Android GestureDetector手势滑动使用实例讲解
gesture在 viewgroup中使用
gesturedetector类可以让我们快速的处理手势事件,如点击,滑动等。
使用gesturedetector分三步:
1. 定义gesturedetector类
2. 初始化手势类,同时设置手势监听
3. 将touch事件交给gesture处理
先来了解一下如何使用,后面会有示例:
package com.example.y2222.myview; import android.content.context; import android.util.attributeset; import android.util.log; import android.view.gesturedetector; import android.view.motionevent; import android.widget.linearlayout; /** * created by raise.yang on 2016/06/29. */ public class gesturedemoview extends linearlayout { //1,定义gesturedetector类 private gesturedetector m_gesturedetector; public gesturedemoview(context context, attributeset attrs) { this(context, attrs, 0); } public gesturedemoview(context context, attributeset attrs, int defstyleattr) { super(context, attrs, defstyleattr); //设置为可点击 setclickable(true); //2,初始化手势类,同时设置手势监听 m_gesturedetector = new gesturedetector(context, ongesturelistener); //双击监听-一般很少用到 m_gesturedetector.setondoubletaplistener(ondoubletaplistener); } @override public boolean ontouchevent(motionevent event) { //3,将touch事件交给gesture处理 m_gesturedetector.ontouchevent(event); return super.ontouchevent(event); } //初始化手势监听对象,使用gesturedetector.ongesturelistener的实现抽象类,因为实际开发中好多方法用不上 private final gesturedetector.ongesturelistener ongesturelistener = new gesturedetector.simpleongesturelistener() { @override public boolean onsingletapup(motionevent e) { log.d("gesturedemoview", "onsingletapup() "); return super.onsingletapup(e); } @override public void onlongpress(motionevent e) { log.d("gesturedemoview", "onlongpress() "); super.onlongpress(e); } @override public boolean onscroll(motionevent e1, motionevent e2, float distancex, float distancey) { log.d("gesturedemoview", "onscroll() distancex = " + distancex); return super.onscroll(e1, e2, distancex, distancey); } @override public boolean onfling(motionevent e1, motionevent e2, float velocityx, float velocityy) { log.d("gesturedemoview", "onfling() velocityx = " + velocityx); return super.onfling(e1, e2, velocityx, velocityy); } @override public void onshowpress(motionevent e) { log.d("gesturedemoview", "onshowpress() "); super.onshowpress(e); } @override public boolean ondown(motionevent e) { log.d("gesturedemoview", "ondown() "); return super.ondown(e); } @override public boolean ondoubletap(motionevent e) { log.d("gesturedemoview", "ondoubletap() "); return super.ondoubletap(e); } @override public boolean ondoubletapevent(motionevent e) { log.d("gesturedemoview", "ondoubletapevent() "); return super.ondoubletapevent(e); } @override public boolean onsingletapconfirmed(motionevent e) { log.d("gesturedemoview", "onsingletapconfirmed() "); return super.onsingletapconfirmed(e); } @override public boolean oncontextclick(motionevent e) { log.d("gesturedemoview", "oncontextclick() "); return super.oncontextclick(e); } }; private final gesturedetector.ondoubletaplistener ondoubletaplistener = new gesturedetector.ondoubletaplistener() { @override public boolean onsingletapconfirmed(motionevent e) { log.d("gesturedemoview", "onsingletapconfirmed() ondoubletaplistener"); return false; } @override public boolean ondoubletap(motionevent e) { log.d("gesturedemoview", "ondoubletap() ondoubletaplistener"); return false; } @override public boolean ondoubletapevent(motionevent e) { log.d("gesturedemoview", "ondoubletapevent() ondoubletaplistener"); return false; } }; }
注意:setclickable(true);一定要加,不然只会收到下例3个事件,被这个整了好长时间才找到原因.(⊙﹏⊙)b
对于单击,双击,拖动等事件调用见下图:
根据上图,每个方法大致都调用了,说明几个容易弄混的回调方法
1. onscroll()
public boolean onscroll(motionevent e1, motionevent e2, float distancex, float distancey)
e1:滑动事件的起点(也就是说ondown()的时候)
e2:当前滑动位置点(手指的位置)
distancex:上次滑动(调用onscroll)到这次滑动的x轴的距离px,不是e1点到e2点的x轴的距离
distancey:上次滑动(调用onscroll)到这次滑动的y轴的距离px,不是e1点到e2点的y轴的距离
