main/src/com/google/android/setupdesign/view/HeaderRecyclerView.java - platform/external/setupdesign - Git at Google

 /*
  * 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.google.android.setupdesign.view;

 import android.content.Context;
 import android.content.res.TypedArray;
 import android.os.Build;
 import androidx.recyclerview.widget.RecyclerView;
 import android.util.AttributeSet;
 import android.view.KeyEvent;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.accessibility.AccessibilityEvent;
 import android.widget.FrameLayout;
 import com.google.android.setupdesign.DividerItemDecoration;
 import com.google.android.setupdesign.R;

 /**
  * A RecyclerView that can display a header item at the start of the list. The header can be set by
  * {@code app:sudHeader} in XML. Note that the header will not be inflated until a layout manager is
  * set.
  */
 public class HeaderRecyclerView extends RecyclerView {

   private static class HeaderViewHolder extends ViewHolder
       implements DividerItemDecoration.DividedViewHolder {

     HeaderViewHolder(View itemView) {
       super(itemView);
     }

     @Override
     public boolean isDividerAllowedAbove() {
       return false;
     }

     @Override
     public boolean isDividerAllowedBelow() {
       return false;
     }
   }

   /**
    * An adapter that can optionally add one header item to the RecyclerView.
    *
    * @param <CVH> Type of the content view holder. i.e. view holder type of the wrapped adapter.
    */
   public static class HeaderAdapter<CVH extends ViewHolder>
       extends RecyclerView.Adapter<ViewHolder> {

     private static final int HEADER_VIEW_TYPE = Integer.MAX_VALUE;

     private final RecyclerView.Adapter<CVH> adapter;
     private View header;

     private final AdapterDataObserver observer =
         new AdapterDataObserver() {

           @Override
           public void onChanged() {
             notifyDataSetChanged();
           }

           @Override
           public void onItemRangeChanged(int positionStart, int itemCount) {
             if (header != null) {
               positionStart++;
             }
             notifyItemRangeChanged(positionStart, itemCount);
           }

           @Override
           public void onItemRangeInserted(int positionStart, int itemCount) {
             if (header != null) {
               positionStart++;
             }
             notifyItemRangeInserted(positionStart, itemCount);
           }

           @Override
           public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) {
             if (header != null) {
               fromPosition++;
               toPosition++;
             }
             // Why is there no notifyItemRangeMoved?
             for (int i = 0; i < itemCount; i++) {
               notifyItemMoved(fromPosition + i, toPosition + i);
             }
           }

           @Override
           public void onItemRangeRemoved(int positionStart, int itemCount) {
             if (header != null) {
               positionStart++;
             }
             notifyItemRangeRemoved(positionStart, itemCount);
           }
         };

     public HeaderAdapter(RecyclerView.Adapter<CVH> adapter) {
       this.adapter = adapter;
       this.adapter.registerAdapterDataObserver(observer);
       setHasStableIds(this.adapter.hasStableIds());
     }

     @Override
     public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
       // Returning the same view (header) results in crash ".. but view is not a real child."
       // The framework creates more than one instance of header because of "disappear"
       // animations applied on the header and this necessitates creation of another header
       // view to use after the animation. We work around this restriction by returning an
       // empty FrameLayout to which the header is attached using #onBindViewHolder method.
       if (viewType == HEADER_VIEW_TYPE) {
         FrameLayout frameLayout = new FrameLayout(parent.getContext());
         FrameLayout.LayoutParams params =
             new FrameLayout.LayoutParams(
                 FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.WRAP_CONTENT);
         frameLayout.setLayoutParams(params);
         return new HeaderViewHolder(frameLayout);
       } else {
         return adapter.onCreateViewHolder(parent, viewType);
       }
     }

     @Override
     @SuppressWarnings("unchecked") // Non-header position always return type CVH
     public void onBindViewHolder(ViewHolder holder, int position) {
       if (header != null) {
         position--;
       }

       if (holder instanceof HeaderViewHolder) {
         if (header == null) {
           throw new IllegalStateException("HeaderViewHolder cannot find mHeader");
         }
         if (header.getParent() != null) {
           ((ViewGroup) header.getParent()).removeView(header);
         }
         FrameLayout mHeaderParent = (FrameLayout) holder.itemView;
         mHeaderParent.addView(header);
       } else {
         adapter.onBindViewHolder((CVH) holder, position);
       }
     }

