create `AlbumPhotoDialog.kt`

app/src/main/java/com/ethosa/ktc/ui/adapters/AlbumAdapter.kt

@@ -1,47 +1,23 @@
 package com.ethosa.ktc.ui.adapters
 
-import android.animation.ObjectAnimator
-import android.animation.PropertyValuesHolder
-import android.annotation.SuppressLint
-import android.app.Dialog
-import android.graphics.Color
-import android.graphics.drawable.ColorDrawable
-import android.os.Build
-import android.util.DisplayMetrics
 import android.view.*
-import android.widget.ImageView
 import androidx.appcompat.app.AppCompatActivity
-import androidx.constraintlayout.widget.ConstraintLayout
 import androidx.recyclerview.widget.RecyclerView
 import com.bumptech.glide.Glide
 import com.ethosa.ktc.R
 import com.ethosa.ktc.databinding.LayoutAlbumImageBinding
-import kotlin.math.abs
+import com.ethosa.ktc.utils.AlbumPhotoDialog
 
 
 /**
  * Provides RecyclerView.Adapter behavior for album photos.
  */
 class AlbumAdapter(
-    private val items: List<String>,
-    private val activity: AppCompatActivity
+    val items: List<String>,
+    val activity: AppCompatActivity
 ) : RecyclerView.Adapter<AlbumAdapter.ViewHolder>() {
 
-    private val dialog = Dialog(activity)
-    private var animator = ObjectAnimator()
-    private var animX = PropertyValuesHolder.ofFloat("x", 0f)
-    private var animY = PropertyValuesHolder.ofFloat("y", 0f)
-    private var img: ImageView? = null
-    private var root: ConstraintLayout? = null
-    private var pos: Int = -1
-
-    companion object {
-        private const val MAX_DIM_AMOUNT = 0.95f
-        private const val HIDE_OFFSET = 400
-        private const val CHANGE_IMAGE_OFFSET = 200
-        private const val Y_PRIORITY = 2
-        private const val DIM_STEP = 0.1f
-    }
+    private var dialog = AlbumPhotoDialog(this)
 
     /**
      * Provides RecyclerView.ViewHolder behavior.
@@ -54,7 +30,6 @@ class AlbumAdapter(
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
         val inflater = LayoutInflater.from(parent.context)
             .inflate(R.layout.layout_album_image, parent, false)
-        setupDialog()
         return ViewHolder(inflater)
     }
 
@@ -71,104 +46,12 @@ class AlbumAdapter(
 
         // Show photo dialog.
         binding.root.setOnClickListener {
-            showImage(image, position)
-        }
-    }
-
-    private fun changeImage(inc: Int = 1) {
-        pos += inc
-        root!!.x = root!!.width.toFloat() * inc
-        Glide.with(dialog.context)
-            .load(items[pos])
-            .into(img!!)
-        animator = ObjectAnimator.ofPropertyValuesHolder(root!!, animX)
-        animator.duration = 600
-        animator.start()
-    }
-
-    private fun showImage(imgUrl: String, position: Int) {
-        // Load image
-        root!!.x = 0f
-        root!!.y = 0f
-        pos = position
-        Glide.with(dialog.context)
-            .load(imgUrl)
-            .into(img!!)
-        // Resize dialog
-        val metrics = DisplayMetrics()
-        @Suppress("DEPRECATION")
-        activity.windowManager.defaultDisplay.getMetrics(metrics)
-        dialog.window!!.attributes.dimAmount = MAX_DIM_AMOUNT
-        dialog.window!!.addFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND)
-        dialog.window?.setLayout(metrics.widthPixels, metrics.heightPixels)
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
-            dialog.window!!.attributes.blurBehindRadius = 5
+            dialog.showImage(image, position)
         }
-        dialog.show()
     }
 
