diff options
Diffstat (limited to 'platform/java/src/kankan/wheel/widget/WheelScroller.java')
-rw-r--r-- | platform/java/src/kankan/wheel/widget/WheelScroller.java | 252 |
1 files changed, 252 insertions, 0 deletions
diff --git a/platform/java/src/kankan/wheel/widget/WheelScroller.java b/platform/java/src/kankan/wheel/widget/WheelScroller.java new file mode 100644 index 00000000..0372da1a --- /dev/null +++ b/platform/java/src/kankan/wheel/widget/WheelScroller.java @@ -0,0 +1,252 @@ +/* + * Android Wheel Control. + * https://code.google.com/p/android-wheel/ + * + * Copyright 2011 Yuri Kanivets + * + * 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 kankan.wheel.widget; + +import android.content.Context; +import android.os.Handler; +import android.os.Message; +import android.view.GestureDetector; +import android.view.MotionEvent; +import android.view.GestureDetector.SimpleOnGestureListener; +import android.view.animation.Interpolator; +import android.widget.Scroller; + +/** + * Scroller class handles scrolling events and updates the + */ +public class WheelScroller { + /** + * Scrolling listener interface + */ + public interface ScrollingListener { + /** + * Scrolling callback called when scrolling is performed. + * @param distance the distance to scroll + */ + void onScroll(int distance); + + /** + * Starting callback called when scrolling is started + */ + void onStarted(); + + /** + * Finishing callback called after justifying + */ + void onFinished(); + + /** + * Justifying callback called to justify a view when scrolling is ended + */ + void onJustify(); + } + + /** Scrolling duration */ + private static final int SCROLLING_DURATION = 400; + + /** Minimum delta for scrolling */ + public static final int MIN_DELTA_FOR_SCROLLING = 1; + + // Listener + private ScrollingListener listener; + + // Context + private Context context; + + // Scrolling + private GestureDetector gestureDetector; + private Scroller scroller; + private int lastScrollY; + private float lastTouchedY; + private boolean isScrollingPerformed; + + /** + * Constructor + * @param context the current context + * @param listener the scrolling listener + */ + public WheelScroller(Context context, ScrollingListener listener) { + gestureDetector = new GestureDetector(context, gestureListener); + gestureDetector.setIsLongpressEnabled(false); + + scroller = new Scroller(context); + + this.listener = listener; + this.context = context; + } + + /** + * Set the the specified scrolling interpolator + * @param interpolator the interpolator + */ + public void setInterpolator(Interpolator interpolator) { + scroller.forceFinished(true); + scroller = new Scroller(context, interpolator); + } + + /** + * Scroll the wheel + * @param distance the scrolling distance + * @param time the scrolling duration + */ + public void scroll(int distance, int time) { + scroller.forceFinished(true); + + lastScrollY = 0; + + scroller.startScroll(0, 0, 0, distance, time != 0 ? time : SCROLLING_DURATION); + setNextMessage(MESSAGE_SCROLL); + + startScrolling(); + } + + /** + * Stops scrolling + */ + public void stopScrolling() { + scroller.forceFinished(true); + } + + /** + * Handles Touch event + * @param event the motion event + * @return + */ + public boolean onTouchEvent(MotionEvent event) { + switch (event.getAction()) { + case MotionEvent.ACTION_DOWN: + lastTouchedY = event.getY(); + scroller.forceFinished(true); + clearMessages(); + break; + + case MotionEvent.ACTION_MOVE: + // perform scrolling + int distanceY = (int)(event.getY() - lastTouchedY); + if (distanceY != 0) { + startScrolling(); + listener.onScroll(distanceY); + lastTouchedY = event.getY(); + } + break; + } + + if (!gestureDetector.onTouchEvent(event) && event.getAction() == MotionEvent.ACTION_UP) { + justify(); + } + + return true; + } + + // gesture listener + private SimpleOnGestureListener gestureListener = new SimpleOnGestureListener() { + public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) { + // Do scrolling in onTouchEvent() since onScroll() are not call immediately + // when user touch and move the wheel + return true; + } + + public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { + lastScrollY = 0; + final int maxY = 0x7FFFFFFF; + final int minY = -maxY; + scroller.fling(0, lastScrollY, 0, (int) -velocityY, 0, 0, minY, maxY); + setNextMessage(MESSAGE_SCROLL); + return true; + } + }; + + // Messages + private final int MESSAGE_SCROLL = 0; + private final int MESSAGE_JUSTIFY = 1; + + /** + * Set next message to queue. Clears queue before. + * + * @param message the message to set + */ + private void setNextMessage(int message) { + clearMessages(); + animationHandler.sendEmptyMessage(message); + } + + /** + * Clears messages from queue + */ + private void clearMessages() { + animationHandler.removeMessages(MESSAGE_SCROLL); + animationHandler.removeMessages(MESSAGE_JUSTIFY); + } + + // animation handler + private Handler animationHandler = new Handler() { + public void handleMessage(Message msg) { + scroller.computeScrollOffset(); + int currY = scroller.getCurrY(); + int delta = lastScrollY - currY; + lastScrollY = currY; + if (delta != 0) { + listener.onScroll(delta); + } + + // scrolling is not finished when it comes to final Y + // so, finish it manually + if (Math.abs(currY - scroller.getFinalY()) < MIN_DELTA_FOR_SCROLLING) { + currY = scroller.getFinalY(); + scroller.forceFinished(true); + } + if (!scroller.isFinished()) { + animationHandler.sendEmptyMessage(msg.what); + } else if (msg.what == MESSAGE_SCROLL) { + justify(); + } else { + finishScrolling(); + } + } + }; + + /** + * Justifies wheel + */ + private void justify() { + listener.onJustify(); + setNextMessage(MESSAGE_JUSTIFY); + } + + /** + * Starts scrolling + */ + private void startScrolling() { + if (!isScrollingPerformed) { + isScrollingPerformed = true; + listener.onStarted(); + } + } + + /** + * Finishes scrolling + */ + void finishScrolling() { + if (isScrollingPerformed) { + listener.onFinished(); + isScrollingPerformed = false; + } + } +} |