util: add reflection utilities

Add lazyReflectedMethod and lazyReflectedField, utility methods that
make handling reflection a bit easier.

This is mostly a readability change.

app/src/main/java/org/oxycblt/auxio/detail/DetailAppBarLayout.kt

@@ -30,8 +30,10 @@ import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
 import com.google.android.material.appbar.AppBarLayout
 import java.lang.Exception
+import java.lang.reflect.Field
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.ui.EdgeAppBarLayout
+import org.oxycblt.auxio.util.lazyReflectedField
 import org.oxycblt.auxio.util.logE
 import org.oxycblt.auxio.util.logTraceOrThrow
 
@@ -68,10 +70,7 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
         // Reflect to get the actual title view to do transformations on
         val newTitleView =
             try {
-                Toolbar::class.java.getDeclaredField("mTitleTextView").run {
-                    isAccessible = true
-                    get(toolbar) as AppCompatTextView
-                }
+                TOOLBAR_TITLE_TEXT_FIELD.get(toolbar) as AppCompatTextView
             } catch (e: Exception) {
                 logE("Could not get toolbar title view (likely an internal code change)")
                 e.logTraceOrThrow()
@@ -152,4 +151,8 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
             appBar.setTitleVisibility(showTitle)
         }
     }
+
+    companion object {
+        private val TOOLBAR_TITLE_TEXT_FIELD: Field by lazyReflectedField<Toolbar>("mTitleTextView")
+    }
 }

app/src/main/java/org/oxycblt/auxio/home/HomeFragment.kt

@@ -35,6 +35,7 @@ import androidx.recyclerview.widget.RecyclerView
 import androidx.viewpager2.adapter.FragmentStateAdapter
 import androidx.viewpager2.widget.ViewPager2
 import com.google.android.material.tabs.TabLayoutMediator
+import java.lang.reflect.Field
 import kotlin.math.abs
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.FragmentHomeBinding
@@ -57,6 +58,7 @@ import org.oxycblt.auxio.ui.ViewBindingFragment
 import org.oxycblt.auxio.util.getColorStateListSafe
 import org.oxycblt.auxio.util.getSystemBarInsetsCompat
 import org.oxycblt.auxio.util.launch
+import org.oxycblt.auxio.util.lazyReflectedField
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.logE
 import org.oxycblt.auxio.util.logTraceOrThrow
@@ -424,4 +426,11 @@ class HomeFragment : ViewBindingFragment<FragmentHomeBinding>(), Toolbar.OnMenuI
             }
         }
     }
+
+    companion object {
+        private val VIEW_PAGER_RECYCLER_FIELD: Field by
+            lazyReflectedField<ViewPager2>("mRecyclerView")
+        private val VIEW_PAGER_TOUCH_SLOP_FIELD: Field by
+            lazyReflectedField<ViewPager2>("mTouchSlop")
+    }
 }

app/src/main/java/org/oxycblt/auxio/image/ImageGroup.kt

@@ -31,7 +31,6 @@ import org.oxycblt.auxio.music.Genre
 import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.settings.SettingsManager
 import org.oxycblt.auxio.util.getColorStateListSafe
-import org.oxycblt.auxio.util.logD
 
 /**
  * Effectively a super-charged [StyledImageView].

app/src/main/java/org/oxycblt/auxio/music/MusicUtil.kt

@@ -23,7 +23,6 @@ import android.database.Cursor
 import android.net.Uri
 import android.provider.MediaStore
 import androidx.core.text.isDigitsOnly
-import org.oxycblt.auxio.util.logD
 
 /** Shortcut for making a [ContentResolver] query with less superfluous arguments. */
 fun ContentResolver.queryCursor(

app/src/main/java/org/oxycblt/auxio/music/StorageFramework.kt

@@ -27,7 +27,9 @@ import android.provider.MediaStore
 import android.webkit.MimeTypeMap
 import com.google.android.exoplayer2.util.MimeTypes
 import java.io.File
+import java.lang.reflect.Method
 import org.oxycblt.auxio.R
+import org.oxycblt.auxio.util.lazyReflectedMethod
 import org.oxycblt.auxio.util.logEOrThrow
 
 data class Path(val name: String, val parent: Directory)
@@ -45,9 +47,9 @@ data class Directory(val volume: StorageVolume, val relativePath: String) {
 
