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);
}
}
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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>
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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");
}
}
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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。