Android自定义View

时间:2022-09-29 东土也人气:0

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
   }
}

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