[UI][Detail Activity] Made background of viewpager is average color of ImageView, and scrolling down with parallax effect.

app/build.gradle

@@ -34,4 +34,4 @@ dependencies {
     implementation 'com.squareup.retrofit2:converter-gson:2.4.0'
     implementation 'com.android.support:recyclerview-v7:27.1.1'
     implementation 'com.squareup.picasso:picasso:2.71828'
-}
+}

app/src/main/java/ru/volgorobot/vrcatalog/additional/ImagePagerAdapter.java

@@ -1,6 +1,9 @@
 package ru.volgorobot.vrcatalog.additional;
 
 import android.content.Context;
+import android.graphics.Bitmap;
+import android.net.Uri;
+import android.provider.MediaStore;
 import android.support.annotation.NonNull;
 import android.support.v4.view.PagerAdapter;
 import android.view.View;
@@ -9,6 +12,9 @@ import android.widget.ImageView;
 
 import com.squareup.picasso.Picasso;
 
+import java.io.FileNotFoundException;
+import java.io.IOException;
+
 public class ImagePagerAdapter extends PagerAdapter {
     /**
      * This class is designed to control the ViewPager (images of item) in the activity of viewing details of items.
@@ -57,4 +63,14 @@ public class ImagePagerAdapter extends PagerAdapter {
     public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
         container.removeView((View) object);
     }
+
+    public Bitmap getBitmap(int position) {
+        Bitmap bitmap = null;
+        try {
+            bitmap = MediaStore.Images.Media.getBitmap(context.getContentResolver(), Uri.parse(imageUris[position]));
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        return bitmap;
+    }
 }

app/src/main/java/ru/volgorobot/vrcatalog/view/DetailActivity.java

@@ -1,22 +1,24 @@
 package ru.volgorobot.vrcatalog.view;
 
 import android.content.Intent;
+import android.graphics.Bitmap;
+import android.graphics.Color;
 import android.os.Bundle;
 import android.support.design.widget.TabLayout;
 import android.support.v4.view.ViewPager;
 import android.support.v7.app.AppCompatActivity;
-import android.text.method.LinkMovementMethod;
+import android.support.v7.widget.LinearLayoutManager;
+import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.Toolbar;
 import android.util.Log;
 import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
-import android.widget.EditText;
 import android.widget.ListAdapter;
 import android.widget.ListView;
 import android.widget.TextView;
 import android.widget.Toast;
 
-import java.util.HashMap;
 import java.util.LinkedHashMap;
 
 import ru.volgorobot.vrcatalog.ItemPresenter;
@@ -29,11 +31,14 @@ public class DetailActivity extends AppCompatActivity implements MainContract.It
     private MainContract.ItemPresenter mPresenter;
     private ViewPager viewPager;
     private ListView propertiesList;
+    private ImagePagerAdapter imagePagerAdapter;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_detail);
+        Toolbar toolbar = findViewById(R.id.itemactivity_toolbar);
+        setSupportActionBar(toolbar);
         getSupportActionBar().setDisplayHomeAsUpEnabled(true);
         getSupportActionBar().setHomeButtonEnabled(true);
         getSupportActionBar().setDisplayShowTitleEnabled(false);
@@ -135,11 +140,102 @@ public class DetailActivity extends AppCompatActivity implements MainContract.It
 
     @Override
     public void setViewPagerContent(String[] uris) {
-        ImagePagerAdapter imagePagerAdapter = new ImagePagerAdapter(DetailActivity.this, uris);
+        imagePagerAdapter = new ImagePagerAdapter(DetailActivity.this, uris);
         TabLayout tabLayout = (TabLayout) findViewById(R.id.tabDots);
         viewPager.setAdapter(imagePagerAdapter);
+        setViewPagerScrollListener();
         tabLayout.setupWithViewPager(viewPager);
         imagePagerAdapter.notifyDataSetChanged();
     }
 
+    private int getImageAverageColor(Bitmap bitmap) {
+        if (null == bitmap) return Color.TRANSPARENT;
+
+        int redBucket = 0;
+        int greenBucket = 0;
+        int blueBucket = 0;
+        int alphaBucket = 0;
+
+        boolean hasAlpha = bitmap.hasAlpha();
+        int pixelCount = bitmap.getWidth() * bitmap.getHeight();
+        int[] pixels = new int[pixelCount];
+        bitmap.getPixels(pixels, 0, bitmap.getWidth(), 0, 0, bitmap.getWidth(), bitmap.getHeight());
+
+        for (int y = 0, h = bitmap.getHeight(); y < h; y++)
+        {
+            for (int x = 0, w = bitmap.getWidth(); x < w; x++)
+            {
+                int color = pixels[x + y * w]; // x + y * width
+                redBucket += (color >> 16) & 0xFF; // Color.red
+                greenBucket += (color >> 8) & 0xFF; // Color.greed
+                blueBucket += (color & 0xFF); // Color.blue
+                if (hasAlpha) alphaBucket += (color >>> 24); // Color.alpha
+            }
+        }
+
+        return Color.argb(
+                (hasAlpha) ? (alphaBucket / pixelCount) : 255,
+                redBucket / pixelCount,
+                greenBucket / pixelCount,
+                blueBucket / pixelCount);
+    }
+
+    private void setViewPagerScrollListener() {
+        ViewPager.OnPageChangeListener listener = new ViewPager.OnPageChangeListener() {
+            boolean firstImageProcessed = false;
+            @Override
+            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
+                if(position == 0 && !firstImageProcessed) {
+                    viewPager.setBackgroundColor(getImageAverageColor(imagePagerAdapter.getBitmap(position)));
+                    firstImageProcessed = true;
+                }
+            }
+
+            @Override
+            public void onPageSelected(int position) {
+                if(firstImageProcessed) {
+                    viewPager.setBackgroundColor(getImageAverageColor(imagePagerAdapter.getBitmap(position)));
+                }
+            }
+
+            @Override
+            public void onPageScrollStateChanged(int state) {
+                //
+            }
+        };
+        viewPager.setOnPageChangeListener(listener);
+    }
+
+    public static boolean setListViewHeightBasedOnItems(ListView listView) {
+
+        ListAdapter listAdapter = listView.getAdapter();
+        if (listAdapter != null) {
+
+            int numberOfItems = listAdapter.getCount();
+
+            // Get total height of all items.
+            int totalItemsHeight = 0;
+            for (int itemPos = 0; itemPos < numberOfItems; itemPos++) {
+                View item = listAdapter.getView(itemPos, null, listView);
+                item.measure(0, 0);
+                totalItemsHeight += item.getMeasuredHeight();
+            }
+
+            // Get total height of all item dividers.
+            int totalDividersHeight = listView.getDividerHeight() *
+                    (numberOfItems - 1);
+
+            // Set list height.
+            ViewGroup.LayoutParams params = listView.getLayoutParams();
+            params.height = totalItemsHeight + totalDividersHeight;
+            listView.setLayoutParams(params);
+            listView.requestLayout();
+
+            return true;
+
+        } else {
+            return false;
+        }
+
+    }
 }

