Java tutorial
/* * Copyright (C) 2014 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.tr4android.support.extension.picker.date; import android.content.Context; import android.content.res.Resources; import android.support.v4.view.accessibility.AccessibilityEventCompat; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.util.AttributeSet; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.view.accessibility.AccessibilityEvent; import android.widget.TextView; import com.tr4android.appcompat.extension.R; import com.tr4android.support.extension.utils.ViewCompatUtils; import java.util.Calendar; /** * Displays a selectable list of years. */ class YearPickerView extends RecyclerView implements View.OnClickListener { private final YearAdapter mAdapter; private final int mChildSize; private OnYearSelectedListener mOnYearSelectedListener; private long mCurrentTimeMillis; public YearPickerView(Context context, AttributeSet attrs) { this(context, attrs, 0); //TODO: look into R.attr.listViewStyle } public YearPickerView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); final LayoutParams frame = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT); setLayoutParams(frame); final Resources res = context.getResources(); mChildSize = res.getDimensionPixelOffset(R.dimen.datepicker_year_label_height); setLayoutManager(new LinearLayoutManager(getContext())); mAdapter = new YearAdapter(getContext(), this); setAdapter(mAdapter); } @Override public void onClick(View view) { final int position = getChildAdapterPosition(view); if (position == -1) return; // Ignore invalid positions final int year = mAdapter.getYearForPosition(position); mAdapter.setSelection(year); if (mOnYearSelectedListener != null) { mOnYearSelectedListener.onYearChanged(YearPickerView.this, year); } } public void setOnYearSelectedListener(OnYearSelectedListener listener) { mOnYearSelectedListener = listener; } public void setDate(long currentTimeMillis) { mCurrentTimeMillis = currentTimeMillis; } /** * Sets the currently selected year. Jumps immediately to the new year. * * @param year the target year */ public void setYear(final int year) { mAdapter.setSelection(year); post(new Runnable() { @Override public void run() { final int position = mAdapter.getPositionForYear(year); if (position >= 0 && position < mAdapter.getItemCount()) { setSelectionCentered(position); } } }); } public void setSelectionCentered(int position) { final int offset = getMeasuredHeight() / 2 - mChildSize / 2; setSelectionFromTop(position, offset); } public void setRange(Calendar min, Calendar max) { mAdapter.setRange(min, max); } private static class YearAdapter extends RecyclerView.Adapter<YearAdapter.ViewHolder> { private static final int ITEM_LAYOUT = R.layout.year_label_text_view; private static final int ITEM_TEXT_APPEARANCE = R.style.TextAppearance_Material_DatePicker_List_YearLabel; private static final int ITEM_TEXT_SELECTED_APPEARANCE = R.style.TextAppearance_Material_DatePicker_List_YearLabel_Selected; private static final int ITEM_IS_SELECTED = R.id.date_picker_year_item_is_selected; private final LayoutInflater mInflater; private final OnClickListener mListener; public static class ViewHolder extends RecyclerView.ViewHolder { public TextView mYearView; public ViewHolder(View itemView) { super(itemView); mYearView = (TextView) itemView; } } private int mSelectedYear; private int mMinYear; private int mCount; public YearAdapter(Context context, OnClickListener listener) { mInflater = LayoutInflater.from(context); mListener = listener; } public void setRange(Calendar minDate, Calendar maxDate) { final int minYear = minDate.get(Calendar.YEAR); final int count = maxDate.get(Calendar.YEAR) - minYear + 1; if (mMinYear != minYear || mCount != count) { mMinYear = minYear; mCount = count; notifyDataSetChanged(); } } public boolean setSelection(int year) { if (mSelectedYear != year) { mSelectedYear = year; notifyDataSetChanged(); return true; } return false; } @Override public int getItemCount() { return mCount; } @Override public long getItemId(int position) { return getYearForPosition(position); } public int getPositionForYear(int year) { return year - mMinYear; } public int getYearForPosition(int position) { return mMinYear + position; } @Override public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { return new ViewHolder(mInflater.inflate(ITEM_LAYOUT, parent, false)); } @Override public void onBindViewHolder(ViewHolder holder, int position) { final int year = getYearForPosition(position); final boolean selected = mSelectedYear == year; Object tag = holder.mYearView.getTag(ITEM_IS_SELECTED); if (tag == null || (boolean) tag != selected) { final int textAppearanceResId; if (selected && ITEM_TEXT_SELECTED_APPEARANCE != 0) { textAppearanceResId = ITEM_TEXT_SELECTED_APPEARANCE; } else { textAppearanceResId = ITEM_TEXT_APPEARANCE; } ViewCompatUtils.setTextAppearance(holder.mYearView, textAppearanceResId); holder.mYearView.setTag(ITEM_IS_SELECTED, selected); } holder.mYearView.setText(Integer.toString(year)); holder.mYearView.setOnClickListener(mListener); } } public void setSelectionFromTop(int position, int offset) { ((LinearLayoutManager) getLayoutManager()).scrollToPositionWithOffset(position, offset); } public int getFirstVisiblePosition() { return ((LinearLayoutManager) getLayoutManager()).findFirstVisibleItemPosition(); } public int getFirstPositionOffset() { final View firstChild = getChildAt(0); if (firstChild == null) { return 0; } return firstChild.getTop(); } /** @hide */ @Override public void onInitializeAccessibilityEvent(AccessibilityEvent event) { super.onInitializeAccessibilityEvent(event); // There are a bunch of years, so don't bother. if (event.getEventType() == AccessibilityEvent.TYPE_VIEW_SCROLLED) { AccessibilityEventCompat.asRecord(event).setFromIndex(0); AccessibilityEventCompat.asRecord(event).setToIndex(0); } } /** * The callback used to indicate the user changed the year. */ public interface OnYearSelectedListener { /** * Called upon a year change. * * @param view The view associated with this listener. * @param year The year that was set. */ void onYearChanged(YearPickerView view, int year); } }