2. onfling()
public boolean onfling(motionevent e1, motionevent e2, float velocityx, float velocityy)
e1:拖动动事件的起点(也就是说ondown()的时候)
e2:onfling()调用时,手指的位置
velocityx:x轴上每秒滑动像素值
velocityy:y轴上每秒滑动像素值
注意:当拖动速率velocityx或velocityy超过viewconfiguration.getminimumflingvelocity()最小拖动速率时,才会调用onfling(),也就是如果只拖动一点,或是慢慢的拖动,是不会触发该方法。
对应源码:
if ((math.abs(velocityy) > mminimumflingvelocity) || (math.abs(velocityx) > mminimumflingvelocity)){ handled = mlistener.onfling(mcurrentdownevent, ev, velocityx, velocityy); }
实践:使用gesturedetector实现左滑删除
在很多listview中都有该效果,现在自己实现下,顺便熟悉gesturedetector的使用。
效果图:
gesturedemoview.java:
package com.example.y2222.myview; import android.content.context; import android.util.attributeset; import android.util.log; import android.view.gesturedetector; import android.view.layoutinflater; import android.view.motionevent; import android.widget.linearlayout; import com.example.y2222.myapplication.r; /** * created by raise.yang on 2016/06/29. */ public class gesturedemoview extends linearlayout { //1,定义gesturedetector类 private gesturedetector m_gesturedetector; private int m_max_scrollx; public gesturedemoview(context context, attributeset attrs) { this(context, attrs, 0); } public gesturedemoview(context context, attributeset attrs, int defstyleattr) { super(context, attrs, defstyleattr); //设置为可点击 setclickable(true); //2,初始化手势类,同时设置手势监听 m_gesturedetector = new gesturedetector(context, ongesturelistener); layoutinflater.from(context).inflate(r.layout.view_gesture, this); } @override public boolean ontouchevent(motionevent event) { //3,将touch事件交给gesture处理 m_gesturedetector.ontouchevent(event); if (event.getaction() == motionevent.action_up) { // gesturedetector没有处理up事件的方法,只能在这里处理了。 int scrollx = getscrollx(); if (scrollx > m_max_scrollx / 2) { show_right_view(); } else { hide_right_view(); } } return super.ontouchevent(event); } @override protected void onmeasure(int widthmeasurespec, int heightmeasurespec) { super.onmeasure(widthmeasurespec, heightmeasurespec); int childcount = getchildcount(); for (int i = 0; i < childcount; i++) { //测量子view的宽高,?不测量,右侧布局会不显示,这里有点疑问 measurechild(getchildat(i), widthmeasurespec, heightmeasurespec); if (i == 1) { m_max_scrollx = getchildat(i).getmeasuredwidth(); } } } //初始化手势监听对象,使用gesturedetector.ongesturelistener的实现抽象类,因为实际开发中好多方法用不上 private final gesturedetector.ongesturelistener ongesturelistener = new gesturedetector.simpleongesturelistener() { @override public boolean onscroll(motionevent e1, motionevent e2, float distancex, float distancey) { log.d("gesturedemoview", "onscroll() distancex = " + distancex + " getscrollx = " + getscrollx() + " max_scrollx = " + m_max_scrollx); int scrollx = getscrollx(); int minscrollx = -scrollx; int maxscrolly = m_max_scrollx - scrollx; // 对滑动的距离边界控制 if (distancex > maxscrolly) { distancex = maxscrolly; } else if (distancex < minscrollx) { distancex = minscrollx; } scrollby((int) distancex, 0); return true; } @override public boolean onfling(motionevent e1, motionevent e2, float velocityx, float velocityy) { log.d("gesturedemoview", "onfling() velocityx = " + velocityx); if (velocityx < 0) { //快速向左滑动 show_right_view(); } else { hide_right_view(); } return super.onfling(e1, e2, velocityx, velocityy); } }; private void show_right_view() { scrollto(m_max_scrollx, 0); } private void hide_right_view() { scrollto(0, 0); } }
view_gesture.xml
<?xml version="1.0" encoding="utf-8"?> <merge xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <textview android:layout_width="match_parent" android:layout_height="wrap_content" android:gravity="center" android:text="左侧布局"/> <linearlayout android:layout_width="wrap_content" android:layout_height="match_parent" android:orientation="horizontal" > <button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="收藏"/> <button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="删除"/> </linearlayout> </merge>
