Added horizontal view for ReaderActivity

Added page selector for ReaderActivity

app/src/main/java/xyz/quaver/pupil/adapters/ReaderAdapter.kt

@@ -0,0 +1,51 @@
+package xyz.quaver.pupil.adapters
+
+import android.graphics.BitmapFactory
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.widget.ImageView
+import androidx.recyclerview.widget.RecyclerView
+import kotlinx.android.synthetic.main.item_reader.view.*
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import xyz.quaver.pupil.R
+
+class ReaderAdapter(private val images: List<String>) : RecyclerView.Adapter<ReaderAdapter.ViewHolder>() {
+
+    class ViewHolder(val view: View) : RecyclerView.ViewHolder(view)
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
+        LayoutInflater.from(parent.context).inflate(
+            R.layout.item_reader, parent, false
+        ).let {
+            return ViewHolder(it)
+        }
+    }
+
+    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
+        with(holder.view as ImageView) {
+            CoroutineScope(Dispatchers.Default).launch {
+                val options = BitmapFactory.Options()
+
+                options.inJustDecodeBounds = true
+                BitmapFactory.decodeFile(images[position], options)
+
+                options.inSampleSize = options.outWidth /
+                        context.resources.displayMetrics.widthPixels
+
+                options.inJustDecodeBounds = false
+
+                val image = BitmapFactory.decodeFile(images[position], options)
+
+                launch(Dispatchers.Main) {
+                    setImageBitmap(image)
+                }
+            }
+        }
+    }
+
+    override fun getItemCount() = images.size
+
+}