improve portrait file recognizing

app/src/main/kotlin/com/simplemobiletools/gallery/pro/activities/ViewPagerActivity.kt

@@ -266,7 +266,18 @@ class ViewPagerActivity : SimpleActivity(), ViewPager.OnPageChangeListener, View
             return
         }
 
-        if (!File(mPath).exists()) {
+        if (mPath.isPortrait() && getPortraitPath() == "") {
+            val newIntent = Intent(this, ViewPagerActivity::class.java)
+            newIntent.putExtras(intent!!.extras!!)
+            newIntent.putExtra(PORTRAIT_PATH, mPath)
+            newIntent.putExtra(PATH, "${mPath.getParentPath().getParentPath()}/${mPath.getFilenameFromPath()}")
+
+            startActivity(newIntent)
+            finish()
+            return
+        }
+
+        if (!File(mPath).exists() && getPortraitPath() == "") {
             finish()
             return
         }
@@ -671,6 +682,8 @@ class ViewPagerActivity : SimpleActivity(), ViewPager.OnPageChangeListener, View
 
     private fun getCurrentPhotoFragment() = getCurrentFragment() as? PhotoFragment
 
+    private fun getPortraitPath() = intent.getStringExtra(PORTRAIT_PATH) ?: ""
+
     private fun isShowHiddenFlagNeeded(): Boolean {
         val file = File(mPath)
         if (file.isHidden) {
@@ -1033,7 +1046,17 @@ class ViewPagerActivity : SimpleActivity(), ViewPager.OnPageChangeListener, View
     private fun getPositionInList(items: MutableList<Medium>): Int {
         mPos = 0
         for ((i, medium) in items.withIndex()) {
-            if (medium.path == mPath) {
+            val portraitPath = getPortraitPath()
+            if (portraitPath != "") {
+                val portraitPaths = File(portraitPath).parentFile?.list()
+                if (portraitPaths != null) {
+                    for (path in portraitPaths) {
+                        if (medium.name == path) {
+                            return i
+                        }
+                    }
+                }
+            } else if (medium.path == mPath) {
                 return i
             }
         }

app/src/main/kotlin/com/simplemobiletools/gallery/pro/helpers/Constants.kt

@@ -127,6 +127,7 @@ const val SET_WALLPAPER_INTENT = "set_wallpaper_intent"
 const val IS_VIEW_INTENT = "is_view_intent"
 const val PICKED_PATHS = "picked_paths"
 const val SHOULD_INIT_FRAGMENT = "should_init_fragment"
+const val PORTRAIT_PATH = "portrait_path"
 
 // rotations
 const val ROTATE_BY_SYSTEM_SETTING = 0