xml文件中根标签使用<merge>,可减少一层view树嵌套,并且使用getchildcount()能得到我们想要的子view个数。
关于<merge>标签的使用,详见郭神的blog:http://blog.csdn.net/guolin_blog/article/details/43376527
实现也很简单,在scroll和fling的时候,得到滑动距离或滑动速度,再调用view自己的scrollto()或scrollby()滑动内部元素即可。
从效果图中,当滑动到一半松手时,立即滑动到最左边,完全没有动画,这样的体验很差,所以还需优化。关于滑动时增加动画效果,可以使用scroller类完成,准备下期补上。
gesture在 view中使用
和在viewgroup中一样,在view中,同样是经过三步来实现:
1. 定义gesturedetector类
2. 初始化手势类,同时设置手势监听
3. 将touch事件交给gesture处理
举个荔枝:
做了一个小球跟随手指移动的效果,先绘制小球,当手指放在小球上滑动时,会调用onscroll(),在这个方法中,修改圆心的位置进行重绘,这样小球就能移动了。
这里有2个难点:
1. 如何判断手指落在了小球上;
2. 滑动到边界时,不能超过边界;
效果图:
gestureview.java代码:
package com.example.y2222.myview; import android.content.context; import android.graphics.canvas; import android.graphics.paint; import android.util.attributeset; import android.view.gesturedetector; import android.view.motionevent; import android.view.view; /** * created by raise.yang on 2016/07/05. */ public class gestureview extends view { private gesturedetector m_gesturedetector; private paint m_paint; //小球的中心点 private float centerx; private float centery; //小球的半径 private int radius; //是否touch在小球上 private boolean touch_bool; public gestureview(context context, attributeset attrs) { this(context, attrs, 0); } public gestureview(context context, attributeset attrs, int defstyleattr) { super(context, attrs, defstyleattr); // 初始画笔 m_paint = new paint(paint.anti_alias_flag); m_paint.setcolor(getresources().getcolor(android.r.color.holo_blue_light)); //设置为可点击 setclickable(true); //2,初始化手势类,同时设置手势监听 m_gesturedetector = new gesturedetector(context, ongesturelistener); radius = 50; } @override public boolean ontouchevent(motionevent event) { //3,将touch事件交给gesture处理 m_gesturedetector.ontouchevent(event); if (event.getaction() == motionevent.action_down) { //判断手指落在了小球上 if (getdistancebypoint((int) centerx, (int) centery, (int) event.getx(), (int) event.gety()) < radius) { touch_bool = true; } else { touch_bool = false; } } return super.ontouchevent(event); } @override protected void onsizechanged(int w, int h, int oldw, int oldh) { // 默认圆心在中心点 if (w > 0) { centerx = w / 2; } if (h > 0) { centery = h / 2; } } @override protected void ondraw(canvas canvas) { canvas.drawcircle(centerx, centery, radius, m_paint); } gesturedetector.ongesturelistener ongesturelistener = new gesturedetector.simpleongesturelistener() { @override public boolean onscroll(motionevent e1, motionevent e2, float distancex, float distancey) { if (touch_bool) { centery -= distancey; centerx -= distancex; //处理边界问题 if (centerx < radius) { centerx = radius; } else if (centerx > getwidth() - radius) { centerx = getwidth() - radius; } if (centery < radius) { centery = radius; } else if (centery > getheight() - radius) { centery = getheight() - radius; } //修改圆心后,通知重绘 postinvalidate(); } return true; } }; /** * 计算两点间的距离 */ private int getdistancebypoint(int x1, int y1, int x2, int y2) { double temp = math.abs((x2 - x1) * (x2 - x1) - (y2 - y1) * (y2 - y1)); return (int) math.sqrt(temp); } }
在处理问题1时,我设置了一个boolean值,在用户触摸的时候去判断,当前点和圆心点的距离是否小于半径,若小于,说明在圆内。这样在滑动的时候,就去判断一下,是否需要滑动小球。
控制边界,其实就是控制圆心点的坐标,只要保证落在(radius,radius),(getwidth()-radius,getheight()-radius)两点矩形中即可。
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持。
下一篇: springMVC的生命周期详解
推荐阅读
-
Android GestureDetector手势滑动使用实例讲解
-
实例讲解Android中SQLiteDatabase使用方法
-
Android Studio应用开发集成百度语音合成使用方法实例讲解
-
Android App中使用SurfaceView制作多线程动画的实例讲解
-
实例讲解Android中SQLiteDatabase使用方法
-
实例讲解Android中ContentProvider组件的使用方法
-
Android计时器chronometer使用实例讲解
-
实例讲解Android App使用自带的SQLite数据库的基本方法
-
Android App中使用LinearLayout进行居中布局的实例讲解
-
Android Studio应用开发集成百度语音合成使用方法实例讲解