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?
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)
}
}
@Tom Esterez的回答，但更新为正确使用view.measure()每个Android getMeasuredHeight返回错误的值!
// http://easings.net/
Interpolator easeInOutQuart = PathInterpolatorCompat.create(0.77f, 0f, 0.175f, 1f);
public static Animation expand(final View view) {
int matchParentMeasureSpec = View.MeasureSpec.makeMeasureSpec(((View) view.getParent()).getWidth(), View.MeasureSpec.EXACTLY);
int wrapContentMeasureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
view.measure(matchParentMeasureSpec, wrapContentMeasureSpec);
final int targetHeight = view.getMeasuredHeight();
// Older versions of android (pre API 21) cancel animations for views with a height of 0 so use 1 instead.
view.getLayoutParams().height = 1;
view.setVisibility(View.VISIBLE);
Animation animation = new Animation() {
@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
view.getLayoutParams().height = interpolatedTime == 1
? ViewGroup.LayoutParams.WRAP_CONTENT
: (int) (targetHeight * interpolatedTime);
view.requestLayout();
}
@Override
public boolean willChangeBounds() {
return true;
}
};
animation.setInterpolator(easeInOutQuart);
animation.setDuration(computeDurationFromHeight(view));
view.startAnimation(animation);
return animation;
}
public static Animation collapse(final View view) {
final int initialHeight = view.getMeasuredHeight();
Animation a = new Animation() {
@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
if (interpolatedTime == 1) {
view.setVisibility(View.GONE);
} else {
view.getLayoutParams().height = initialHeight - (int) (initialHeight * interpolatedTime);
view.requestLayout();
}
}
@Override
public boolean willChangeBounds() {
return true;
}
};
a.setInterpolator(easeInOutQuart);
int durationMillis = computeDurationFromHeight(view);
a.setDuration(durationMillis);
view.startAnimation(a);
return a;
}
private static int computeDurationFromHeight(View view) {
// 1dp/ms * multiplier
return (int) (view.getMeasuredHeight() / view.getContext().getResources().getDisplayMetrics().density);
}
利用Kotlin扩展函数这是测试和最短的答案
在任何视图上调用animateVisibility(expand/collapse)即可。
fun View.animateVisibility(setVisible: Boolean) {
if (setVisible) expand(this) else collapse(this)
}
private fun expand(view: View) {
view.measure(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT)
val initialHeight = 0
val targetHeight = view.measuredHeight
// Older versions of Android (pre API 21) cancel animations for views with a height of 0.
//v.getLayoutParams().height = 1;
view.layoutParams.height = 0
view.visibility = View.VISIBLE
animateView(view, initialHeight, targetHeight)
}
private fun collapse(view: View) {
val initialHeight = view.measuredHeight
val targetHeight = 0
animateView(view, initialHeight, targetHeight)
}
private fun animateView(v: View, initialHeight: Int, targetHeight: Int) {
val valueAnimator = ValueAnimator.ofInt(initialHeight, targetHeight)
valueAnimator.addUpdateListener { animation ->
v.layoutParams.height = animation.animatedValue as Int
v.requestLayout()
}
valueAnimator.addListener(object : Animator.AnimatorListener {
override fun onAnimationEnd(animation: Animator) {
v.layoutParams.height = targetHeight
}
override fun onAnimationStart(animation: Animator) {}
override fun onAnimationCancel(animation: Animator) {}
override fun onAnimationRepeat(animation: Animator) {}
})
valueAnimator.duration = 300
valueAnimator.interpolator = DecelerateInterpolator()
valueAnimator.start()
}
这是我的解决方案。我认为这样更简单。它只是扩展了视图，但很容易扩展。
public class WidthExpandAnimation extends Animation
{
int _targetWidth;
View _view;
public WidthExpandAnimation(View view)
{
_view = view;
}
@Override
protected void applyTransformation(float interpolatedTime, Transformation t)
{
if (interpolatedTime < 1.f)
{
int newWidth = (int) (_targetWidth * interpolatedTime);
_view.layout(_view.getLeft(), _view.getTop(),
_view.getLeft() + newWidth, _view.getBottom());
}
else
_view.requestLayout();
}
@Override
public void initialize(int width, int height, int parentWidth, int parentHeight)
{
super.initialize(width, height, parentWidth, parentHeight);
_targetWidth = width;
}
@Override
public boolean willChangeBounds() {
return true;
}
}
