Android example source code file (Ticker.java)

This example Android source code file (Ticker.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, arraylist, charsequence, drawable, handler, imageswitcher, notificationdata, runnable, runtimeexception, segment, staticlayout, statusbarview, text, textpaint, textswitcher, ticker_segment_delay, ui, util, view, widget

The Ticker.java Android example source code

/*
 * Copyright (C) 2008 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.server.status;

import com.android.internal.R;

import android.content.Context;
import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.text.StaticLayout;
import android.text.Layout.Alignment;
import android.text.TextPaint;
import android.text.TextUtils;
import android.util.Slog;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.TextSwitcher;
import android.widget.TextView;
import android.widget.ImageSwitcher;

import java.util.ArrayList;


abstract class Ticker {
    private static final int TICKER_SEGMENT_DELAY = 3000;
    
    private final class Segment {
        NotificationData notificationData;
        Drawable icon;
        CharSequence text;
        int current;
        int next;
        boolean first;

        StaticLayout getLayout(CharSequence substr) {
            int w = mTextSwitcher.getWidth() - mTextSwitcher.getPaddingLeft()
                    - mTextSwitcher.getPaddingRight();
            return new StaticLayout(substr, mPaint, w, Alignment.ALIGN_NORMAL, 1, 0, true);
        }

        CharSequence rtrim(CharSequence substr, int start, int end) {
            while (end > start && !TextUtils.isGraphic(substr.charAt(end-1))) {
                end--;
            }
            if (end > start) {
                return substr.subSequence(start, end);
            }
            return null;
        }

        /** returns null if there is no more text */
        CharSequence getText() {
            if (this.current > this.text.length()) {
                return null;
            }
            CharSequence substr = this.text.subSequence(this.current, this.text.length());
            StaticLayout l = getLayout(substr);
            int lineCount = l.getLineCount();
            if (lineCount > 0) {
                int start = l.getLineStart(0);
                int end = l.getLineEnd(0);
                this.next = this.current + end;
                return rtrim(substr, start, end);
            } else {
                throw new RuntimeException("lineCount=" + lineCount + " current=" + current +
                        " text=" + text);
            }
        }

        /** returns null if there is no more text */
        CharSequence advance() {
            this.first = false;
            int index = this.next;
            final int len = this.text.length();
            while (index < len && !TextUtils.isGraphic(this.text.charAt(index))) {
                index++;
            }
            if (index >= len) {
                return null;
            }

            CharSequence substr = this.text.subSequence(index, this.text.length());
            StaticLayout l = getLayout(substr);
            final int lineCount = l.getLineCount();
            int i;
            for (i=0; i<lineCount; i++) {
                int start = l.getLineStart(i);
                int end = l.getLineEnd(i);
                if (i == lineCount-1) {
                    this.next = len;
                } else {
                    this.next = index + l.getLineStart(i+1);
                }
                CharSequence result = rtrim(substr, start, end);
                if (result != null) {
                    this.current = index + start;
                    return result;
                }
            }
            this.current = len;
            return null;
        }

        Segment(NotificationData n, Drawable icon, CharSequence text) {
            this.notificationData = n;
            this.icon = icon;
            this.text = text;
            int index = 0;
            final int len = text.length();
            while (index < len && !TextUtils.isGraphic(text.charAt(index))) {
                index++;
            }
            this.current = index;
            this.next = index;
            this.first = true;
        }
    };

    private Handler mHandler = new Handler();
    private ArrayList<Segment> mSegments = new ArrayList();
    private TextPaint mPaint;
    private View mTickerView;
    private ImageSwitcher mIconSwitcher;
    private TextSwitcher mTextSwitcher;

    Ticker(Context context, StatusBarView sb) {
        mTickerView = sb.findViewById(R.id.ticker);

        mIconSwitcher = (ImageSwitcher)sb.findViewById(R.id.tickerIcon);
        mIconSwitcher.setInAnimation(
                    AnimationUtils.loadAnimation(context, com.android.internal.R.anim.push_up_in));
        mIconSwitcher.setOutAnimation(
                    AnimationUtils.loadAnimation(context, com.android.internal.R.anim.push_up_out));

        mTextSwitcher = (TextSwitcher)sb.findViewById(R.id.tickerText);
        mTextSwitcher.setInAnimation(
                    AnimationUtils.loadAnimation(context, com.android.internal.R.anim.push_up_in));
        mTextSwitcher.setOutAnimation(
                    AnimationUtils.loadAnimation(context, com.android.internal.R.anim.push_up_out));

        // Copy the paint style of one of the TextSwitchers children to use later for measuring
        TextView text = (TextView)mTextSwitcher.getChildAt(0);
        mPaint = text.getPaint();
    }

    void addEntry(NotificationData n, Drawable icon, CharSequence text) {
        int initialCount = mSegments.size();

        Segment newSegment = new Segment(n, icon, text);

        // prune out any preexisting ones for this notification, but not the current one.
        // let that finish, even if it's the same id
        for (int i=1; i<initialCount; i++) {
            Segment seg = mSegments.get(i);
            if (n.id == seg.notificationData.id && n.pkg.equals(seg.notificationData.pkg)) {
                // just update that one to use this new data instead
                mSegments.set(i, newSegment);
                // and since we know initialCount != 0, just return
                return ;
            }
        }

        mSegments.add(newSegment);

        if (initialCount == 0 && mSegments.size() > 0) {
            Segment seg = mSegments.get(0);
            seg.first = false;
            
            mIconSwitcher.setAnimateFirstView(false);
            mIconSwitcher.reset();
            mIconSwitcher.setImageDrawable(seg.icon);
            
            mTextSwitcher.setAnimateFirstView(false);
            mTextSwitcher.reset();
            mTextSwitcher.setText(seg.getText());
            
            tickerStarting();
            scheduleAdvance();
        }
    }

    void halt() {
        mHandler.removeCallbacks(mAdvanceTicker);
        mSegments.clear();
        tickerHalting();
    }

    void reflowText() {
        if (mSegments.size() > 0) {
            Segment seg = mSegments.get(0);
            CharSequence text = seg.getText();
            mTextSwitcher.setCurrentText(text);
        }
    }

    private Runnable mAdvanceTicker = new Runnable() {
        public void run() {
            while (mSegments.size() > 0) {
                Segment seg = mSegments.get(0);

                if (seg.first) {
                    // this makes the icon slide in for the first one for a given
                    // notification even if there are two notifications with the
                    // same icon in a row
                    mIconSwitcher.setImageDrawable(seg.icon);
                }
                CharSequence text = seg.advance();
                if (text == null) {
                    mSegments.remove(0);
                    continue;
                }
                mTextSwitcher.setText(text);

                scheduleAdvance();
                break;
            }
            if (mSegments.size() == 0) {
                tickerDone();
            }
        }
    };

    private void scheduleAdvance() {
        mHandler.postDelayed(mAdvanceTicker, TICKER_SEGMENT_DELAY);
    }

    abstract void tickerStarting();
    abstract void tickerDone();
    abstract void tickerHalting();
}