編輯:關於Android編程
在Android系統API中,有兩個Camera類:
第二個應用於手機硬件中的相機相關的操作,本文講述的是利用第一個Camera類實現中軸3D轉換的卡牌翻轉效果,開始之前,先看一下Android系統中的坐標系:
對應於三維坐標系中的三個方向,Camera提供了三種旋轉方法:
調用這三種方法,傳入旋轉角度參數,即可實現視圖沿著坐標軸旋轉的功能。本文的中軸3D旋轉效果就是讓視圖沿著Y軸旋轉的。
系統API Demos中已經為我們提供了一個非常好用的3D旋轉動畫的工具類:
Rotate3dAnimation.java:
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 總共做了兩件事:在構造函數中賦值了旋轉動畫所需要的參數,以及重寫(override)父類Animation中的applyTransformation()方法,下面分類闡述一下:
activity_main.xml布局文件:
<?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="打開" 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="本站。" android:textColor="@android:color/white" android:textSize="18sp" android:visibility="gone"/> </RelativeLayout> </RelativeLayout>
布局中配置了卡牌正面的圖片控件,卡牌背面的文本控件,以及他們的parent容器,也就是本文中的旋轉動畫的執行對象。
MainActivity.java文件:
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); } /** * 卡牌文本介紹打開效果:注意旋轉角度 */ private void initOpenAnim() { //從0到90度,順時針旋轉視圖,此時reverse參數為true,達到90度時動畫結束時視圖變得不可見, 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); //從270到360度,順時針旋轉視圖,此時reverse參數為false,達到360度動畫結束時視圖變得可見 Rotate3dAnimation rotateAnimation = new Rotate3dAnimation(270, 360, centerX, centerY, depthZ, false); rotateAnimation.setDuration(duration); rotateAnimation.setFillAfter(true); rotateAnimation.setInterpolator(new DecelerateInterpolator()); mContentRl.startAnimation(rotateAnimation); } }); } /** * 卡牌文本介紹關閉效果:旋轉角度與打開時逆行即可 */ 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) { //以旋轉對象的中心點為旋轉中心點,這裡主要不要再onCreate方法中獲取,因為視圖初始繪制時,獲取的寬高為0 centerX = mContentRl.getWidth()/2; centerY = mContentRl.getHeight()/2; if (openAnimation == null) { initOpenAnim(); initCloseAnim(); } //用作判斷當前點擊事件發生時動畫是否正在執行 if (openAnimation.hasStarted() && !openAnimation.hasEnded()) { return; } if (closeAnimation.hasStarted() && !closeAnimation.hasEnded()) { return; } //判斷動畫執行 if (isOpen) { mContentRl.startAnimation(closeAnimation); }else { mContentRl.startAnimation(openAnimation); } isOpen = !isOpen; mOpenBtn.setText(isOpen ? "關閉" : "打開"); } }
代碼中已對核心的地方做了注釋解釋,主要弄清楚 rotate3dAnimation構造參數中的 fromDegrees和toDegrees、depthZ、reverse參數,同時在動畫中設置了速度插播器,如動畫的前半程使用加速器 AccelerateInterpolator,後半程使用減速器 DecelerateInterpolator,使動畫體驗更加人性化。
以上就是本文的全部內容,希望對大家的學習Android軟件編程有所幫助。
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