Add a menu item to toggle screen brightness

So this setting can be enabled/disabled where it's required, too.

app/src/main/kotlin/de/markusfisch/android/binaryeye/fragment/BarcodeFragment.kt

@@ -57,6 +57,7 @@ class BarcodeFragment : Fragment() {
 
 	private lateinit var barcode: Barcode<*>
 	private lateinit var addToHistoryItem: MenuItem
+	private lateinit var brightenScreenItem: MenuItem
 
 	private var currentBrightness = -1f;
 
@@ -144,9 +145,9 @@ class BarcodeFragment : Fragment() {
 	override fun onResume() {
 		super.onResume()
 		if (prefs.brightenScreen) {
-			activity?.let {
-				currentBrightness = it.getScreenBrightness()
-				it.setScreenBrightness(1f);
+			// Post to make sure brightenScreenItem is initialized.
+			view?.post {
+				brightenScreen()
 			}
 		}
 	}
@@ -154,8 +155,7 @@ class BarcodeFragment : Fragment() {
 	override fun onPause() {
 		super.onPause()
 		if (currentBrightness > -1f) {
-			activity?.setScreenBrightness(currentBrightness);
-			currentBrightness = -1f
+			restoreScreenBrightness()
 		}
 	}
 
@@ -167,6 +167,7 @@ class BarcodeFragment : Fragment() {
 	override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
 		inflater.inflate(R.menu.fragment_barcode, menu)
 		addToHistoryItem = menu.findItem(R.id.add_to_history)
+		brightenScreenItem = menu.findItem(R.id.brighten_screen)
 	}
 
 	override fun onOptionsItemSelected(item: MenuItem): Boolean {
@@ -193,6 +194,17 @@ class BarcodeFragment : Fragment() {
 				true
 			}
 
+			R.id.brighten_screen -> {
+				prefs.brightenScreen = if (currentBrightness > -1f) {
+					restoreScreenBrightness()
+					false
+				} else {
+					brightenScreen()
+					true
+				}
+				true
+			}
+
 			else -> super.onOptionsItemSelected(item)
 		}
 	}
@@ -317,6 +329,22 @@ class BarcodeFragment : Fragment() {
 		}
 	}
 
+	private fun brightenScreen() {
+		activity?.let {
+			currentBrightness = it.getScreenBrightness()
+			it.setScreenBrightness(1f);
+			brightenScreenItem.isChecked = true
+		}
+	}
+
+	private fun restoreScreenBrightness() {
+		if (currentBrightness > -1f) {
+			activity?.setScreenBrightness(currentBrightness);
+			currentBrightness = -1f
+			brightenScreenItem.isChecked = false
+		}
+	}
+
 	companion object {
 		private const val CONTENT_TEXT = "content_text"
 		private const val CONTENT_RAW = "content_raw"

app/src/main/res/drawable/ic_action_bright.xml

@@ -0,0 +1,5 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android" android:height="24dp" android:tint="#FFFFFF" android:viewportHeight="24" android:viewportWidth="24" android:width="24dp">
+      
+    <path android:fillColor="@android:color/white" android:pathData="M20,8.69L20,4h-4.69L12,0.69 8.69,4L4,4v4.69L0.69,12 4,15.31L4,20h4.69L12,23.31 15.31,20L20,20v-4.69L23.31,12 20,8.69zM12,18c-3.31,0 -6,-2.69 -6,-6s2.69,-6 6,-6 6,2.69 6,6 -2.69,6 -6,6zM12,8c-2.21,0 -4,1.79 -4,4s1.79,4 4,4 4,-1.79 4,-4 -1.79,-4 -4,-4z"/>
+    
+</vector>

app/src/main/res/menu/fragment_barcode.xml

@@ -16,4 +16,10 @@
 		android:title="@string/export_to_file"
 		android:icon="@drawable/ic_action_save"
 		material:showAsAction="ifRoom"/>
+	<item
+		android:id="@+id/brighten_screen"
+		android:title="@string/brighten_screen"
+		android:icon="@drawable/ic_action_bright"
+		android:checkable="true"
+		material:showAsAction="ifRoom"/>
 </menu>