LevelListDrawablepublic class LevelListDrawable extends DrawableContainer | A resource that manages a number of alternate Drawables, each assigned a maximum numerical value.
Setting the level value of the object with {@link #setLevel(int)} will load the image with the next
greater or equal value assigned to its max attribute.
A good example use of
a LevelListDrawable would be a battery level indicator icon, with different images to indicate the current
battery level.
It can be defined in an XML file with the <level-list> element.
Each Drawable level is defined in a nested <item>. For example:
<level-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:maxLevel="0" android:drawable="@drawable/ic_wifi_signal_1" />
<item android:maxLevel="1" android:drawable="@drawable/ic_wifi_signal_2" />
<item android:maxLevel="2" android:drawable="@drawable/ic_wifi_signal_3" />
<item android:maxLevel="3" android:drawable="@drawable/ic_wifi_signal_4" />
</level-list>
With this XML saved into the res/drawable/ folder of the project, it can be referenced as
the drawable for an {@link android.widget.ImageView}. The default image is the first in the list.
It can then be changed to one of the other levels with
{@link android.widget.ImageView#setImageLevel(int)}. |
| Fields Summary |
|---|
| private final LevelListState | mLevelListState | | private boolean | mMutated |
| Constructors Summary |
|---|
public LevelListDrawable()
this(null);
| private LevelListDrawable(LevelListState state)
LevelListState as = new LevelListState(state, this);
mLevelListState = as;
setConstantState(as);
onLevelChange(getLevel());
|
| Methods Summary |
|---|
| public void | addLevel(int low, int high, Drawable drawable)
if (drawable != null) {
mLevelListState.addLevel(low, high, drawable);
// in case the new state matches our current state...
onLevelChange(getLevel());
}
| | public void | inflate(android.content.res.Resources r, org.xmlpull.v1.XmlPullParser parser, android.util.AttributeSet attrs)
super.inflate(r, parser, attrs);
int type;
int low = 0;
final int innerDepth = parser.getDepth() + 1;
int depth;
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
&& ((depth = parser.getDepth()) >= innerDepth
|| type != XmlPullParser.END_TAG)) {
if (type != XmlPullParser.START_TAG) {
continue;
}
if (depth > innerDepth || !parser.getName().equals("item")) {
continue;
}
TypedArray a = r.obtainAttributes(attrs,
com.android.internal.R.styleable.LevelListDrawableItem);
low = a.getInt(
com.android.internal.R.styleable.LevelListDrawableItem_minLevel, 0);
int high = a.getInt(
com.android.internal.R.styleable.LevelListDrawableItem_maxLevel, 0);
int drawableRes = a.getResourceId(
com.android.internal.R.styleable.LevelListDrawableItem_drawable, 0);
a.recycle();
if (high < 0) {
throw new XmlPullParserException(parser.getPositionDescription()
+ ": <item> tag requires a 'maxLevel' attribute");
}
Drawable dr;
if (drawableRes != 0) {
dr = r.getDrawable(drawableRes);
} else {
while ((type = parser.next()) == XmlPullParser.TEXT) {
}
if (type != XmlPullParser.START_TAG) {
throw new XmlPullParserException(
parser.getPositionDescription()
+ ": <item> tag requires a 'drawable' attribute or "
+ "child tag defining a drawable");
}
dr = Drawable.createFromXmlInner(r, parser, attrs);
}
mLevelListState.addLevel(low, high, dr);
}
onLevelChange(getLevel());
| | public Drawable | mutate()
if (!mMutated && super.mutate() == this) {
mLevelListState.mLows = mLevelListState.mLows.clone();
mLevelListState.mHighs = mLevelListState.mHighs.clone();
mMutated = true;
}
return this;
| | protected boolean | onLevelChange(int level)
int idx = mLevelListState.indexOfLevel(level);
if (selectDrawable(idx)) {
return true;
}
return super.onLevelChange(level);
|
|
