本文主要是介绍android书架，可以拖动的图书，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
需要实现这样的功能：
1）书架的风格可以切换;
2）书籍在整个书架上可以随意拖动，书架可以上下滚动;
3）书籍只能放在书架层上;
4）点击书籍可以动画放大书籍;
依次来解决问题，1）书架的风格可以切换，可以定义几个xml界面，在需要的时候分别切换就可以了。2）书籍可以在书架上随意拖动，而且书架也可以上下滚动，这样会有手势事件冲突的问题，仔细分析一下可以这样解决：点击书籍移动的时候屏蔽掉外层书架的上下滚动事件，点击书架上下查看移动的时候不理会书籍事件的处理。3）要实现书籍只能放在书架层上可以这样做：在书架层上定义一部分空间，当书籍移动后用户的手指离开屏幕时获取书籍在屏幕的位置，依次判断是否在某个书架层上，如果在就将书籍放在合适的位置，若不在就将书籍放回上一个合适的位置。4）点击书籍要放大查看也比较简单，需要定义一个xml动画文件，在监听到书籍点击事件的时候将书籍置于屏幕中央，并且展开动画放大书籍，动画结束之后将书籍放回原位。
这个demo难点在于手势事件的处理，书架的上下滚动我使用了ScrollView来包裹 一个RelativeLayout实现，书籍我使用一个自定义的ImageView来展示。难点在于当手指点住书籍滑动过程中，有可能手滑动得快一点，滑到书籍 Imageview 控件外面去了，也就是滑到了外层的ScrollView上面，这样一来书籍就无法上下滑动了，只能够左右滑动。我的处理方法是将当手滑动到scrollview里面的时候将该滑动时间传递给imageview，同时在scrollview的ontouch方法里面返回true。看代码：
package com.shelfstyles;import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;/*** scrollview的ontouch事件监听器* @author swerit**/
public class ScrollViewOnTouchListener implements OnTouchListener {/** scrollview的滑动状态*/private final static int SCROLLVIEW_STATE_REST = -1;private final static int SCROLLVIEW_STATE_DOWN = 0;private final static int SCROLLVIEW_STATE_MOVE = 1;private int scrollviewTouchState = SCROLLVIEW_STATE_REST;/** scrollview在一次完整的触摸事件中是否经历过DOWN事件*/private boolean varTouchStateDOWN = false;private Book mBook;private BookOnTouchListener mBookOnTouchListener;public ScrollViewOnTouchListener(Book book, BookOnTouchListener bookOnTouchListener){this.mBook = book;this.mBookOnTouchListener = bookOnTouchListener;}@Overridepublic boolean onTouch(View v, MotionEvent event) {switch (event.getAction()) {case MotionEvent.ACTION_DOWN:scrollviewTouchState = SCROLLVIEW_STATE_DOWN;varTouchStateDOWN = true;break;case MotionEvent.ACTION_MOVE:if (scrollviewTouchState == SCROLLVIEW_STATE_DOWN){//正常滑动scrollviewscrollviewTouchState = SCROLLVIEW_STATE_MOVE;return false;}else if (scrollviewTouchState == SCROLLVIEW_STATE_REST){//由book滑动进入scrollview，将事件传递给书籍if (mBookOnTouchListener != null){mBookOnTouchListener.onTouch(mBook, event);}return true;}break;case MotionEvent.ACTION_UP://scrollview上终止滑动scrollviewTouchState = SCROLLVIEW_STATE_REST;if (!varTouchStateDOWN){//检测书籍是否包含在可放置区域if (mBookOnTouchListener != null){mBookOnTouchListener.judgeWhetherContainBook();}}varTouchStateDOWN = false;break;}return false;}}
那么书籍的滑动和点击事件呢也是很重要的，里面需要判断书籍下一步移动位置，和书籍的点击事件的处理。看代码：
package com.shelfstyles;import android.content.Context;
import android.graphics.Point;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.Toast;/*** 书籍ontouch监听事件* @author swerit**/
public class BookOnTouchListener implements OnTouchListener{/** 受事件影响的书籍对象*/private Book mBook;/** 书架层对象数组*/private OneFloor[] mFloorList;/** 整个书架的宽度和高度*/private int shelfWidth, shelfHeight;private Context mContext;public BookOnTouchListener(Context context, Book book, OneFloor[] floorList){this.mBook = book;this.mFloorList = floorList;this.mContext = context;}@Overridepublic boolean onTouch(View v, MotionEvent event) {Book book = (Book) v;switch (event.getAction()) {case MotionEvent.ACTION_DOWN:book.setnTraceX((int) event.getRawX());book.setnTraceY((int)event.getRawY());break;case