Add an overlay on top of the reader to simulate a lower brightness. Closes #362

app/build.gradle

@@ -163,6 +163,7 @@ dependencies {
     compile 'com.afollestad.material-dialogs:core:0.8.6.1'
     compile 'net.xpece.android:support-preference:0.8.1'
     compile 'me.zhanghai.android.systemuihelper:library:1.0.0'
+    compile 'org.adw.library:discrete-seekbar:1.0.1'
 
     // Tests
     testCompile 'junit:junit:4.12'

app/src/main/java/eu/kanade/tachiyomi/data/preference/PreferencesHelper.kt

@@ -48,7 +48,7 @@ class PreferencesHelper(context: Context) {
 
     fun customBrightness() = rxPrefs.getBoolean(keys.customBrightness, false)
 
-    fun customBrightnessValue() = rxPrefs.getFloat(keys.customBrightnessValue, 0f)
+    fun customBrightnessValue() = rxPrefs.getInteger(keys.customBrightnessValue, 0)
 
     fun defaultViewer() = prefs.getInt(keys.defaultViewer, 1)
 

app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderActivity.kt

@@ -415,20 +415,39 @@ class ReaderActivity : BaseRxActivity<ReaderPresenter>() {
     private fun setCustomBrightness(enabled: Boolean) {
         if (enabled) {
             customBrightnessSubscription = preferences.customBrightnessValue().asObservable()
-                    .map { Math.max(0.01f, it) }
                     .subscribe { setCustomBrightnessValue(it) }
 
             subscriptions.add(customBrightnessSubscription)
         } else {
-            if (customBrightnessSubscription != null) {
-                subscriptions.remove(customBrightnessSubscription)
-            }
-            setCustomBrightnessValue(WindowManager.LayoutParams.BRIGHTNESS_OVERRIDE_NONE)
+            customBrightnessSubscription?.let { subscriptions.remove(it) }
+            setCustomBrightnessValue(0)
         }
     }
 
-    private fun setCustomBrightnessValue(value: Float) {
-        window.attributes = window.attributes.apply { screenBrightness = value }
+    /**
+     * Sets the brightness of the screen. Range is [-50, 100].
+     * From -50 to -1 a semi-transparent black view is shown at the top with the minimum brightness.
+     * From 1 to 100 it sets that value as brightness.
+     * 0 sets system brightness and hides the overlay.
+     */
+    private fun setCustomBrightnessValue(value: Int) {
+        // Calculate and set reader brightness.
+        val readerBrightness = if (value > 0) {
+            value / 100f
+        } else if (value < 0) {
+            0.01f
+        } else WindowManager.LayoutParams.BRIGHTNESS_OVERRIDE_NONE
+
+        window.attributes = window.attributes.apply { screenBrightness = readerBrightness }
+
+        // Set black overlay visibility.
+        if (value < 0) {
+            brightness_overlay.visibility = View.VISIBLE
+            val alpha = (Math.abs(value) * 2.56).toInt()
+            brightness_overlay.setBackgroundColor(Color.argb(alpha, 0, 0, 0))
+        } else {
+            brightness_overlay.visibility = View.GONE
+        }
     }
 
     private fun applyTheme(theme: Int) {

app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderSettingsDialog.kt

@@ -4,15 +4,14 @@ import android.app.Dialog
 import android.os.Bundle
 import android.support.v4.app.DialogFragment
 import android.view.View
-import android.widget.SeekBar
 import com.afollestad.materialdialogs.MaterialDialog
 import eu.kanade.tachiyomi.R
 import eu.kanade.tachiyomi.data.preference.PreferencesHelper
 import eu.kanade.tachiyomi.data.preference.getOrDefault
 import eu.kanade.tachiyomi.util.plusAssign
 import eu.kanade.tachiyomi.widget.IgnoreFirstSpinnerListener
-import eu.kanade.tachiyomi.widget.SimpleSeekBarListener
 import kotlinx.android.synthetic.main.dialog_reader_settings.view.*
+import org.adw.library.widgets.discreteseekbar.DiscreteSeekBar
 import rx.Observable
 import rx.android.schedulers.AndroidSchedulers
 import rx.subscriptions.CompositeSubscription
@@ -108,17 +107,18 @@ class ReaderSettingsDialog : DialogFragment() {
             preferences.customBrightness().set(isChecked)
         }
 
-        brightness_seekbar.max = 100
-        brightness_seekbar.progress = Math.round(
-                preferences.customBrightnessValue().getOrDefault() * brightness_seekbar.max)
-        brightness_seekbar.setOnSeekBarChangeListener(object : SimpleSeekBarListener() {
-            override fun onProgressChanged(seekBar: SeekBar, progress: Int, fromUser: Boolean) {
+        brightness_seekbar.progress = preferences.customBrightnessValue().getOrDefault()
+        brightness_seekbar.setOnProgressChangeListener(object : DiscreteSeekBar.OnProgressChangeListener {
+            override fun onProgressChanged(seekBar: DiscreteSeekBar, value: Int, fromUser: Boolean) {
                 if (fromUser) {
-                    preferences.customBrightnessValue().set(progress.toFloat() / seekBar.max)
+                    preferences.customBrightnessValue().set(value)
                 }
             }
-        })
 
+            override fun onStartTrackingTouch(seekBar: DiscreteSeekBar) {}
+
+            override fun onStopTrackingTouch(seekBar: DiscreteSeekBar) {}
+        })
     }
 
     override fun onDestroyView() {

app/src/main/res/layout/activity_reader.xml

@@ -99,4 +99,10 @@
 
     </FrameLayout>
 
+    <View
+        android:id="@+id/brightness_overlay"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:visibility="gone"/>
+
 </FrameLayout>

app/src/main/res/layout/dialog_reader_settings.xml

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:orientation="vertical"
@@ -188,10 +189,15 @@
         android:layout_height="wrap_content"
         android:text="@string/pref_custom_brightness"/>
 
-    <SeekBar
+    <org.adw.library.widgets.discreteseekbar.DiscreteSeekBar
         android:id="@+id/brightness_seekbar"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        style="@style/TextAppearance.Regular.Body1.Light"/>
+        app:dsb_min="-50"
+        app:dsb_max="100"
+        app:dsb_indicatorFormatter="%d%%"
+        app:dsb_indicatorTextAppearance="@style/TextAppearance.Regular"
+        app:dsb_indicatorColor="?colorAccent"
+        app:dsb_progressColor="?colorAccent" />
 
 </LinearLayout>

app/src/main/res/values/keys.xml

@@ -27,7 +27,7 @@
     <string name="pref_show_page_number_key">pref_show_page_number_key</string>
     <string name="pref_keep_screen_on_key">pref_keep_screen_on_key</string>
     <string name="pref_custom_brightness_key">pref_custom_brightness_key</string>
-    <string name="pref_custom_brightness_value_key">pref_custom_brightness_value_key</string>
+    <string name="pref_custom_brightness_value_key">custom_brightness_value</string>
     <string name="pref_reader_theme_key">pref_reader_theme_key</string>
     <string name="pref_image_decoder_key">pref_image_decoder_key</string>
     <string name="pref_read_with_volume_keys_key">reader_volume_keys</string>