Question

我希望在Animation将其可见性设置为View时生成GONE。 View应该“崩溃”，而不仅仅是消失。我尝试使用ScaleAnimation，但View崩溃，但布局只会在Animation停止（或开始）之后（或之前）调整其空间大小。

如何设置Animation，以便在设置动画时，较低的View将直接位于内容的下方，而不是空格？

Answer 1

如果不是布局，请将视图置于布局中，并为该布局设置android:animateLayoutChanges="true"。

Answer 2

似乎没有一种简单的方法可以通过API执行此操作，因为动画只会更改视图的渲染矩阵，而不是实际大小。但是我们可以设置一个负余量来欺骗LinearLayout，使其认为视图变小了。

所以我建议你创建自己的Animation类，基于ScaleAnimation，并覆盖“applyTransformation”方法来设置新的边距并更新布局。像这样......

public class Q2634073 extends Activity implements OnClickListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.q2634073);
        findViewById(R.id.item1).setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        view.startAnimation(new MyScaler(1.0f, 1.0f, 1.0f, 0.0f, 500, view, true));
    }

    public class MyScaler extends ScaleAnimation {

        private View mView;

        private LayoutParams mLayoutParams;

        private int mMarginBottomFromY, mMarginBottomToY;

        private boolean mVanishAfter = false;

        public MyScaler(float fromX, float toX, float fromY, float toY, int duration, View view,
                boolean vanishAfter) {
            super(fromX, toX, fromY, toY);
            setDuration(duration);
            mView = view;
            mVanishAfter = vanishAfter;
            mLayoutParams = (LayoutParams) view.getLayoutParams();
            int height = mView.getHeight();
            mMarginBottomFromY = (int) (height * fromY) + mLayoutParams.bottomMargin - height;
            mMarginBottomToY = (int) (0 - ((height * toY) + mLayoutParams.bottomMargin)) - height;
        }

        @Override
        protected void applyTransformation(float interpolatedTime, Transformation t) {
            super.applyTransformation(interpolatedTime, t);
            if (interpolatedTime < 1.0f) {
                int newMarginBottom = mMarginBottomFromY
                        + (int) ((mMarginBottomToY - mMarginBottomFromY) * interpolatedTime);
                mLayoutParams.setMargins(mLayoutParams.leftMargin, mLayoutParams.topMargin,
                    mLayoutParams.rightMargin, newMarginBottom);
                mView.getParent().requestLayout();
            } else if (mVanishAfter) {
                mView.setVisibility(View.GONE);
            }
        }

    }

}

通常的警告适用：因为我们覆盖了受保护的方法（applyTransformation），所以不能保证在未来的Android版本中可以使用。

Answer 3

我使用的技术与Andy在此提出的相同。我为此编写了自己的动画类，使边距的值动画化，导致项目的效果消失/出现。它看起来像这样：

public class ExpandAnimation extends Animation {

// Initializations...

@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
    super.applyTransformation(interpolatedTime, t);

    if (interpolatedTime < 1.0f) {

        // Calculating the new bottom margin, and setting it
        mViewLayoutParams.bottomMargin = mMarginStart
                + (int) ((mMarginEnd - mMarginStart) * interpolatedTime);

        // Invalidating the layout, making us seeing the changes we made
        mAnimatedView.requestLayout();
    }
}
}

我有一个完整的例子可以在我的博客文章中使用 http://udinic.wordpress.com/2011/09/03/expanding-listview-items/

Answer 4

我在这里使用了与Andy相同的技术，并对其进行了改进，以便它可以用于扩展和折叠而不会出现故障，同时使用此处描述的技术：https://stackoverflow.com/a/11426510/1317564

import android.view.View;
import android.view.ViewTreeObserver;
import android.view.animation.ScaleAnimation;
import android.view.animation.Transformation;
import android.widget.LinearLayout;

class LinearLayoutVerticalScaleAnimation extends ScaleAnimation {
    private final LinearLayout view;
    private final LinearLayout.LayoutParams layoutParams;

    private final float beginY;
    private final float endY;
    private final int originalBottomMargin;

    private int expandedHeight;
    private boolean marginsInitialized = false;
    private int marginBottomBegin;
    private int marginBottomEnd;

    private ViewTreeObserver.OnPreDrawListener preDrawListener;

    LinearLayoutVerticalScaleAnimation(float beginY, float endY,
            LinearLayout linearLayout) {
        super(1f, 1f, beginY, endY);

        this.view = linearLayout;
        this.layoutParams = (LinearLayout.LayoutParams) linearLayout.getLayoutParams();

        this.beginY = beginY;
        this.endY = endY;
        this.originalBottomMargin = layoutParams.bottomMargin;

        if (view.getHeight() != 0) {
            expandedHeight = view.getHeight();
            initializeMargins();
        }
    }

    private void initializeMargins() {
        final int beginHeight = (int) (expandedHeight * beginY);
        final int endHeight = (int) (expandedHeight * endY);

        marginBottomBegin = beginHeight + originalBottomMargin - expandedHeight;
        marginBottomEnd = endHeight + originalBottomMargin - expandedHeight;
        marginsInitialized = true;
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        super.applyTransformation(interpolatedTime, t);     

        if (!marginsInitialized && preDrawListener == null) {                       
            // To avoid glitches, don't draw until we've initialized everything.
            preDrawListener = new ViewTreeObserver.OnPreDrawListener() {
                @Override
                public boolean onPreDraw() {                    
                    if (view.getHeight() != 0) {
                        expandedHeight = view.getHeight();
                        initializeMargins();
                        adjustViewBounds(0f);
                        view.getViewTreeObserver().removeOnPreDrawListener(this);                               
                    }

                    return false;
                }
            };

            view.getViewTreeObserver().addOnPreDrawListener(preDrawListener);                   
        }

        if (interpolatedTime < 1.0f && view.getVisibility() != View.VISIBLE) {          
            view.setVisibility(View.VISIBLE);           
        }

        if (marginsInitialized) {           
            if (interpolatedTime < 1.0f) {
                adjustViewBounds(interpolatedTime);
            } else if (endY <= 0f && view.getVisibility() != View.GONE) {               
                view.setVisibility(View.GONE);
            }
        }
    }

    private void adjustViewBounds(float interpolatedTime) {
        layoutParams.bottomMargin = 
                marginBottomBegin + (int) ((marginBottomEnd - marginBottomBegin) * interpolatedTime);       

        view.getParent().requestLayout();
    }
}

如何为View.setVisibility（GONE）设置动画

4 个答案: