Initial implementation of a drawable cache

application/tools/src/main/java/org/videolan/tools/DrawableCache.kt

@@ -0,0 +1,57 @@
+/*
+ * ************************************************************************
+ * DrawableCache.kt
+ * *************************************************************************
+ * Copyright © 2022 VLC authors and VideoLAN
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ * **************************************************************************
+ *
+ *
+ */
+package org.videolan.tools
+
+import android.content.Context
+import android.util.LruCache
+import androidx.annotation.DrawableRes
+
+/**
+ * Cache results from {@link android.content.res.Resources#getIdentifier} which uses reflection to
+ * perform lookups by string name. Adjust the max-size as application use increases.
+ */
+object DrawableCache {
+    private const val TAG = "VLC/DrawableCache"
+    private val memCache = LruCache<String, Int>(8)
+
+    fun getDrawableFromMemCache(ctx: Context, name: String, @DrawableRes defaultDrawable: Int): Int {
+        return getOrPutDrawable(name) { ctx.resources.getDrawableOrDefault(name, ctx.packageName, defaultDrawable) }
+    }
+
+    @Synchronized
+    private fun getOrPutDrawable(key: String, defaultValue: () -> Int): Int {
+        val value = memCache.get(key)
+        return if (value == null) {
+            val answer = defaultValue()
+            memCache.put(key, defaultValue())
+            answer
+        } else {
+            value
+        }
+    }
+
+    @Synchronized
+    fun clear() {
+        memCache.evictAll()
+    }
+}