[SetupWizardLib] Add support for require scrolling

Add SetupWizardLayout.requireScrollToBottom method that will register
a RequireScrollHelper on the layout. When the helper is registered
and the content view can scroll, the next button will be hidden and a
down-arrow button is shown, which will scroll the page down when
clicked.

Change-Id: Ib9ddcbeec24169cc00265fe107deb1b5099cba8d

3 files changed, 111 insertions, 0 deletions

diff --git a/library/main/src/com/android/setupwizardlib/SetupWizardLayout.java b/library/main/src/com/android/setupwizardlib/SetupWizardLayout.java
index a628d9e..60da563 100644
--- a/library/main/src/com/android/setupwizardlib/SetupWizardLayout.java
+++ b/library/main/src/com/android/setupwizardlib/SetupWizardLayout.java
@@ -29,6 +29,7 @@ import android.os.Build.VERSION_CODES;
 import android.os.Parcel;
 import android.os.Parcelable;
 import android.util.AttributeSet;
+import android.util.Log;
 import android.util.TypedValue;
 import android.view.Gravity;
 import android.view.LayoutInflater;
@@ -38,6 +39,8 @@ import android.view.ViewStub;
 import android.widget.FrameLayout;
 import android.widget.TextView;
 
+import com.android.setupwizardlib.util.RequireScrollHelper;
+import com.android.setupwizardlib.view.BottomScrollView;
 import com.android.setupwizardlib.view.Illustration;
 import com.android.setupwizardlib.view.NavigationBar;
 
@@ -222,6 +225,22 @@ public class SetupWizardLayout extends FrameLayout {
         return view instanceof NavigationBar ? (NavigationBar) view : null;
     }
 
+    private BottomScrollView getScrollView() {
+        final View view = findViewById(R.id.suw_bottom_scroll_view);
+        return view instanceof BottomScrollView ? (BottomScrollView) view : null;
+    }
+
+    public void requireScrollToBottom() {
+        final NavigationBar navigationBar = getNavigationBar();
+        final BottomScrollView scrollView = getScrollView();
+        if (navigationBar != null && scrollView != null) {
+            RequireScrollHelper.requireScroll(navigationBar, scrollView);
+        } else {
+            Log.e(TAG, "Both suw_layout_navigation_bar and suw_bottom_scroll_view must exist in"
+                    + " the template to require scrolling.");
+        }
+    }
+
     public void setHeaderText(int title) {
         final TextView titleView = (TextView) findViewById(R.id.suw_layout_title);
         if (titleView != null) {
diff --git a/library/main/src/com/android/setupwizardlib/util/RequireScrollHelper.java b/library/main/src/com/android/setupwizardlib/util/RequireScrollHelper.java
new file mode 100644
index 0000000..8d796d7
--- /dev/null
+++ b/library/main/src/com/android/setupwizardlib/util/RequireScrollHelper.java
@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.setupwizardlib.util;
+
+import android.view.View;
+import android.widget.ScrollView;
+
+import com.android.setupwizardlib.view.BottomScrollView;
+import com.android.setupwizardlib.view.NavigationBar;
+
+/**
+ * Add this helper to require the scroll view to be scrolled to the bottom, making sure that the
+ * user sees all content on the screen. This will change the navigation bar to show the more button
+ * instead of the next button when there is more content to be seen. When the more button is
+ * clicked, the scroll view will be scrolled one page down.
+ */
+public class RequireScrollHelper implements BottomScrollView.BottomScrollListener,
+        View.OnClickListener {
+
+    /**
+     * Require scrolling on the scrollView, so that if the scrollView has content hidden beneath the
+     * fold, the next button will be hidden and the more button will be shown instead. The more
+     * button will scroll the scrollView downwards when clicked until the bottom is reached.
+     *
+     * @param navigationBar The navigation bar in which the next button's label will be changed.
+     * @param scrollView The {@link BottomScrollView} to be scrolled.
+     */
+    public static RequireScrollHelper requireScroll(NavigationBar navigationBar,
+            BottomScrollView scrollView) {
+        final RequireScrollHelper helper = new RequireScrollHelper(navigationBar, scrollView);
+        helper.requireScroll();
+        return helper;
+    }
+
+    private final BottomScrollView mScrollView;
+    private final NavigationBar mNavigationBar;
+
+    private boolean mScrollNeeded;
+
+    private RequireScrollHelper(NavigationBar navigationBar, BottomScrollView scrollView) {
+        mNavigationBar = navigationBar;
+        mScrollView = scrollView;
+    }
+
+    private void requireScroll() {
+        mNavigationBar.getMoreButton().setOnClickListener(this);
+        mScrollView.setBottomScrollListener(this);
+    }
+
+    @Override
+    public void onScrolledToBottom() {
+        if (mScrollNeeded) {
+            mNavigationBar.getNextButton().setVisibility(View.VISIBLE);
+            mNavigationBar.getMoreButton().setVisibility(View.GONE);
+            mScrollNeeded = false;
+        }
+    }
+
+    @Override
+    public void onRequiresScroll() {
+        if (!mScrollNeeded) {
+            mNavigationBar.getNextButton().setVisibility(View.GONE);
+            mNavigationBar.getMoreButton().setVisibility(View.VISIBLE);
+            mScrollNeeded = true;
+        }
+    }
+
+    @Override
+    public void onClick(View view) {
+        mScrollView.pageScroll(ScrollView.FOCUS_DOWN);
+    }
+}
diff --git a/library/main/src/com/android/setupwizardlib/view/NavigationBar.java b/library/main/src/com/android/setupwizardlib/view/NavigationBar.java
index bc06976..d2bef6c 100644
--- a/library/main/src/com/android/setupwizardlib/view/NavigationBar.java
+++ b/library/main/src/com/android/setupwizardlib/view/NavigationBar.java
@@ -68,6 +68,7 @@ public class NavigationBar extends LinearLayout implements View.OnClickListener
 
     private Button mNextButton;
     private Button mBackButton;
+    private Button mMoreButton;
     private NavigationBarListener mListener;
 
     public NavigationBar(Context context) {
@@ -92,6 +93,7 @@ public class NavigationBar extends LinearLayout implements View.OnClickListener
         View.inflate(getContext(), R.layout.suw_navbar_view, this);
         mNextButton = (Button) findViewById(R.id.suw_navbar_next);
         mBackButton = (Button) findViewById(R.id.suw_navbar_back);
+        mMoreButton = (Button) findViewById(R.id.suw_navbar_more);
     }
 
     public Button getBackButton() {
@@ -102,6 +104,10 @@ public class NavigationBar extends LinearLayout implements View.OnClickListener
         return mNextButton;
     }
 
+    public Button getMoreButton() {
+        return mMoreButton;
+    }
+
     public void setNavigationBarListener(NavigationBarListener listener) {
         mListener = listener;
         if (mListener != null) {