在android系统api中，有两个camera类：
- android.graphics.camera
- android.hardware.camera
第二个应用于手机硬件中的相机相关的操作，本文讲述的是利用第一个camera类实现中轴3d转换的卡牌翻转效果，开始之前，先看一下android系统中的坐标系：
对应于三维坐标系中的三个方向，camera提供了三种旋转方法：
- rotatex()
- rotatey()
- rotatex()
调用这三种方法，传入旋转角度参数，即可实现视图沿着坐标轴旋转的功能。本文的中轴3d旋转效果就是让视图沿着y轴旋转的。
系统api demos中已经为我们提供了一个非常好用的3d旋转动画的工具类：
rotate3danimation.java：
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package com.feng.androidtest;import android.graphics.camera;import android.graphics.matrix;import android.util.log;import android.view.animation.animation;import android.view.animation.transformation;/** * an animation that rotates the view on the y axis between two specified angles. * this animation also adds a translation on the z axis (depth) to improve the effect. */public class rotate3danimation extends animation { private final float mfromdegrees; private final float mtodegrees; private final float mcenterx; private final float mcentery; private final float mdepthz; private final boolean mreverse; private camera mcamera; /** * creates a new 3d rotation on the y axis. the rotation is defined by its * start angle and its end angle. both angles are in degrees. the rotation * is performed around a center point on the 2d space, definied by a pair * of x and y coordinates, called centerx and centery. when the animation * starts, a translation on the z axis (depth) is performed. the length * of the translation can be specified, as well as whether the translation * should be reversed in time. * * @param fromdegrees the start angle of the 3d rotation * @param todegrees the end angle of the 3d rotation * @param centerx the x center of the 3d rotation * @param centery the y center of the 3d rotation * @param reverse true if the translation should be reversed, false otherwise */ public rotate3danimation(float fromdegrees, float todegrees, float centerx, float centery, float depthz, boolean reverse) { mfromdegrees = fromdegrees; mtodegrees = todegrees; mcenterx = centerx; mcentery = centery; mdepthz = depthz; mreverse = reverse; } @override public void initialize(int width, int height, int parentwidth, int parentheight) { super.initialize(width, height, parentwidth, parentheight); mcamera = new camera(); } @override protected void applytransformation(float interpolatedtime, transformation t) { final float fromdegrees = mfromdegrees; float degrees = fromdegrees + ((mtodegrees - fromdegrees) * interpolatedtime); final float centerx = mcenterx; final float centery = mcentery; final camera camera = mcamera; final matrix matrix = t.getmatrix(); log.i("interpolatedtime", interpolatedtime+""); camera.save(); if (mreverse) { camera.translate(0.0f, 0.0f, mdepthz * interpolatedtime); } else { camera.translate(0.0f, 0.0f, mdepthz * (1.0f - interpolatedtime)); } camera.rotatey(degrees); camera.getmatrix(matrix); camera.restore(); matrix.pretranslate(-centerx, -centery); matrix.posttranslate(centerx, centery); }} |
可以看出， rotate3danimation 总共做了两件事：在构造函数中赋值了旋转动画所需要的参数，以及重写（override）父类animation中的applytransformation()方法，下面分类阐述一下：
- fromdegrees与todegrees
- 视图旋转的开始角度和结束角度，当todegree处于90倍数时，视图将变得不可见。
- centerx与centery
- 视图旋转的中心点。
- depthz
- z轴移动基数，用于计算camera在z轴移动距离
- reverse
- boolean类型，控制z轴移动方向，达到视觉远近移动导致的视图放大缩小效果。
- applytransformation()
- 根据动画播放的时间 interpolatedtime （动画start到end的过程，interpolatedtime从0.0变化到1.0），让camera在z轴方向上进行相应距离的移动，实现视觉上远近移动的效果。然后调用 rotatex()方法，让视图围绕y轴进行旋转，产生3d立体旋转效果。最后再通过matrix来确定旋转的中心点的位置。
activity_main.xml布局文件：
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<?xml version="1.0" encoding="utf-8"?><relativelayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="fill_parent" android:layout_height="fill_parent" android:background="@android:color/white" > <button android:id="@+id/btn_open" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_margin="16dp" android:onclick="onclickview" android:text="打开" android:textcolor="@android:color/black" android:textsize="16sp" /> <relativelayout android:id="@+id/rl_content" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_below="@id/btn_open" android:layout_margintop="16dp" android:background="@android:color/black"> <imageview android:id="@+id/iv_logo" android:layout_width="match_parent" android:layout_height="match_parent" android:contentdescription="@null" android:src="@drawable/ic_qrcode" android:scaletype="centerinside"/> <textview android:id="@+id/tv_desc" android:layout_width="wrap_content" android:layout_height="wrap_content" android:padding="16dp" android:text="服务器之家。" android:textcolor="@android:color/white" android:textsize="18sp" android:visibility="gone"/> </relativelayout></relativelayout> |
