GIF1.gif
要做到这种动画效果我们需要用到捕获所有view并对view 进行一系列操作
上一节讲了了解了view的创建流程现，现在通过demo的形式来完成此功能
首先创建一个framgment 来实现LayoutInflaterFactory接口，这一步骤做完 所有的view都会走接口中的方法了，可以照抄系统的源码一直往下走 AppCompatViewInflater 这个类发现是new不出来的，直接把这个类的内容复制出来我们新建一个类命名相同，这样整个fragment内的布局里面的view都会走我们自己的方法
//我重新复制一个LayoutInflater ，因为LayoutInflater是单例 否则下面会报错
LayoutInflater layoutInflater = inflater.cloneInContext(getActivity());
LayoutInflaterCompat.setFactory(layoutInflater, this);
return layoutInflater.inflate(mlayoutId, container, false);
实现接口所调用的方法
@Override
public View onCreateView(View parent, String name, Context context, AttributeSet attrs) {
View view = createView(parent, name, context, attrs);
if (view != null) {
// Log.e("TAG", "我来创建View");
// 解析所有的我们自己关注属性
analysisAttrs(view, context, attrs);
}
return view;
}
public View createView(View parent, final String name, @NonNull Context context,
@NonNull AttributeSet attrs) {
final boolean isPre21 = Build.VERSION.SDK_INT < 21;
if (mAppCompatViewInflater == null) {
mAppCompatViewInflater = new AppCompatViewInflater();
}
// 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 mAppCompatViewInflater.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 (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();
}
}
//获取所有的view 并拿到view中的参数 设置到tag中 通过viewpager的滑动而一起滑动
private void analysisAttrs(View view, Context context, AttributeSet attrs) {
TypedArray typedArray = context.obtainStyledAttributes(attrs, mAttrs);
if (view != null && typedArray.getIndexCount() != 0) {
int n = typedArray.getIndexCount();
ParallaxTag parallaxTag = new ParallaxTag();
for (int i = 0; i <= n; i++) {
int attr = typedArray.getIndex(i);
switch (attr) {
case 0:
parallaxTag.translationXIn = typedArray.getFloat(attr, 0f);
break;
case 1:
parallaxTag.translationXOut = typedArray.getFloat(attr, 0f);
break;
case 2:
parallaxTag.translationYIn = typedArray.getFloat(attr, 0f);
break;
case 3:
parallaxTag.translationYOut = typedArray.getFloat(attr, 0f);
break;
}
}
view.setTag(R.id.parallax_tag,parallaxTag);
parallaxView.add(view);
Log.e("TAG",parallaxTag.toString());
}
typedArray.recycle();
}
上面的代码已经把所有的view拿到，现在自定义一个viewpager实现监听接口
addOnPageChangeListener(new OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
Log.e("TAG","position->"+position+" positionOffset->"+positionOffset+" positionOffsetPixels->"+positionOffsetPixels);
ParallaxFragment outFragment = (ParallaxFragment) mFragmentList.get(position);
List<View> parallaxViewsOut = outFragment.getParallaxView();
for (View parallaxView : parallaxViewsOut) {
ParallaxTag tag = (ParallaxTag) parallaxView.getTag(R.id.parallax_tag);
parallaxView.setTranslationX((- positionOffsetPixels) * tag.translationXOut);
parallaxView.setTranslationY((- positionOffsetPixels) * tag.translationYOut);
}
try {
ParallaxFragment inFragment = (ParallaxFragment) mFragmentList.get(position+1);
List<View> parallaxViewsIn = inFragment.getParallaxView();
for (View parallaxView : parallaxViewsIn) {
ParallaxTag tag = (ParallaxTag) parallaxView.getTag();
parallaxView.setTranslationX(( positionOffsetPixels) * tag.translationXIn);
parallaxView.setTranslationY((positionOffsetPixels) * tag.translationYIn);
}
}catch (Exception e){
e.printStackTrace();
}
}
@Override
public void onPageSelected(int position) {
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
使用方法
mParallaxViewPager = (ParallaxViewPager) findViewById(R.id.viewpager);
mParallaxViewPager.setLayout(new int[]
{R.layout.fragment_page_first, R.layout.fragment_page_second,
R.layout.fragment_page_third}, getSupportFragmentManager());
demo地址
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