假设我有一个垂直线性布局:

[v1]
[v2]

默认情况下,v1已经可见= GONE。我想用一个展开动画显示v1,同时下推v2。

我是这样做的:

Animation a = new Animation()
{
    int initialHeight;

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        final int newHeight = (int)(initialHeight * interpolatedTime);
        v.getLayoutParams().height = newHeight;
        v.requestLayout();
    }

    @Override
    public void initialize(int width, int height, int parentWidth, int parentHeight) {
        super.initialize(width, height, parentWidth, parentHeight);
        initialHeight = height;
    }

    @Override
    public boolean willChangeBounds() {
        return true;
    }
};

但是用这个解决方案,当动画开始时我有一个眨眼。我认为这是由于v1在应用动画之前显示全尺寸。

用javascript,这是一行jQuery!android有什么简单的方法吗?


当前回答

我试图做一个我认为非常相似的动画,并找到了一个优雅的解决方案。这段代码假设你总是从0->h或h->0 (h是最大高度)。三个构造函数参数是view =要动画的视图(在我的例子中是webview), targetHeight =视图的最大高度,以及down =一个布尔值,用于指定方向(true =展开,false =折叠)。

public class DropDownAnim extends Animation {
    private final int targetHeight;
    private final View view;
    private final boolean down;

    public DropDownAnim(View view, int targetHeight, boolean down) {
        this.view = view;
        this.targetHeight = targetHeight;
        this.down = down;
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        int newHeight;
        if (down) {
            newHeight = (int) (targetHeight * interpolatedTime);
        } else {
            newHeight = (int) (targetHeight * (1 - interpolatedTime));
        }
        view.getLayoutParams().height = newHeight;
        view.requestLayout();
    }

    @Override
    public void initialize(int width, int height, int parentWidth,
            int parentHeight) {
        super.initialize(width, height, parentWidth, parentHeight);
    }

    @Override
    public boolean willChangeBounds() {
        return true;
    }
}

其他回答

我今天也遇到了同样的问题,我想这个问题的真正解决方案是这样的

<LinearLayout android:id="@+id/container"
android:animateLayoutChanges="true"
...
 />

您必须为所有涉及移位的最顶层布局设置此属性。如果你现在将一个布局的可见性设置为GONE,另一个将在消失的布局释放它时占据空间。会有一个默认的动画,这是某种“淡出”,但我认为你可以改变这个-但最后一个我没有测试,现在。


如果在RecyclerView项目中使用这个,在onBindViewHolder中设置视图的可见性来展开/折叠,并调用notifyItemChanged(position)来触发转换。

override fun onBindViewHolder(holder: ItemViewHolder, position: Int) {
        ...

        holder.list.visibility = data[position].listVisibility
        holder.expandCollapse.setOnClickListener {
            data[position].listVisibility = if (data[position].listVisibility == View.GONE) View.VISIBLE else View.GONE
            notifyItemChanged(position)
        }
    }

如果你在onBindViewHolder中执行昂贵的操作,你可以使用notifyItemChanged(位置,有效载荷)优化部分更改

private const val UPDATE_LIST_VISIBILITY = 1

    override fun onBindViewHolder(holder: ItemViewHolder, position: Int, payloads: MutableList<Any>) {
        if (payloads.contains(UPDATE_LIST_VISIBILITY)) {
            holder.list.visibility = data[position].listVisibility
        } else {
            onBindViewHolder(holder, position)
        }
    }

    override fun onBindViewHolder(holder: ItemViewHolder, position: Int) {
        ...

        holder.list.visibility = data[position].listVisibility
        holder.expandCollapse.setOnClickListener {
            data[position].listVisibility = if (data[position].listVisibility == View.GONE) View.VISIBLE else View.GONE
            notifyItemChanged(position, UPDATE_LIST_VISIBILITY)
        }
    }
public static void slide(View v, int speed, int pos) {
    v.animate().setDuration(speed);
    v.animate().translationY(pos);
    v.animate().start();
}

// slide down
slide(yourView, 250, yourViewHeight);
// slide up
slide(yourView, 250, 0);

