Add new rust-based decoder implementation

.gitignore

@@ -8,3 +8,11 @@
 .externalNativeBuild
 .cxx
 local.properties
+
+# Rust
+**/target/
+**/*.rs.bk
+library/src/main/rust/native-libs/**
+
+# Benchmarking
+**/benchmark/build/

.vscode/settings.json

@@ -0,0 +1,7 @@
+{
+    "rust-analyzer.linkedProjects": [
+        "library/src/main/rust/core/Cargo.toml",
+        "library/src/main/rust/jni/Cargo.toml",
+        "library/src/main/rust/Cargo.toml"
+    ]
+}

benchmark/build.gradle

@@ -0,0 +1,78 @@
+plugins {
+    id 'com.android.library'
+    id 'kotlin-android'
+}
+
+android {
+    namespace 'tachiyomi.decoder.benchmark'
+    compileSdk 34
+    ndkVersion "26.2.11394342"
+
+    defaultConfig {
+        minSdk 21
+        targetSdk 34
+
+        testInstrumentationRunner "androidx.benchmark.junit4.AndroidBenchmarkRunner"
+
+        // Pass the benchmark output directory to the runner.
+        testInstrumentationRunnerArguments["additionalTestOutputDir"] =
+            "/sdcard/Download/benchmark_results"
+
+        // Allow running on emulators (results will be noisier than on real hardware).
+        testInstrumentationRunnerArguments["androidx.benchmark.suppressErrors"] = "EMULATOR"
+
+        externalNativeBuild {
+            cmake {
+                abiFilters "arm64-v8a", "armeabi-v7a", "x86", "x86_64"
+            }
+        }
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+        }
+    }
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
+
+    // Build the C++ benchmark decoder (libimagedecoder_cpp.so).
+    externalNativeBuild {
+        cmake {
+            path "../library/src/main/cpp/benchmark/CMakeLists.txt"
+        }
+    }
+
+    // Note: libheifcodec.so and libimagedecoder.so are provided by the
+    // :library dependency (its AAR includes both native libraries).
+    // Do NOT add jniLibs.srcDirs here to avoid APK merge conflicts.
+
+    // Suppress the benchmark "not a release build" warning — we need
+    // debuggable=false in the androidTest manifest, which is already set.
+    testBuildType = "release"
+}
+
+dependencies {
+    implementation project(':library')
+
+    androidTestImplementation 'androidx.benchmark:benchmark-junit4:1.3.3'
+    androidTestImplementation 'androidx.test:runner:1.6.2'
+    androidTestImplementation 'androidx.test:core:1.6.1'
+    androidTestImplementation 'androidx.test.ext:junit:1.2.1'
+    androidTestImplementation 'junit:junit:4.13.2'
+}
+
+afterEvaluate {
+    // The benchmark CMake links against libheifcodec.so at build time.
+    // Ensure the library module's CMake (which produces libheifcodec.so)
+    // runs first.
+    tasks.matching { it.name.startsWith("buildCMake") && it.project == project }.configureEach { benchCmakeTask ->
+        benchCmakeTask.dependsOn project(':library').tasks.matching { it.name.startsWith("buildCMake") }
+    }
+}

benchmark/src/androidTest/assets/README.md

@@ -0,0 +1,33 @@
+# Benchmark Test Images
+
+Place sample images here for benchmarking.  JPEG, PNG, and WebP test images
+are generated automatically (512×512 gradient) when not present, but you can
+provide your own for more realistic benchmarks.
+
+## Required filenames
+
+| File              | Format   | Notes                                      |
+|-------------------|----------|--------------------------------------------|
+| `test_image.jpg`  | JPEG     | Auto-generated if missing                  |
+| `test_image.png`  | PNG      | Auto-generated if missing                  |
+| `test_image.webp` | WebP     | Auto-generated if missing                  |
+| `test_image.heif` | HEIF     | Must be provided (skipped if missing)      |
+| `test_image.avif` | AVIF     | Must be provided (skipped if missing)      |
+| `test_image.jxl`  | JPEG XL  | Must be provided (skipped if missing)      |
+
+## Recommended test images
+
+For best benchmark results, use images that are:
+
+- **512×512** or **1024×1024** pixels (large enough to be meaningful)
+- **Realistic** (photos or manga pages rather than solid colours)
+- **Representative** of the actual workload (manga/comic pages)
+
+You can convert between formats using ImageMagick:
+
+```bash
+# Convert a JPEG to HEIF / AVIF / JXL
+convert input.jpg test_image.heif
+convert input.jpg test_image.avif
+cjxl input.jpg test_image.jxl
+```