Java tutorial
/* * Copyright 2013 RedInput * * 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.redinput.datetimepickercompat.date; import java.text.DateFormatSymbols; import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Locale; import android.annotation.SuppressLint; import android.content.Context; import android.os.Build; import android.os.Bundle; import android.os.Handler; import android.support.v4.view.AccessibilityDelegateCompat; import android.support.v4.view.ViewCompat; import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat; import android.util.Log; import android.view.View; import android.view.ViewConfiguration; import android.view.accessibility.AccessibilityEvent; import android.widget.AbsListView; import android.widget.AbsListView.OnScrollListener; import android.widget.ListView; import com.redinput.datetimepickercompat.Utils; import com.redinput.datetimepickercompat.date.DatePickerDialog.OnDateChangedListener; import com.redinput.datetimepickercompat.date.SimpleMonthAdapter.CalendarDay; /** * This displays a list of months in a calendar format with selectable days. */ public class DayPickerView extends ListView implements OnScrollListener, OnDateChangedListener { private static final String TAG = "MonthFragment"; // Affects when the month selection will change while scrolling up protected static final int SCROLL_HYST_WEEKS = 2; // How long the GoTo fling animation should last protected static final int GOTO_SCROLL_DURATION = 250; // How long to wait after receiving an onScrollStateChanged notification // before acting on it protected static final int SCROLL_CHANGE_DELAY = 40; // The number of days to display in each week public static final int DAYS_PER_WEEK = 7; public static int LIST_TOP_OFFSET = -1; // so that the top line will be // under the separator // You can override these numbers to get a different appearance protected int mNumWeeks = 6; protected boolean mShowWeekNumber = false; protected int mDaysPerWeek = 7; private static SimpleDateFormat YEAR_FORMAT = new SimpleDateFormat("yyyy", Locale.getDefault()); // These affect the scroll speed and feel protected float mFriction = 1.0f; protected Context mContext; protected Handler mHandler; // highlighted time protected CalendarDay mSelectedDay = new CalendarDay(); protected SimpleMonthAdapter mAdapter; protected CalendarDay mTempDay = new CalendarDay(); private static float mScale = 0; // When the week starts; numbered like Time.<WEEKDAY> (e.g. SUNDAY=0). protected int mFirstDayOfWeek; // The last name announced by accessibility protected CharSequence mPrevMonthName; // which month should be displayed/highlighted [0-11] protected int mCurrentMonthDisplayed; // used for tracking during a scroll protected long mPreviousScrollPosition; // used for tracking what state listview is in protected int mPreviousScrollState = OnScrollListener.SCROLL_STATE_IDLE; // used for tracking what state listview is in protected int mCurrentScrollState = OnScrollListener.SCROLL_STATE_IDLE; private final DatePickerController mController; private boolean mPerformingScroll; public DayPickerView(Context context, DatePickerController controller) { super(context); mHandler = new Handler(); mController = controller; mController.registerOnDateChangedListener(this); setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT)); setDrawSelectorOnTop(false); init(context); onDateChanged(); installAccessibilityDelegate(); } public void init(Context context) { mContext = context; setUpListView(); setUpAdapter(); setAdapter(mAdapter); } public void onChange() { setUpAdapter(); setAdapter(mAdapter); } /** * Creates a new adapter if necessary and sets up its parameters. Override * this method to provide a custom adapter. */ protected void setUpAdapter() { if (mAdapter == null) { mAdapter = new SimpleMonthAdapter(getContext(), mController); } else { mAdapter.setSelectedDay(mSelectedDay); mAdapter.notifyDataSetChanged(); } // refresh the view with the new parameters mAdapter.notifyDataSetChanged(); } /* * Sets all the required fields for the list view. Override this method to * set a different list view behavior. */ @SuppressLint("NewApi") protected void setUpListView() { // Transparent background on scroll setCacheColorHint(0); // No dividers setDivider(null); // Items are clickable setItemsCanFocus(true); // The thumb gets in the way, so disable it setFastScrollEnabled(false); setVerticalScrollBarEnabled(false); setOnScrollListener(this); setFadingEdgeLength(0); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { // Make the scrolling behavior nicer setFriction(ViewConfiguration.getScrollFriction() * mFriction); } } /** * This moves to the specified time in the view. If the time is not already * in range it will move the list so that the first of the month containing * the time is at the top of the view. If the new time is already in view * the list will not be scrolled unless forceScroll is true. This time may * optionally be highlighted as selected as well. * * @param time * The time to move to * @param animate * Whether to scroll to the given time or just redraw at the * new location * @param setSelected * Whether to set the given time as selected * @param forceScroll * Whether to recenter even if the time is already * visible * @return Whether or not the view animated to the new location */ @SuppressLint("NewApi") public boolean goTo(CalendarDay day, boolean animate, boolean setSelected, boolean forceScroll) { // Set the selected day if (setSelected) { mSelectedDay.set(day); } mTempDay.set(day); final int position = (day.year - mController.getMinYear()) * SimpleMonthAdapter.MONTHS_IN_YEAR + day.month; View child; int i = 0; int top = 0; // Find a child that's completely in the view do { child = getChildAt(i++); if (child == null) { break; } top = child.getTop(); if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "child at " + (i - 1) + " has top " + top); } } while (top < 0); // Compute the first and last position visible int selectedPosition; if (child != null) { selectedPosition = getPositionForView(child); } else { selectedPosition = 0; } if (setSelected) { mAdapter.setSelectedDay(mSelectedDay); } if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "GoTo position " + position); } // Check if the selected day is now outside of our visible range // and if so scroll to the month that contains it if (position != selectedPosition || forceScroll) { setMonthDisplayed(mTempDay); mPreviousScrollState = OnScrollListener.SCROLL_STATE_FLING; if (animate) { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { smoothScrollToPositionFromTop(position, LIST_TOP_OFFSET, GOTO_SCROLL_DURATION); } else { postSetSelection(position); } return true; } else { postSetSelection(position); } } else if (setSelected) { setMonthDisplayed(mSelectedDay); } return false; } public void postSetSelection(final int position) { clearFocus(); post(new Runnable() { @Override public void run() { setSelection(position); } }); onScrollStateChanged(this, OnScrollListener.SCROLL_STATE_IDLE); } /** * Updates the title and selected month if the view has moved to a new * month. */ @Override public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) { SimpleMonthView child = (SimpleMonthView) view.getChildAt(0); if (child == null) { return; } // Figure out where we are long currScroll = view.getFirstVisiblePosition() * child.getHeight() - child.getBottom(); mPreviousScrollPosition = currScroll; mPreviousScrollState = mCurrentScrollState; } /** * Sets the month displayed at the top of this view based on time. Override * to add custom events when the title is changed. */ protected void setMonthDisplayed(CalendarDay date) { mCurrentMonthDisplayed = date.month; invalidateViews(); } @Override public void onScrollStateChanged(AbsListView view, int scrollState) { // use a post to prevent re-entering onScrollStateChanged before it // exits mScrollStateChangedRunnable.doScrollStateChange(view, scrollState); } protected ScrollStateRunnable mScrollStateChangedRunnable = new ScrollStateRunnable(); protected class ScrollStateRunnable implements Runnable { private int mNewState; /** * Sets up the runnable with a short delay in case the scroll state * immediately changes again. * * @param view * The list view that changed state * @param scrollState * The new state it changed to */ public void doScrollStateChange(AbsListView view, int scrollState) { mHandler.removeCallbacks(this); mNewState = scrollState; mHandler.postDelayed(this, SCROLL_CHANGE_DELAY); } @SuppressLint("NewApi") @Override public void run() { mCurrentScrollState = mNewState; if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "new scroll state: " + mNewState + " old state: " + mPreviousScrollState); } // Fix the position after a scroll or a fling ends if (mNewState == OnScrollListener.SCROLL_STATE_IDLE && mPreviousScrollState != OnScrollListener.SCROLL_STATE_IDLE && mPreviousScrollState != OnScrollListener.SCROLL_STATE_TOUCH_SCROLL) { mPreviousScrollState = mNewState; int i = 0; View child = getChildAt(i); while (child != null && child.getBottom() <= 0) { child = getChildAt(++i); } if (child == null) { // The view is no longer visible, just return return; } int firstPosition = getFirstVisiblePosition(); int lastPosition = getLastVisiblePosition(); boolean scroll = firstPosition != 0 && lastPosition != getCount() - 1; final int top = child.getTop(); final int bottom = child.getBottom(); final int midpoint = getHeight() / 2; if (scroll && top < LIST_TOP_OFFSET) { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.FROYO) { if (bottom > midpoint) { smoothScrollBy(top, GOTO_SCROLL_DURATION); } else { smoothScrollBy(bottom, GOTO_SCROLL_DURATION); } } else { if (bottom > midpoint) { scrollBy(top, GOTO_SCROLL_DURATION); } else { scrollBy(bottom, GOTO_SCROLL_DURATION); } } } } else { mPreviousScrollState = mNewState; } } } /** * Gets the position of the view that is most prominently displayed within the list view. */ public int getMostVisiblePosition() { final int firstPosition = getFirstVisiblePosition(); final int height = getHeight(); int maxDisplayedHeight = 