我想对上面非常有用的答案补充一些东西。如果你不知道你最终得到的高度,因为你的views .getHeight()返回0,你可以做下面的事情来获得高度:

contentView.measure(DUMMY_HIGH_DIMENSION, DUMMY_HIGH_DIMENSION);
int finalHeight = view.getMeasuredHeight();

其中DUMMY_HIGH_DIMENSIONS是宽度/高度(以像素为单位),您的视图被限制为…当视图被ScrollView封装时,有这么大的数字是合理的。

我采用了@LenaYan的解决方案,但它并没有正常工作 对我来说(因为它在折叠和/或扩展之前将视图转换为0高度视图)并做了一些更改。

现在它工作得很好,通过获取视图之前的高度并开始扩展这个大小。坍缩也是一样的。

你可以简单地复制和粘贴下面的代码:

public static void expand(final View v, int duration, int targetHeight) {

    int prevHeight  = v.getHeight();

    v.setVisibility(View.VISIBLE);
    ValueAnimator valueAnimator = ValueAnimator.ofInt(prevHeight, targetHeight);
    valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            v.getLayoutParams().height = (int) animation.getAnimatedValue();
            v.requestLayout();
        }
    });
    valueAnimator.setInterpolator(new DecelerateInterpolator());
    valueAnimator.setDuration(duration);
    valueAnimator.start();
}

public static void collapse(final View v, int duration, int targetHeight) {
    int prevHeight  = v.getHeight();
    ValueAnimator valueAnimator = ValueAnimator.ofInt(prevHeight, targetHeight);
    valueAnimator.setInterpolator(new DecelerateInterpolator());
    valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            v.getLayoutParams().height = (int) animation.getAnimatedValue();
            v.requestLayout();
        }
    });
    valueAnimator.setInterpolator(new DecelerateInterpolator());
    valueAnimator.setDuration(duration);
    valueAnimator.start();
}

用法:

//Expanding the View
   expand(yourView, 2000, 200);

// Collapsing the View     
   collapse(yourView, 2000, 100);

很容易!

感谢LenaYan提供的初始代码!

我看到这个问题很受欢迎,所以我发布了我的实际解决方案。主要的优点是你不需要知道扩展的高度来应用动画,一旦视图被扩展,它会在内容改变时适应高度。这对我来说很有效。

public static void expand(final View v) {
    int matchParentMeasureSpec = View.MeasureSpec.makeMeasureSpec(((View) v.getParent()).getWidth(), View.MeasureSpec.EXACTLY);
    int wrapContentMeasureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
    v.measure(matchParentMeasureSpec, wrapContentMeasureSpec);
    final int targetHeight = v.getMeasuredHeight();
    
    // Older versions of android (pre API 21) cancel animations for views with a height of 0.
    v.getLayoutParams().height = 1;
    v.setVisibility(View.VISIBLE);
    Animation a = new Animation()
    {
        @Override
        protected void applyTransformation(float interpolatedTime, Transformation t) {
            v.getLayoutParams().height = interpolatedTime == 1
                    ? LayoutParams.WRAP_CONTENT
                    : (int)(targetHeight * interpolatedTime);
            v.requestLayout();
        }

        @Override
        public boolean willChangeBounds() {
            return true;
        }
    };
    
    // Expansion speed of 1dp/ms
    a.setDuration((int)(targetHeight / v.getContext().getResources().getDisplayMetrics().density));
    v.startAnimation(a);
}

public static void collapse(final View v) {
    final int initialHeight = v.getMeasuredHeight();

    Animation a = new Animation()
    {
        @Override
        protected void applyTransformation(float interpolatedTime, Transformation t) {
            if(interpolatedTime == 1){
                v.setVisibility(View.GONE);
            }else{
                v.getLayoutParams().height = initialHeight - (int)(initialHeight * interpolatedTime);
                v.requestLayout();
            }
        }

        @Override
        public boolean willChangeBounds() {
            return true;
        }
    };
    
    // Collapse speed of 1dp/ms
    a.setDuration((int)(initialHeight / v.getContext().getResources().getDisplayMetrics().density));
    v.startAnimation(a);
}

正如@Jefferson在评论中提到的,你可以通过改变动画的持续时间(以及速度)来获得更流畅的动画。目前,它已设置为1dp/ms的速度