Android 动画仅在滚动其父 View 后才开始

Question

我正在尝试在android中创建一个可扩展的菜单项，它看起来像一个按钮，单击按钮时，按钮将通过动画向下扩展。我为布局设置了展开动画，当单击我的 View 时我想展开该布局，但我遇到了动画问题。当我单击 View 时，它不会立即启动，而是当我向下滚动或向上 ScrollView 的容器时启动。如果容器不可滚动，我的动画将永远不会开始。我做错了什么？

这是我的展开方法、onClick 方法和自定义 View 的布局 xml 文件，它将执行以下操作:

展开:

public void expand(final View v) {

        try {
            Method m = v.getClass().getDeclaredMethod("onMeasure", int.class, int.class);
            m.setAccessible(true);
            m.invoke(v,
                    MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED),
                    MeasureSpec.makeMeasureSpec(((View)v.getParent()).getMeasuredWidth(), MeasureSpec.AT_MOST)
            );
        } catch (Exception e) {
            Log.e(TAG , "Caught an exception!", e);
        }
        final int initialHeight = v.getMeasuredHeight();
        Log.d("test", "initialHeight="+initialHeight);

        v.getLayoutParams().height = 0;
        v.setVisibility(View.VISIBLE);


        Animation a = new Animation() {

            @Override
            protected void applyTransformation(float interpolatedTime,
                    Transformation t) {
                final int newHeight = (int) (initialHeight * interpolatedTime);
                v.getLayoutParams().height = newHeight;
                v.requestLayout();
            }

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

        };

        a.setDuration(1000);
        a.setInterpolator(AnimationUtils.loadInterpolator(context,
                android.R.anim.accelerate_decelerate_interpolator));
        v.startAnimation(a);

        isExpanded = !isExpanded;

    }

单击时:

public void onClick(View v) {
    if (!isExpanded) {
        expand(subButtonsLayout);
    } else {
        collapse(subButtonsLayout);
    }
}

自定义菜单项 View 的布局 xml:

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:mtx="http://schemas.android.com/apk/res/com.matriksdata.trademaster"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:gravity="center_horizontal">
    <LinearLayout
        android:id="@+id/xExpandableMenuButtonTop"
        android:background="@drawable/opened_menu_bg_top"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
    </LinearLayout>
    <LinearLayout
        android:background="@drawable/opened_menu_bg_center"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:gravity="center_vertical">
        <LinearLayout
            android:id="@+id/xExpandableMenuButtonTitle"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:gravity="center_vertical">
            <TextView
                android:id="@+id/xExpandableMenuButtonText"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:layout_marginLeft="10dip"
                android:layout_marginRight="10dip"
                        android:textAppearance="@style/expandable_menu_button_textstyle"
                android:text="Button Text">
            </TextView>
            <ImageView
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="6"
                android:src="@drawable/menu_button_down_arrow">
            </ImageView>
        </LinearLayout>
    </LinearLayout>
    <LinearLayout
        android:id="@+id/xExpandableMenuButtonSubButtonsLayout"
        android:background="@drawable/opened_menu_bg_center"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:gravity="center_vertical"
        android:visibility="gone">
        <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:orientation="vertical">

            <com.myproject.control.XSubMenuButton
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                mtx:XSubMenuButtonText="SubMenu1">
            </ccom.myproject.control.XSubMenuButton>
            <com.myproject.control.XSubMenuButton
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                mtx:XSubMenuButtonText="SubMenu2">
            </com.myproject.control.XSubMenuButton>
            <com.myproject.control.XSubMenuButton
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                mtx:XSubMenuButtonText="SubMenu3">
            </com.myproject.control.XSubMenuButton>

        </LinearLayout>
    </LinearLayout>
    <LinearLayout
        android:id="@+id/xExpandableMenuButtonBottom"
        android:background="@drawable/opened_menu_bg_bottom"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
    </LinearLayout>
</LinearLayout>

Answer 1

如果您还没有解决问题，或者其他人也遇到过此问题，这里有一个快速解决方案。每次点击时使父 View 失效(在 onClick 方法中)。无论父级是否可滚动，这都应该有效。

也就是说，您的代码将类似于:

public void onClick(View v) {
    if (!isExpanded) {
        expand(subButtonsLayout);
    } else {
        collapse(subButtonsLayout);
    }
    rootView.invalidate();
}