Android如何通过组合的方式自定义View

前言：

自定义View可以分为两种方式：

• 第一种通过继承ViewGroup，内部通过addView的方式将其他的View组合到一起。
• 第二种则是通过继承View，重启View的onMeasure，onLayout，onDraw方法来绘制不规则图形，如折线图等。

本文介绍的是第一种方式通过组合的方式去实现自定义View。

实现自定义View首先要自定义属性。对于自定义属性，第一步是在项目res/values文件夹中新建attrs.xml文件，在文件中设置自定义属性的名称和类型，

代码如下：

<resources>
    <declare-styleable name="InputItemLayout">
        <attr name="hint" format="string"></attr>
        <attr name="title" format="string"/>
        <attr name="inputType" format="enum">
            <enum name="text" value="0"/>
            <enum name="password" value="1"/>
            <enum name="number" value="2"/>
        </attr>
        <attr name="inputTextAppearance" format="reference"/>
        <attr name="titleTextAppearance" format="reference"/>
        <attr name="topLineAppearance" format="reference"/>
        <attr name="bottomLineAppearance" format="reference"/>
    </declare-styleable>
    <declare-styleable name="inputTextAppearance">
        <attr name="hintColor" format="color" />
        <attr name="inputColor" format="color" />
        <attr name="textSize" format="dimension" />
        <attr name="maxInputLength" format="integer" />
    </declare-styleable>
    <declare-styleable name="titleTextAppearance">
        <attr name="titleColor" format="color" />
        <attr name="titleSize" format="dimension" />
        <attr name="minWidth" format="dimension" />
    </declare-styleable>

    <declare-styleable name="lineAppearance">
        <attr name="color" format="color" />
        <attr name="height" format="dimension" />
        <attr name="leftMargin" format="dimension" />
        <attr name="rightMargin" format="dimension" />
        <attr name="enable" format="boolean" />
    </declare-styleable>
</resources>

自定义属性都需要包裹在declare-styleable标签中，name属性标志这个属性集合的名字，其中的attr标志属性。对于自定义属性的类型，主要的有以下几种

string字符串类型 reference引用类型，一般是指向另外的一个资源属性 color颜色代码 dimension尺寸 float浮点型 boolean布尔型 integer整型 enum枚举型

当你定义完上面的文件，接下来我们需要在自定义View中解析它们，从而获得用户传递进来的属性。 属性的解析可以使用以下代码完成

val array = context.obtainStyledAttributes(attributeSet, R.styleable.InputItemLayout)
val title = array.getString(R.styleable.InputItemLayout_title)
val titleResId = array.getResourceId(R.styleable.InputItemLayout_titleTextAppearance, 0)

上面的代码中，第一句是通过obtainStyledAttributes解析上面XML文件中属性名为InputItemLayout的属性内容，并返回TypedArray，后续该命名空间中的所有属性都可以通过TypedArray.getXX()来获得XX是属性类型。

但是引用类型除外，因为引用类型中还包含了其他属性，所以需要如下代码去提取属性。

val array1 = context.obtainStyledAttributes(attributeSet, R.styleable.InputItemLayout)
val titleResId = array1.getResourceId(R.styleable.InputItemLayout_titleTextAppearance, 0)
val array = context.obtainStyledAttributes(titleResId, R.styleable.titleTextAppearance)
val titleColor = array.getColor(
    R.styleable.titleTextAppearance_titleColor,
    resources.getColor(R.color.color_565)
)

如上代码，我们先获取在InputItemLayout属性中titleTextAppearance的属性，这时候发现titleTextAppearance是一个引用类型的属性，在使用 context.obtainStyledAttributes(titleResId, R.styleable.titleTextAppearance)获取titleTextAppearance中的属性值，第一个参数titleResId是titleTextAppearance的资源ID。 最终我们获取了所有的属性，这时候就可以开始自定义你的View了。

当我们最终完成了所有的代码，怎么在布局文件中使用呢。对于普通的属性，如String Int等就和平常一样，但是对于引用类型，我们需要在style.xml文件中定义资源文件

<com.slowtd.tcommon.InputItemLayout
   android:layout_marginTop="10dp"
   android:layout_width="match_parent"
   android:layout_height="55dp"
   app:hint="请输入密码"
   app:title="密码"
   app:inputType="text"
   app:titleTextAppearance="@style/titleTextAppearance"
   app:inputTextAppearance="@style/inputTextAppearance_limitLength"
   app:topLineAppearance="@style/lineAppearance"
   app:bottomLineAppearance="@style/lineAppearance"
   />

