Inline definition of non-Bitmap drawables in LayerList or LevelList XML items

Question

The documentation of the XML resource specification of LayerList and LevelList drawables says that the item element will only accept bitmap as child element. On some answers concerning level lists, I see that people are adding shape tags as children to the item tags. I tried out the following and it seems to work nicely.

<?xml version="1.0" encoding="utf-8"?>
<level-list xmlns:android="http://schemas.android.com/apk/res/android">
  <item android:maxLevel="0">
    <shape android:shape="rectangle">
      <solid android:color="#ff0000" />
    </shape>
  </item>
  <item android:maxLevel="1">
    <shape android:shape="oval">
      <solid android:color="#0000ff" />
    </shape>
  </item>
</level-list>

Here is my question. Is this documented anywhere, or should I avoid this kind of construct because it is not supported in all API versions, or is the documentation simply incomplete and the above is perfectly legal?

To clarify, I know that I can specify any sort of drawable by using separate resource files and referring to them using the android:drawable attribute. The question refers to the inline specification of arbitrary drawables within the XML of the layer list or level list.

score 1 · Answer 1 · answered Jan 08 '14 at 17:20

1

It doesn't state that it only accepts Bitmap objects, but that it will accept them. You can use the android:drawable to specify a drawable. Pull your shapes into their own drawable XML definition and reference them in the level-list.

answered Jan 08 '14 at 17:20

Larry Schiefer

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I know that I can specify any kind of drawable using the `android:drawable` attribute. My question refers to the XML specification. Can I specify shapes (or other drawables for that matter) inline inside the item tag. his means that I don't create multiple resources for every level or layer. – mikail sheikh Jan 08 '14 at 17:56
You're right in that the documentation isn't exactly clear, other than it states that any child of will work. – Larry Schiefer Jan 08 '14 at 20:30
No, that's not quite correct. In the documentation of `` it is stated that `` "must be a child of a `` element." This is clearly wrong because `` defines a `StateListDrawable` and `` defines a `LevelListDrawable`. The documentation also states that `` "accepts child `` elements". While this is true, it is incomplete. Apparently it can accept child `` elements as well. I just wanted to know if it is safe for me to do so or if there might be some incompatibilities on some API versions. – mikail sheikh Jan 08 '14 at 20:47

score 0 · Accepted Answer · answered Feb 10 '14 at 14:18

The answer is YES, it is allowed and supported behaviour.

While it is not documented, non-bitmap tags are used in the official Android XML resources. For example the source of progress_large_holo.xml contains the following.

<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <rotate
             android:drawable="@drawable/spinner_76_outer_holo"
             android:pivotX="50%"
             android:pivotY="50%"
             android:fromDegrees="0"
             android:toDegrees="1080" />
    </item>
    <item>
        <rotate
             android:drawable="@drawable/spinner_76_inner_holo"
             android:pivotX="50%"
             android:pivotY="50%"
             android:fromDegrees="720"
             android:toDegrees="0" />
    </item>
</layer-list>

Other sources also reveal that any XML that is accepted as a drawable resource can be placed inside the item tags.

Inline definition of non-Bitmap drawables in LayerList or LevelList XML items

2 Answers2