MotionEvent.ACTION_MOVE:int deltaX = (int) (event.getRawX() - book.getnTraceX());int deltaY = (int) (event.getRawY() - book.getnTraceY());int top = book.getTop() + deltaY;int left = book.getLeft() + deltaX;if (top < 0){top = 0;}if (top > shelfHeight - book.getHeight()){top = shelfHeight - book.getHeight();}if (left > shelfWidth - book.getWidth()){left = shelfWidth - book.getWidth();}if (left < 0){left = 0;}book.layout(left, top, left + book.getWidth(), top + book.getHeight());book.setnTraceX((int)event.getRawX());book.setnTraceY((int)event.getRawY());break;case MotionEvent.ACTION_UP://手指抬起时判断书籍是否在可以放置的位置judgeWhetherContainBook();
// Toast.makeText(mContext, "点击书籍", Toast.LENGTH_SHORT).show();//将书籍放在屏幕中央int l = MainActivity.screenWidth / 2 - mBook.getWidth() / 2;int t = MainActivity.screenHeight / 2 - mBook.getHeight() / 2;int r = MainActivity.screenWidth / 2 + mBook.getWidth() / 2;int b = MainActivity.screenHeight / 2 + mBook.getHeight() / 2;mBook.layout(l, t, r, b);Animation animation = AnimationUtils.loadAnimation(mContext, R.anim.anim);mBook.startAnimation(animation);mBook.postDelayed(new Runnable() {@Overridepublic void run() {int left = mBook.getnLastLocationX();int bottom = mBook.getnLastLocationY();if (left == 0 && bottom == 0){return;}mBook.layout(left, bottom - mBook.getHeight(), left + mBook.getWidth(), bottom);}}, animation.getDuration());break;}return true;}public void judgeWhetherContainBook(){Point pointLeftTop, pointLeftBottom, pointRightTop, pointRightBottom;pointLeftTop = new Point(mBook.getLeft(), mBook.getTop());pointLeftBottom = new Point(mBook.getLeft(), mBook.getBottom());pointRightTop = new Point(mBook.getRight(), mBook.getTop());pointRightBottom = new Point(mBook.getRight(), mBook.getBottom());for (int i = 0; i < mFloorList.length; i++){if (judge(mFloorList[i].judgeContain(pointLeftTop, Book.POINT_LEFT_TOP, mBook), mBook) || judge(mFloorList[i].judgeContain(pointLeftBottom, Book.POINT_LEFT_BOTTOM, mBook), mBook)|| judge(mFloorList[i].judgeContain(pointRightTop, Book.POINT_RIGHT_TOP, mBook), mBook) || judge(mFloorList[i].judgeContain(pointRightBottom, Book.POINT_RIGHT_BOTTOM, mBook), mBook)){//检测到书籍包含在可放置区域break;}}}private boolean judge(Point newLeftBottom, Book book){if (newLeftBottom != null){//找到下一个放置的位置book.setnLastLocationX(newLeftBottom.x);book.setnLastLocationY(newLeftBottom.y);//这里可以添加移动时的动画效果/*** TODO*/book.layout(newLeftBottom.x, newLeftBottom.y - book.getHeight(), newLeftBottom.x + book.getWidth(), newLeftBottom.y);return true;}else {//书籍没有到达正确的放置空间，将书籍放回原位int left = book.getnLastLocationX();int bottom = book.getnLastLocationY();if (left == 0 && bottom == 0){return false;}book.layout(left, bottom - book.getHeight(), left + book.getWidth(), bottom);}return false;}public void setShelfWidth(int shelfWidth){this.shelfWidth = shelfWidth;}public void setShelfHeight(int shelfHeight){this.shelfHeight = shelfHeight;}
}
重点提醒，在这个demo中对坐标的计算都是以子控件相对于父控件的坐标来实现的，特别要理清楚子控件坐标位置的来源，大家都使用同一个参照物才能计算准确。
整个工程源代码下载地址：点击打开下载链接
这篇关于android书架，可以拖动的图书的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！
