app引导页视差动画效果

GIF.gif
public class ParallaxViewPager extends ViewPager {
    private List fragments;

    public ParallaxViewPager(Context context) {
        this(context, null);
    }

    public ParallaxViewPager(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public void attach(FragmentManager fm, int[] layoutIdRes) {
        fragments = new ArrayList<>();
        for (int i = 0; i < layoutIdRes.length; i++) {
            ParallaxFragment fragment = new ParallaxFragment();
            Bundle bundle = new Bundle();
            bundle.putInt(fragment.LAYOUT_ID_KEY, layoutIdRes[i]);
            if(i==layoutIdRes.length-1){
                bundle.putBoolean("isLastFragment", true);
            }else{
                bundle.putBoolean("isLastFragment", false);
            }
            fragment.setArguments(bundle);
            fragments.add(fragment);
        }
        ParallaxViewAdapter adapter = new ParallaxViewAdapter(fm);
        setAdapter(adapter);
        //监听滑动事件
        addOnPageChangeListener(new OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
                //出厂fragment
                ParallaxFragment outFragment = fragments.get(position);
                List parallaxViews = outFragment.getParallaxViews();
                for (View parallaxView : parallaxViews) {
                    ParallaxTag tag = (ParallaxTag) parallaxView.getTag(R.id.parallax_tag);
                    parallaxView.setTranslationX((-positionOffsetPixels)*tag.translationXOut);
                    parallaxView.setTranslationY((-positionOffsetPixels)*tag.translationYOut);
                }
                try {
                    //进场fragment
                    ParallaxFragment inFragment = fragments.get(position+1);
                    parallaxViews = inFragment.getParallaxViews();
                    for (View parallaxView : parallaxViews) {
                        ParallaxTag tag = (ParallaxTag) parallaxView.getTag(R.id.parallax_tag);
                        parallaxView.setTranslationX((getMeasuredWidth()-positionOffsetPixels)*tag.translationXIn);
                        parallaxView.setTranslationY((getMeasuredWidth()-positionOffsetPixels)*tag.translationYIn);
                    }
                }catch (Exception e){

                }
            }

            @Override
            public void onPageSelected(int position) {

            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });
    }

    class ParallaxViewAdapter extends FragmentPagerAdapter {

        public ParallaxViewAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            return (Fragment) fragments.get(position);
        }

        @Override
        public int getCount() {
            return fragments.size();
        }
    }
}
public class ParallaxFragment extends Fragment implements LayoutInflaterFactory {
    public static final String LAYOUT_ID_KEY = "LAYOUT_ID_KEY";
    private CompatViewInflater mCompatViewInflater;
    private List mParallaxViews = new ArrayList<>();
    private int[] attrsB = new int[]{R.attr.translationXIn, R.attr.translationXOut, R.attr.translationYIn, R.attr.translationYOut,};

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        //获取布局资源id
        int anInt = getArguments().getInt(LAYOUT_ID_KEY);
        // 2.2.2 把所有需要移动的属性解析出来,内涵端子插件式换肤
        // View创建的时候 我们去解析属性  这里传 inflater 有没有问题? 单例设计模式 代表着所有的View的创建都会是该 Fragment 去创建的
        inflater = inflater.cloneInContext(getActivity());
        LayoutInflaterCompat.setFactory(inflater, this);
        return inflater.inflate(anInt, container, false);
    }

    @Override
    public View onCreateView(View parent, String name, Context context, AttributeSet attrs) {
        View view = createView(parent, name, context, attrs);
        if (view != null) {
            //进行属性解析
            analysisAttrs(view, context, attrs);
        }
        //判断是否是最后一个fragment 是的话点击按钮进入程序主页
        boolean isLastFragment = getArguments().getBoolean("isLastFragment", false);
        if (isLastFragment) {
            TextView goMain = (TextView) view.findViewById(R.id.go_main);
            if (goMain != null) {
                goMain.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        startActivity(new Intent(getActivity(), SecondActivity.class));
                        getActivity().finish();
                    }
                });
            }
        }
        return view;
    }

    private void analysisAttrs(View view, Context context, AttributeSet attrs) {
        TypedArray array = context.obtainStyledAttributes(attrs, attrsB);
        if (array != null && array.getIndexCount() != 0) {
            int indexCount = array.getIndexCount();
            ParallaxTag tag = new ParallaxTag();
            //进行 遍历循环
            for (int i = 0; i < indexCount; i++) {
                int attr = array.getIndex(i);
                switch (attr) {
                    case 0:
                        tag.translationXIn = array.getFloat(attr, 0f);
                        break;
                    case 1:
                        tag.translationXOut = array.getFloat(attr, 0f);
                        break;
                    case 2:
                        tag.translationYIn = array.getFloat(attr, 0f);
                        break;
                    case 3:
                        tag.translationYOut = array.getFloat(attr, 0f);
                        break;
                }
            }
            // 自定义属性怎么存? 还要一一绑定  在View上面设置一个tag
            view.setTag(R.id.parallax_tag, tag);
            Log.e("TAG", tag.toString());
            mParallaxViews.add(view);
        }
        array.recycle();
    }

    public View createView(View parent, final String name, @NonNull Context context,
                           @NonNull AttributeSet attrs) {
        final boolean isPre21 = Build.VERSION.SDK_INT < 21;

        if (mCompatViewInflater == null) {
            mCompatViewInflater = new CompatViewInflater();
        }

