輕量級自定義NumberPicker

摘要： 前言 一款自定義的WheelPicker控制元件，它的實現基於Android原生NumberPicker，有佔用記憶體小，滾動靈敏的優點。不同於預設風格NumberPicker的是，這款NumberPicker支援使用者通過設定Adapter的方式來實現各種不同的需求，比如迴圈顯示週一至週...

前言

一款自定義的WheelPicker控制元件，它的實現基於Android原生NumberPicker，有佔用記憶體小，滾動靈敏的優點。不同於預設風格NumberPicker的是，這款NumberPicker支援使用者通過設定Adapter的方式來實現各種不同的需求，比如迴圈顯示週一至週日，日期選擇等。

Github Link: ofollow,noindex">GitHub - SuperRabbitD/NumberPicker

控制元件截圖

控制元件說明

WheelPicker的特性：

1.支援自定義字型，文字顏色，文字大小，文字對齊方式。

2.支援設定可見選項個數。

3.支援負數。

4.支援無限滾動，迴圈滾動。

5.支援使用者設定Adapter以滿足不同的需求，如：文字選擇，時間選擇，日期選擇等。

6.支援設定摩擦值以改變滑動速度。

7.提供更好的動畫效果，支援選中項放大，支援仿IOS的OverScrolling等。

8.相容NumberPicker的重要方法和介面。

使用方法

1.Gradle:

compile 'com.super_rabbit.wheel_picker:NumberPicker:1.0.1'

2.自定義屬性

attribute name	attribute description
fadingEdgeEnabled	enable/disable the fading edge attribute.
max	The max index(value) of the picker, can be negative, default is Integer.MAX_VALUE.
min	The minimum index(value) of the picker, can be negative, default is Integer.MIN_VALUE
selectedTextColor	The text color of selected item.
textColor	The text color of unselected item.
textSize	Text size.
typeface	Text font typeface.
wheelItemCount	The visible item count of the picker.
wrapSelectorWheel	true if the picker is rounded wrapped, default is false.
align	The text alignment, can be LEFT, CENTER, RIGHT.

3.介面文件

function name	function description
String getValue(position: Int)	return the current value of the picker.
void setValue(value: String)	set the current value of the picker.
void setWrapSelectorWheel(wrap: Boolean)	Sets whether the selector wheel shown during flinging/scrolling should wrap around the min and max values.
Boolean getWrapSelectorWheel()	Gets whether the selector wheel wraps when reaching the min/max value.
void setWheelItemCount(count: Int)	Set how many visible item show in the picker.
void setSelectedTextColor(colorId: Int)	Set color for current selected item.
void setUnselectedTextColor(colorId: Int)	Set color for unselected item.
scrollTo(position: Int)	Scroll to a specific position, without animation.
smoothScrollTo(position: Int)	Scroll to a specific position, with animation.
scrollToValue(value: String)	Scroll to a specific value, without animation.
smoothScrollToValue(value: String)	Scroll to a specific value, with animation.
setOnValueChangedListener(onValueChangeListener: OnValueChangeListener)	Set listener listening value change.
setAdapter(adapter: WheelAdapter?, indexRangeBasedOnAdapterSize: Boolean = true)	Set user define adapter, @indexRangeBasedOnAdapterSize specific if the picker's min~max range is based on adapter's size

4.程式碼舉例

以下程式碼使用WheelPicker實現了一個簡單的日期選擇控制元件：

// Set rounded wrap enable

numberPicker.setSelectorRoundedWrapPreferred(true)

// Set wheel item count

numberPicker.setWheelItemCount(5)

// Set wheel max index

numberPicker.setMax(1000)

// Set wheel min index

numberPicker.setMax(1000)

// Set selected text color

numberPicker.setSelectedTextColor(R.color.color_4_blue)

// Set unselected text color

numberPicker.setUnselectedTextColor(R.color.color_3_dark_blue)

// Set user defined adapter

numberPicker.setAdapter(WPDayPickerAdapter())

// OnValueChangeListener

val context = this

numberPicker.setOnValueChangeListener(object : OnValueChangeListener{

override fun onValueChange(picker: WheelPicker, oldVal: String, newVal: String) {

val out = String.format("Current: %s", newVal)

Toast.makeText(context, out, Toast.LENGTH_SHORT).show()

}

})

// Adapter sample 

/**

 * Custom wheel picker adapter for implementing a date picker

 */

class WPDayPickerAdapter : WheelAdapter {

//get item value based on item position in wheel

override fun getValue(position: Int): String {

if (position == 0)

return "Today"

if(position == -1)

return "Yesterday"

if (position == 1)

return "Tomorrow"

val curDate = Date(System.currentTimeMillis())

val rightNow = Calendar.getInstance()

rightNow.time = curDate;

rightNow.add(Calendar.DATE, position)

val simpleDateFormat = SimpleDateFormat("MMM d, yyyy")

return simpleDateFormat.format(rightNow.time)

}

//get item position based on item string value

override fun getPosition(vale: String): Int {

return 0

}

//return a string with the approximate longest text width, for supporting WRAP_CONTENT

override fun getTextWithMaximumLength(): String {

return "Mmm 00, 0000"

}

//return the maximum index

override fun getMaxIndex(): Int {

return Integer.MAX_VALUE

}

//return the minimum index

override fun getMinIndex(): Int {

return Integer.MIN_VALUE

}

}

總結

WheelPicker實現基於原生Android NumberPicker, 除了實現NumberPicker的標準方法外，還提供了更多自定義的屬性，專案中如要替換，僅需要將NumberPicker替換成WheelPicker即可。

總之：給個Star吧？

Github Link: GitHub - SuperRabbitD/NumberPicker