Drawable资源之LevelListDrawable资源

A Drawable that manages a number of alternate Drawables, each assigned a maximum numerical value. Setting the level value of the drawable with setLevel() loads the drawable resource in the level list that has aandroid:maxLevel value greater than or equal to the value passed to the method.

file location:

res/drawable/filename.xml
The filename is used as the resource ID.

compiled resource datatype:

Resource pointer to a   LevelListDrawable.

resource reference:

In Java:   R.drawable.filename
In XML:   @[package:]drawable/filename

syntax:

<?xml version="1.0" encoding="utf-8"?>
<level-list
    xmlns:android="http://schemas.android.com/apk/res/android" >
    <item
        android:drawable="@drawable/drawable_resource"
        android:maxLevel="integer"
        android:minLevel="integer" />
</level-list>

 

elements:

<level-list>

This must be the root element. Contains one or more   <item>  elements.

attributes:

xmlns:android

String.   Required.  Defines the XML namespace, which must be "http://schemas.android.com/apk/res/android".

<item>

Defines a drawable to use at a certain level.

attributes:

android:drawable

Drawable resource.   Required. Reference to a drawable resource to be inset.

android:maxLevel

Integer. The maximum level allowed for this item.

android:minLevel

Integer. The minimum level allowed for this item.

example:

 

<?xml version="1.0" encoding="utf-8"?>
<level-list xmlns:android="http://schemas.android.com/apk/res/android" >
    <item
        android:drawable="@drawable/status_off"
        android:maxLevel="0" />
    <item
        android:drawable="@drawable/status_on"
        android:maxLevel="1" />
</level-list>

 

Once this is applied to a View, the level can be changed with setLevel() or setImageLevel().