layout_gravity上的动画

Question

在Android中,是否可以应用动画layout_gravity？例如,假设我想要从右到左改变layout_gravitya View(例如Button)

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent" android:layout_height="match_parent">
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="New Button"
        android:id="@+id/button"
        android:layout_gravity="right|top" />
</FrameLayout>

在上面的布局文件中,我希望通过动画将布局重力从运动时right|top更改left|top为运行时,是否可以？谢谢

Answer 1

您可以在父ViewGroup上使用LayoutTransition使其对子视图的更改进行动画处理,例如布局更改.在下面的示例中,我将一个浮动动作按钮从屏幕右下角设置为右上角,同时也旋转它(所以'+'图标变成'x'图标).

在包含的布局上将animateLayoutChanges设置为true:

<FrameLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/pnlFabContainer"
    android:animateLayoutChanges="true"
    android:clipChildren="false">

    <ExpandableListView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@android:color/white"
        android:id="@+id/lstWhatever"
        android:divider="@color/DividerDarkGrey"
        android:dividerHeight="1dp"
        android:choiceMode="singleChoice"
        android:groupIndicator="@null"
        android:padding="20dp"/>

    <com.melnykov.fab.FloatingActionButton
        android:id="@+id/fabMultiSelect"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="24dp"
        android:src="@drawable/button_plus"
        android:scaleType="center"
        fab:fab_type="normal"
        fab:fab_colorNormal="@color/FloatingActionButton"
        fab:fab_colorPressed="@color/FloatingActionButtonPressed"
        fab:fab_colorRipple="@color/FloatingActionButtonRipple" />

</FrameLayout>

启用容器上的"更改"转换:

FrameLayout pnlFabContainer = (FrameLayout)view.findViewById(R.id.pnlFabContainer);
LayoutTransition transition = pnlFabContainer.getLayoutTransition();
transition.enableTransitionType(LayoutTransition.CHANGING);

animateFabButton(fab);

然后以编程方式更改布局重力 - 我也在同时进行旋转动画:

protected void animateFabButton(FloatingActionButton fab) {
    if (fab.isSelected()) {
        FrameLayout.LayoutParams layoutParams = (FrameLayout.LayoutParams)fab.getLayoutParams();
        layoutParams.gravity = Gravity.TOP | Gravity.END;
        layoutParams.topMargin = -(fab.getMeasuredHeight() / 2);
        fab.setLayoutParams(layoutParams);

        Animation rotate = new RotateAnimation(0, 45, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
        rotate.setFillBefore(true);
        rotate.setFillAfter(true);
        rotate.setFillEnabled(true);
        rotate.setDuration(750);
        rotate.setRepeatCount(0);
        rotate.setInterpolator(new LinearInterpolator());
        fab.startAnimation(rotate);
    }
    else {
        FrameLayout.LayoutParams layoutParams = (FrameLayout.LayoutParams)fab.getLayoutParams();
        layoutParams.gravity = Gravity.BOTTOM | Gravity.END;
        layoutParams.topMargin = layoutParams.bottomMargin;
        fab.setLayoutParams(layoutParams);

        Animation rotate = new RotateAnimation(45, 0, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
        rotate.setFillBefore(true);
        rotate.setFillAfter(true);
        rotate.setFillEnabled(true);
        rotate.setDuration(750);
        rotate.setRepeatCount(0);
        rotate.setInterpolator(new LinearInterpolator());
        fab.startAnimation(rotate);
    }
}

Answer 2

使用layout_gravity 属性是不可能的。您可以借助永久运行的平移动画来实现效果。

Animation animation = new TranslateAnimation(0, 500,0, 0);
animation.setDuration(1000);
animation.setFillAfter(true);
myImage.startAnimation(animation);

此代码只会将 x 轴上的位置更改为 +500