     /**
      * @return image urls count
      */
     override fun getItemCount(): Int = items.size
-
-    /**
-     * Provides dialog behavior
-     */
-    @SuppressLint("ClickableViewAccessibility")
-    private fun setupDialog() {
-        // set content view
-        dialog.window?.setContentView(R.layout.layout_album_photo)
-        dialog.window?.setBackgroundDrawable(ColorDrawable(Color.TRANSPARENT))
-        root = dialog.findViewById(R.id.album_photo_root)
-        img = dialog.findViewById(R.id.album_photo)
-        var touchX = 0f
-        var touchY = 0f
-        var lastMotionEvent = 0
-
-        // Provides touch
-        root!!.setOnTouchListener { _, motionEvent ->
-            when (motionEvent.action) {
-                MotionEvent.ACTION_DOWN -> {
-                    touchY = motionEvent.y
-                    touchX = motionEvent.x
-                }
-                // Move img on X
-                MotionEvent.ACTION_MOVE -> {
-                    val tmpX = motionEvent.x - touchX
-                    val tmpY = motionEvent.y - touchY
-                    if (lastMotionEvent == MotionEvent.ACTION_DOWN) {
-                        if (abs(tmpX) > abs(tmpY)* Y_PRIORITY)
-                            touchY = 0f
-                        else
-                            touchX = 0f
-                    }
-                    else if(touchY != 0f) {
-                        root!!.y += tmpY
-                        dialog.window!!.attributes.dimAmount -= abs(tmpY * DIM_STEP)
-                    }
-                    else if(touchX != 0f)
-                        root!!.x += tmpX
-                }
-                // Hide and change image.
-                MotionEvent.ACTION_UP -> {
-                    if (lastMotionEvent == MotionEvent.ACTION_DOWN) {
-                        dialog.dismiss()
-                    } else if (root!!.y < -HIDE_OFFSET || root!!.y > root!!.width - HIDE_OFFSET) {
-                        dialog.dismiss()
-                    } else if (root!!.x < -CHANGE_IMAGE_OFFSET && pos < itemCount-1) {
-                        changeImage()
-                    } else if (root!!.x > CHANGE_IMAGE_OFFSET && pos > 0) {
-                        changeImage(-1)
-                    } else {
-                        animator = ObjectAnimator.ofPropertyValuesHolder(root!!, animX, animY)
-                        animator.duration = 600
-                        animator.start()
-                    }
-                }
-            }
-            lastMotionEvent = motionEvent.action
-            return@setOnTouchListener true
-        }
-    }
 }

