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?
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。
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;
}
}
如果你不想扩展或折叠所有的方式-这里是一个简单的HeightAnimation -
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.Transformation;
public class HeightAnimation extends Animation {
protected final int originalHeight;
protected final View view;
protected float perValue;
public HeightAnimation(View view, int fromHeight, int toHeight) {
this.view = view;
this.originalHeight = fromHeight;
this.perValue = (toHeight - fromHeight);
}
@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
view.getLayoutParams().height = (int) (originalHeight + perValue * interpolatedTime);
view.requestLayout();
}
@Override
public boolean willChangeBounds() {
return true;
}
}
用法:
HeightAnimation heightAnim = new HeightAnimation(view, view.getHeight(), viewPager.getHeight() - otherView.getHeight());
heightAnim.setDuration(1000);
view.startAnimation(heightAnim);