        // We only want the View to inherit it's context if we're running pre-v21
        final boolean inheritContext = isPre21 && true
                && shouldInheritContext((ViewParent) parent);

        return mCompatViewInflater.createView(parent, name, context, attrs, inheritContext,
                isPre21, /* Only read android:theme pre-L (L+ handles this anyway) */
                true /* Read read app:theme as a fallback at all times for legacy reasons */
        );
    }

    private boolean shouldInheritContext(ViewParent parent) {
        if (parent == null) {
            // The initial parent is null so just return false
            return false;
        }
        while (true) {
            if (parent == null) {
                // Bingo. We've hit a view which has a null parent before being terminated from
                // the loop. This is (most probably) because it's the root view in an inflation
                // call, therefore we should inherit. This works as the inflated layout is only
                // added to the hierarchy at the end of the inflate() call.
                return true;
            } else if (!(parent instanceof View)
                    || ViewCompat.isAttachedToWindow((View) parent)) {
                // We have either hit the window's decor view, a parent which isn't a View
                // (i.e. ViewRootImpl), or an attached view, so we know that the original parent
                // is currently added to the view hierarchy. This means that it has not be
                // inflated in the current inflate() call and we should not inherit the context.
                return false;
            }
            parent = parent.getParent();
        }
    }

    public List getParallaxViews() {
        return mParallaxViews;
    }
}
public class CompatViewInflater {

    private static final Class[] sConstructorSignature = new Class[]{
            Context.class, AttributeSet.class};
    private static final int[] sOnClickAttrs = new int[]{android.R.attr.onClick};

    private static final String LOG_TAG = "AppCompatViewInflater";

    private static final Map> sConstructorMap
            = new ArrayMap<>();

    private final Object[] mConstructorArgs = new Object[2];

    public final View createView(View parent, final String name, @NonNull Context context,
                                 @NonNull AttributeSet attrs, boolean inheritContext,
                                 boolean readAndroidTheme, boolean readAppTheme) {
        final Context originalContext = context;

        // We can emulate Lollipop's android:theme attribute propagating down the view hierarchy
        // by using the parent's context
        if (inheritContext && parent != null) {
            context = parent.getContext();
        }
        if (readAndroidTheme || readAppTheme) {
            // We then apply the theme on the context, if specified
            context = themifyContext(context, attrs, readAndroidTheme, readAppTheme);
        }

        View view = null;

        // We need to 'inject' our tint aware Views in place of the standard framework versions
        switch (name) {
            case "TextView":
                view = new AppCompatTextView(context, attrs);
                break;
            case "ImageView":
                view = new AppCompatImageView(context, attrs);
                break;
            case "Button":
                view = new AppCompatButton(context, attrs);
                break;
            case "EditText":
                view = new AppCompatEditText(context, attrs);
                break;
            case "Spinner":
                view = new AppCompatSpinner(context, attrs);
                break;
            case "ImageButton":
                view = new AppCompatImageButton(context, attrs);
                break;
            case "CheckBox":
                view = new AppCompatCheckBox(context, attrs);
                break;
            case "RadioButton":
                view = new AppCompatRadioButton(context, attrs);
                break;
            case "CheckedTextView":
                view = new AppCompatCheckedTextView(context, attrs);
                break;
            case "AutoCompleteTextView":
                view = new AppCompatAutoCompleteTextView(context, attrs);
                break;
            case "MultiAutoCompleteTextView":
                view = new AppCompatMultiAutoCompleteTextView(context, attrs);
                break;
            case "RatingBar":
                view = new AppCompatRatingBar(context, attrs);
                break;
            case "SeekBar":
                view = new AppCompatSeekBar(context, attrs);
                break;
        }

        if (view == null) {
            // If the original context does not equal our themed context, then we need to manually
            // inflate it using the name so that android:theme takes effect.
            view = createViewFromTag(context, name, attrs);
        }

        if (view != null) {
            // If we have created a view, check it's android:onClick
            checkOnClickListener(view, attrs);
        }

        return view;
    }

    private View createViewFromTag(Context context, String name, AttributeSet attrs) {
        if (name.equals("view")) {
            name = attrs.getAttributeValue(null, "class");
        }

        try {
            mConstructorArgs[0] = context;
            mConstructorArgs[1] = attrs;

            if (-1 == name.indexOf('.')) {
                // try the android.widget prefix first...
                return createView(context, name, "android.widget.");
            } else {
                return createView(context, name, null);
            }
        } catch (Exception e) {
            // We do not want to catch these, lets return null and let the actual LayoutInflater
            // try
            return null;
        } finally {
            // Don't retain references on context.
            mConstructorArgs[0] = null;
            mConstructorArgs[1] = null;
        }
    }

