Revert "Remove no-longer-needed FloatListPreference"

This reverts commit 19993199db400e0276966dacba5511115e907170.

app/src/main/java/eu/kanade/tachiyomi/ui/setting/PreferenceDSL.kt

@@ -3,6 +3,7 @@ package eu.kanade.tachiyomi.ui.setting
 import android.support.graphics.drawable.VectorDrawableCompat
 import android.support.v4.graphics.drawable.DrawableCompat
 import android.support.v7.preference.*
+import eu.kanade.tachiyomi.widget.preference.FloatListPreference
 import eu.kanade.tachiyomi.widget.preference.IntListPreference
 
 @DslMarker
@@ -37,6 +38,10 @@ inline fun PreferenceGroup.intListPreference(block: (@DSL IntListPreference).()
     return initThenAdd(IntListPreference(context), block).also(::initDialog)
 }
 
+inline fun PreferenceGroup.floatListPreference(block: (@DSL FloatListPreference).() -> Unit): FloatListPreference {
+    return initThenAdd(FloatListPreference(context), block).also(::initDialog)
+}
+
 inline fun PreferenceGroup.multiSelectListPreference(block: (@DSL MultiSelectListPreference).() -> Unit): MultiSelectListPreference {
     return initThenAdd(MultiSelectListPreference(context), block).also(::initDialog)
 }

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsReaderController.kt

@@ -113,7 +113,7 @@ class SettingsReaderController : SettingsController() {
                 defaultValue = false
             }
 
-            intListPreference {
+            floatListPreference {
                 key = Keys.webtoonMarginRatio
                 titleRes = R.string.pref_reader_theme
                 entriesRes = arrayOf(R.string.webtoon_margin_ratio_0,

app/src/main/java/eu/kanade/tachiyomi/widget/preference/FloatListPreference.kt

@@ -0,0 +1,26 @@
+package eu.kanade.tachiyomi.widget.preference
+
+import android.content.Context
+import android.support.v7.preference.ListPreference
+import android.util.AttributeSet
+
+class FloatListPreference @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null) :
+        ListPreference(context, attrs) {
+
+    override fun persistString(value: String?): Boolean {
+        return value != null && persistFloat(value.toFloat())
+    }
+
+    override fun getPersistedString(defaultReturnValue: String?): String? {
+        // When the underlying preference is using a PreferenceDataStore, there's no way (for now)
+        // to check if a value is in the store, so we use a most likely unused value as workaround
+        val defaultIntValue = Float.NEGATIVE_INFINITY
+
+        val value = getPersistedFloat(defaultIntValue)
+        return if (value != defaultIntValue) {
+            value.toString()
+        } else {
+            defaultReturnValue
+        }
+    }
+}