     @Override
     public int getItemViewType(int position) {
       if (header != null) {
         position--;
       }
       if (position < 0) {
         return HEADER_VIEW_TYPE;
       }
       return adapter.getItemViewType(position);
     }

     @Override
     public int getItemCount() {
       int count = adapter.getItemCount();
       if (header != null) {
         count++;
       }
       return count;
     }

     @Override
     public long getItemId(int position) {
       if (header != null) {
         position--;
       }
       if (position < 0) {
         return Long.MAX_VALUE;
       }
       return adapter.getItemId(position);
     }

     public void setHeader(View header) {
       this.header = header;
     }

     public RecyclerView.Adapter<CVH> getWrappedAdapter() {
       return adapter;
     }
   }

   private View header;
   private int headerRes;

   public HeaderRecyclerView(Context context) {
     super(context);
     init(null, 0);
   }

   public HeaderRecyclerView(Context context, AttributeSet attrs) {
     super(context, attrs);
     init(attrs, 0);
   }

   public HeaderRecyclerView(Context context, AttributeSet attrs, int defStyleAttr) {
     super(context, attrs, defStyleAttr);
     init(attrs, defStyleAttr);
   }

   private void init(AttributeSet attrs, int defStyleAttr) {
     if (isInEditMode()) {
       return;
     }

     final TypedArray a =
         getContext()
             .obtainStyledAttributes(attrs, R.styleable.SudHeaderRecyclerView, defStyleAttr, 0);
     headerRes = a.getResourceId(R.styleable.SudHeaderRecyclerView_sudHeader, 0);
     a.recycle();
   }

   @Override
   public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
     super.onInitializeAccessibilityEvent(event);

     // Decoration-only headers should not count as an item for accessibility, adjust the
     // accessibility event to account for that.
     final int numberOfHeaders = header != null ? 1 : 0;
     event.setItemCount(event.getItemCount() - numberOfHeaders);
     event.setFromIndex(Math.max(event.getFromIndex() - numberOfHeaders, 0));
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
       event.setToIndex(Math.max(event.getToIndex() - numberOfHeaders, 0));
     }
   }

   private boolean handleDpadDown() {
     View focusedView = findFocus();
     if (focusedView == null) {
       return false;
     }

     int[] focusdLocationInWindow = new int[2];
     int[] myLocationInWindow = new int[2];

     focusedView.getLocationInWindow(focusdLocationInWindow);
     getLocationInWindow(myLocationInWindow);

     int offset =
         (focusdLocationInWindow[1] + focusedView.getMeasuredHeight())
             - (myLocationInWindow[1] + getMeasuredHeight());

     /*
       (focusdLocationInWindow[1] + focusedView.getMeasuredHeight())
       is the bottom position of focused view

       (myLocationInWindow[1] + getMeasuredHeight())
       is the bottom position of recycler view

       If the bottom of focused view is out of recycler view, means we need to scroll down to show
       more detail

       We scroll 70% of recycler view to make sure user can have 30% of previous information, to make
       sure user can keep reading easily.
     */
     if (offset > 0) {
       // We expect only scroll 70% of recycler view
       int scrollLength = (int) (getMeasuredHeight() * 0.7f);
       smoothScrollBy(0, Math.min(scrollLength, offset));
       return true;
     }

     return false;
   }

   private boolean handleDpadUp() {
     View focusedView = findFocus();
     if (focusedView == null) {
       return false;
     }

     int[] focusedLocationInWindow = new int[2];
     int[] myLocationInWindow = new int[2];

     focusedView.getLocationInWindow(focusedLocationInWindow);
     getLocationInWindow(myLocationInWindow);

     int offset = (focusedLocationInWindow[1] - myLocationInWindow[1]);

     /*
       focusedLocationInWindow[1] is top of focused view
       myLocationInWindow[1] is top of recycler view

