Aperture: Better handle left/right swipe gesture

Change-Id: I4f6f108ce9f79f93c5e13165b8154ff0f74d4d70

app/src/main/java/org/lineageos/aperture/CameraActivity.kt

@@ -310,18 +310,10 @@ open class CameraActivity : AppCompatActivity() {
                 ) {
                     if (e2.x > e1.x) {
                         // Left to right
-                        when (cameraMode) {
-                            CameraMode.PHOTO -> changeCameraMode(CameraMode.QR)
-                            CameraMode.VIDEO -> changeCameraMode(CameraMode.PHOTO)
-                            CameraMode.QR -> changeCameraMode(CameraMode.VIDEO)
-                        }
+                        changeCameraMode(cameraMode.previous())
                     } else {
                         // Right to left
-                        when (cameraMode) {
-                            CameraMode.PHOTO -> changeCameraMode(CameraMode.VIDEO)
-                            CameraMode.VIDEO -> changeCameraMode(CameraMode.QR)
-                            CameraMode.QR -> changeCameraMode(CameraMode.PHOTO)
-                        }
+                        changeCameraMode(cameraMode.next())
                     }
                 }
                 return true

app/src/main/java/org/lineageos/aperture/camera/CameraMode.kt

@@ -5,8 +5,20 @@
 
 package org.lineageos.aperture.camera
 
+import org.lineageos.aperture.ext.*
+
 enum class CameraMode {
     PHOTO,
     VIDEO,
-    QR,
+    QR;
+
+    /**
+     * Get the next mode.
+     */
+    fun next() = values().next(this)
+
+    /**
+     * Get the previous mode.
+     */
+    fun previous() = values().previous(this)
 }

app/src/main/java/org/lineageos/aperture/ext/Collections.kt

@@ -15,6 +15,16 @@ internal fun <T> Array<T>.next(current: T): T {
     return getOrElse(currentIndex + 1) { first() }
 }
 
+/**
+ * Get the previous item in the array.
+ * If the element is the first of the list or it's not present in the list
+ * it will return the last item.
+ */
+internal fun <T> Array<T>.previous(current: T): T {
+    val currentIndex = indexOf(current)
+    return getOrElse(currentIndex - 1) { last() }
+}
+
 /**
  * Get the next item in the list.
  * If the element is the last of the list or it's not present in the list
@@ -24,3 +34,13 @@ internal fun <T> List<T>.next(current: T): T {
     val currentIndex = indexOf(current)
     return getOrElse(currentIndex + 1) { first() }
 }
+
+/**
+ * Get the previous item in the list.
+ * If the element is the first of the list or it's not present in the list
+ * it will return the last item.
+ */
+internal fun <T> List<T>.previous(current: T): T {
+    val currentIndex = indexOf(current)
+    return getOrElse(currentIndex - 1) { last() }
+}