From def8389960696562b202b6d70453f3c3b4c03754 Mon Sep 17 00:00:00 2001
From: Heinrich Reimer <heinrich@heinrichreimersoftware.com>
Date: Sat, 25 Jun 2016 00:44:30 +0200
Subject: [PATCH] Behavior change: page scroll change now reacts to the
 distance to scroll to implement
 https://material.google.com/motion/duration-easing.html#duration-easing-dynamic-durations
 (check
 https://github.com/HeinrichReimer/material-intro/blob/master/library/src/main/java/com/heinrichreimersoftware/materialintro/app/IntroActivity.java#L343
 for the exact formula) Fixed bug when switching pages before the current page
 change animation is finished

---
 .../demo/CanteenIntroActivity.java            |  2 +-
 .../materialintro/app/IntroActivity.java      | 29 ++++++++++++++-----
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/app/src/main/java/com/heinrichreimersoftware/materialintro/demo/CanteenIntroActivity.java b/app/src/main/java/com/heinrichreimersoftware/materialintro/demo/CanteenIntroActivity.java
index 3a90ae1..6ef48f9 100644
--- a/app/src/main/java/com/heinrichreimersoftware/materialintro/demo/CanteenIntroActivity.java
+++ b/app/src/main/java/com/heinrichreimersoftware/materialintro/demo/CanteenIntroActivity.java
@@ -24,7 +24,7 @@ protected void onCreate(Bundle savedInstanceState) {
         label.setSpan(labelSpan, 0, label.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
         setButtonCtaLabel(label);
 
-        setPageScrollDuration(800);
+        setPageScrollDuration(500);
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
             setPagerInterpolator(android.R.interpolator.fast_out_slow_in);
         }
diff --git a/library/src/main/java/com/heinrichreimersoftware/materialintro/app/IntroActivity.java b/library/src/main/java/com/heinrichreimersoftware/materialintro/app/IntroActivity.java
index 44295eb..c8f7172 100644
--- a/library/src/main/java/com/heinrichreimersoftware/materialintro/app/IntroActivity.java
+++ b/library/src/main/java/com/heinrichreimersoftware/materialintro/app/IntroActivity.java
@@ -287,6 +287,9 @@ public void onClick(View v) {
     }
 
     private void smoothScrollPagerTo(final int position) {
+        if (pager.isFakeDragging())
+            return;
+
         ValueAnimator animator = ValueAnimator.ofFloat(pager.getCurrentItem(), position);
         animator.addListener(new AnimatorListenerAdapter() {
             @Override
@@ -329,11 +332,17 @@ else if (position < currentPosition && Math.ceil(position) != currentPosition &&
             }
         });
 
+        int distance = Math.abs(position - pager.getCurrentItem());
+
         animator.setInterpolator(pageScrollInterpolator);
-        animator.setDuration(pageScrollDuration);
+        animator.setDuration(calculateScrollDuration(distance));
         animator.start();
     }
 
+    private long calculateScrollDuration(int distance) {
+        return Math.round(pageScrollDuration * (distance + Math.sqrt(distance)) / 2);
+    }
+
     public void nextSlide() {
         int currentItem = pager.getCurrentItem();
         if (currentItem > adapter.getCount() - 1) finishIfNeeded();
@@ -343,16 +352,15 @@ public void nextSlide() {
         }
         else {
             AnimUtils.applyShakeAnimation(this, buttonNext);
-
         }
     }
 
-    private boolean nextSlideAuto() {
+    private int nextSlideAuto() {
         int endPosition = pager.getCurrentItem();
         int count = getCount();
 
         if (count == 1) {
-            return false;
+            return 0;
         }
         else if (pager.getCurrentItem() >= count - 1) {
             while (endPosition >= 0 && canGoBackward(endPosition, true)) {
@@ -365,12 +373,16 @@ else if (canGoForward(endPosition, true)) {
             endPosition++;
         }
 
+        int distance = Math.abs(endPosition - pager.getCurrentItem());
+
         if (endPosition == pager.getCurrentItem())
-            return false;
+            return 0;
 
         smoothScrollPagerTo(endPosition);
 
-        return autoplayCounter != 0;
+        if (autoplayCounter == 0)
+            return 0;
+        return distance;
 
     }
 
@@ -793,8 +805,9 @@ public void run() {
                     cancelAutoplay();
                     return;
                 }
-                if (nextSlideAuto())
-                    autoplayHandler.postDelayed(autoplayCallback, autoplayDelay);
+                int distance = nextSlideAuto();
+                if (distance != 0)
+                    autoplayHandler.postDelayed(autoplayCallback, autoplayDelay + calculateScrollDuration(distance));
             }
         };
         autoplayHandler.postDelayed(autoplayCallback, autoplayDelay);