       If top of focused view is higher than recycler view we need scroll up to show more information
       we try to scroll up 70% of recycler view ot scroll up to the top of focused view
     */
     if (offset < 0) {
       // We expect only scroll 70% of recycler view
       int scrollLength = (int) (getMeasuredHeight() * -0.7f);

       smoothScrollBy(0, Math.max(scrollLength, offset));
       return true;
     }
     return false;
   }

   private boolean shouldHandleActionUp = false;

   private boolean handleKeyEvent(KeyEvent keyEvent) {
     if (shouldHandleActionUp && keyEvent.getAction() == KeyEvent.ACTION_UP) {
       shouldHandleActionUp = false;
       return true;
     } else if (keyEvent.getAction() == KeyEvent.ACTION_DOWN) {
       boolean eventHandled = false;
       switch (keyEvent.getKeyCode()) {
         case KeyEvent.KEYCODE_DPAD_DOWN:
           eventHandled = handleDpadDown();
           break;
         case KeyEvent.KEYCODE_DPAD_UP:
           eventHandled = handleDpadUp();
           break;
         default: // fall out
       }
       shouldHandleActionUp = eventHandled;
       return eventHandled;
     }
     return false;
   }

   @Override
   public boolean dispatchKeyEvent(KeyEvent event) {
     if (handleKeyEvent(event)) {
       return true;
     }
     return super.dispatchKeyEvent(event);
   }

   /** Gets the header view of this RecyclerView, or {@code null} if there are no headers. */
   public View getHeader() {
     return header;
   }

   /**
    * Set the view to use as the header of this recycler view. Note: This must be called before
    * setAdapter.
    */
   public void setHeader(View header) {
     this.header = header;
   }

   @Override
   public void setLayoutManager(LayoutManager layout) {
     super.setLayoutManager(layout);
     if (layout != null && header == null && headerRes != 0) {
       // Inflating a child view requires the layout manager to be set. Check here to see if
       // any header item is specified in XML and inflate them.
       final LayoutInflater inflater = LayoutInflater.from(getContext());
       header = inflater.inflate(headerRes, this, false);
     }
   }

   @Override
   @SuppressWarnings("rawtypes,unchecked") // RecyclerView.setAdapter uses raw type :(
   public void setAdapter(Adapter adapter) {
     if (header != null && adapter != null) {
       final HeaderAdapter headerAdapter = new HeaderAdapter(adapter);
       headerAdapter.setHeader(header);
       adapter = headerAdapter;
     }
     super.setAdapter(adapter);
   }
 }
	/*
	* 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.google.android.setupdesign.view;

	import android.content.Context;
	import android.content.res.TypedArray;
	import android.os.Build;
	import androidx.recyclerview.widget.RecyclerView;
	import android.util.AttributeSet;
	import android.view.KeyEvent;
	import android.view.LayoutInflater;
	import android.view.View;
	import android.view.ViewGroup;
	import android.view.accessibility.AccessibilityEvent;
	import android.widget.FrameLayout;
	import com.google.android.setupdesign.DividerItemDecoration;
	import com.google.android.setupdesign.R;

	/**
	* A RecyclerView that can display a header item at the start of the list. The header can be set by
	* {@code app:sudHeader} in XML. Note that the header will not be inflated until a layout manager is
	* set.
	*/
	public class HeaderRecyclerView extends RecyclerView {

	private static class HeaderViewHolder extends ViewHolder
	implements DividerItemDecoration.DividedViewHolder {

	HeaderViewHolder(View itemView) {
	super(itemView);
	}

	@Override
	public boolean isDividerAllowedAbove() {
	return false;
	}

	@Override
	public boolean isDividerAllowedBelow() {
	return false;
	}
	}

	/**
	* An adapter that can optionally add one header item to the RecyclerView.
	*
	* @param <CVH> Type of the content view holder. i.e. view holder type of the wrapped adapter.
	*/
	public static class HeaderAdapter<CVH extends ViewHolder>
	extends RecyclerView.Adapter<ViewHolder> {

	private static final int HEADER_VIEW_TYPE = Integer.MAX_VALUE;

	private final RecyclerView.Adapter<CVH> adapter;
	private View header;

	private final AdapterDataObserver observer =
	new AdapterDataObserver() {

	@Override
	public void onChanged() {
	notifyDataSetChanged();
	}

	@Override
	public void onItemRangeChanged(int positionStart, int itemCount) {
	if (header != null) {
	positionStart++;
	}
	notifyItemRangeChanged(positionStart, itemCount);
	}

	@Override
	public void onItemRangeInserted(int positionStart, int itemCount) {
	if (header != null) {
	positionStart++;
	}
	notifyItemRangeInserted(positionStart, itemCount);
	}