布局中配置了卡牌正面的图片控件，卡牌背面的文本控件，以及他们的parent容器，也就是本文中的旋转动画的执行对象。
mainactivity.java文件：
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package com.feng.androidtest;import android.app.activity;import android.os.bundle;import android.view.view;import android.view.animation.accelerateinterpolator;import android.view.animation.animation;import android.view.animation.animation.animationlistener;import android.view.animation.decelerateinterpolator;import android.widget.button;import android.widget.imageview;import android.widget.relativelayout;import android.widget.textview;import com.example.androidtest.r;public class mainactivity extends activity { private relativelayout mcontentrl; private imageview mlogoiv; private textview mdesctv; private button mopenbtn; private int centerx; private int centery; private int depthz = 400; private int duration = 600; private rotate3danimation openanimation; private rotate3danimation closeanimation; private boolean isopen = false; @override protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_main); mcontentrl = (relativelayout) findviewbyid(r.id.rl_content); mlogoiv = (imageview) findviewbyid(r.id.iv_logo); mdesctv = (textview) findviewbyid(r.id.tv_desc); mopenbtn = (button) findviewbyid(r.id.btn_open); } /** * 卡牌文本介绍打开效果：注意旋转角度 */ private void initopenanim() { //从0到90度，顺时针旋转视图，此时reverse参数为true，达到90度时动画结束时视图变得不可见， openanimation = new rotate3danimation(0, 90, centerx, centery, depthz, true); openanimation.setduration(duration); openanimation.setfillafter(true); openanimation.setinterpolator(new accelerateinterpolator()); openanimation.setanimationlistener(new animationlistener() { @override public void onanimationstart(animation animation) { } @override public void onanimationrepeat(animation animation) { } @override public void onanimationend(animation animation) { mlogoiv.setvisibility(view.gone); mdesctv.setvisibility(view.visible); //从270到360度，顺时针旋转视图，此时reverse参数为false，达到360度动画结束时视图变得可见 rotate3danimation rotateanimation = new rotate3danimation(270, 360, centerx, centery, depthz, false); rotateanimation.setduration(duration); rotateanimation.setfillafter(true); rotateanimation.setinterpolator(new decelerateinterpolator()); mcontentrl.startanimation(rotateanimation); } }); } /** * 卡牌文本介绍关闭效果：旋转角度与打开时逆行即可 */ private void initcloseanim() { closeanimation = new rotate3danimation(360, 270, centerx, centery, depthz, true); closeanimation.setduration(duration); closeanimation.setfillafter(true); closeanimation.setinterpolator(new accelerateinterpolator()); closeanimation.setanimationlistener(new animationlistener() { @override public void onanimationstart(animation animation) { } @override public void onanimationrepeat(animation animation) { } @override public void onanimationend(animation animation) { mlogoiv.setvisibility(view.visible); mdesctv.setvisibility(view.gone); rotate3danimation rotateanimation = new rotate3danimation(90, 0, centerx, centery, depthz, false); rotateanimation.setduration(duration); rotateanimation.setfillafter(true); rotateanimation.setinterpolator(new decelerateinterpolator()); mcontentrl.startanimation(rotateanimation); } }); } public void onclickview(view v) { //以旋转对象的中心点为旋转中心点，这里主要不要再oncreate方法中获取，因为视图初始绘制时，获取的宽高为0 centerx = mcontentrl.getwidth()/2; centery = mcontentrl.getheight()/2; if (openanimation == null) { initopenanim(); initcloseanim(); } //用作判断当前点击事件发生时动画是否正在执行 if (openanimation.hasstarted() && !openanimation.hasended()) { return; } if (closeanimation.hasstarted() && !closeanimation.hasended()) { return; } //判断动画执行 if (isopen) { mcontentrl.startanimation(closeanimation); }else { mcontentrl.startanimation(openanimation); } isopen = !isopen; mopenbtn.settext(isopen ? "关闭" : "打开"); }} |
代码中已对核心的地方做了注释解释，主要弄清楚 rotate3danimation构造参数中的 fromdegrees和todegrees、depthz、reverse参数，同时在动画中设置了速度插播器，如动画的前半程使用加速器 accelerateinterpolator，后半程使用减速器 decelerateinterpolator，使动画体验更加人性化。
以上就是本文的全部内容，希望对大家的学习android软件编程有所帮助。
