6.4 Android Framework - StateListDrawable

对应xml中selector标签, 每个Drawable对应一个View的状态, 系统根据View的状态选择不同的Drawable.

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android"
android:constantSize=["true" | "false"]
android:dither=["true" | "false"]
android:variablePadding=["true" | "false"] >
<item
android:drawable="@[package:]drawable/drawable_res"
android:state_pressed=["true" | "false"]
android:state_focused=["true" | "false"]
android:state_hovered=["true" | "false"]
android:state_selected=["true" | "false"]
android:state_checkable=["true" | "false"]
android:state_checked=["true" | "false"]
android:state_enabled=["true" | "false"]
android:state_activated=["true" | "false"]
android:state_window_focused=["true" | "false"] />
</selector>

android:constantSize

固有大小是否随着其状态的改变而改变, 默认值为false

android:dither

是否开启防抖动效果

android:variablePadding

padding是否随着其状态改变而改变, 默认值为false, 不建议开启

一般情况下将默认的item放在最后一条并且不附带任何状态, 作为默认item