	@Override
	public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) {
	if (header != null) {
	fromPosition++;
	toPosition++;
	}
	// Why is there no notifyItemRangeMoved?
	for (int i = 0; i < itemCount; i++) {
	notifyItemMoved(fromPosition + i, toPosition + i);
	}
	}

	@Override
	public void onItemRangeRemoved(int positionStart, int itemCount) {
	if (header != null) {
	positionStart++;
	}
	notifyItemRangeRemoved(positionStart, itemCount);
	}
	};

	public HeaderAdapter(RecyclerView.Adapter<CVH> adapter) {
	this.adapter = adapter;
	this.adapter.registerAdapterDataObserver(observer);
	setHasStableIds(this.adapter.hasStableIds());
	}

	@Override
	public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
	// Returning the same view (header) results in crash ".. but view is not a real child."
	// The framework creates more than one instance of header because of "disappear"
	// animations applied on the header and this necessitates creation of another header
	// view to use after the animation. We work around this restriction by returning an
	// empty FrameLayout to which the header is attached using #onBindViewHolder method.
	if (viewType == HEADER_VIEW_TYPE) {
	FrameLayout frameLayout = new FrameLayout(parent.getContext());
	FrameLayout.LayoutParams params =
	new FrameLayout.LayoutParams(
	FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.WRAP_CONTENT);
	frameLayout.setLayoutParams(params);
	return new HeaderViewHolder(frameLayout);
	} else {
	return adapter.onCreateViewHolder(parent, viewType);
	}
	}

	@Override
	@SuppressWarnings("unchecked") // Non-header position always return type CVH
	public void onBindViewHolder(ViewHolder holder, int position) {
	if (header != null) {
	position--;
	}

	if (holder instanceof HeaderViewHolder) {
	if (header == null) {
	throw new IllegalStateException("HeaderViewHolder cannot find mHeader");
	}
	if (header.getParent() != null) {
	((ViewGroup) header.getParent()).removeView(header);
	}
	FrameLayout mHeaderParent = (FrameLayout) holder.itemView;
	mHeaderParent.addView(header);
	} else {
	adapter.onBindViewHolder((CVH) holder, position);
	}
	}

	@Override
	public int getItemViewType(int position) {
	if (header != null) {
	position--;
	}
	if (position < 0) {
	return HEADER_VIEW_TYPE;
	}
	return adapter.getItemViewType(position);
	}

	@Override
	public int getItemCount() {
	int count = adapter.getItemCount();
	if (header != null) {
	count++;
	}
	return count;
	}

	@Override
	public long getItemId(int position) {
	if (header != null) {
	position--;
	}
	if (position < 0) {
	return Long.MAX_VALUE;
	}
	return adapter.getItemId(position);
	}

	public void setHeader(View header) {
	this.header = header;
	}

	public RecyclerView.Adapter<CVH> getWrappedAdapter() {
	return adapter;
	}
	}

	private View header;
	private int headerRes;

	public HeaderRecyclerView(Context context) {
	super(context);
	init(null, 0);
	}

	public HeaderRecyclerView(Context context, AttributeSet attrs) {
	super(context, attrs);
	init(attrs, 0);
	}

	public HeaderRecyclerView(Context context, AttributeSet attrs, int defStyleAttr) {
	super(context, attrs, defStyleAttr);
	init(attrs, defStyleAttr);
	}

	private void init(AttributeSet attrs, int defStyleAttr) {
	if (isInEditMode()) {
	return;
	}

	final TypedArray a =
	getContext()
	.obtainStyledAttributes(attrs, R.styleable.SudHeaderRecyclerView, defStyleAttr, 0);
	headerRes = a.getResourceId(R.styleable.SudHeaderRecyclerView_sudHeader, 0);
	a.recycle();
	}

	@Override
	public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
	super.onInitializeAccessibilityEvent(event);

