[android] Implement basic Android markdown rendering

android/build.gradle

@@ -74,4 +74,5 @@ def kotlin_version = getExtOrDefault("kotlinVersion")
 dependencies {
   implementation "com.facebook.react:react-android"
   implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+  implementation "org.commonmark:commonmark:0.27.0"
 }

android/src/main/java/com/richtext/RichTextView.kt

@@ -1,15 +1,138 @@
 package com.richtext
 
 import android.content.Context
+import android.graphics.Color
+import android.text.method.LinkMovementMethod
 import android.util.AttributeSet
-import android.view.View
+import androidx.appcompat.widget.AppCompatTextView
+import com.facebook.react.common.ReactConstants
+import com.facebook.react.views.text.ReactTypefaceUtils.applyStyles
+import com.facebook.react.views.text.ReactTypefaceUtils.parseFontStyle
+import com.facebook.react.views.text.ReactTypefaceUtils.parseFontWeight
+import com.richtext.parser.Parser
+import com.richtext.renderer.Renderer
 
-class RichTextView : View {
-  constructor(context: Context?) : super(context)
-  constructor(context: Context?, attrs: AttributeSet?) : super(context, attrs)
-  constructor(context: Context?, attrs: AttributeSet?, defStyleAttr: Int) : super(
+class RichTextView : AppCompatTextView {
+
+  private val parser = Parser()
+  private val renderer = Renderer()
+  private var onLinkPressCallback: ((String) -> Unit)? = null
+
+  private var typefaceDirty = false
+  private var didAttachToWindow = false
+
+  var fontSize: Float? = null
+  private var fontFamily: String? = null
+  private var fontStyle: Int = ReactConstants.UNSET
+  private var fontWeight: Int = ReactConstants.UNSET
+
+  constructor(context: Context) : super(context) {
+    prepareComponent()
+  }
+
+  constructor(context: Context, attrs: AttributeSet) : super(context, attrs) {
+    prepareComponent()
+  }
+
+  constructor(context: Context, attrs: AttributeSet, defStyleAttr: Int) : super(
     context,
     attrs,
     defStyleAttr
-  )
+  ) {
+    prepareComponent()
+  }
+
+  private fun prepareComponent() {
+    movementMethod = LinkMovementMethod.getInstance()
+    setPadding(0, 0, 0, 0)
+    setBackgroundColor(Color.TRANSPARENT)
+  }
+
+  fun setMarkdownContent(markdown: String) {
+    try {
+      val document = parser.parseMarkdown(markdown)
+      if (document != null) {
+        val styledText = renderer.renderDocument(document, onLinkPressCallback)
+        text = styledText
+        movementMethod = LinkMovementMethod.getInstance()
+      } else {
+        android.util.Log.e("RichTextView", "Failed to parse markdown - Document is null")
+        text = ""
+      }
+    } catch (e: Exception) {
+      android.util.Log.e("RichTextView", "Error parsing markdown: ${e.message}")
+      text = ""
+    }
+  }
+
+
+  fun setOnLinkPressCallback(callback: (String) -> Unit) {
+    onLinkPressCallback = callback
+  }
+
+  fun emitOnLinkPress(url: String) {
+    val context = this.context as? com.facebook.react.bridge.ReactContext ?: return
+    val surfaceId = com.facebook.react.uimanager.UIManagerHelper.getSurfaceId(context)
+    val dispatcher =
+      com.facebook.react.uimanager.UIManagerHelper.getEventDispatcherForReactTag(context, id)
+
+    dispatcher?.dispatchEvent(
+      com.richtext.events.LinkPressEvent(
+        surfaceId,
+        id,
+        url
+      )
+    )
+  }
+
+  fun setFontSize(size: Float) {
+    fontSize = size
+    textSize = size
+    typefaceDirty = true
+    updateTypeface()
+  }
+
+  fun setFontFamily(family: String?) {
+    fontFamily = family
+    typefaceDirty = true
+    updateTypeface()
+  }
+
+  fun setFontWeight(weight: String?) {
+    val parsedWeight = parseFontWeight(weight)
+    if (parsedWeight != fontWeight) {
+      fontWeight = parsedWeight
+      typefaceDirty = true
+      updateTypeface()
+    }
+  }
+
+  fun setFontStyle(style: String?) {
+    val parsedStyle = parseFontStyle(style)
+    if (parsedStyle != fontStyle) {
+      fontStyle = parsedStyle
+      typefaceDirty = true
+      updateTypeface()
+    }
+  }
+
+  fun setColor(color: Int?) {
+    if (color != null) {
+      setTextColor(color)
+    }
+  }
+
+  fun updateTypeface() {
+    if (!typefaceDirty) return
+    typefaceDirty = false
+
+    val newTypeface = applyStyles(typeface, fontStyle, fontWeight, fontFamily, context.assets)
+    setTypeface(newTypeface)
+  }
+
+  override fun onAttachedToWindow() {
+    super.onAttachedToWindow()
+    didAttachToWindow = true
+    updateTypeface()
+  }
 }

android/src/main/java/com/richtext/RichTextViewManager.kt

@@ -1,22 +1,22 @@
 package com.richtext
 
-import android.graphics.Color
 import com.facebook.react.module.annotations.ReactModule
 import com.facebook.react.uimanager.SimpleViewManager
 import com.facebook.react.uimanager.ThemedReactContext
-import com.facebook.react.uimanager.ViewManagerDelegate
 import com.facebook.react.uimanager.annotations.ReactProp
-import com.facebook.react.viewmanagers.RichTextViewManagerInterface
+import com.facebook.react.uimanager.UIManagerHelper
+import com.facebook.react.uimanager.ViewProps
+import com.facebook.react.uimanager.ViewDefaults
+import com.facebook.react.uimanager.ViewManagerDelegate
 import com.facebook.react.viewmanagers.RichTextViewManagerDelegate
+import com.facebook.react.viewmanagers.RichTextViewManagerInterface
+import com.richtext.events.LinkPressEvent
 
