From 2c9ac6e4403834f3e913fce6159d724f992eff52 Mon Sep 17 00:00:00 2001
From: tibbi <tibor@kaputa.sk>
Date: Thu, 20 Jun 2019 15:17:55 +0200
Subject: [PATCH] adding an implementation of slideshow fade animations

---
 .../pro/activities/ViewPagerActivity.kt        | 14 ++++++++++++--
 .../gallery/pro/helpers/Constants.kt           |  3 ++-
 .../pro/helpers/DefaultPageTransformer.kt      |  8 ++++++++
 .../gallery/pro/helpers/FadePageTransformer.kt | 18 ++++++++++++++++++
 4 files changed, 40 insertions(+), 3 deletions(-)
 create mode 100644 app/src/main/kotlin/com/simplemobiletools/gallery/pro/helpers/DefaultPageTransformer.kt
 create mode 100644 app/src/main/kotlin/com/simplemobiletools/gallery/pro/helpers/FadePageTransformer.kt

diff --git a/app/src/main/kotlin/com/simplemobiletools/gallery/pro/activities/ViewPagerActivity.kt b/app/src/main/kotlin/com/simplemobiletools/gallery/pro/activities/ViewPagerActivity.kt
index 0fe36ff5c..361cbc326 100644
--- a/app/src/main/kotlin/com/simplemobiletools/gallery/pro/activities/ViewPagerActivity.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/gallery/pro/activities/ViewPagerActivity.kt
@@ -396,6 +396,10 @@ class ViewPagerActivity : SimpleActivity(), ViewPager.OnPageChangeListener, View
         if (getMediaForSlideshow()) {
             view_pager.onGlobalLayout {
                 if (!isDestroyed) {
+                    if (config.slideshowAnimation == SLIDESHOW_ANIMATION_FADE) {
+                        view_pager.setPageTransformer(false, FadePageTransformer())
+                    }
+
                     hideSystemUI(true)
                     mSlideshowInterval = config.slideshowInterval
                     mSlideshowMoveBackwards = config.slideshowMoveBackwards
@@ -436,7 +440,13 @@ class ViewPagerActivity : SimpleActivity(), ViewPager.OnPageChangeListener, View
             }
         })
 
-        animator.interpolator = DecelerateInterpolator()
+        if (config.slideshowAnimation == SLIDESHOW_ANIMATION_SLIDE) {
+            animator.interpolator = DecelerateInterpolator()
+            animator.duration = SLIDESHOW_SLIDE_DURATION
+        } else {
+            animator.duration = SLIDESHOW_FADE_DURATION
+        }
+
         animator.addUpdateListener(object : ValueAnimator.AnimatorUpdateListener {
             var oldDragPosition = 0
             override fun onAnimationUpdate(animation: ValueAnimator) {
@@ -453,7 +463,6 @@ class ViewPagerActivity : SimpleActivity(), ViewPager.OnPageChangeListener, View
             }
         })
 
-        animator.duration = SLIDESHOW_SCROLL_DURATION
         view_pager.beginFakeDrag()
         animator.start()
     }
@@ -473,6 +482,7 @@ class ViewPagerActivity : SimpleActivity(), ViewPager.OnPageChangeListener, View
 
     private fun stopSlideshow() {
         if (mIsSlideshowActive) {
+            view_pager.setPageTransformer(false, DefaultPageTransformer())
             mIsSlideshowActive = false
             showSystemUI(true)
             mSlideshowHandler.removeCallbacksAndMessages(null)
diff --git a/app/src/main/kotlin/com/simplemobiletools/gallery/pro/helpers/Constants.kt b/app/src/main/kotlin/com/simplemobiletools/gallery/pro/helpers/Constants.kt
index 267ec5ab2..8193e9de8 100644
--- a/app/src/main/kotlin/com/simplemobiletools/gallery/pro/helpers/Constants.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/gallery/pro/helpers/Constants.kt
@@ -88,7 +88,8 @@ const val SLIDESHOW_MOVE_BACKWARDS = "slideshow_move_backwards"
 const val SLIDESHOW_ANIMATION = "slideshow_animation"
 const val SLIDESHOW_LOOP = "loop_slideshow"
 const val SLIDESHOW_DEFAULT_INTERVAL = 5
-const val SLIDESHOW_SCROLL_DURATION = 500L
+const val SLIDESHOW_SLIDE_DURATION = 500L
+const val SLIDESHOW_FADE_DURATION = 1500L
 const val SLIDESHOW_START_ON_ENTER = "slideshow_start_on_enter"
 
 // slideshow animations
diff --git a/app/src/main/kotlin/com/simplemobiletools/gallery/pro/helpers/DefaultPageTransformer.kt b/app/src/main/kotlin/com/simplemobiletools/gallery/pro/helpers/DefaultPageTransformer.kt
new file mode 100644
index 000000000..95981ba4a
--- /dev/null
+++ b/app/src/main/kotlin/com/simplemobiletools/gallery/pro/helpers/DefaultPageTransformer.kt
@@ -0,0 +1,8 @@
+package com.simplemobiletools.gallery.pro.helpers
+
+import android.view.View
+import androidx.viewpager.widget.ViewPager
+
+class DefaultPageTransformer : ViewPager.PageTransformer {
+    override fun transformPage(view: View, position: Float) {}
+}
diff --git a/app/src/main/kotlin/com/simplemobiletools/gallery/pro/helpers/FadePageTransformer.kt b/app/src/main/kotlin/com/simplemobiletools/gallery/pro/helpers/FadePageTransformer.kt
new file mode 100644
index 000000000..3ed113b40
--- /dev/null
+++ b/app/src/main/kotlin/com/simplemobiletools/gallery/pro/helpers/FadePageTransformer.kt
@@ -0,0 +1,18 @@
+package com.simplemobiletools.gallery.pro.helpers
+
+import android.view.View
+import androidx.viewpager.widget.ViewPager
+
+class FadePageTransformer : ViewPager.PageTransformer {
+    override fun transformPage(view: View, position: Float) {
+        view.translationX = view.width * -position
+
+        view.alpha = if (position <= -1f || position >= 1f) {
+            0f
+        } else if (position == 0f) {
+            1f
+        } else {
+            1f - Math.abs(position)
+        }
+    }
+}