	// Decoration-only headers should not count as an item for accessibility, adjust the
	// accessibility event to account for that.
	final int numberOfHeaders = header != null ? 1 : 0;
	event.setItemCount(event.getItemCount() - numberOfHeaders);
	event.setFromIndex(Math.max(event.getFromIndex() - numberOfHeaders, 0));
	if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
	event.setToIndex(Math.max(event.getToIndex() - numberOfHeaders, 0));
	}
	}

	private boolean handleDpadDown() {
	View focusedView = findFocus();
	if (focusedView == null) {
	return false;
	}

	int[] focusdLocationInWindow = new int[2];
	int[] myLocationInWindow = new int[2];

	focusedView.getLocationInWindow(focusdLocationInWindow);
	getLocationInWindow(myLocationInWindow);

	int offset =
	(focusdLocationInWindow[1] + focusedView.getMeasuredHeight())
	- (myLocationInWindow[1] + getMeasuredHeight());

	/*
	(focusdLocationInWindow[1] + focusedView.getMeasuredHeight())
	is the bottom position of focused view

	(myLocationInWindow[1] + getMeasuredHeight())
	is the bottom position of recycler view

	If the bottom of focused view is out of recycler view, means we need to scroll down to show
	more detail

	We scroll 70% of recycler view to make sure user can have 30% of previous information, to make
	sure user can keep reading easily.
	*/
	if (offset > 0) {
	// We expect only scroll 70% of recycler view
	int scrollLength = (int) (getMeasuredHeight() * 0.7f);
	smoothScrollBy(0, Math.min(scrollLength, offset));
	return true;
	}

	return false;
	}

	private boolean handleDpadUp() {
	View focusedView = findFocus();
	if (focusedView == null) {
	return false;
	}

	int[] focusedLocationInWindow = new int[2];
	int[] myLocationInWindow = new int[2];

	focusedView.getLocationInWindow(focusedLocationInWindow);
	getLocationInWindow(myLocationInWindow);

	int offset = (focusedLocationInWindow[1] - myLocationInWindow[1]);

	/*
	focusedLocationInWindow[1] is top of focused view
	myLocationInWindow[1] is top of recycler view

	If top of focused view is higher than recycler view we need scroll up to show more information
	we try to scroll up 70% of recycler view ot scroll up to the top of focused view
	*/
	if (offset < 0) {
	// We expect only scroll 70% of recycler view
	int scrollLength = (int) (getMeasuredHeight() * -0.7f);

	smoothScrollBy(0, Math.max(scrollLength, offset));
	return true;
	}
	return false;
	}

	private boolean shouldHandleActionUp = false;

	private boolean handleKeyEvent(KeyEvent keyEvent) {
	if (shouldHandleActionUp && keyEvent.getAction() == KeyEvent.ACTION_UP) {
	shouldHandleActionUp = false;
	return true;
	} else if (keyEvent.getAction() == KeyEvent.ACTION_DOWN) {
	boolean eventHandled = false;
	switch (keyEvent.getKeyCode()) {
	case KeyEvent.KEYCODE_DPAD_DOWN:
	eventHandled = handleDpadDown();
	break;
	case KeyEvent.KEYCODE_DPAD_UP:
	eventHandled = handleDpadUp();
	break;
	default: // fall out
	}
	shouldHandleActionUp = eventHandled;
	return eventHandled;
	}
	return false;
	}

	@Override
	public boolean dispatchKeyEvent(KeyEvent event) {
	if (handleKeyEvent(event)) {
	return true;
	}
	return super.dispatchKeyEvent(event);
	}

	/** Gets the header view of this RecyclerView, or {@code null} if there are no headers. */
	public View getHeader() {
	return header;
	}

	/**
	* Set the view to use as the header of this recycler view. Note: This must be called before
	* setAdapter.
	*/
	public void setHeader(View header) {
	this.header = header;
	}

	@Override
	public void setLayoutManager(LayoutManager layout) {
	super.setLayoutManager(layout);
	if (layout != null && header == null && headerRes != 0) {
	// Inflating a child view requires the layout manager to be set. Check here to see if
	// any header item is specified in XML and inflate them.
	final LayoutInflater inflater = LayoutInflater.from(getContext());
	header = inflater.inflate(headerRes, this, false);
	}
	}

	@Override
	@SuppressWarnings("rawtypes,unchecked") // RecyclerView.setAdapter uses raw type :(
	public void setAdapter(Adapter adapter) {
	if (header != null && adapter != null) {
	final HeaderAdapter headerAdapter = new HeaderAdapter(adapter);
	headerAdapter.setHeader(header);
	adapter = headerAdapter;
	}
	super.setAdapter(adapter);
	}
	}