使用淡入淡出动画在视图之间切换 [英] Switch between views with crossfade animation

问题描述

我写了一个小活动，可以在两个视图之间切换.现在，我尝试添加一些动画(淡入/淡出效果).有人可以解释一下该怎么做吗?

I've wrote a small activity that is able to switch between two views. Now I am trying to add some animation (fade-in/fade-out effect). Can anybody explain me how to do that right?

我自己尝试执行此操作的确有点问题(如果我将非常快地单击按钮，则我的应用程序将冻结).我使用下面列出的代码:

My own attempt to do this works kinda buggy (if I will click buttons very fast, my application freezes). I use code listed below:

public class WelcomeActivity extends Activity {
private boolean isLogin = false;
private String KEY_IS_LOGIN = "KEY_IS_LOGIN";
private Animation anim_fadein;
private RelativeLayout welcome, login;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    welcome = (RelativeLayout)getLayoutInflater().inflate(R.layout.activity_welcome_menu, null);
    login = (RelativeLayout)getLayoutInflater().inflate(R.layout.activity_welcome_login, null);
    anim_fadein = AnimationUtils.loadAnimation(this, R.anim.anim_fadein);
    if (savedInstanceState != null)
        isLogin = savedInstanceState.getBoolean(KEY_IS_LOGIN, false);
    if (isLogin)
        setContentView(login);
    else
        setContentView(welcome);
}

@Override
public void onBackPressed() {
    if (isLogin) {
        setContentView(welcome);
        welcome.startAnimation(anim_fadein);
        isLogin = false;
    } else {
        super.onBackPressed();
    }
}

@Override
public void onSaveInstanceState(Bundle outState) {
    outState.putBoolean(KEY_IS_LOGIN, isLogin);
    super.onSaveInstanceState(outState);
}

public void onButton1Click(View v) {
    setContentView(login);
    login.startAnimation(anim_fadein);
}

public void onButtonLoginClick(View v) {
    Intent i = new Intent(getApplicationContext(), MainActivity.class);
    startActivity(i);
}

public void onButtonBackClick(View v) {
    setContentView(welcome);
    welcome.startAnimation(anim_fadein);
}

动画XML文件:

<?xml version="1.0" encoding="utf-8"?>
<alpha
xmlns:android="http://schemas.android.com/apk/res/android"
android:fromAlpha="0.0"
android:toAlpha="1.0"
android:duration="800" />

提前谢谢！

推荐答案

我过去完成此操作的方法是使用

The way I have done this in the past is by using the ViewFlipper class and utilizing the built-in animation functions that the package provides.

这里是有关如何执行此操作的示例；以我的经验，过渡非常顺利:

Here is an example on how to do this; in my experience the transitions have been very smooth:

<LinearLayout
    //Ommitted...
    <ViewFlipper
        android:id="@+id/[your_id_here]"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent">
            <RelativeLayout
                <!--Your first layout XML here...-->
            </RelativeLayout>
            <RelativeLayout
                <!--Your second layout XML here...-->
            </RelativeLayout>
    </ViewFlipper>
</LinearLayout>

请注意，您不必使用相对布局，为了清楚起见，我只是使用它们.

Please note that you do not have to use relative layouts, I simply used them for the sake of clarity.

在您的活动中获取对 ViewFlipper 的引用:

Get a reference to the ViewFlipper in your activity:

ViewFlipper v = (ViewFlipper) findViewById(R.id.[your_id]);

根据需要设置动画:

v.setInAnimation(AnimationUtils.loadAnimation([your_activity_name].this, R.anim.[your_in_animation here]));
v.setOutAnimation(AnimationUtils.loadAnimation([your_activity_name].this, R.anim.[your_out_animation here]));

请注意，您可以在以下目录的Android类文件中找到一些非常好的预制动画:

Please note that you can find some really good prebuilt animations in the Android class files located in the following directory:

[android-sdks]/samples/android-[VERSION_NUMBER_HERE]/ApiDemos/res/anim

如果可以的话，我强烈建议您使用它们-这样可以节省很多时间.

I highly recommend using these if you can - it will save you much time.

现在，如果要在视图之间切换，请使用以下命令:

Now, if you wish to switch between the views, use the following commands:

v.showNext();
v.showPrevious();

您可能必须稍稍更改动画文件，以确保动画正确过渡(即，使右和向左淡出动画).

You might have to change the animation files slightly to make sure the animations transition properly (i.e. make a fade right and left animation).

希望这会有所帮助！

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