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

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

其他回答

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;
    }
}

我想对上面非常有用的答案补充一些东西。如果你不知道你最终得到的高度,因为你的views .getHeight()返回0,你可以做下面的事情来获得高度:

contentView.measure(DUMMY_HIGH_DIMENSION, DUMMY_HIGH_DIMENSION);
int finalHeight = view.getMeasuredHeight();

其中DUMMY_HIGH_DIMENSIONS是宽度/高度(以像素为单位),您的视图被限制为…当视图被ScrollView封装时,有这么大的数字是合理的。

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。

这是非常简单的droidQuery。首先,考虑这样的布局:

<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical" >
    <LinearLayout
        android:id="@+id/v1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" 
            android:text="View 1" />
    </LinearLayout>
    <LinearLayout
        android:id="@+id/v2"
        android:layout_width="wrap_content"
        android:layout_height="0dp" >
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" 
            android:text="View 2" />
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" 
            android:text="View 3" />
    </LinearLayout>
</LinearLayout>

我们可以使用下面的代码将高度动画到所需的值-比如100dp:

//convert 100dp to pixel value
int height = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 100, getResources().getDisplayMetrics());

然后使用droidQuery进行动画。最简单的方法是:

$.animate("{ height: " + height + "}", new AnimationOptions());

为了让动画更吸引人,可以考虑添加一个easing:

$.animate("{ height: " + height + "}", new AnimationOptions().easing($.Easing.BOUNCE));

你也可以使用duration()方法改变AnimationOptions上的持续时间,或者处理动画结束时发生的事情。对于一个复杂的例子,试试:

$.animate("{ height: " + height + "}", new AnimationOptions().easing($.Easing.BOUNCE)
                                                             .duration(1000)
                                                             .complete(new Function() {
                                                                 @Override
                                                                 public void invoke($ d, Object... args) {
                                                                     $.toast(context, "finished", Toast.LENGTH_SHORT);
                                                                 }
                                                             }));

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。