Android: Add activities to display open source notices

android/app/src/main/java/io/github/kichikuou/xsystem35/LauncherActivity.kt

@@ -106,6 +106,11 @@ class LauncherActivity : Activity(), LauncherObserver {
                                        SAVEDATA_IMPORT_REQUEST)
                 true
             }
+            R.id.licenses -> {
+                val intent = Intent(this, LicensesMenuActivity::class.java)
+                startActivity(intent)
+                true
+            }
             else -> super.onOptionsItemSelected(item)
         }
     }

android/app/src/main/java/io/github/kichikuou/xsystem35/LicensesActivity.kt

@@ -0,0 +1,23 @@
+package io.github.kichikuou.xsystem35
+
+import android.app.Activity
+import android.os.Bundle
+import android.widget.TextView
+import java.io.BufferedReader
+
+class LicensesActivity : Activity() {
+    companion object {
+        const val EXTRA_DISPLAY_NAME = "DISPLAY_NAME"
+        const val EXTRA_FILE_NAME = "FILE_NAME"
+    }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_licenses)
+
+        actionBar?.title = intent.getStringExtra(EXTRA_DISPLAY_NAME)
+        val path = "licenses/" + intent.getStringExtra(EXTRA_FILE_NAME)
+        val text = assets.open(path).bufferedReader().use(BufferedReader::readText)
+        findViewById<TextView>(R.id.license_text).text = text
+    }
+}

android/app/src/main/java/io/github/kichikuou/xsystem35/LicensesMenuActivity.kt

@@ -0,0 +1,38 @@
+package io.github.kichikuou.xsystem35
+
+import android.app.Activity
+import android.content.Intent
+import android.os.Bundle
+import android.widget.ListView
+import android.widget.SimpleAdapter
+
+class LicensesMenuActivity : Activity() {
+    class Entry(val displayName: String, val fileName: String, val url: String)
+    private val entries: ArrayList<Entry> = arrayListOf(
+        Entry("xsystem35-sdl2", "xsystem35", "https://github.com/kichikuou/xsystem35-sdl2"),
+        Entry("SDL", "SDL", "https://www.libsdl.org/"),
+        Entry("SDL_mixer", "SDL_mixer", "https://github.com/libsdl-org/SDL_mixer"),
+        Entry("SDL_ttf", "SDL_ttf", "https://github.com/libsdl-org/SDL_ttf"),
+        Entry("FreeType", "freetype", "https://freetype.org/"),
+        Entry("HarfBuzz", "harfbuzz", "https://harfbuzz.github.io/"),
+        Entry("MotoyaLCedar W3 mono", "MTLc3m", "https://github.com/aosp-mirror/platform_frameworks_base/tree/lollipop-release/data/fonts"),
+        Entry("Source Han Serif", "mincho", "https://github.com/adobe-fonts/source-han-serif/"),
+    )
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_licenses_menu)
+
+        val items = entries.map { mapOf("name" to it.displayName, "url" to it.url)}
+        val listView = findViewById<ListView>(R.id.list)
+        listView.adapter = SimpleAdapter(this, items, android.R.layout.simple_list_item_2,
+            arrayOf("name", "url"), intArrayOf(android.R.id.text1, android.R.id.text2))
+        listView.setOnItemClickListener { _, _, pos, _ ->
+            val intent = Intent(this, LicensesActivity::class.java).apply {
+                putExtra(LicensesActivity.EXTRA_DISPLAY_NAME, entries[pos].displayName)
+                putExtra(LicensesActivity.EXTRA_FILE_NAME, entries[pos].fileName)
+            }
+            startActivity(intent)
+        }
+    }
+}