) {
-        mathAscent = GET_ASCENT_METHOD?.invoke(dl) as? Float ?: (height * 0.7f)
-        mathDescent = GET_DESCENT_METHOD?.invoke(dl) as? Float ?: (height * 0.3f)
-      } else {
-        mathAscent = height * 0.7f
-        mathDescent = height * 0.3f
-      }
-    } catch (e: Exception) {
-      mathAscent = height * 0.7f
-      mathDescent = height * 0.3f
-    }
-  }
-
   override fun getSize(
     paint: Paint,
     text: CharSequence?,
@@ -87,9 +62,10 @@ class MathInlineSpan(
     prepareResources()
 
     fm?.apply {
-      ascent = -mathAscent.roundToInt()
+      val ascentPx = ceil(mathAscent).toInt()
+      ascent = -ascentPx
       top = ascent
-      descent = mathDescent.roundToInt()
+      descent = (cachedBitmap?.height ?: ceil(mathAscent + mathDescent).toInt()) - ascentPx
       bottom = descent
     }
 
@@ -109,25 +85,8 @@ class MathInlineSpan(
   ) {
     prepareResources()
     cachedBitmap?.let {
-      val bitmapY = y - mathAscent
+      val bitmapY = y - ceil(mathAscent)
       canvas.drawBitmap(it, x, bitmapY, paint)
     }
   }
-
-  companion object {
-    private val DISPLAY_LIST_FIELD =
-      runCatching {
-        MTMathView::class.java.getDeclaredField("displayList").apply { isAccessible = true }
-      }.getOrNull()
-
-    private val GET_ASCENT_METHOD =
-      runCatching {
-        DISPLAY_LIST_FIELD?.type?.getMethod("getAscent")
-      }.getOrNull()
-
-    private val GET_DESCENT_METHOD =
-      runCatching {
-        DISPLAY_LIST_FIELD?.type?.getMethod("getDescent")
-      }.getOrNull()
-  }
 }

android/src/math/java/com/swmansion/enriched/markdown/spans/MathMeasureHelper.kt

@@ -1,84 +1,46 @@
 package com.swmansion.enriched.markdown.spans
 
 import android.content.Context
-import android.os.Handler
-import android.os.Looper
-import android.view.View.MeasureSpec
-import com.agog.mathdisplay.MTMathView
-import java.util.concurrent.CountDownLatch
-import java.util.concurrent.TimeUnit
+import android.util.Log
+import io.ratex.RaTeXEngine
+import io.ratex.RaTeXFontLoader
+import io.ratex.RaTeXRenderer
 
 object MathMeasureHelper {
-  private const val BASE_TIMEOUT_MS = 500L
-  private const val PER_ITEM_TIMEOUT_MS = 50L
-  private val mainHandler = Handler(Looper.getMainLooper())
-  private var sharedMathView: MTMathView? = null
-
   @JvmStatic
-  fun measureOnMainThread(
+  fun measure(
     context: Context,
     requests: List<MathMeasureRequest>,
   ): List<MathMetrics> {
     if (requests.isEmpty()) return emptyList()
 
-    if (Looper.myLooper() == Looper.getMainLooper()) {
-      return requests.map { measureSingle(context, it) }
-    }
-
-    val results = mutableListOf<MathMetrics?>()
-    val latch = CountDownLatch(1)
-    val timeout = BASE_TIMEOUT_MS + (PER_ITEM_TIMEOUT_MS * requests.size)
-
-    mainHandler.post {
-      requests.mapTo(results) { request ->
-        runCatching { measureSingle(context, request) }.getOrNull()
-      }
-      latch.countDown()
-    }
-
-    val completed = latch.await(timeout, TimeUnit.MILLISECONDS)
+    RaTeXFontLoader.ensureLoaded(context)
 
-    return requests.mapIndexed { i, req ->
-      if (completed) {
-        results.getOrNull(i) ?: estimateFallback(req)
-      } else {
-        estimateFallback(req)
-      }
+    return requests.map { request ->
+      runCatching { measureSingle(context, request) }.getOrElse { estimateFallback(request) }
     }
   }
 
   private fun measureSingle(
     context: Context,
     request: MathMeasureRequest,
   ): MathMetrics {
-    val mathView =
-      (
-        sharedMathView ?: MTMathView(context.applicationContext).also {
-          sharedMathView = it
-        }
-      ).apply {
-        labelMode =
-          when (request.mode) {
-            MathRenderMode.Display -> MTMathView.MTMathViewMode.KMTMathViewModeDisplay
-            else -> MTMathView.MTMathViewMode.KMTMathViewModeText
-          }
-        textAlignment = MTMathView.MTTextAlignment.KMTTextAlignmentLeft
-        fontSize = request.fontSize
-        latex = request.latex
+    val displayList =
+      RaTeXEngine.parseBlocking(
+        request.latex,
+        displayMode = request.mode == MathRenderMode.Display,
+      )
+
+    val renderer =
+      RaTeXRenderer(displayList, request.fontSize) {
+        RaTeXFontLoader.getTypeface(it)
       }
 
-    val spec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)
-    mathView.measure(spec, spec)
-
-    val width = mathView.measuredWidth.coerceAtLeast(1)
-    val height = mathView.measuredHeight.coerceAtLeast(1).toFloat()
-
-    return runCatching {
-      val dl = displayListField?.get(mathView) ?: throw Exception()
-      val ascent = getAscentMethod?.invoke(dl) as Float
-      val descent = getDescentMethod?.invoke(dl) as Float
-      MathMetrics(width, ascent, descent)
-    }.getOrDefault(MathMetrics(width, height * 0.7f, height * 0.3f))
+    return MathMetrics(
+      renderer.widthPx.toInt(),
+      renderer.heightPx,
+      renderer.depthPx,
+    )
   }
 
   private fun estimateFallback(request: MathMeasureRequest): MathMetrics {
@@ -92,12 +54,4 @@ object MathMeasureHelper {
       descent = h * 0.3f,
     )
   }
-
-  private val displayListField =
-    runCatching {
-      MTMathView::class.java.getDeclaredField("displayList").apply { isAccessible = true }
-    }.getOrNull()
-
-  private val getAscentMethod = runCatching { displayListField?.type?.getMethod("getAscent") }.getOrNull()
-  private val getDescentMethod = runCatching { displayListField?.type?.getMethod("getDescent") }.getOrNull()
 }