Kotlin自定义实现支付密码数字键盘的方法实例

你能学到什么

• kotlin的使用, 扩展特性的写法等
• 自定义ViewGroup的一些基础知识
• xml属性的编写和读取

因为每个按键都考虑到需要支持背景设置等其他个性设置和Touch手势的处理, 所以我决定采用 每个按键 对应一个View的思路实现. 否则可以使用Canvas.drawText实现

这样可以提高扩展性和可自定义性

1.根据效果图先定义按键

//首先定义需要的那些按键
//顺序打乱,展示的时候也就是乱序的,可以更安全.
//特殊按键-> "":表示空白占位按键; "-1":表示回退键, 也就是删除.
var keys = arrayOf("1", "2", "3", "4", "5", "6", "7", "8", "9", "", "0", "-1")

更新对应的按键, 创建对应的view

 keys.forEach {
  val keyView: View = when (it) {
   "-1" -> {
    //删除
    imageView(R.drawable.keyboard_del, R.drawable.keyboard_del_press).apply {
     background = null
     setBackgroundColor(Color.parseColor("#E2E7ED"))
    }
   }
   "" -> {
    //占位View
    View(context).apply {
     setBackgroundColor(Color.parseColor("#E2E7ED"))
    }
   }
   else -> {
    createKeyView(it)
   }
  }

  keyView.tag = it //通过tag, 保存按键对应的值
  addView(keyView)
 }

private fun createKeyView(key: String): View {
  return if (useImageKey) {
   val keyRes = when (key) {
    "1" -> R.drawable.keyboard_1
    "2" -> R.drawable.keyboard_2
    "3" -> R.drawable.keyboard_3
    "4" -> R.drawable.keyboard_4
    "5" -> R.drawable.keyboard_5
    "6" -> R.drawable.keyboard_6
    "7" -> R.drawable.keyboard_7
    "8" -> R.drawable.keyboard_8
    "9" -> R.drawable.keyboard_9
    else -> R.drawable.keyboard_0
   }
   imageView(keyRes)
  } else {
   textView(key)
  }
 }

 private fun imageView(res: Int, pressRes: Int = -1): ImageView {
  return ImageView(context).apply {

   if (pressRes == -1) {
    setImageResource(res)
   } else {
    setImageResource(res)
    //setImageDrawable(ResUtil.selector(getDrawable(res), getDrawable(pressRes)))
   }

   scaleType = ImageView.ScaleType.CENTER

   keyViewBGDrawable?.let {
    background = it.constantState.newDrawable()
   }

   setOnClickListener(this@KeyboardLayout)
  }
 }

 private fun textView(text: String): TextView {
  return TextView(context).apply {
   gravity = Gravity.CENTER
   this.text = text
   setTextSize(TypedValue.COMPLEX_UNIT_PX, keyTextSize)

   keyViewBGDrawable?.let {
    background = it.constantState.newDrawable()
   }
   setTextColor(Color.BLACK)

   setOnClickListener(this@KeyboardLayout)
  }
 }

2.按键元素创建好之后, 开始自定义ViewGroup的标准操作

onMeasure:测量每个按键的宽度和高度

 override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
  //super.onMeasure(widthMeasureSpec, heightMeasureSpec)
  var widthSize = MeasureSpec.getSize(widthMeasureSpec)
  val widthMode = MeasureSpec.getMode(widthMeasureSpec)
  var heightSize = MeasureSpec.getSize(heightMeasureSpec)
  val heightMode = MeasureSpec.getMode(heightMeasureSpec)

  if (widthMode != MeasureSpec.EXACTLY) {
   widthSize = resources.displayMetrics.widthPixels
  }

  if (heightMode != MeasureSpec.EXACTLY) {
   heightSize = (4 * keyViewHeight + 3 * vSpace).toInt()
  }

  childWidth = ((widthSize - 2 * hSpace - paddingLeft - paddingRight) / 3).toInt()
  childHeight = ((heightSize - 3 * vSpace - paddingTop - paddingBottom) / 4).toInt()
  childs { _, view ->
   view.measure(exactlyMeasure(childWidth), exactlyMeasure(childHeight))
  }
  setMeasuredDimension(widthSize, heightSize)
 }

onLayout:决定按键在ViewGroup中的坐标位置

override fun onLayout(changed: Boolean, l: Int, t: Int, r: Int, b: Int) {
 //一行一行布局, 共4行
 for (line in 0..3) {

  var top: Int = (paddingTop + line * (childHeight + vSpace)).toInt()

  //3列
  for (i in 0..2) {
   var left: Int = (paddingLeft + i * (childWidth + hSpace)).toInt()

   getChildAt(line * 3 + i).layout(left, top, left + childWidth, top + childHeight)
  }
 }
}

3:事件监听和回调

 override fun onClick(v: View?) {
  if (onKeyboardInputListener == null) {
   return
  }

  v?.let { view ->
   val tag = view.tag
   if (tag is String) {
    val isDel = "-1" == tag
    onKeyboardInputListener?.onKeyboardInput(tag, isDel)
   }
  }
 }

4:xml中的属性声明

需要在 values 文件夹中创建一个任意文件名的xml文件

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <declare-styleable name="KeyboardLayout">
  <attr name="r_key_height" format="dimension"/>
  <attr name="r_key_width" format="dimension"/>
  <attr name="r_key_text_size" format="dimension"/>
  <attr name="r_key_background" format="reference"/>
  <attr name="r_background" format="reference"/>
  <attr name="r_use_image_key" format="boolean"/>
 </declare-styleable>
</resources>

declare-styleable 都是标准写法, name对应的就是自定义view的类型, 都是标准写法, 不同的format对应不同的get方法. 熟悉了就很容易使用.

5:xml中的属性读取

 init {
  val typedArray = context.obtainStyledAttributes(attributeSet, R.styleable.KeyboardLayout) //注意1:
  keyViewHeight = typedArray.getDimensionPixelOffset(R.styleable.KeyboardLayout_r_key_height, keyViewHeight)
  //typedArray.getDimensionPixelOffset(R.styleable.KeyboardLayout_r_key_width, keyViewHeight)
  keyTextSize = typedArray.getDimension(R.styleable.KeyboardLayout_r_key_text_size, keyTextSize)
  useImageKey = typedArray.getBoolean(R.styleable.KeyboardLayout_r_use_image_key, useImageKey)

  keyViewBGDrawable = typedArray.getDrawable(R.styleable.KeyboardLayout_r_key_background)

  if (keyViewBGDrawable == null) {
   keyViewBGDrawable = getDrawable(R.drawable.base_white_bg_selector)
  }
  mBackgroundDrawable = typedArray.getDrawable(R.styleable.KeyboardLayout_r_background)
  if (mBackgroundDrawable == null) {
   mBackgroundDrawable = ColorDrawable(getColor(R.color.base_chat_bg_color))
  }

  setWillNotDraw(false)
  typedArray.recycle() //注意2
 }

注意1,2: 都是必备的写法, 中间部分才是对应的属性读取操作.

源码地址 https://github.com/angcyo/KeyboardLayout （本地下载）

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