Fixed #20, fragments get reused from fragment manager on configuratio…

…n changes; Added RestorableSlide which youo can extend if you want your custom Slides to get restored too

library/src/main/java/com/heinrichreimersoftware/materialintro/app/IntroActivity.java

@@ -39,6 +39,11 @@
 
 @SuppressLint("Registered")
 public class IntroActivity extends AppCompatActivity {
+    private static final String KEY_CURRENT_ITEM =
+            "com.heinrichreimersoftware.materialintro.app.IntroActivity.KEY_CURRENT_ITEM";
+
+    private static final String KEY_SLIDES =
+            "com.heinrichreimersoftware.materialintro.app.IntroActivity.KEY_SLIDES";
 
     private final ArgbEvaluator evaluator = new ArgbEvaluator();
     private FrameLayout frame;
@@ -68,6 +73,10 @@ protected void onCreate(Bundle savedInstanceState) {
             setFullscreenFlags(fullscreen);
         }
 
+        if (savedInstanceState != null && savedInstanceState.containsKey(KEY_CURRENT_ITEM)) {
+            position = savedInstanceState.getInt(KEY_CURRENT_ITEM, position);
+        }
+
         setContentView(R.layout.activity_intro);
         findViews();
     }
@@ -82,12 +91,12 @@ protected void onPostCreate(Bundle savedInstanceState) {
         updateButtonSkipDrawable();
         frame.addOnLayoutChangeListener(new View.OnLayoutChangeListener() {
             @Override
-            public void onLayoutChange(View v, int left, int top, int right, int bottom, int oldLeft, int oldTop, int oldRight, int oldBottom) {
+            public void onLayoutChange(View v, int left, int top, int right, int bottom,
+                                       int oldLeft, int oldTop, int oldRight, int oldBottom) {
                 updateViewPositions();
                 v.removeOnLayoutChangeListener(this);
             }
         });
-        lockSwipeIfNeeded();
     }
 
     @Override
@@ -96,6 +105,12 @@ protected void onResume() {
         setFullscreenFlags(fullscreen);
     }
 
+    @Override
+    protected void onSaveInstanceState(Bundle outState) {
+        super.onSaveInstanceState(outState);
+        outState.putInt(KEY_CURRENT_ITEM, pager.getCurrentItem());
+    }
+
     @Override
     public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
                                            @NonNull int[] grantResults) {
@@ -133,10 +148,12 @@ private void findViews(){
         buttonNext = findViewById(R.id.mi_button_next);
         buttonSkip = findViewById(R.id.mi_button_skip);
 
-        adapter = new SlideAdapter(getSupportFragmentManager());
+        FragmentManager fragmentManager = getSupportFragmentManager();
+        adapter = new SlideAdapter(fragmentManager);
 
         pager.setAdapter(adapter);
         pager.addOnPageChangeListener(listener);
+        pager.setCurrentItem(position);
 
         pagerIndicator.setViewPager(pager);
 
@@ -533,7 +550,7 @@ protected boolean isEmpty() {
     }
 
     protected int getCount() {
-        return adapter.getCount();
+        return adapter == null ? 0 : adapter.getCount();
     }
 
     protected int lastIndexOfSlide(Object object) {
@@ -571,6 +588,11 @@ public void onPageScrolled(int position, float positionOffset, int positionOffse
             IntroActivity.this.position = position;
             IntroActivity.this.positionOffset = positionOffset;
 
+            //Lock while scrolling a slide near its edges to lock (uncommon) multiple page swipes
+            if (Math.abs(positionOffset) < 0.1f) {
+                lockSwipeIfNeeded();
+            }
+
             updateBackground();
             updateViewPositions();
             updateFullscreen();

library/src/main/java/com/heinrichreimersoftware/materialintro/app/SlideFragment.java

@@ -12,7 +12,7 @@ public boolean canGoBackward() {
         return true;
     }
 
-    protected void updateNavigation() {
+    public void updateNavigation() {
         if (getActivity() instanceof IntroActivity) {
             ((IntroActivity) getActivity()).lockSwipeIfNeeded();
         }

library/src/main/java/com/heinrichreimersoftware/materialintro/slide/FragmentSlide.java

