build: Improve R8 rules and enable aggressive optimization modes

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

gradle.properties

@@ -17,3 +17,17 @@ org.gradle.jvmargs=-Xmx1536m
 # This option should only be used with decoupled projects. More details, visit
 # http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
 # org.gradle.parallel=true
+
+# R8 Full mode
+android.enableR8.fullMode=true
+
+# https://jakewharton.com/increased-accuracy-of-aapt2-keep-rules/
+android.useMinimalKeepRules=true
+
+# Enable rudimentary R class namespacing where each library only contains
+# references to the resources it declares instead of declarations plus all
+# transitive dependency references.
+android.namespacedRClass=true
+
+# Suppress warnings for some features that aren't yet stabilized
+android.suppressUnsupportedOptionWarnings=android.enableR8.fullMode,android.useMinimalKeepRules,android.namespacedRClass,android.suppressUnsupportedOptionWarnings

ui/build.gradle

@@ -57,7 +57,7 @@ android {
                 }
             }
             minifyEnabled true
-            proguardFiles getDefaultProguardFile("proguard-android-optimize.txt"), "proguard-rules.pro"
+            proguardFiles "proguard-android-optimize.txt", "proguard-rules.pro"
         }
         debug {
             applicationIdSuffix ".debug"

ui/proguard-android-optimize.txt

@@ -0,0 +1,36 @@
+-allowaccessmodification
+-dontpreverify
+-dontusemixedcaseclassnames
+-dontskipnonpubliclibraryclasses
+-verbose
+
+-keepattributes *Annotation*
+
+-keepclasseswithmembernames class * {
+    native <methods>;
+}
+
+-keepclassmembers enum * {
+    public static **[] values();
+    public static ** valueOf(java.lang.String);
+}
+
+-keepclassmembers class * implements android.os.Parcelable {
+  public static final ** CREATOR;
+}
+
+-keep class androidx.annotation.Keep
+
+-keep @androidx.annotation.Keep class * {*;}
+
+-keepclasseswithmembers class * {
+    @androidx.annotation.Keep <methods>;
+}
+
+-keepclasseswithmembers class * {
+    @androidx.annotation.Keep <fields>;
+}
+
+-keepclasseswithmembers class * {
+    @androidx.annotation.Keep <init>(...);
+}