     /** Converts this dir into an opaque document URI in the form of VOLUME:PATH. */
     fun toDocumentUri(): String? {
-        // "primary" actually corresponds to the primary *emulated* storage. External storage
-        // can also be the primary storage, but is represented as a document ID using the UUID.
-        return if (volume.isPrimaryCompat && volume.isEmulatedCompat) {
+        // "primary" actually corresponds to the internal storage, not the primary volume.
+        // Removable storage is represented with the UUID.
+        return if (volume.isInternalCompat) {
             "${DOCUMENT_URI_PRIMARY_NAME}:${relativePath}"
         } else {
             "${(volume.uuidCompat ?: return null).uppercase()}:${relativePath}"
@@ -78,6 +80,10 @@ data class Directory(val volume: StorageVolume, val relativePath: String) {
     }
 }
 
+private val SM_API21_GET_VOLUME_LIST_METHOD: Method by
+    lazyReflectedMethod<StorageManager>("getVolumeList")
+private val SV_API21_GET_PATH_METHOD: Method by lazyReflectedMethod<StorageVolume>("getPath")
+
 /**
  * A list of recognized volumes, retrieved in a compatible manner. Note that these volumes may be
  * mounted or unmounted.
@@ -88,9 +94,7 @@ val StorageManager.storageVolumesCompat: List<StorageVolume>
             storageVolumes.toList()
         } else {
             @Suppress("UNCHECKED_CAST")
-            (StorageManager::class.java.getDeclaredMethod("getVolumeList").invoke(this)
-                    as Array<StorageVolume>)
-                .toList()
+            (SM_API21_GET_VOLUME_LIST_METHOD.invoke(this) as Array<StorageVolume>).toList()
         }
 
 /** Returns the absolute path to a particular volume in a compatible manner. */
@@ -104,7 +108,7 @@ val StorageVolume.directoryCompat: String?
             when (stateCompat) {
                 Environment.MEDIA_MOUNTED,
                 Environment.MEDIA_MOUNTED_READ_ONLY ->
-                    StorageVolume::class.java.getDeclaredMethod("getPath").invoke(this) as String
+                    SV_API21_GET_PATH_METHOD.invoke(this) as String
                 else -> null
             }
         }
@@ -121,6 +125,13 @@ val StorageVolume.isPrimaryCompat: Boolean
 val StorageVolume.isEmulatedCompat: Boolean
     @SuppressLint("NewApi") get() = isEmulated
 
+/**
+ * If this volume corresponds to "Internal shared storage", represented in document URIs as
+ * "primary". These volumes are primary volumes, but are also non-removable and emulated.
+ */
+val StorageVolume.isInternalCompat: Boolean
+    get() = isPrimaryCompat && isEmulatedCompat
+
 val StorageVolume.uuidCompat: String?
     @SuppressLint("NewApi") get() = uuid
 

app/src/main/java/org/oxycblt/auxio/settings/SettingsCompat.kt

@@ -27,8 +27,7 @@ import android.util.Log
 import androidx.core.content.edit
 import org.oxycblt.auxio.music.Directory
 import org.oxycblt.auxio.music.directoryCompat
-import org.oxycblt.auxio.music.isEmulatedCompat
-import org.oxycblt.auxio.music.isPrimaryCompat
+import org.oxycblt.auxio.music.isInternalCompat
 import org.oxycblt.auxio.music.storageVolumesCompat
 import org.oxycblt.auxio.ui.accent.Accent
 import org.oxycblt.auxio.util.logD
@@ -103,8 +102,7 @@ fun handleExcludedCompat(context: Context, storageManager: StorageManager): List
     val db = LegacyExcludedDatabase(context)
     // /storage/emulated/0 (the old path prefix) should correspond to primary *emulated* storage.
     val primaryVolume =
-        storageManager.storageVolumesCompat.find { it.isPrimaryCompat && it.isEmulatedCompat }
-            ?: return emptyList()
+        storageManager.storageVolumesCompat.find { it.isInternalCompat } ?: return emptyList()
     val primaryDirectory = primaryVolume.directoryCompat ?: return emptyList()
     return db.readPaths().map { path ->
         val relativePath = path.removePrefix(primaryDirectory)

