Aperture: Implement volume key shutter feature

This is necessaary to make Mi Band 7's "Camera Remote" feature to work.

Change-Id: I4431ccb3e944b15920484b5c2313109908fd02aa
diff --git a/app/src/main/java/org/lineageos/aperture/MainActivity.kt b/app/src/main/java/org/lineageos/aperture/MainActivity.kt
index 3098a09..504fb63 100644
--- a/app/src/main/java/org/lineageos/aperture/MainActivity.kt
+++ b/app/src/main/java/org/lineageos/aperture/MainActivity.kt
@@ -27,6 +27,7 @@
 import android.provider.MediaStore
 import android.util.Log
 import android.util.Size
+import android.view.KeyEvent
 import android.view.MotionEvent
 import android.view.View
 import android.view.ViewConfiguration
@@ -391,6 +392,19 @@
         }
     }
 
+    override fun onKeyDown(keyCode: Int, event: KeyEvent?): Boolean {
+        return when (keyCode) {
+            KeyEvent.KEYCODE_VOLUME_UP,
+            KeyEvent.KEYCODE_VOLUME_DOWN -> {
+                if (shutterButton.isEnabled) {
+                    shutterButton.performClick()
+                }
+                true
+            }
+            else -> super.onKeyDown(keyCode, event)
+        }
+    }
+
     private fun takePhoto() {
         // Bail out if a photo is already being taken
         if (isTakingPhoto) {