@@ -5,16 +5,17 @@
 import android.support.annotation.ColorRes;
 import android.support.annotation.LayoutRes;
 import android.support.annotation.StyleRes;
+import android.support.v4.app.Fragment;
 import android.support.v7.view.ContextThemeWrapper;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
 import com.heinrichreimersoftware.materialintro.app.SlideFragment;
 
-public class FragmentSlide extends Slide{
+public class FragmentSlide extends RestorableSlide {
 
-    private final android.support.v4.app.Fragment fragment;
+    private Fragment fragment;
     @ColorRes
     private final int background;
     @ColorRes
@@ -33,10 +34,15 @@ private FragmentSlide(Builder builder) {
     }
 
     @Override
-    public android.support.v4.app.Fragment getFragment() {
+    public Fragment getFragment() {
         return fragment;
     }
 
+    @Override
+    public void setFragment(Fragment fragment) {
+        this.fragment = fragment;
+    }
+
     @Override
     public int getBackground() {
         return background;
@@ -49,22 +55,22 @@ public int getBackgroundDark() {
 
     @Override
     public boolean canGoForward() {
-        if (fragment instanceof SlideFragment) {
-            return ((SlideFragment) fragment).canGoForward();
+        if (getFragment() instanceof SlideFragment) {
+            return ((SlideFragment) getFragment()).canGoForward();
         }
         return canGoForward;
     }
 
     @Override
     public boolean canGoBackward() {
-        if (fragment instanceof SlideFragment) {
-            return ((SlideFragment) fragment).canGoBackward();
+        if (getFragment() instanceof SlideFragment) {
+            return ((SlideFragment) getFragment()).canGoBackward();
         }
         return canGoBackward;
     }
 
     public static class Builder{
-        private android.support.v4.app.Fragment fragment;
+        private Fragment fragment;
         @ColorRes
         private int background;
         @ColorRes
@@ -74,18 +80,18 @@ public static class Builder{
 
         private boolean canGoBackward = true;
 
-        public Builder fragment(android.support.v4.app.Fragment fragment) {
+        public Builder fragment(Fragment fragment) {
             this.fragment = fragment;
             return this;
         }
 
         public Builder fragment(@LayoutRes int layoutRes, @StyleRes int themeRes) {
-            this.fragment = Fragment.newInstance(layoutRes, themeRes);
+            this.fragment = FragmentSlideFragment.newInstance(layoutRes, themeRes);
             return this;
         }
 
         public Builder fragment(@LayoutRes int layoutRes) {
-            this.fragment = Fragment.newInstance(layoutRes);
+            this.fragment = FragmentSlideFragment.newInstance(layoutRes);
             return this;
         }
 
@@ -116,17 +122,17 @@ public FragmentSlide build(){
         }
     }
 
-    public static class Fragment extends android.support.v4.app.Fragment{
+    public static class FragmentSlideFragment extends Fragment {
         private static final String ARGUMENT_LAYOUT_RES =
                 "com.heinrichreimersoftware.materialintro.SimpleFragment.ARGUMENT_LAYOUT_RES";
         private static final String ARGUMENT_THEME_RES =
                 "com.heinrichreimersoftware.materialintro.SimpleFragment.ARGUMENT_THEME_RES";
 
-        public Fragment() {
+        public FragmentSlideFragment() {
         }
 
-        public static Fragment newInstance(@LayoutRes int layoutRes, @StyleRes int themeRes) {
-            Fragment fragment = new Fragment();
+        public static FragmentSlideFragment newInstance(@LayoutRes int layoutRes, @StyleRes int themeRes) {
+            FragmentSlideFragment fragment = new FragmentSlideFragment();
 
             Bundle arguments = new Bundle();
             arguments.putInt(ARGUMENT_LAYOUT_RES, layoutRes);
@@ -136,7 +142,7 @@ public static Fragment newInstance(@LayoutRes int layoutRes, @StyleRes int theme
             return fragment;
         }
 
-        public static Fragment newInstance(@LayoutRes int layoutRes) {
+        public static FragmentSlideFragment newInstance(@LayoutRes int layoutRes) {
             return newInstance(layoutRes, 0);
         }
 

library/src/main/java/com/heinrichreimersoftware/materialintro/slide/RestorableSlide.java

@@ -0,0 +1,7 @@
+package com.heinrichreimersoftware.materialintro.slide;
+
+import android.support.v4.app.Fragment;
+
+public abstract class RestorableSlide extends Slide {
+    public abstract void setFragment(Fragment fragment);
+}