/*
* Copyright (C) 2013 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.example.android.supportv7.widget;
import com.example.android.supportv7.Cheeses;
import com.example.android.supportv7.widget.adapter.SimpleStringAdapter;
import com.example.android.supportv7.widget.decorator.DividerItemDecoration;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.view.MenuItemCompat;
import android.support.v7.widget.RecyclerView;
import android.util.DisplayMetrics;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
public class RecyclerViewActivity extends Activity {
private static final String TAG = "RecyclerViewActivity";
private RecyclerView mRecyclerView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final RecyclerView rv = new RecyclerView(this);
rv.setLayoutManager(new MyLayoutManager(this));
rv.setHasFixedSize(true);
rv.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT));
rv.setAdapter(new SimpleStringAdapter(this, Cheeses.sCheeseStrings) {
@Override
public SimpleStringAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
final SimpleStringAdapter.ViewHolder vh = super
.onCreateViewHolder(parent, viewType);
vh.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
final int pos = vh.getAdapterPosition();
if (pos == RecyclerView.NO_POSITION) {
return;
}
if (pos + 1 < getItemCount()) {
swap(pos, pos + 1);
}
}
});
return vh;
}
});
rv.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL_LIST));
setContentView(rv);
mRecyclerView = rv;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
MenuItemCompat.setShowAsAction(menu.add("Layout"), MenuItemCompat.SHOW_AS_ACTION_IF_ROOM);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
mRecyclerView.requestLayout();
return super.onOptionsItemSelected(item);
}
private static final int SCROLL_DISTANCE = 80; // dp
/**
* A basic ListView-style LayoutManager.
*/
class MyLayoutManager extends RecyclerView.LayoutManager {
private static final String TAG = "MyLayoutManager";
private int mFirstPosition;
private final int mScrollDistance;
public MyLayoutManager(Context c) {
final DisplayMetrics dm = c.getResources().getDisplayMetrics();
mScrollDistance = (int) (SCROLL_DISTANCE * dm.density + 0.5f);
}
@Override
public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
final int parentBottom = getHeight() - getPaddingBottom();
final View oldTopView = getChildCount() > 0 ? getChildAt(0) : null;
int oldTop = getPaddingTop();
if (oldTopView != null) {
oldTop = oldTopView.getTop();
}
detachAndScrapAttachedViews(recycler);
int top = oldTop;
int bottom;
final int left = getPaddingLeft();
final int right = getWidth() - getPaddingRight();
final int count = state.getItemCount();
for (int i = 0; mFirstPosition + i < count && top < parentBottom; i++, top = bottom) {
View v = recycler.getViewForPosition(mFirstPosition + i);
addView(v, i);
measureChildWithMargins(v, 0, 0);
bottom = top + getDecoratedMeasuredHeight(v);
layoutDecorated(v, left, top, right, bottom);
}
}
@Override
public RecyclerView.LayoutParams generateDefaultLayoutParams() {
return new RecyclerView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
}
@Override
public boolean canScrollVertically() {
return true;
}
@Override
public int scrollVerticallyBy(int dy, RecyclerView.Recycler recycler,
RecyclerView.State state) {
if (getChildCount() == 0) {
return 0;
}
int scrolled = 0;
final int left = getPaddingLeft();
final int right = getWidth() - getPaddingRight();
if (dy < 0) {
while (scrolled > dy) {
final View topView = getChildAt(0);
final int hangingTop = Math.max(-getDecoratedTop(topView), 0);
final int scrollBy = Math.min(scrolled - dy, hangingTop);
scrolled -= scrollBy;
offsetChildrenVertical(scrollBy);
if (mFirstPosition > 0 && scrolled > dy) {
mFirstPosition--;
View v = recycler.getViewForPosition(mFirstPosition);
addView(v, 0);
measureChildWithMargins(v, 0, 0);
final int bottom = getDecoratedTop(topView);
final int top = bottom - getDecoratedMeasuredHeight(v);
layoutDecorated(v, left, top, right, bottom);
} else {
break;
}
}
} else if (dy > 0) {
final int parentHeight = getHeight();
while (scrolled < dy) {
final View bottomView = getChildAt(getChildCount() - 1);
final int hangingBottom =
Math.max(getDecoratedBottom(bottomView) - parentHeight, 0);
final int scrollBy = -Math.min(dy - scrolled, hangingBottom);
scrolled -= scrollBy;
offsetChildrenVertical(scrollBy);
if (scrolled < dy && state.getItemCount() > mFirstPosition + getChildCount()) {
View v = recycler.getViewForPosition(mFirstPosition + getChildCount());
final int top = getDecoratedBottom(getChildAt(getChildCount() - 1));
addView(v);
measureChildWithMargins(v, 0, 0);
final int bottom = top + getDecoratedMeasuredHeight(v);
layoutDecorated(v, left, top, right, bottom);
} else {
break;
}
}
}
recycleViewsOutOfBounds(recycler);
return scrolled;
}
@Override
public View onFocusSearchFailed(View focused, int direction,
RecyclerView.Recycler recycler, RecyclerView.State state) {
final int oldCount = getChildCount();
if (oldCount == 0) {
return null;
}
final int left = getPaddingLeft();
final int right = getWidth() - getPaddingRight();
View toFocus = null;
int newViewsHeight = 0;
if (direction == View.FOCUS_UP || direction == View.FOCUS_BACKWARD) {
while (mFirstPosition > 0 && newViewsHeight < mScrollDistance) {
mFirstPosition--;
View v = recycler.getViewForPosition(mFirstPosition);
final int bottom = getDecoratedTop(getChildAt(0));
addView(v, 0);
measureChildWithMargins(v, 0, 0);
final int top = bottom - getDecoratedMeasuredHeight(v);
layoutDecorated(v, left, top, right, bottom);
if (v.isFocusable()) {
toFocus = v;
break;
}
}
}
if (direction == View.FOCUS_DOWN || direction == View.FOCUS_FORWARD) {
while (mFirstPosition + getChildCount() < state.getItemCount() &&
newViewsHeight < mScrollDistance) {
View v = recycler.getViewForPosition(mFirstPosition + getChildCount());
final int top = getDecoratedBottom(getChildAt(getChildCount() - 1));
addView(v);
measureChildWithMargins(v, 0, 0);
final int bottom = top + getDecoratedMeasuredHeight(v);
layoutDecorated(v, left, top, right, bottom);
if (v.isFocusable()) {
toFocus = v;
break;
}
}
}
return toFocus;
}
public void recycleViewsOutOfBounds(RecyclerView.Recycler recycler) {
final int childCount = getChildCount();
final int parentWidth = getWidth();
final int parentHeight = getHeight();
boolean foundFirst = false;
int first = 0;
int last = 0;
for (int i = 0; i < childCount; i++) {
final View v = getChildAt(i);
if (v.hasFocus() || (getDecoratedRight(v) >= 0 &&
getDecoratedLeft(v) <= parentWidth &&
getDecoratedBottom(v) >= 0 &&
getDecoratedTop(v) <= parentHeight)) {
if (!foundFirst) {
first = i;
foundFirst = true;
}
last = i;
}
}
for (int i = childCount - 1; i > last; i--) {
removeAndRecycleViewAt(i, recycler);
}
for (int i = first - 1; i >= 0; i--) {
removeAndRecycleViewAt(i, recycler);
}
if (getChildCount() == 0) {
mFirstPosition = 0;
} else {
mFirstPosition += first;
}
}
}
}