如何在RecyclerView中使用GridLayoutAnimation？

Question

我正在尝试用新的RecyclerView(使用GridLayoutManager)替换我的GridView,但似乎它不能很好地处理gridLayoutAnimation(ClassCastException: LayoutAnimationController$AnimationParameters cannot be cast to GridLayoutAnimationController$AnimationParameters).它适用于常规布局动画,但因为它是一个网格,所以在平板电脑上完成需要很长时间.

我想要完成的是类似于Hierarchical Timing.如果您查看示例视频,它会显示布局动画从左上角到右下角.常规布局动画将逐行执行动画,因此在更大的网格(例如平板电脑)上花费太多时间来完成.我也尝试过探索ItemAnimator,但这只会像在"不要"的例子中那样同时在所有单元格上运行动画.

有没有办法在RecyclerView中完成此网格布局动画？

这是gridview_layout_animation.xml:

<!-- replace gridLayoutAnimation with layoutAnimation and -->
<!-- replace column- and rowDelay with delay for RecyclerView -->

<gridLayoutAnimation xmlns:android="http://schemas.android.com/apk/res/android"
    android:columnDelay="15%"
    android:rowDelay="15%"
    android:animation="@anim/grow_in"
    android:animationOrder="normal"
    android:direction="top_to_bottom|left_to_right"
    android:interpolator="@android:interpolator/linear"
/>

这是动画grow_in.xml:

<set android:shareInterpolator="false"
 xmlns:android="http://schemas.android.com/apk/res/android">
    <scale
        android:interpolator="@android:interpolator/decelerate_quint"
        android:fromXScale="0.0"
        android:toXScale="1.0"
        android:fromYScale="0.0"
        android:toYScale="1.0"
        android:pivotX="50%"
        android:pivotY="50%"
        android:fillAfter="true"
        android:duration="400"
        android:startOffset="200"
    />
</set>

编辑:基于Galaxas0的答案,这是一个解决方案,只需要您使用扩展的自定义视图RecyclerView.基本上只覆盖attachLayoutAnimationParameters()方法.这<gridLayoutAnimation>与GridView一样.

public class GridRecyclerView extends RecyclerView {

    public GridRecyclerView(Context context) {
        super(context);
    }

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

    public GridRecyclerView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    public void setLayoutManager(LayoutManager layout) {
        if (layout instanceof GridLayoutManager){
            super.setLayoutManager(layout);
        } else {
            throw new ClassCastException("You should only use a GridLayoutManager with GridRecyclerView.");
            }
        }

    @Override
    protected void attachLayoutAnimationParameters(View child, ViewGroup.LayoutParams params, int index, int count) {

        if (getAdapter() != null && getLayoutManager() instanceof GridLayoutManager){

            GridLayoutAnimationController.AnimationParameters animationParams =
                (GridLayoutAnimationController.AnimationParameters) params.layoutAnimationParameters;

            if (animationParams == null) {
                animationParams = new GridLayoutAnimationController.AnimationParameters();
                params.layoutAnimationParameters = animationParams;
            }

            int columns = ((GridLayoutManager) getLayoutManager()).getSpanCount();

            animationParams.count = count;
            animationParams.index = index;
            animationParams.columnsCount = columns;
            animationParams.rowsCount = count / columns;

            final int invertedIndex = count - 1 - index;
            animationParams.column = columns - 1 - (invertedIndex % columns);
            animationParams.row = animationParams.rowsCount - 1 - invertedIndex / columns;

        } else {
            super.attachLayoutAnimationParameters(child, params, index, count);
        }
    }
}

Answer 1

LayoutAnimationController被耦合到ViewGroup并且两个ListView和GridView下方延伸的方法来提供孩子的animationParams.问题是GridLayoutAnimationController需要自己的AnimationParameters,不能分类.

    /**
     * Subclasses should override this method to set layout animation
     * parameters on the supplied child.
     *
     * @param child the child to associate with animation parameters
     * @param params the child's layout parameters which hold the animation
     *        parameters
     * @param index the index of the child in the view group
     * @param count the number of children in the view group
     */
    protected void attachLayoutAnimationParameters(View child,
            LayoutParams params, int index, int count) {
        LayoutAnimationController.AnimationParameters animationParams =
                    params.layoutAnimationParameters;
        if (animationParams == null) {
            animationParams = new LayoutAnimationController.AnimationParameters();
            params.layoutAnimationParameters = animationParams;
        }

        animationParams.count = count;
        animationParams.index = index;
    }

由于此方法默认添加一个LayoutAnimationController.AnimationParameters而不是GridLayoutAnimationController.AnimationParameters,因此修复应该是事先创建并附加一个.我们需要实现的是GridView已经做的事情:

@Override
protected void attachLayoutAnimationParameters(View child,
        ViewGroup.LayoutParams params, int index, int count) {

    GridLayoutAnimationController.AnimationParameters animationParams =
            (GridLayoutAnimationController.AnimationParameters) params.layoutAnimationParameters;

    if (animationParams == null) {
        animationParams = new GridLayoutAnimationController.AnimationParameters();
        params.layoutAnimationParameters = animationParams;
    }

    animationParams.count = count;
    animationParams.index = index;
    animationParams.columnsCount = mNumColumns;
    animationParams.rowsCount = count / mNumColumns;

    if (!mStackFromBottom) {
        animationParams.column = index % mNumColumns;
        animationParams.row = index / mNumColumns;
    } else {
        final int invertedIndex = count - 1 - index;

        animationParams.column = mNumColumns - 1 - (invertedIndex % mNumColumns);
        animationParams.row = animationParams.rowsCount - 1 - invertedIndex / mNumColumns;
    }
}

要复制GridView,我们可以做的最接近的事情就是将onBindViewHolder()之前允许它们运行的修改dispatchDraw,即触发动画的调用.

ViewGroup.LayoutParams params = holder.itemView.getLayoutParams();
        GridLayoutAnimationController.AnimationParameters animationParams = new GridLayoutAnimationController.AnimationParameters();
        params.layoutAnimationParameters = animationParams;

        animationParams.count = 9;
        animationParams.columnsCount = 3;
        animationParams.rowsCount = 3;
        animationParams.index = position;
        animationParams.column = position / animationParams.columnsCount;
        animationParams.row = position % animationParams.columnsCount;

如果使用RecyclerViewnew GridLayoutManager,请尝试从中获取参数.上面的示例是一个概念证明,表明它的工作原理.我的硬编码值也不适用于我的应用程序.

由于这是一个自API 1以来一直没有真正的文档或样本的API,我强烈建议不要使用它,因为有很多方法可以复制它的功能.