Android works better

android/build.gradle

@@ -53,11 +53,16 @@ android {
     minSdkVersion getExtOrIntegerDefault("minSdkVersion")
     targetSdkVersion getExtOrIntegerDefault("targetSdkVersion")
     buildConfigField "boolean", "IS_NEW_ARCHITECTURE_ENABLED", isNewArchitectureEnabled().toString()
-
+    externalNativeBuild {
+      cmake {
+        arguments "-DANDROID_STL=c++_shared", "-DANDROID_TOOLCHAIN=clang"
+      }
+    }
   }
 
   buildFeatures {
     buildConfig true
+    prefab true
   }
 
   buildTypes {
@@ -88,6 +93,25 @@ android {
       }
     }
   }
+
+  externalNativeBuild {
+    cmake {
+      path file('src/main/cpp/CMakeLists.txt')
+      version '3.22.1'
+    }
+  }
+
+  packagingOptions {
+    doNotStrip '**/**/*.so'
+    excludes = [
+      "META-INF",
+      "META-INF/**",
+      "**/libc++_shared.so",
+      "**/libfbjni.so",
+      "**/libjsi.so",
+      "**/libreactnativejni.so",
+    ]
+  }
 }
 
 repositories {
@@ -97,10 +121,8 @@ repositories {
 
 
 dependencies {
-  // For < 0.71, this will be from the local maven repo
-  // For > 0.71, this will be replaced by `com.facebook.react:react-android:$version` by react gradle plugin
-  //noinspection GradleDynamicVersion
-  implementation "com.facebook.react:react-native:+"
+  implementation "com.facebook.react:react-android" // version substituted by RNGP
+  implementation "com.facebook.react:hermes-android" // version substituted by RNGP
 }
 
 if (isNewArchitectureEnabled()) {

android/src/main/cpp/CMakeLists.txt

@@ -0,0 +1,23 @@
+project("markdowntextinput")
+
+cmake_minimum_required(VERSION 3.13)
+
+set(CMAKE_VERBOSE_MAKEFILE on)
+
+add_compile_options(-fvisibility=hidden -fexceptions -frtti)
+
+file(GLOB markdowntextinput_SRC CONFIGURE_DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/*.cpp)
+
+add_library(${CMAKE_PROJECT_NAME} SHARED ${markdowntextinput_SRC})
+
+target_include_directories(${CMAKE_PROJECT_NAME} PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
+
+find_package(fbjni REQUIRED CONFIG)
+find_package(ReactAndroid REQUIRED CONFIG)
+find_package(hermes-engine REQUIRED CONFIG)
+
+target_link_libraries(${CMAKE_PROJECT_NAME}
+        fbjni::fbjni
+        ReactAndroid::jsi
+        ReactAndroid::reactnativejni
+        hermes-engine::libhermes)

android/src/main/cpp/MarkdownUtils.h

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <fbjni/fbjni.h>
+#include <jsi/jsi.h>
+
+using namespace facebook;
+
+namespace markdowntextinput {
+
+  class MarkdownUtils : public jni::HybridClass<MarkdownUtils>,
+                        public jsi::HostObject {
+  public:
+    static constexpr auto kJavaDescriptor =
+        "Lcom/markdowntextinput/MarkdownUtils;";
+
+    static jni::local_ref<jni::JString> nativeParseMarkdown(
+        jni::alias_ref<jhybridobject> jThis,
+        jni::alias_ref<jni::JString> input);
+
+    static void registerNatives();
+
+  private:
+    friend HybridBase;
+  };
+
+} // namespace markdowntextinput

android/src/main/cpp/OnLoad.cpp

@@ -0,0 +1,8 @@
+#include <fbjni/fbjni.h>
+
+#include "MarkdownUtils.h"
+
+JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved) {
+    return facebook::jni::initialize(
+            vm, [] { markdowntextinput::MarkdownUtils::registerNatives(); });
+}

android/src/main/java/com/markdowntextinput/MarkdownUtils.java

@@ -1,20 +1,86 @@
 package com.markdowntextinput;
 
