在APP的啟動(dòng)頁(yè)經(jīng)常會(huì)有一些漸變效果。

如果是從半透明漸變?yōu)椴煌该鳎肰iew動(dòng)畫(huà)AlphaAnimation就能完成。

而View動(dòng)畫(huà)只有漸變，旋轉(zhuǎn)，平移，和縮放四種動(dòng)畫(huà)效果，是完成不了顏色變化的任務(wù)的。所以需要用到屬性動(dòng)畫(huà)。

demo下載：http://download.csdn.net/download/qq_25806863/9934747

下面是三種用屬性動(dòng)畫(huà)讓啟動(dòng)頁(yè)背景顏色漸變的方法：

界面準(zhǔn)備

幾個(gè)啟動(dòng)頁(yè)面都用同一套布局，很簡(jiǎn)單

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/launch"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical">


    <ImageView
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_gravity="center_horizontal|bottom"
        android:src="@mipmap/ic_launcher" />


    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginTop="20dp"
        android:gravity="center"
        android:text="V5.1" />

</LinearLayout>

1.ValueAnimator.ofArgb,由紅變白

ValueAnimator動(dòng)畫(huà)改變的是數(shù)值，不會(huì)直接改變屬性，所以需要在監(jiān)聽(tīng)數(shù)值變化的時(shí)候自己去設(shè)置屬性。

public class Launch1Activity extends AppCompatActivity {

    private LinearLayout launch;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_launch1);

        launch = (LinearLayout) findViewById(R.id.launch);

        startAnimate();
    }

    private void startAnimate() {
        ValueAnimator valueAnimator = ValueAnimator.ofArgb(Color.RED, Color.WHITE);
        valueAnimator.setDuration(3000);

        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator valueAnimator) {
              //這里設(shè)置背景顏色
                launch.setBackgroundColor((Integer) valueAnimator.getAnimatedValue());
            }
        });

        valueAnimator.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                super.onAnimationEnd(animation);
              //跳轉(zhuǎn)到首頁(yè)
                skip();
            }
        });
        valueAnimator.start();
    }

    private void skip() {
        startActivity(new Intent(this, MainActivity.class));
        finish();
    }
}

2.ObjectAnimator.ofObject由紅變藍(lán)

這里用到了ColorDrawable來(lái)作為背景。

通過(guò)改變ColorDrawable的顏色來(lái)達(dá)到效果。

public class Launch2Activity extends AppCompatActivity {

    private LinearLayout launch;

    private ColorDrawable background;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_launch1);

        launch = (LinearLayout) findViewById(R.id.launch);

        background = new ColorDrawable(Color.RED);

        launch.setBackground(background);

        startAnimate();
    }

    private void startAnimate() {

        ArgbEvaluator evaluator = new ArgbEvaluator();
        ObjectAnimator objectAnimator = ObjectAnimator.ofObject(this, property, evaluator, Color.BLUE);
        objectAnimator.setDuration(3000);
        objectAnimator.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                super.onAnimationEnd(animation);
                skip();
            }
        });
        objectAnimator.start();

    }

    private void skip() {
        startActivity(new Intent(this, MainActivity.class));
        finish();
    }

    private  Property<Launch2Activity, Object> property = new Property<Launch2Activity, Object>(Object.class, "background") {
        @Override
        public void set(Launch2Activity object, Object value) {
            object.background.setColor((Integer) value);
        }

        @Override
        public Object get(Launch2Activity object) {
            return object.background.getColor();
        }
    };
}

3.ObjectAnimator.ofInt由紅變黃

這個(gè)就是簡(jiǎn)單的屬性動(dòng)畫(huà)了。

public class Launch3Activity extends AppCompatActivity {

    private LinearLayout launch;

    private ColorDrawable background;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_launch1);
        launch = (LinearLayout) findViewById(R.id.launch);
        startAnimate();
    }

    private void startAnimate() {

        ArgbEvaluator evaluator = new ArgbEvaluator();
        ObjectAnimator objectAnimator = ObjectAnimator.ofInt(launch, "backgroundColor", Color.RED, Color.YELLOW);
        objectAnimator.setEvaluator(new ArgbEvaluator());
        objectAnimator.setDuration(3000);
        objectAnimator.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                super.onAnimationEnd(animation);
                skip();
            }
        });
        objectAnimator.start();

    }

    private void skip() {
        startActivity(new Intent(this, MainActivity.class));
        finish();
    }
}

。。。