第6章 Android的Drawable

<?xml version = "1.0" encoding = "utf-8"?>
<bitmap
  xmls:android="http://schemas.android.com/apk/res/android"
  android:src="@[package:]drawable/drawable_resource"
  android:antialias=["true"|"false"]//抗锯齿
  android:dither=["true"|"false"]//开启抖动效果
  android:filter=["true"|"false"]//过滤效果
  android:gravity
  android:tileMode /> //平铺模式

<?xml version = "1.0" encoding = "utf-8"?>
<shape
  xmls:android="http://schemas.android.com/apk/res/android"
  android:shape=["rectangle"|"oval"|"line"|"ring"]>
  <corners/> //四个角的角度，只适应矩形shape
  <gradient/> //渐变效果
  <padding/> //包含这个drawable的view的空白
  <size/>  //大小，width&height
  <solid/> //纯色填充
  <stroke/> //shape的描边
</shape>

<?xml version = "1.0" encoding = "utf-8"?>
<layer-list
  xmls:android="http://schemas.android.com/apk/res/android"
  <item
     android:drawable=""
     android:id=""
     android:top=""//drawable相对于view上下左右偏移量
     android:right=""
     android:bottom=""
     android:left=""/>
</layer-list>

TransitionDrawable drawable = (TransitionDrawable) mBtn.getBackground();
drawable.startTransition(5000);

ScaleDrawable drawable = (ScaleDrawable) mBtn.getBackground();
drawable.setLevel(8000);