feat(android): enable minify on release, add proguard rules (#6257)

Author: lucasfernog

.changes/enable-minify.md

@@ -0,0 +1,6 @@
+---
+"cli.rs": patch
+"cli.js": patch
+---
+
+Change the Android template to enable minification on release and pull ProGuard rules from proguard-tauri.pro.

.changes/inject-proguard.md

@@ -0,0 +1,5 @@
+---
+"tauri": patch
+---
+
+Inject `proguard-tauri.pro` file in the Android project.

core/tauri/build.rs

@@ -154,6 +154,15 @@ fn main() {
         &[],
       )
       .expect("failed to copy tauri-api Android project");
+      let tauri_proguard = include_str!("./mobile/proguard-tauri.pro").replace(
+        "$PACKAGE",
+        &var("WRY_ANDROID_PACKAGE").expect("missing `WRY_ANDROID_PACKAGE` environment variable"),
+      );
+      std::fs::write(
+        project_dir.join("app").join("proguard-tauri.pro"),
+        tauri_proguard,
+      )
+      .expect("failed to write proguard-tauri.pro");
     }
     let lib_path =
       PathBuf::from(std::env::var_os("CARGO_MANIFEST_DIR").unwrap()).join("mobile/android");

core/tauri/mobile/android/build.gradle.kts

@@ -12,7 +12,7 @@ android {
         targetSdk = 33
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
-        consumerProguardFiles("consumer-rules.pro")
+        consumerProguardFiles("proguard-rules.pro")
     }
 
     buildTypes {
@@ -41,4 +41,4 @@ dependencies {
     testImplementation("junit:junit:4.13.2")
     androidTestImplementation("androidx.test.ext:junit:1.1.5")
     androidTestImplementation("androidx.test.espresso:espresso-core:3.5.1")
-}
+}

core/tauri/mobile/android/consumer-rules.pro

@@ -1,21 +1,7 @@
-# Add project specific ProGuard rules here.
-# You can control the set of applied configuration files using the
-# proguardFiles setting in build.gradle.
-#
-# For more details, see
-#   http://developer.android.com/guide/developing/tools/proguard.html
+-keep class app.tauri.** {
+  @app.tauri.JniMethod public <methods>;
+}
 
-# If your project uses WebView with JS, uncomment the following
-# and specify the fully qualified class name to the JavaScript interface
-# class:
-#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
-#   public *;
-#}
-
-# Uncomment this to preserve the line number information for
-# debugging stack traces.
-#-keepattributes SourceFile,LineNumberTable
-
-# If you keep the line number information, uncomment this to
-# hide the original source file name.
-#-renamesourcefileattribute SourceFile
+-keep class app.tauri.JSArray,app.tauri.JSObject {
+  public <init>(...);
+}

core/tauri/mobile/android/proguard-rules.pro

@@ -0,0 +1,4 @@
+package app.tauri
+
+@Retention(AnnotationRetention.RUNTIME)
+internal annotation class JniMethod() { }

core/tauri/mobile/android/src/main/java/app/tauri/JniMethod.kt

@@ -1,11 +1,13 @@
 package app.tauri.plugin
 
 import android.webkit.WebView
+import app.tauri.JniMethod
 import app.tauri.Logger
 
 class PluginManager {
   private val plugins: HashMap<String, PluginHandle> = HashMap()
 
+  @JniMethod
   fun onWebViewCreated(webView: WebView) {
     for ((_, plugin) in plugins) {
       if (!plugin.loaded) {
@@ -14,6 +16,7 @@ class PluginManager {
     }
   }
 
+  @JniMethod
   fun load(webView: WebView?, name: String, plugin: Plugin) {
     val handle = PluginHandle(plugin)
     plugins[name] = handle
@@ -22,6 +25,7 @@ class PluginManager {
     }
   }
 
+  @JniMethod
   fun postIpcMessage(webView: WebView, pluginId: String, methodName: String, data: JSObject, callback: Long, error: Long) {
     val invoke = Invoke({ successResult, errorResult ->
       val (fn, result) = if (errorResult == null) Pair(callback, successResult) else Pair(
@@ -34,6 +38,7 @@ class PluginManager {
     dispatchPluginMessage(invoke, pluginId, methodName)
   }
 
+  @JniMethod
   fun runPluginMethod(id: Int, pluginId: String, methodName: String, data: JSObject) {
     val invoke = Invoke({ successResult, errorResult ->
       handlePluginResponse(id, successResult?.toString(), errorResult?.toString())

core/tauri/mobile/android/src/main/java/app/tauri/plugin/PluginManager.kt

@@ -0,0 +1,4 @@
+package app.tauri.plugin
+
+@Retention(AnnotationRetention.RUNTIME)
+annotation class TauriPlugin() { }

core/tauri/mobile/android/src/main/java/app/tauri/plugin/TauriPlugin.kt

@@ -0,0 +1,29 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+
+-keep class $PACKAGE.TauriActivity {
+  getAppClass(...);
+  getVersion();
+}
+
+-keep class $PACKAGE.RustWebView {
+  public <init>(...);
+  loadUrlMainThread(...);
+}
+
+-keep class $PACKAGE.Ipc {
+  public <init>(...);
+  @android.webkit.JavascriptInterface public <methods>;
+}
+
+-keep class $PACKAGE.RustWebChromeClient,$PACKAGE.RustWebViewClient {
+  public <init>(...);
+}
+
+-keep class $PACKAGE.MainActivity {
+  public getPluginManager();
+}
+
+-keep @app.tauri.plugin.TauriPlugin public class * {
+  @app.tauri.plugin.PluginMethod public <methods>;
+  public <init>(...);
+}