 @ReactModule(name = RichTextViewManager.NAME)
 class RichTextViewManager : SimpleViewManager<RichTextView>(),
   RichTextViewManagerInterface<RichTextView> {
-  private val mDelegate: ViewManagerDelegate<RichTextView>
 
-  init {
-    mDelegate = RichTextViewManagerDelegate(this)
-  }
+  private val mDelegate: ViewManagerDelegate<RichTextView> = RichTextViewManagerDelegate(this)
 
   override fun getDelegate(): ViewManagerDelegate<RichTextView>? {
     return mDelegate
@@ -26,13 +26,63 @@ class RichTextViewManager : SimpleViewManager<RichTextView>(),
     return NAME
   }
 
-  public override fun createViewInstance(context: ThemedReactContext): RichTextView {
-    return RichTextView(context)
+  override fun createViewInstance(reactContext: ThemedReactContext): RichTextView {
+    return RichTextView(reactContext)
+  }
+
+  override fun getExportedCustomDirectEventTypeConstants(): MutableMap<String, Any> {
+    val map = mutableMapOf<String, Any>()
+    map.put(LinkPressEvent.EVENT_NAME, mapOf("registrationName" to LinkPressEvent.EVENT_NAME))
+    return map
+  }
+
+  @ReactProp(name = "markdown")
+  override fun setMarkdown(view: RichTextView?, markdown: String?) {
+    view?.setOnLinkPressCallback { url ->
+      emitOnLinkPress(view, url)
+    }
+
+    view?.setMarkdownContent(markdown ?: "No markdown content")
+  }
+
+
+  @ReactProp(name = "fontSize", defaultInt = ViewDefaults.FONT_SIZE_SP.toInt())
+  override fun setFontSize(view: RichTextView?, fontSize: Int) {
+    view?.setFontSize(fontSize.toFloat())
+  }
+
+  @ReactProp(name = "fontFamily")
+  override fun setFontFamily(view: RichTextView?, family: String?) {
+    view?.setFontFamily(family)
+  }
+
+  @ReactProp(name = ViewProps.COLOR, customType = "Color")
+  override fun setColor(view: RichTextView?, color: Int?) {
+    view?.setColor(color)
+  }
+
+  @ReactProp(name = "fontWeight")
+  override fun setFontWeight(view: RichTextView?, weight: String?) {
+    view?.setFontWeight(weight)
+  }
+
+  @ReactProp(name = "fontStyle")
+  override fun setFontStyle(view: RichTextView?, style: String?) {
+    view?.setFontStyle(style)
   }
 
-  @ReactProp(name = "color")
-  override fun setColor(view: RichTextView?, color: String?) {
-    view?.setBackgroundColor(Color.parseColor(color))
+  override fun onAfterUpdateTransaction(view: RichTextView) {
+    super.onAfterUpdateTransaction(view)
+    view.updateTypeface()
+  }
+
+  private fun emitOnLinkPress(view: RichTextView, url: String) {
+    val context = view.context as com.facebook.react.bridge.ReactContext
+    val surfaceId = UIManagerHelper.getSurfaceId(context)
+    val eventDispatcher = UIManagerHelper.getEventDispatcherForReactTag(context, view.id)
+    val event = LinkPressEvent(surfaceId, view.id, url)
+
+    eventDispatcher?.dispatchEvent(event)
   }
 
   companion object {

android/src/main/java/com/richtext/events/LinkPressEvent.kt

@@ -0,0 +1,23 @@
+package com.richtext.events
+
+import com.facebook.react.bridge.Arguments
+import com.facebook.react.bridge.WritableMap
+import com.facebook.react.uimanager.events.Event
+
+class LinkPressEvent(surfaceId: Int, viewId: Int, private val url: String) :
+    Event<LinkPressEvent>(surfaceId, viewId) {
+
+    override fun getEventName(): String {
+        return EVENT_NAME
+    }
+
+    override fun getEventData(): WritableMap {
+        val eventData: WritableMap = Arguments.createMap()
+        eventData.putString("url", url)
+        return eventData
+    }
+
+    companion object {
+        const val EVENT_NAME: String = "onLinkPress"
+    }
+}

android/src/main/java/com/richtext/parser/Parser.kt

@@ -0,0 +1,30 @@
+package com.richtext.parser
+
+import android.util.Log
+import org.commonmark.node.Document
+import org.commonmark.parser.Parser
+
+class Parser {
+
+    private val parser = Parser.builder().build()
+
+    fun parseMarkdown(markdown: String): Document? {
+        if (markdown.isBlank()) {
+            return null
+        }
+
+        try {
+            val document = parser.parse(markdown) as? Document
+
+            if (document != null) {
+                return document
+            } else {
+                Log.w("MarkdownParser", "Failed to cast parsed result to Document")
+                return null
+            }
+        } catch (e: Exception) {
+            Log.e("MarkdownParser", "CommonMark parsing failed: ${e.message}")
+            return null
+        }
+    }
+}