Android 欢迎界面四个跳转页（Fragment实现渐变渲染）。

来源：互联网发布：腐烂国度生命线优化编辑：程序博客网时间：2024/06/03 12:59

注：本文内容为网上代码，自己整理出来看看效果，以后项目或者练习可以用上。
首先，自定义View：

public class ColorAnimationView extends View implements        ValueAnimator.AnimatorUpdateListener, Animator.AnimatorListener {    private static final int RED = 0xffFF8080;    private static final int BLUE = 0xff8080FF;    private static final int WHITE = 0xffffffff;    private static final int GREEN = 0xff80ff80;    private static final int DURATION = 3000;    ValueAnimator colorAnim = null;    private PageChangeListener mPageChangeListener;    ViewPager.OnPageChangeListener onPageChangeListener;    public void setOnPageChangeListener(            ViewPager.OnPageChangeListener onPageChangeListener) {        this.onPageChangeListener = onPageChangeListener;    }    /**     * 这是你唯一需要关心的方法     *      * @param mViewPager     *            你必须在设置 Viewpager 的 Adapter 这后，才能调用这个方法。     * @param obj     *            ,这个obj实现了 ColorAnimationView.OnPageChangeListener ，实现回调     * @param count     *            ,viewpager 数据的数量     * @param colors     *            int... colors ，你需要设置的颜色变化值~~ 如何你传人 空，那么触发默认设置的颜色动画     * */    public void setmViewPager(ViewPager mViewPager, int count, int... colors) {        if (mViewPager.getAdapter() == null) {            throw new IllegalStateException(                    "ViewPager does not have adapter instance.");        }        mPageChangeListener.setViewPagerChildCount(count);        mViewPager.setOnPageChangeListener(mPageChangeListener);        if (colors.length == 0) {            createDefaultAnimation();        } else {            createAnimation(colors);        }    }    public ColorAnimationView(Context context) {        this(context, null, 0);    }    public ColorAnimationView(Context context, AttributeSet attrs) {        this(context, attrs, 0);    }    public ColorAnimationView(Context context, AttributeSet attrs,            int defStyleAttr) {        super(context, attrs, defStyleAttr);        mPageChangeListener = new PageChangeListener();    }    private void seek(long seekTime) {        if (colorAnim == null) {            createDefaultAnimation();        }        colorAnim.setCurrentPlayTime(seekTime);    }    private void createAnimation(int... colors) {        if (colorAnim == null) {            colorAnim = ObjectAnimator.ofInt(this, "backgroundColor", colors);            colorAnim.setEvaluator(new ArgbEvaluator());            colorAnim.setDuration(DURATION);            colorAnim.addUpdateListener(this);        }    }    private void createDefaultAnimation() {        colorAnim = ObjectAnimator.ofInt(this, "backgroundColor", WHITE, RED,                BLUE, GREEN, WHITE);        colorAnim.setEvaluator(new ArgbEvaluator());        colorAnim.setDuration(DURATION);        colorAnim.addUpdateListener(this);    }    @Override    public void onAnimationStart(Animator animation) {    }    @Override    public void onAnimationEnd(Animator animation) {    }    @Override    public void onAnimationCancel(Animator animation) {    }    @Override    public void onAnimationRepeat(Animator animation) {    }    @Override    public void onAnimationUpdate(ValueAnimator animation) {        invalidate();    }    private class PageChangeListener implements ViewPager.OnPageChangeListener {        private int viewPagerChildCount;        public void setViewPagerChildCount(int viewPagerChildCount) {            this.viewPagerChildCount = viewPagerChildCount;        }        public int getViewPagerChildCount() {            return viewPagerChildCount;        }        @Override        public void onPageScrolled(int position, float positionOffset,                int positionOffsetPixels) {            int count = getViewPagerChildCount() - 1;            if (count != 0) {                float length = (position + positionOffset) / count;                int progress = (int) (length * DURATION);                ColorAnimationView.this.seek(progress);            }            if (onPageChangeListener != null) {                onPageChangeListener.onPageScrolled(position, positionOffset,                        positionOffsetPixels);            }        }        @Override        public void onPageSelected(int position) {            if (onPageChangeListener != null) {                onPageChangeListener.onPageSelected(position);            }        }        @Override        public void onPageScrollStateChanged(int state) {            if (onPageChangeListener != null) {                onPageChangeListener.onPageScrollStateChanged(state);            }        }    }}