<style name="inputTextAppearance">
   <item name="hintColor">@color/color_C1B</item>
   <item name="inputColor">@color/color_565</item>
   <item name="textSize">15sp</item>
</style>

<style name="inputTextAppearance_limitLength" parent="inputTextAppearance">
   <item name="maxInputLength">4</item>
</style>
<style name="titleTextAppearance">
   <item name="titleColor">@color/color_565</item>
   <item name="titleSize">15sp</item>
   <item name="minWidth">100dp</item>
</style>
<style name="lineAppearance">
   <item name="color">@color/black</item>
   <item name="height">2dp</item>
   <item name="leftMargin">0dp</item>
   <item name="rightMargin">0dp</item>
   <item name="enable">true</item>
</style>

下面的代码是一个简单的自定义输入框代码，供大家参考，配合上面的XML属性资源就可以使用了。

class InputItemLayout : LinearLayout {
   private lateinit var titleView: TextView
   private lateinit var editText: EditText
   private var bottomLine: Line
   private var topLine: Line
   private var topPaint = Paint(Paint.ANTI_ALIAS_FLAG)
   private var bottomPaint = Paint(Paint.ANTI_ALIAS_FLAG)

   constructor(context: Context) : this(context, null)
   constructor(context: Context, attributeSet: AttributeSet?) : this(context, attributeSet, 0)
   constructor(context: Context, attributeSet: AttributeSet?, defStyle: Int) : super(
       context,
       attributeSet,
       defStyle
   ) {
       dividerDrawable = ColorDrawable()
       showDividers = SHOW_DIVIDER_BEGINNING

       //去加载 去读取 自定义sytle属性
       orientation = HORIZONTAL
       val array = context.obtainStyledAttributes(attributeSet, R.styleable.InputItemLayout)

       //解析title 属性
       val title = array.getString(R.styleable.InputItemLayout_title)
       val titleResId = array.getResourceId(R.styleable.InputItemLayout_titleTextAppearance, 0)
       parseTitleStyle(title, titleResId)

       //解析右侧的输入框属性
       val hint = array.getString(R.styleable.InputItemLayout_hint)
       val inputResId = array.getResourceId(R.styleable.InputItemLayout_inputTextAppearance, 0)
       val inputType = array.getInteger(R.styleable.InputItemLayout_inputType, 0)
       parseInputStyle(hint, inputResId, inputType)
       //上下分割线属性
       val topResId = array.getResourceId(R.styleable.InputItemLayout_topLineAppearance, 0)
       val bottomResId = array.getResourceId(R.styleable.InputItemLayout_bottomLineAppearance, 0)
       topLine = parseLineStyle(topResId)
       bottomLine = parseLineStyle(bottomResId)

       if (topLine.enable) {
           topPaint.color = topLine.color
           topPaint.style = Paint.Style.FILL_AND_STROKE
           topPaint.strokeWidth = topLine.height
       }
       if (bottomLine.enable) {
           bottomPaint.color = bottomLine.color
           bottomPaint.style = Paint.Style.FILL_AND_STROKE
           bottomPaint.strokeWidth = bottomLine.height
       }
       array.recycle()
   }
   @SuppressLint("CustomViewStyleable")
   private fun parseLineStyle(resId: Int): Line {
       val line = Line()
       val array = context.obtainStyledAttributes(resId, R.styleable.lineAppearance)
       line.color =
           array.getColor(
               R.styleable.lineAppearance_color,
               ContextCompat.getColor(context, R.color.color_d1d2)
           )
       line.height = array.getDimensionPixelOffset(R.styleable.lineAppearance_height, 0).toFloat()
       line.leftMargin =
           array.getDimensionPixelOffset(R.styleable.lineAppearance_leftMargin, 0).toFloat()
       line.rightMargin =
           array.getDimensionPixelOffset(R.styleable.lineAppearance_rightMargin, 0).toFloat()
       line.enable = array.getBoolean(R.styleable.lineAppearance_enable, false)

