[转] Android: Expand/collapse animation

最新推荐文章于 2022-12-17 01:15:56 发布

MikeoLeo

最新推荐文章于 2022-12-17 01:15:56 发布

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分类专栏： Android 文章标签： android animation expand collapse

本文链接：https://blog.youkuaiyun.com/yhz61010/article/details/84905441

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本文提供了一种在Android中实现视图展开与折叠动画的方法。通过自定义Animation类，可以根据视图的高度变化来平滑地调整布局，实现视图的渐进显示与隐藏效果。

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原文地址：[url]https://stackoverflow.com/a/13381228/6091500[/url]

亲测可用。

import android.view.View;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.Transformation;

public class ViewAnimation {
    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);
        Animation a = new Animation()
        {
            @Override
            protected void applyTransformation(float interpolatedTime, Transformation t) {
                v.getLayoutParams().height = interpolatedTime == 1
                        ? ViewGroup.LayoutParams.WRAP_CONTENT
                        : (int)(targetHeight * interpolatedTime);
                v.requestLayout();
            }

            @Override
            public boolean willChangeBounds() {
                return true;
            }
        };

        // 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;
            }
        };

        // 1dp/ms
        a.setDuration((int)(initialHeight / v.getContext().getResources().getDisplayMetrics().density));
        v.startAnimation(a);
    }
}