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?
@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);
}
我改编了汤姆·埃斯特兹(Tom Esterez)目前接受的答案,这个答案有效,但动画起伏不定,不太流畅。我的解决方案基本上是用ValueAnimator替换动画,它可以与你选择的Interpolator相匹配,以实现各种效果,如超调、反弹、加速等。
这个解决方案非常适用于具有动态高度的视图(即使用WRAP_CONTENT),因为它首先测量实际所需的高度,然后动画到该高度。
public static void expand(final View v) {
v.measure(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
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);
ValueAnimator va = ValueAnimator.ofInt(1, targetHeight);
va.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
public void onAnimationUpdate(ValueAnimator animation) {
v.getLayoutParams().height = (Integer) animation.getAnimatedValue();
v.requestLayout();
}
});
va.addListener(new Animator.AnimatorListener() {
@Override
public void onAnimationEnd(Animator animation) {
v.getLayoutParams().height = ViewGroup.LayoutParams.WRAP_CONTENT;
}
@Override public void onAnimationStart(Animator animation) {}
@Override public void onAnimationCancel(Animator animation) {}
@Override public void onAnimationRepeat(Animator animation) {}
});
va.setDuration(300);
va.setInterpolator(new OvershootInterpolator());
va.start();
}
public static void collapse(final View v) {
final int initialHeight = v.getMeasuredHeight();
ValueAnimator va = ValueAnimator.ofInt(initialHeight, 0);
va.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
public void onAnimationUpdate(ValueAnimator animation) {
v.getLayoutParams().height = (Integer) animation.getAnimatedValue();
v.requestLayout();
}
});
va.addListener(new Animator.AnimatorListener() {
@Override
public void onAnimationEnd(Animator animation) {
v.setVisibility(View.GONE);
}
@Override public void onAnimationStart(Animator animation) {}
@Override public void onAnimationCancel(Animator animation) {}
@Override public void onAnimationRepeat(Animator animation) {}
});
va.setDuration(300);
va.setInterpolator(new DecelerateInterpolator());
va.start();
}
然后你只需调用expand(myView);或崩溃(myView);。
我创建的版本中,你不需要指定布局高度,因此它更容易和更干净的使用。解决方案是在动画的第一帧中获取高度(至少在我的测试中是可用的)。通过这种方式,您可以为视图提供任意高度和底边距。
在构造函数中还有一个小hack -底部边距被设置为-10000,以便视图在转换之前保持隐藏(防止闪烁)。
public class ExpandAnimation extends Animation {
private View mAnimatedView;
private ViewGroup.MarginLayoutParams mViewLayoutParams;
private int mMarginStart, mMarginEnd;
public ExpandAnimation(View view) {
mAnimatedView = view;
mViewLayoutParams = (ViewGroup.MarginLayoutParams) view.getLayoutParams();
mMarginEnd = mViewLayoutParams.bottomMargin;
mMarginStart = -10000; //hide before viewing by settings very high negative bottom margin (hack, but works nicely)
mViewLayoutParams.bottomMargin = mMarginStart;
mAnimatedView.setLayoutParams(mViewLayoutParams);
}
@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
super.applyTransformation(interpolatedTime, t);
//view height is already known when the animation starts
if(interpolatedTime==0){
mMarginStart = -mAnimatedView.getHeight();
}
mViewLayoutParams.bottomMargin = (int)((mMarginEnd-mMarginStart) * interpolatedTime)+mMarginStart;
mAnimatedView.setLayoutParams(mViewLayoutParams);
}
}
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