       array.recycle()
       return line
   }
   inner class Line {
       var color = 0
       var height = 0f
       var leftMargin = 0f
       var rightMargin = 0f;
       var enable: Boolean = false
   }
   @SuppressLint("CustomViewStyleable")
   private fun parseInputStyle(hint: String?, resId: Int, inputType: Int) {

       val array = context.obtainStyledAttributes(resId, R.styleable.inputTextAppearance)

       val hintColor = array.getColor(
           R.styleable.inputTextAppearance_hintColor,
           ContextCompat.getColor(context, R.color.color_d1d2)
       )
       val inputColor = array.getColor(
           R.styleable.inputTextAppearance_inputColor,
           ContextCompat.getColor(context, R.color.color_565)
       )
       //px
       val textSize = array.getDimensionPixelSize(
           R.styleable.inputTextAppearance_textSize,
           applyUnit(TypedValue.COMPLEX_UNIT_SP, 15f)
       )
       val maxInputLength = array.getInteger(R.styleable.inputTextAppearance_maxInputLength, 0)

       editText = EditText(context)
       if (maxInputLength > 0) {
           editText.filters = arrayOf(InputFilter.LengthFilter(maxInputLength))//最多可输入的字符数
       }
       editText.setPadding(0, 0, 0, 0)
       val params = LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT)
       params.weight = 1f
       editText.layoutParams = params
       editText.hint = hint
       editText.setTextColor(inputColor)
       editText.setHintTextColor(hintColor)
       editText.gravity = LEFT or (CENTER)
       editText.setBackgroundColor(Color.TRANSPARENT)
       editText.setTextSize(TypedValue.COMPLEX_UNIT_PX, textSize.toFloat())
       /**
        * <enum name="text" value="0"></enum>
        * <enum name="password" value="1"></enum>
        * <enum name="number" value="2"></enum>
        */
       if (inputType == 0) {
           editText.inputType = InputType.TYPE_CLASS_TEXT
       } else if (inputType == 1) {
           editText.inputType =
               InputType.TYPE_TEXT_VARIATION_PASSWORD or (InputType.TYPE_CLASS_TEXT)
       } else if (inputType == 2) {
           editText.inputType = InputType.TYPE_CLASS_NUMBER
       }
       addView(editText)
       array.recycle()
   }
   @SuppressLint("CustomViewStyleable")
   private fun parseTitleStyle(title: String?, resId: Int) {
       val array = context.obtainStyledAttributes(resId, R.styleable.titleTextAppearance)
       val titleColor = array.getColor(
           R.styleable.titleTextAppearance_titleColor,
           resources.getColor(R.color.color_565)
       )
       //px
       val titleSize = array.getDimensionPixelSize(
           R.styleable.titleTextAppearance_titleSize,
           applyUnit(TypedValue.COMPLEX_UNIT_SP, 15f)
       )
       val minWidth = array.getDimensionPixelOffset(R.styleable.titleTextAppearance_minWidth, 0)

       titleView = TextView(context)
       titleView.setTextSize(TypedValue.COMPLEX_UNIT_PX, titleSize.toFloat())  //sp---当做sp在转换一次
       titleView.setTextColor(titleColor)
       titleView.layoutParams = LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT)
       titleView.minWidth = minWidth
       titleView.gravity = LEFT or (CENTER)
       titleView.text = title
       addView(titleView)
       array.recycle()
   }
   override fun onDraw(canvas: Canvas?) {
       super.onDraw(canvas)

       //巨坑
       if (topLine.enable) {
           canvas!!.drawLine(
               topLine.leftMargin,
               0f,
               measuredWidth - topLine.rightMargin,
               0f,
               topPaint
           )
       }

       if (bottomLine.enable) {
           canvas!!.drawLine(
               bottomLine.leftMargin,
               height - bottomLine.height,
               measuredWidth - bottomLine.rightMargin,
               height - bottomLine.height,
               bottomPaint
           )
       }
   }
   private fun applyUnit(applyUnit: Int, value: Float): Int {
       return TypedValue.applyDimension(applyUnit, value, resources.displayMetrics).toInt()
   }
   fun getTitleView(): TextView {
       return titleView
   }
   fun getEditText(): EditText {
       return editText
   }
}

到此这篇关于Android如何通过组合的方式自定义View的文章就介绍到这了,更多相关Android自定义View内容请搜索我们以前的文章或继续浏览下面的相关文章希望大家以后多多支持我们！