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?
这是一个片段，我用来调整一个视图(线性布局)的宽度与动画。
代码应该根据目标大小进行扩展或收缩。如果你想要一个fill_parent宽度，你必须在将标志设置为true时将父类. getmeasuredwidth作为目标宽度。
希望它能帮助到你们中的一些人。
public class WidthResizeAnimation extends Animation {
int targetWidth;
int originaltWidth;
View view;
boolean expand;
int newWidth = 0;
boolean fillParent;
public WidthResizeAnimation(View view, int targetWidth, boolean fillParent) {
this.view = view;
this.originaltWidth = this.view.getMeasuredWidth();
this.targetWidth = targetWidth;
newWidth = originaltWidth;
if (originaltWidth > targetWidth) {
expand = false;
} else {
expand = true;
}
this.fillParent = fillParent;
}
@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
if (expand && newWidth < targetWidth) {
newWidth = (int) (newWidth + (targetWidth - newWidth) * interpolatedTime);
}
if (!expand && newWidth > targetWidth) {
newWidth = (int) (newWidth - (newWidth - targetWidth) * interpolatedTime);
}
if (fillParent && interpolatedTime == 1.0) {
view.getLayoutParams().width = -1;
} else {
view.getLayoutParams().width = newWidth;
}
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;
}
}
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;
}
}
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;
}
}
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
来自@Tom Esterez和@Geraldo Neto的组合解决方案
public static void expandOrCollapseView(View v,boolean expand){
if(expand){
v.measure(ViewGroup.LayoutParams.MATCH_PARENT,ViewGroup.LayoutParams.WRAP_CONTENT);
final int targetHeight = v.getMeasuredHeight();
v.getLayoutParams().height = 0;
v.setVisibility(View.VISIBLE);
ValueAnimator valueAnimator = ValueAnimator.ofInt(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(500);
valueAnimator.start();
}
else
{
final int initialHeight = v.getMeasuredHeight();
ValueAnimator valueAnimator = ValueAnimator.ofInt(initialHeight,0);
valueAnimator.setInterpolator(new DecelerateInterpolator());
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
v.getLayoutParams().height = (int) animation.getAnimatedValue();
v.requestLayout();
if((int)animation.getAnimatedValue() == 0)
v.setVisibility(View.GONE);
}
});
valueAnimator.setInterpolator(new DecelerateInterpolator());
valueAnimator.setDuration(500);
valueAnimator.start();
}
}
//sample usage
expandOrCollapseView((Your ViewGroup),(Your ViewGroup).getVisibility()!=View.VISIBLE);