app/src/main/java/org/oxycblt/auxio/settings/ui/IntListPreference.kt

@@ -22,7 +22,9 @@ import android.content.res.TypedArray
 import android.util.AttributeSet
 import androidx.preference.DialogPreference
 import androidx.preference.Preference
+import java.lang.reflect.Field
 import org.oxycblt.auxio.R
+import org.oxycblt.auxio.util.lazyReflectedField
 
 class IntListPreference
 @JvmOverloads
@@ -38,7 +40,7 @@ constructor(
 
     // Reflect into Preference to get the (normally inaccessible) default value.
     private val defValue: Int
-        get() = defValueField.get(this) as Int
+        get() = PREFERENCE_DEFAULT_VALUE_FIELD.get(this) as Int
 
     init {
         val prefAttrs =
@@ -108,7 +110,7 @@ constructor(
     }
 
     companion object {
-        private val defValueField =
-            Preference::class.java.getDeclaredField("mDefaultValue").apply { isAccessible = true }
+        private val PREFERENCE_DEFAULT_VALUE_FIELD: Field by
+            lazyReflectedField<Preference>("mDefaultValue")
     }
 }

app/src/main/java/org/oxycblt/auxio/ui/BottomSheetLayout.kt

@@ -34,6 +34,7 @@ import android.widget.FrameLayout
 import androidx.core.view.isInvisible
 import androidx.customview.widget.ViewDragHelper
 import com.google.android.material.shape.MaterialShapeDrawable
+import java.lang.reflect.Field
 import kotlin.math.abs
 import kotlin.math.max
 import kotlin.math.min
@@ -45,6 +46,7 @@ import org.oxycblt.auxio.util.getDimenSafe
 import org.oxycblt.auxio.util.getDrawableSafe
 import org.oxycblt.auxio.util.getSystemBarInsetsCompat
 import org.oxycblt.auxio.util.isUnder
+import org.oxycblt.auxio.util.lazyReflectedField
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.pxOfDp
 import org.oxycblt.auxio.util.replaceSystemBarInsetsCompat
@@ -488,7 +490,7 @@ constructor(context: Context, attrs: AttributeSet? = null, defStyle: Int = 0) :
             // want to vendor ViewDragHelper so I just do reflection instead.
             val state =
                 try {
-                    DRAG_STATE_FIELD.get(this)
+                    VIEW_DRAG_HELPER_STATE_FIELD.get(this)
                 } catch (e: Exception) {
                     ViewDragHelper.STATE_IDLE
                 }
@@ -669,8 +671,8 @@ constructor(context: Context, attrs: AttributeSet? = null, defStyle: Int = 0) :
 
     companion object {
         private val INIT_PANEL_STATE = PanelState.HIDDEN
-        private val DRAG_STATE_FIELD =
-            ViewDragHelper::class.java.getDeclaredField("mDragState").apply { isAccessible = true }
+        private val VIEW_DRAG_HELPER_STATE_FIELD: Field by
+            lazyReflectedField<ViewDragHelper>("mDragState")
 
         private const val MIN_FLING_VEL = 400
         private const val KEY_PANEL_STATE = BuildConfig.APPLICATION_ID + ".key.PANEL_STATE"

app/src/main/java/org/oxycblt/auxio/util/PrimitiveUtil.kt

@@ -20,6 +20,8 @@ package org.oxycblt.auxio.util
 import android.os.Looper
 import android.text.format.DateUtils
 import androidx.core.math.MathUtils
+import java.lang.reflect.Field
+import java.lang.reflect.Method
 import org.oxycblt.auxio.BuildConfig
 
 /** Assert that we are on a background thread. */
@@ -64,3 +66,19 @@ fun Long.formatDuration(isElapsed: Boolean): String {
 
     return durationString
 }
+
+/** Lazily reflect to retrieve a [Field]. */
+inline fun <reified T : Any> lazyReflectedField(field: String): Lazy<Field> = lazy {
+    T::class.java.getDeclaredField(field).also { it.isAccessible = true }
+}
+
+/** Lazily reflect to retrieve a [Method]. */
+inline fun <reified T : Any> lazyReflectedMethod(
+    methodName: String,
+    vararg parameterTypes: Any
+): Lazy<Method> = lazy {
+    T::class
+        .java
+        .getDeclaredMethod(methodName, *parameterTypes.map { it::class.java }.toTypedArray())
+        .also { it.isAccessible = true }
+}