[app] layer-list 加载多个图层

1、xml 资源实现

<!-- /drawable/layer.xml -->
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">                 
    <item android:drawable="@drawable/icon0">
    <item android:drawable="@drawable/icon1">
    <item android:drawable="@drawable/icon2">
</layer-list>

使用

/// 使用图层资源
ImageView.setImageDrawable(getResources().getDrawable(R.drawable.layer));

2.代码实现

Resources res = getResources();
/// 构建 Drawable 数组
Drawable[] layers = new Drawable[3];
layers[0] = res.getDrawable(R.drawable.icon0);
layers[1] = res.getDrawable(R.drawable.icon1);
layers[2] = res.getDrawable(R.drawable.icon2);
/// 将 Drawable 数组转为 LayerDrawable 图层资源
LayerDrawable layerDrawable = new LayerDrawable(layers);
/// 使用图层资源
ImageView.setImageDrawable(layerDrawable);