Scroll articles using the volume keys (#401)

CHANGELOG.md

@@ -48,6 +48,8 @@
 
 - Dropped support for android 4, the last version supporting it is v1721030811
 
+- Added ability to scroll articles up and down using the volume keys #400
+
 **1.6.x**
 
 - Handling hidden tags.

app/src/main/java/apps/amine/bou/readerforselfoss/ReaderActivity.kt

@@ -4,6 +4,7 @@ import android.content.Context
 import android.content.SharedPreferences
 import android.graphics.Color
 import android.os.Bundle
+import android.view.KeyEvent
 import androidx.preference.PreferenceManager
 import androidx.appcompat.app.AppCompatActivity
 import android.view.Menu
@@ -135,13 +136,30 @@ class ReaderActivity : AppCompatActivity() {
     private inner class ScreenSlidePagerAdapter(fa: FragmentActivity) :
         FragmentStateAdapter(fa) {
 
-
         override fun getItemCount(): Int = allItems.size
 
         override fun createFragment(position: Int): Fragment = ArticleFragment.newInstance(allItems[position])
 
     }
 
+    override fun onKeyDown(keyCode: Int, event: KeyEvent?): Boolean {
+        return when (keyCode) {
+            KeyEvent.KEYCODE_VOLUME_DOWN -> {
+                val currentFragment = supportFragmentManager.findFragmentByTag("f" + binding.pager.currentItem) as ArticleFragment
+                currentFragment.scrollDown()
+                true
+            }
+            KeyEvent.KEYCODE_VOLUME_UP -> {
+                val currentFragment = supportFragmentManager.findFragmentByTag("f" + binding.pager.currentItem) as ArticleFragment
+                currentFragment.scrollUp()
+                true
+            }
+            else -> {
+                super.onKeyDown(keyCode, event)
+            }
+        }
+    }
+
     private fun alignmentMenu(showJustify: Boolean) {
         toolbarMenu.findItem(R.id.align_left).isVisible = !showJustify
         toolbarMenu.findItem(R.id.align_justify).isVisible = showJustify

app/src/main/java/apps/amine/bou/readerforselfoss/fragments/ArticleFragment.kt

@@ -511,6 +511,16 @@ class ArticleFragment : Fragment() {
         )
     }
 
+    fun scrollDown() {
+        val height = binding.nestedScrollView.measuredHeight
+        binding.nestedScrollView.smoothScrollBy(0, height/2)
+    }
+
+    fun scrollUp() {
+        val height = binding.nestedScrollView.measuredHeight
+        binding.nestedScrollView.smoothScrollBy(0, -height/2)
+    }
+
     private fun openInBrowserAfterFailing(customTabsIntent: CustomTabsIntent) {
         binding.progressBar.visibility = View.GONE
         requireActivity().openItemUrlInternalBrowser(