我遇到了同样的问题,为了解决它,我更进了一步。但唯一的问题是您不能在xml中指定NavStateListDrawable,所以您必须通过代码设置UI元素的背景。然后必须覆盖onStateChange方法,以确保每次更改主要可绘制对象的级别时,您还要更新子级别列表的级别。
构造NavStateListDrawable时,您必须传入要显示的图标的级别。
public class NavStateListDrawable extends StateListDrawable {
private int level;
public NavStateListDrawable(Context context, int level) {
this.level = level;
int stateFocused = android.R.attr.state_focused;
int statePressed = android.R.attr.state_pressed;
int stateSelected = android.R.attr.state_selected;
addState(new int[]{ stateSelected }, context.getResources().getDrawable(R.drawable.nav_btn_pressed));
addState(new int[]{ statePressed }, context.getResources().getDrawable(R.drawable.nav_btn_selected));
addState(new int[]{ stateFocused }, context.getResources().getDrawable(R.drawable.nav_btn_focused));
addState(new int[]{-stateFocused, -statePressed, -stateSelected}, context.getResources().getDrawable(R.drawable.nav_btn_default));
}
@Override
protected boolean onStateChange(int[] stateSet) {
boolean nowstate = super.onStateChange(stateSet);
try{
LayerDrawable defaultDrawable = (LayerDrawable)this.getCurrent();
LevelListDrawable bar2 = (LevelListDrawable)defaultDrawable.findDrawableByLayerId(R.id.nav_icons);
bar2.setLevel(level);
}catch(Exception exception)
{
}
return nowstate;
}
}
对于我拥有的所有不同导航按钮可绘制状态,我有以下内容。
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/top_bar_default" >
</item>
<item android:id="@+id/nav_icons" android:bottom="0dip">
<level-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:maxLevel="0" >
<bitmap
android:src="@drawable/top_bar_icon_back"
android:gravity="center" />
</item>
<item android:maxLevel="1" >
<bitmap
android:src="@drawable/top_bar_icon_nav"
android:gravity="center" />
</item>
<item android:maxLevel="2" >
<bitmap
android:src="@drawable/top_bar_icon_settings"
android:gravity="center" />
</item>
<item android:maxLevel="3" >
<bitmap
android:src="@drawable/top_bar_icon_search"
android:gravity="center" />
</item>
</level-list>
</item>
</layer-list>
我原本想把这个发出来作为一个问题和答案,但是既然你已经问了这个问题,那么这里就是答案。注意,这样可以省去大量的xml文件定义。我从大约50-100个xml定义减少到了大约4个!