自定义view之自定义属性

一、基本使用流程

1. 自定义 CustomAttrsView 类；

2. 编写values/attrs.xml，在其中编写styleable和item等标签元素；

   <?xml version="1.0" encoding="utf-8"?>
   <resources>
       <declare-styleable name="CustomAttrsView">
           <attr name="name" format="string|reference"></attr>
           <attr name="text" format="string|reference"></attr>
           <attr name="android:textSize"></attr>
           <attr name="skinColor" format="color|reference"></attr>
           <attr name="isMVP" format="boolean"></attr>
           <attr name="kobeheight" format="float|reference"></attr>
           <attr name="weight" format="float|reference"></attr>
           <attr name="radius" format="dimension|reference"></attr>
           <attr name="maxPoints" format="integer|reference"></attr>
           <attr name="freeThrowPercent" format="fraction"></attr>
           <attr name="team" format="enum">
               <enum name="lakers" value="0"/>
               <enum name="Sixers" value="1"/>
               <enum name="nets" value="2"/>
               <enum name="rockets" value="3"/>
           </attr>
           <attr name="point" format="flags">
               <flag name="shoot" value="0"/>
               <flag name="freethrow" value="1"/>
               <flag name="dunk" value="2"/>
           </attr>
       </declare-styleable>
   </resources>
   

3. xml中引入自定义view，并使用自定义的属性

   xmlns:tj="http://schemas.android.com/apk/res-auto" 
   
   <com.yellowhat.study.customview.CustomAttrsView
           tj:name="kobe"
           tj:skinColor="#000000"
           tj:isMVP="true"
           tj:kobeheight="203"
           tj:weight="198"
           tj:radius="@dimen/dp_10"
           tj:maxPoints="81"
           tj:freeThrowPercent="8.24%"
           tj:team="lakers"
           tj:text="55"
           android:textSize="20sp"
           tj:point="dunk|shoot|freethrow"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           app:layout_constraintEnd_toEndOf="parent"
           app:layout_constraintStart_toStartOf="parent"
           app:layout_constraintTop_toTopOf="parent" />
   

4. 在CustomAttrsView中通过TypeArray获取各个属性；

   class CustomAttrsView @JvmOverloads constructor(
       context: Context,
       attributeSet: AttributeSet? = null,
       defStyleAttr: Int = 0
   ) : AppCompatTextView(context, attributeSet, defStyleAttr) {
       init {
           val typeArray = context.obtainStyledAttributes(attributeSet, R.styleable.CustomAttrsView)
           val name = typeArray.getString(R.styleable.CustomAttrsView_name)
           val skinColor = typeArray.getColor(R.styleable.CustomAttrsView_skinColor, Color.RED)
           val isMvp = typeArray.getBoolean(R.styleable.CustomAttrsView_isMVP, true)
           val height = typeArray.getFloat(R.styleable.CustomAttrsView_kobeheight, 195.2f)
           val weight = typeArray.getFloat(R.styleable.CustomAttrsView_weight, 100.0f)
           val circleRadius = typeArray.getDimension(R.styleable.CustomAttrsView_radius, 20.0f)
           val maxPoints = typeArray.getInt(R.styleable.CustomAttrsView_maxPoints, 25)
           val freethowPercent =
               typeArray.getFraction(R.styleable.CustomAttrsView_freeThrowPercent, 1, 1, 50f)
           val team = typeArray.getInt(R.styleable.CustomAttrsView_team, 1)
           val point = typeArray.getInt(R.styleable.CustomAttrsView_point, 1)
           val text = typeArray.getString(R.styleable.CustomAttrsView_text)
           val textSize = typeArray.getDimension(R.styleable.CustomAttrsView_android_textSize,22f)
           Log.e(
               "tj24",
               "name = ${name}\n skinColor = ${skinColor}\n isMvp = ${isMvp}\n height = ${height}\n weight = ${weight}\n circleRadius = ${circleRadius}\n maxPoints = ${maxPoints}\n freethowPercent = ${freethowPercent}\n team = ${team}\n point = ${point}\n text = ${text}\n" +
                       " textSize = ${textSize}"
           )
           typeArray.recycle()
       }
   }
   

   log输出如下：

   08-09 14:51:14.694 27403-27403/com.yellowhat.study E/tj24: name = kobe
        skinColor = -16777216
        isMvp = true
        height = 203.0
        weight = 198.0
        circleRadius = 10.0
        maxPoints = 81
        freethowPercent = 0.082399964
        team = 0
        point = 3
        text = 55
        textSize = 20.0
   

二、属性值的类型format

三、注意事项：

• styleable 的 name 建议和自定义view 类名保持一致，不然xml中代码不会自动提示！
• xml中使用自定义属性注意命名空间，如上面 text属性有tj:text 和android:text之分；
• attr name 可以直接使用系统已定义的属性，但不能有format，如上面 textSize 属性；
• enum和 flag 的属性，value只能为int。 enum只可选一个，flag可以位运算多个。
• format可混合使用，如 format="float|reference"