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

根据@Tom Esterez和@Seth Nelson的解决方案,我对它们进行了简化。与原始解决方案一样,它不依赖于开发人员选项(动画设置)。

private void resizeWithAnimation(final View view, int duration, final int targetHeight) {
    final int initialHeight = view.getMeasuredHeight();
    final int distance = targetHeight - initialHeight;

    view.setVisibility(View.VISIBLE);

    Animation a = new Animation() {
        @Override
        protected void applyTransformation(float interpolatedTime, Transformation t) {
            if (interpolatedTime == 1 && targetHeight == 0) {
                view.setVisibility(View.GONE);
            }
            view.getLayoutParams().height = (int) (initialHeight + distance * interpolatedTime);
            view.requestLayout();
        }

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

    a.setDuration(duration);
    view.startAnimation(a);
}

其他回答

我已经使用了相同的代码块,已经在接受的答案,但它不会像在android 9一样工作,所以更新措施根据这一点

v.measure(MeasureSpec.makeMeasureSpec(parentView.getWidth(), MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(parentView.getWidth(), MeasureSpec.AT_MOST));

约束的工作方式在android 9中有所不同。

你可以稍微改变一下使用ViewPropertyAnimator。若要折叠,请将视图缩放到1像素的高度,然后隐藏它。展开,显示它,然后展开到它的高度。

private void collapse(final View view) {
    view.setPivotY(0);
    view.animate().scaleY(1/view.getHeight()).setDuration(1000).withEndAction(new Runnable() {
        @Override public void run() {
            view.setVisibility(GONE);
        }
    });
}

private void expand(View view, int height) {
    float scaleFactor = height / view.getHeight();

    view.setVisibility(VISIBLE);
    view.setPivotY(0);
    view.animate().scaleY(scaleFactor).setDuration(1000);
}

枢轴告诉视图从哪里开始缩放,默认是在中间。持续时间是可选的(默认= 1000)。你也可以设置插值器来使用,比如.setInterpolator(new accelerateeraderateinterpolator ())

你不需要实现动画, 你可以输入android:animateLayoutChanges="true" 以便每当子视图布局发生变化时, 它将是动画……

这是一个合适的工作解决方案,我已经测试过了:

例如:

private void expand(View v) {
    v.setVisibility(View.VISIBLE);

    v.measure(View.MeasureSpec.makeMeasureSpec(PARENT_VIEW.getWidth(), View.MeasureSpec.EXACTLY),
            View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));

    final int targetHeight = v.getMeasuredHeight();

    mAnimator = slideAnimator(0, targetHeight);
    mAnimator.setDuration(800);
    mAnimator.start();
}

崩溃:

private void collapse(View v) {
    int finalHeight = v.getHeight();

    mAnimator = slideAnimator(finalHeight, 0);

    mAnimator.addListener(new Animator.AnimatorListener() {
        @Override
        public void onAnimationStart(Animator animator) {

        }

        @Override
        public void onAnimationEnd(Animator animator) {
            //Height=0, but it set visibility to GONE
            llDescp.setVisibility(View.GONE);
        }

        @Override
        public void onAnimationCancel(Animator animator) {

        }

        @Override
        public void onAnimationRepeat(Animator animator) {

        }
    });
    mAnimator.start();
}

动画师的值:

private ValueAnimator slideAnimator(int start, int end) {
    ValueAnimator mAnimator = ValueAnimator.ofInt(start, end);

    mAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator valueAnimator) {
            //Update Height
            int value = (Integer) valueAnimator.getAnimatedValue();
            ViewGroup.LayoutParams layoutParams = llDescp.getLayoutParams();
            layoutParams.height = value;
            v.setLayoutParams(layoutParams);
        }
    });
    return mAnimator;
}

视图v是要被动画的视图,PARENT_VIEW是包含该视图的容器视图。

你的思路是对的。确保在动画开始之前将v1设置为布局高度为0。在开始动画之前,您需要初始化您的设置,使其看起来像动画的第一帧。