+import android.graphics.Color;
 import android.graphics.Typeface;
 import android.text.SpannableStringBuilder;
 import android.text.Spanned;
+import android.text.style.AbsoluteSizeSpan;
+import android.text.style.BackgroundColorSpan;
+import android.text.style.ForegroundColorSpan;
+import android.text.style.LeadingMarginSpan;
+import android.text.style.StrikethroughSpan;
 import android.text.style.StyleSpan;
+import android.text.style.TypefaceSpan;
+import android.text.style.UnderlineSpan;
+
+import com.facebook.soloader.SoLoader;
+
+import org.json.JSONArray;
+import org.json.JSONException;
 
 public class MarkdownUtils {
-  public static void applyMarkdownFormatting(SpannableStringBuilder ssb) {
-    String text = ssb.toString();
-    ssb.clear();
-    ssb.append(text);
+  static {
+    SoLoader.loadLibrary("markdowntextinput");
+  }
 
-    // TODO: parse Markdown here
+  private static native String nativeParseMarkdown(String input);
 
-    // TODO: apply formatting here
-    int flag = Spanned.SPAN_EXCLUSIVE_EXCLUSIVE;
-    ssb.setSpan(new StyleSpan(Typeface.BOLD), 0, Math.min(5, text.length()), flag);
+  public static void applyMarkdownFormatting(SpannableStringBuilder ssb) {
+    String input = ssb.toString();
+    String output = nativeParseMarkdown(input);
+    try {
+      JSONArray array = new JSONArray(output);
+      String text = array.getString(0);
+      ssb.clear();
+      ssb.append(text);
+      JSONArray ranges = array.getJSONArray(1);
+      for (int i = 0; i < ranges.length(); i++) {
+        JSONArray range = ranges.getJSONArray(i);
+        String type = range.getString(0);
+        int start = range.getInt(1);
+        int end = start + range.getInt(2);
+        int flag = Spanned.SPAN_EXCLUSIVE_EXCLUSIVE;
+        switch (type) {
+          case "bold":
+            ssb.setSpan(new StyleSpan(Typeface.BOLD), start, end, flag);
+            break;
+          case "italic":
+            ssb.setSpan(new StyleSpan(Typeface.ITALIC), start, end, flag);
+            break;
+          case "strikethrough":
+            ssb.setSpan(new StrikethroughSpan(), start, end, flag);
+            break;
+          case "mention":
+            ssb.setSpan(new StyleSpan(Typeface.BOLD), start, end, flag);
+            ssb.setSpan(new BackgroundColorSpan(Color.rgb(252, 232, 142)), start, end, flag);
+            break;
+          case "syntax":
+            ssb.setSpan(new StyleSpan(Typeface.BOLD), start, end, flag);
+            ssb.setSpan(new ForegroundColorSpan(Color.GRAY), start, end, flag);
+            break;
+          case "link":
+            ssb.setSpan(new UnderlineSpan(), start, end, flag);
+            ssb.setSpan(new ForegroundColorSpan(Color.BLUE), start, end, flag);
+            break;
+          case "code":
+          case "pre":
+            ssb.setSpan(new TypefaceSpan("monospace"), start, end, flag);
+            ssb.setSpan(new ForegroundColorSpan(Color.rgb(6, 25, 109)), start, end, flag);
+            ssb.setSpan(new BackgroundColorSpan(Color.LTGRAY), start, end, flag);
+            break;
+          case "h1":
+            ssb.setSpan(new AbsoluteSizeSpan(25, true), start, end, flag);
+            ssb.setSpan(new StyleSpan(Typeface.BOLD), start, end, flag);
+            break;
+          case "blockquote":
+            ssb.setSpan(new LeadingMarginSpan.Standard(20), start, end, flag);
+            break;
+          default:
+            throw new IllegalStateException("Unsupported type: " + type);
+        }
+      }
+    } catch (JSONException e) {
+      // Do nothing
+    }
   }
 }