0; int mostVisibleIndex = 0; int i = 0; int bottom = 0; while (bottom < height) { View child = getChildAt(i); if (child == null) { break; } bottom = child.getBottom(); int displayedHeight = Math.min(bottom, height) - Math.max(0, child.getTop()); if (displayedHeight > maxDisplayedHeight) { mostVisibleIndex = i; maxDisplayedHeight = displayedHeight; } i++; } return firstPosition + mostVisibleIndex; } @Override public void onDateChanged() { goTo(mController.getSelectedDay(), false, true, true); } /** * Attempts to return the date that has accessibility focus. * * @return The date that has accessibility focus, or {@code null} if no date * has focus. */ private CalendarDay findAccessibilityFocus() { final int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { final View child = getChildAt(i); if (child instanceof SimpleMonthView) { final CalendarDay focus = ((SimpleMonthView) child).getAccessibilityFocus(); if (focus != null) { // Clear focus to avoid ListView bug in Jelly Bean MR1. ((SimpleMonthView) child).clearAccessibilityFocus(); return focus; } } } return null; } /** * Attempts to restore accessibility focus to a given date. No-op if {@code day} is {@code null} * . * * @param day * The date that should receive accessibility focus * @return {@code true} if focus was restored */ private boolean restoreAccessibilityFocus(CalendarDay day) { if (day == null) { return false; } final int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { final View child = getChildAt(i); if (child instanceof SimpleMonthView) { if (((SimpleMonthView) child).restoreAccessibilityFocus(day)) { return true; } } } return false; } @Override protected void layoutChildren() { final CalendarDay focusedDay = findAccessibilityFocus(); super.layoutChildren(); if (mPerformingScroll) { mPerformingScroll = false; } else { restoreAccessibilityFocus(focusedDay); } } private void installAccessibilityDelegate() { // The accessibility delegate enables customizing accessibility behavior // via composition as opposed as inheritance. The main benefit is that // one can write a backwards compatible application by setting the delegate // only if the API level is high enough i.e. the delegate is part of the APIs. // The easiest way to achieve that is by using the support library which // takes the burden of checking API version and knowing which API version // introduced the delegate off the developer. ViewCompat.setAccessibilityDelegate(this, new AccessibilityDelegateCompat() { @Override public void onInitializeAccessibilityEvent(View host, AccessibilityEvent event) { super.onInitializeAccessibilityEvent(host, event); // Note that View.onInitializeAccessibilityNodeInfo was introduced in // ICS and we would like to tweak a bit the text that is reported to // accessibility services via the AccessibilityNodeInfo. event.setItemCount(-1); } @Override public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info) { super.onInitializeAccessibilityNodeInfo(host, info); // Note that View.onInitializeAccessibilityNodeInfo was introduced in // ICS and we would like to tweak a bit the text that is reported to // accessibility services via the AccessibilityNodeInfo. info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD); info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD); } @Override public boolean performAccessibilityAction(View host, int action, Bundle args) { if (action != AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD && action != AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD) { return super.performAccessibilityAction(host, action, args); } // Figure out what month is showing. int firstVisiblePosition = getFirstVisiblePosition(); int month = firstVisiblePosition % 12; int year = firstVisiblePosition / 12 + mController.getMinYear(); CalendarDay day = new CalendarDay(year, month, 1); // Scroll either forward or backward one month. if (action == AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD) { day.month++; if (day.month == 12) { day.month = 0; day.year++; } } else if (action == AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD) { View firstVisibleView = getChildAt(0); // If the view is fully visible, jump one month back. Otherwise, we'll just jump // to the first day of first visible month. if (firstVisibleView != null && firstVisibleView.getTop() >= -1) { // There's an off-by-one somewhere, so the top of the first visible item // will // actually be -1 when it's at the exact top. day.month--; if (day.month == -1) { day.month = 11; day.year--; } } } // Go to that month. Utils.tryAccessibilityAnnounce(host, getMonthAndYearString(day)); goTo(day, true, false, true); mPerformingScroll = true; return true; } }); } private String getMonthAndYearString(CalendarDay day) { Calendar cal = Calendar.getInstance(); cal.set(day.year, day.month, day.day); StringBuffer sbuf = new StringBuffer(); sbuf.append(new DateFormatSymbols(Locale.getDefault()).getWeekdays()[cal.get(Calendar.MONTH)]); sbuf.append(" "); sbuf.append(YEAR_FORMAT.format(cal.getTime())); return sbuf.toString(); } }