    /**
     * android:onClick doesn't handle views with a ContextWrapper context. This method
     * backports new framework functionality to traverse the Context wrappers to find a
     * suitable target.
     */
    private void checkOnClickListener(View view, AttributeSet attrs) {
        final Context context = view.getContext();

        if (!ViewCompat.hasOnClickListeners(view) || !(context instanceof ContextWrapper)) {
            // Skip our compat functionality if: the view doesn't have an onClickListener,
            // or the Context isn't a ContextWrapper
            return;
        }

        final TypedArray a = context.obtainStyledAttributes(attrs, sOnClickAttrs);
        final String handlerName = a.getString(0);
        if (handlerName != null) {
            view.setOnClickListener(new DeclaredOnClickListener(view, handlerName));
        }
        a.recycle();
    }

    private View createView(Context context, String name, String prefix)
            throws ClassNotFoundException, InflateException {
        Constructor constructor = sConstructorMap.get(name);

        try {
            if (constructor == null) {
                // Class not found in the cache, see if it's real, and try to add it
                Class clazz = context.getClassLoader().loadClass(
                        prefix != null ? (prefix + name) : name).asSubclass(View.class);

                constructor = clazz.getConstructor(sConstructorSignature);
                sConstructorMap.put(name, constructor);
            }
            constructor.setAccessible(true);
            return constructor.newInstance(mConstructorArgs);
        } catch (Exception e) {
            // We do not want to catch these, lets return null and let the actual LayoutInflater
            // try
            return null;
        }
    }

    /**
     * Allows us to emulate the {@code android:theme} attribute for devices before L.
     */
    private static Context themifyContext(Context context, AttributeSet attrs,
                                          boolean useAndroidTheme, boolean useAppTheme) {
        final TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.View, 0, 0);
        int themeId = 0;
        if (useAndroidTheme) {
            // First try reading android:theme if enabled
            themeId = a.getResourceId(R.styleable.View_android_theme, 0);
        }
        if (useAppTheme && themeId == 0) {
            // ...if that didn't work, try reading app:theme (for legacy reasons) if enabled
            themeId = a.getResourceId(R.styleable.View_theme, 0);

            if (themeId != 0) {
                Log.i(LOG_TAG, "app:theme is now deprecated. "
                        + "Please move to using android:theme instead.");
            }
        }
        a.recycle();

        if (themeId != 0 && (!(context instanceof ContextThemeWrapper)
                || ((ContextThemeWrapper) context).getThemeResId() != themeId)) {
            // If the context isn't a ContextThemeWrapper, or it is but does not have
            // the same theme as we need, wrap it in a new wrapper
            context = new ContextThemeWrapper(context, themeId);
        }
        return context;
    }

    /**
     * An implementation of OnClickListener that attempts to lazily load a
     * named click handling method from a parent or ancestor context.
     */
    private static class DeclaredOnClickListener implements View.OnClickListener {
        private final View mHostView;
        private final String mMethodName;

        private Method mResolvedMethod;
        private Context mResolvedContext;

        public DeclaredOnClickListener(@NonNull View hostView, @NonNull String methodName) {
            mHostView = hostView;
            mMethodName = methodName;
        }

        @Override
        public void onClick(@NonNull View v) {
            if (mResolvedMethod == null) {
                resolveMethod(mHostView.getContext(), mMethodName);
            }

            try {
                mResolvedMethod.invoke(mResolvedContext, v);
            } catch (IllegalAccessException e) {
                throw new IllegalStateException(
                        "Could not execute non-public method for android:onClick", e);
            } catch (InvocationTargetException e) {
                throw new IllegalStateException(
                        "Could not execute method for android:onClick", e);
            }
        }

        @NonNull
        private void resolveMethod(@Nullable Context context, @NonNull String name) {
            while (context != null) {
                try {
                    if (!context.isRestricted()) {
                        final Method method = context.getClass().getMethod(mMethodName, View.class);
                        if (method != null) {
                            mResolvedMethod = method;
                            mResolvedContext = context;
                            return;
                        }
                    }
                } catch (NoSuchMethodException e) {
                    // Failed to find method, keep searching up the hierarchy.
                }

                if (context instanceof ContextWrapper) {
                    context = ((ContextWrapper) context).getBaseContext();
                } else {
                    // Can't search up the hierarchy, null out and fail.
                    context = null;
                }
            }

            final int id = mHostView.getId();
            final String idText = id == View.NO_ID ? "" : " with id '"
                    + mHostView.getContext().getResources().getResourceEntryName(id) + "'";
            throw new IllegalStateException("Could not find method " + mMethodName
                    + "(View) in a parent or ancestor Context for android:onClick "
                    + "attribute defined on view " + mHostView.getClass() + idText);
        }
    }
}
public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ParallaxViewPager parallaxVp = (ParallaxViewPager) findViewById(R.id.parallax_vp);
        parallaxVp.attach(getSupportFragmentManager(),new int[]{R.layout.fragment_page_first,
                R.layout.fragment_page_second,R.layout.fragment_page_third});
    }
}

源码地址

你可能感兴趣的:(app引导页视差动画效果)