app/src/main/java/com/ethosa/ktc/utils/AlbumPhotoDialog.kt

@@ -0,0 +1,170 @@
+package com.ethosa.ktc.utils
+
+import android.animation.ObjectAnimator
+import android.animation.PropertyValuesHolder
+import android.annotation.SuppressLint
+import android.app.Dialog
+import android.graphics.Color
+import android.graphics.drawable.ColorDrawable
+import android.os.Build
+import android.util.DisplayMetrics
+import android.view.MotionEvent
+import android.view.View
+import android.view.WindowManager
+import android.widget.ImageView
+import androidx.constraintlayout.widget.ConstraintLayout
+import com.bumptech.glide.Glide
+import com.ethosa.ktc.R
+import com.ethosa.ktc.ui.adapters.AlbumAdapter
+import kotlin.math.abs
+
+/**
+ * Provides photo dialog.
+ */
+@SuppressLint("ClickableViewAccessibility")
+class AlbumPhotoDialog(
+    private val adapter: AlbumAdapter
+) : View.OnTouchListener {
+    private var animator = ObjectAnimator()
+    private var animX = PropertyValuesHolder.ofFloat("x", 0f)
+    private var animY = PropertyValuesHolder.ofFloat("y", 0f)
+    private var root: ConstraintLayout? = null
+    private val dialog = Dialog(adapter.activity)
+    private var img: ImageView? = null
+    private var pos: Int = -1
+    private var percentHeight: Float = 1f
+
+    private var touchX = 0f
+    private var touchY = 0f
+    private var lastMotionEvent = 0
+
+    companion object {
+        private const val MAX_DIM_AMOUNT = 0.95f
+        private const val HIDE_OFFSET = 400
+        private const val CHANGE_IMAGE_OFFSET = 200
+        private const val Y_PRIORITY = 2
+    }
+
+    /**
+     * Setups dialog.
+     */
+    init {
+        // set content view
+        dialog.window?.setContentView(R.layout.layout_album_photo)
+        dialog.window?.setBackgroundDrawable(ColorDrawable(Color.TRANSPARENT))
+        img = dialog.findViewById(R.id.album_photo)
+
+        // Provides touch
+        root = dialog.findViewById(R.id.album_photo_root)
+        root!!.setOnTouchListener(this)
+    }
+
+    /**
+     * Shows this dialog.
+     */
+    fun showImage(imgUrl: String, position: Int) {
+        // Load image
+        root!!.x = 0f
+        root!!.y = 0f
+        pos = position
+        Glide.with(dialog.context)
+            .load(imgUrl)
+            .into(img!!)
+        // Resize dialog
+        val metrics = DisplayMetrics()
+        @Suppress("DEPRECATION")
+        adapter.activity.windowManager.defaultDisplay.getMetrics(metrics)
+        dialog.window!!.attributes.dimAmount = MAX_DIM_AMOUNT
+        dialog.window!!.addFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND)
+        dialog.window!!.addFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND)
+        dialog.window?.setLayout(metrics.widthPixels, metrics.heightPixels)
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
+            dialog.window!!.attributes.blurBehindRadius = 5
+        }
+        dialog.show()
+    }
+
+    private fun changeImage(inc: Int = 1) {
+        pos += inc
+        root!!.x = root!!.width.toFloat() * inc
+        Glide.with(dialog.context)
+            .load(adapter.items[pos])
+            .into(img!!)
+        animator = ObjectAnimator.ofPropertyValuesHolder(root!!, animX)
+        animator.duration = 600
+        animator.start()
+    }
+
+    /**
+     * Provides horizontal and vertical swipes
+     */
+    @SuppressLint("ClickableViewAccessibility")
+    override fun onTouch(view: View, motionEvent: MotionEvent): Boolean {
+        when (motionEvent.action) {
+            MotionEvent.ACTION_DOWN -> onTouchDown(motionEvent)
+            MotionEvent.ACTION_MOVE -> onTouchMove(motionEvent)
+            MotionEvent.ACTION_UP -> onTouchUp()
+        }
+        lastMotionEvent = motionEvent.action
+        return true
+    }
+
+    /**
+     * Calls when photo just touched.
+     */
+    private fun onTouchDown(motionEvent: MotionEvent) {
+        touchY = motionEvent.y
+        touchX = motionEvent.x
+    }
+
+    /**
+     * Calls when moves touch
+     */
+    private fun onTouchMove(motionEvent: MotionEvent) {
+        // calculate tmp positions
+        val tmpX = motionEvent.x - touchX
+        val tmpY = motionEvent.y - touchY
+        // if user just tapped
+        if (lastMotionEvent == MotionEvent.ACTION_DOWN) {
+            if (abs(tmpX) > abs(tmpY) * Y_PRIORITY)
+                // user swipes right or left
+                touchY = 0f
+            else
+                // user swipes up or down
+                touchX = 0f
+        }
+        else if(touchY != 0f) {
+            root!!.y += tmpY
+            percentHeight = root!!.height / 100f
+            dialog.window!!.setDimAmount(
+                MAX_DIM_AMOUNT - (abs(root!!.y / percentHeight) * 0.01f)
+            )
+        }
+        else if(touchX != 0f)
+            root!!.x += tmpX
+    }
+
+    /**
+     * Calls when canceled touch
+     */
+    private fun onTouchUp() {
+        if (lastMotionEvent == MotionEvent.ACTION_DOWN) {
+            // last event is just touch
+            dialog.dismiss()
+        } else if (root!!.y < -HIDE_OFFSET || root!!.y > root!!.width - HIDE_OFFSET) {
+            // user swipes image up or down
+            dialog.dismiss()
+        } else if (root!!.x < -CHANGE_IMAGE_OFFSET && pos < adapter.itemCount-1) {
+            // user swipes image left
+            changeImage()
+        } else if (root!!.x > CHANGE_IMAGE_OFFSET && pos > 0) {
+            // user swipes image right
+            changeImage(-1)
+        } else {
+            dialog.window!!.setDimAmount(MAX_DIM_AMOUNT)
+            animator = ObjectAnimator.ofPropertyValuesHolder(root!!, animX, animY)
+            animator.duration = 600
+            animator.start()
+        }
+    }
+}