app/src/main/res/layout/activity_detail.xml

@@ -5,7 +5,9 @@
     android:layout_width="match_parent"
     android:layout_height="wrap_content">
 
-    <LinearLayout
+
+
+    <!-- <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:orientation="vertical">
@@ -27,7 +29,7 @@
         <TextView
             android:id="@+id/itemName"
             android:layout_width="match_parent"
-            android:layout_height="40dp"
+            android:layout_height="wrap_content"
             android:text="Item Name"
             android:textAppearance="@style/TextAppearance.AppCompat.Body1"
             android:textSize="30sp"
@@ -46,9 +48,77 @@
             android:layout_width="match_parent"
             android:layout_height="wrap_content"/>
 
-    </LinearLayout>
+    </LinearLayout>-->
 
 
 
+    <android.support.design.widget.AppBarLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:fitsSystemWindows="true">
+        <android.support.design.widget.CollapsingToolbarLayout
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            app:layout_scrollFlags="scroll|enterAlways">
 
+            <android.support.v4.view.ViewPager
+                android:id="@+id/viewPager"
+                android:layout_width="wrap_content"
+                android:layout_height="311dp"
+                app:layout_collapseMode="parallax" />
+            <android.support.design.widget.TabLayout
+                android:id="@+id/tabDots"
+                android:layout_width="match_parent"
+                android:layout_height="62dp"
+                android:layout_alignParentBottom="true"
+                app:tabBackground="@drawable/tab_selector"
+                app:tabGravity="center"
+                app:tabIndicatorHeight="0dp" />
+            <android.support.v7.widget.Toolbar
+                android:id="@+id/itemactivity_toolbar"
+                android:layout_width="match_parent"
+                android:layout_height="?attr/actionBarSize"
+                app:layout_collapseMode="pin"
+                app:popupTheme="@style/AppTheme" />
+
+        </android.support.design.widget.CollapsingToolbarLayout>
+    </android.support.design.widget.AppBarLayout>
+
+    <android.support.v4.widget.NestedScrollView
+        android:layout_width="match_parent"
+        android:layout_height="619dp"
+        app:layout_behavior="@string/appbar_scrolling_view_behavior"
+        android:fillViewport="true">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:orientation="vertical">
+
+            <TextView
+                android:id="@+id/itemName"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginLeft="9dp"
+                android:text="Item Name"
+                android:textAppearance="@style/TextAppearance.AppCompat.Body1"
+                android:textSize="30sp" />
+
+            <TextView
+                android:id="@+id/itemPrice"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginLeft="9dp"
+                android:text="Item Price"
+                android:textAppearance="@style/TextAppearance.AppCompat.Body1"
+                android:textSize="24sp" />
+
+            <ListView
+                android:id="@+id/propertiesList"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                app:layout_behavior="@string/appbar_scrolling_view_behavior"
+                android:nestedScrollingEnabled="false"/>
+        </LinearLayout>
+    </android.support.v4.widget.NestedScrollView>
 </android.support.design.widget.CoordinatorLayout>

app/src/main/res/values-v21/styles.xml

@@ -5,16 +5,13 @@
         <item name="windowNoTitle">true</item>
         <item name="android:statusBarColor">@android:color/transparent</item>
     </style>
-    <style name="ItemActivityTheme" parent="Theme.AppCompat.Light.DarkActionBar">
+    <style name="ItemActivityTheme" parent="AppTheme">
-        <item name="android:windowDrawsSystemBarBackgrounds">true</item>
-        <item name="colorPrimary">@android:color/transparent</item>
-        <item name="actionBarStyle">@style/MyActionBar</item>
-        <item name="windowActionBarOverlay">true</item>
         <item name="android:windowTranslucentStatus">true</item>
+        <item name="windowActionBar">false</item>
+        <item name="windowNoTitle">true</item>
     </style>
     <style name="MyActionBar" parent="Widget.AppCompat.ActionBar.Solid">
         <item name="android:background">@android:color/transparent</item>
-        <!--For compatibility-->
         <item name="background">@android:color/transparent</item>
     </style>
 </resources>