其次，main布局文件：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent" >    <com.包名.viewpager.ColorAnimationView        android:id="@+id/ColorAnimationView"        android:layout_width="match_parent"        android:layout_height="match_parent" />    <android.support.v4.view.ViewPager        android:id="@+id/viewPager"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:padding="30dp" />    <RelativeLayout        android:layout_width="match_parent"        android:layout_height="match_parent" >        <Button            android:id="@+id/btn_go"            android:layout_width="100dp"            android:layout_height="wrap_content"            android:layout_alignParentBottom="true"            android:layout_centerHorizontal="true"            android:layout_marginBottom="43dp"            android:background="@drawable/colorbu"            android:text="开始"            android:visibility="gone" />    </RelativeLayout></FrameLayout>

最后，MainActivity中代码：

public class MainActivity extends FragmentActivity {    private static final int[] resource = new int[] { R.drawable.welcome1,            R.drawable.welcome4, R.drawable.welcome3, R.drawable.welcome4 };    private static final String TAG = MainActivity.class.getSimpleName();    private Button btn_go;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        btn_go = (Button) findViewById(R.id.btn_go);        MyFragmentStatePager adpter = new MyFragmentStatePager(                getSupportFragmentManager());        ColorAnimationView colorAnimationView = (ColorAnimationView) findViewById(R.id.ColorAnimationView);        ViewPager viewPager = (ViewPager) findViewById(R.id.viewPager);        viewPager.setAdapter(adpter);        colorAnimationView.setmViewPager(viewPager, resource.length);        colorAnimationView                .setOnPageChangeListener(new ViewPager.OnPageChangeListener() {                    @Override                    public void onPageScrolled(int position,                            float positionOffset, int positionOffsetPixels) {                        Log.e("TAG", "onPageScrolled");                    }                    @Override                    public void onPageSelected(int position) {                        if (position == 3) {                            btn_go.setVisibility(View.VISIBLE);                            btn_go.setOnClickListener(new OnClickListener() {                                @Override                                public void onClick(View v) {                                    // TODO Auto-generated method stub                                    //跳转到Main2Activity ，欢迎页结束                                    Intent intent = new Intent(MainActivity.this,Main2Activity.class);                                    startActivity(intent);    //这里用finish();方法可以直接销毁MainActivity ，这样在手机上按返回按钮    //就不会退到欢迎页，而是直接将程序放到后台。                                    finish();                                }                            });                        } else {                            btn_go.setVisibility(View.GONE);                        }                        Log.e("TAG", "onPageSelected");                    }                    @Override                    public void onPageScrollStateChanged(int state) {                        Log.e("TAG", "onPageScrollStateChanged");                    }                });    }    public class MyFragmentStatePager extends FragmentStatePagerAdapter {        public MyFragmentStatePager(FragmentManager fm) {            super(fm);        }        @Override        public Fragment getItem(int position) {            return new MyFragment(position);        }        @Override        public int getCount() {            return resource.length;        }    }    @SuppressLint("ValidFragment")    public class MyFragment extends Fragment {        private int position;        public MyFragment(int position) {            this.position = position;        }        @Override        public View onCreateView(LayoutInflater inflater, ViewGroup container,                Bundle savedInstanceState) {            ImageView imageView = new ImageView(getActivity());            imageView.setImageResource(resource[position]);            return imageView;        }    }}

接着，colorbu.xml选择器：

<selector xmlns:android="http://schemas.android.com/apk/res/android">    <item android:state_pressed="true"><shape>            <solid android:color="#5cb57c" />            <corners android:radius="8dp" />        </shape></item>    <item android:state_pressed="false"><shape>            <solid android:color="#80ff80" />            <corners android:radius="8dp" />        </shape></item></selector>

完，效果如下：
欢迎页

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