概述
今天再写一个之前很想尝试的开关按钮，大概的效果是这样的。
运行效果
custom_switch.gif
开关组成
-
- 带圆弧的矩形背景
-
- 中间的圆形开关按钮
动画效果
选中时会由白色慢慢变成绿色，然后中间的圆形按钮阴影逐渐向左移，且整个圆形按钮也在不断往右移，切换未选中状态时则相反，那么接下来我们开始coding~
参数定义
// 初始化画笔
var paint = Paint()
// 定义绘制背景的路径
var path = Path()
// 定义动画
private lateinit var animator : ValueAnimator
init {
paint.isAntiAlias = true
setLayerType(LAYER_TYPE_SOFTWARE,null)
}
// 控件的宽
var w = 0f
// 控件的高
var h = 0f
// 圆形按钮的半径
var radius = 0f
// 圆形按钮的中心的x坐标
var centerX = 0f
// 圆形按钮中心的y坐标
var centerY = 0f
// 底层的颜色背景
var color = Color.rgb(255,255,255)
// 当前状态的圆形按钮的中心的x坐标
var currentCenterX = 0f
// 动画执行时间
var animatorDuration = 500L
// 定义的未选中时的阴影偏移量
var shadowOffSet = 10f
// 绘制的当前状态的阴影偏移量
var currentShadow = 10f
绘制背景
我们在这里实现渐变是在底层给了一个白色的背景，然后再绘制一层绿色背景，并不断修改绿色背景的透明度来实现颜色渐变的过程这样实现并不是最优解有尝试过渐变但效果不佳，可能是没有正确运用吧~改天再琢磨琢磨
- 1.初始化路径
大概流程就是我们从左边第一个直线的左边开始绘制，到了右上的直线末端然后绘制一个半圆，就这样最后绘制到出发点。
这里要注意arcTo函数不要打程addArc函数了~不然画出来结果不对的
private fun initPath(){
path.moveTo(radius,centerY-radius)
path.lineTo(radius*3,centerY-radius)
var rightRect = RectF()
rightRect.left = radius*2
rightRect.top = centerY-radius
rightRect.right = radius*4
rightRect.bottom = centerY+radius
path.arcTo(rightRect,-90f,180f)
path.lineTo(radius,centerY+radius)
var leftRect = RectF()
leftRect.left = 0f
leftRect.top = centerY-radius
leftRect.right = radius*2
leftRect.bottom = centerY+radius
path.arcTo(leftRect,90f,180f)
}
- 2.绘制背景
很简单，绘制path，给两个背景，一个是底层的白色，第二个是会变化透明度的绿色
private fun drawBg(canvas: Canvas){
paint.style = Paint.Style.FILL
paint.setShadowLayer(5f,2f,2f,Color.BLACK)
paint.color = Color.WHITE
canvas.drawPath(path,paint)
paint.color = this.color
canvas.drawPath(path,paint)
}
绘制圆形按钮
很简单哦，就是绘制一个带阴影的圆
private fun drawSwitch(canvas: Canvas){
paint.shader = null
paint.color = Color.WHITE
paint.style = Paint.Style.FILL
paint.strokeWidth = 5f
paint.setShadowLayer(10f,currentShadow,shadowOffSet,Color.parseColor("#DDA69E9E"))
canvas.drawCircle(centerX,centerY,radius/10*9,paint)
}
初始化动画
动画里主要会发生变化的就是中心点半径，绿色的背景的颜色值变化，以及阴影在x轴上的偏移量的变化。
private fun initAnimator(){
animator = ValueAnimator.ofFloat(0f,100f)
animator.duration = animatorDuration
animator.interpolator = LinearInterpolator()
animator.addUpdateListener { valueAnimator ->
var currentValue = valueAnimator.animatedValue as Float
Log.d("animator","currentValue $currentValue")
if (isChecked){
centerX = (3*radius-currentCenterX)*(currentValue/100f)+currentCenterX
color = Color.argb((currentValue/100f*255).toInt(),0,255,0)
currentShadow = (shadowOffSet-20*((currentValue/100f)))
}else{
centerX = currentCenterX - (currentCenterX-radius)*(currentValue/100f)
color = Color.argb((255-currentValue/100f*255).toInt(),0,255,0)
currentShadow = 20*((currentValue/100f))-shadowOffSet
}
postInvalidate()
}
animator.addListener(object : Animator.AnimatorListener{
override fun onAnimationStart(p0: Animator?) {
Log.d("animator","onAnimationStart")
}
override fun onAnimationEnd(p0: Animator?) {
currentCenterX = centerX
Log.d("animator","onAnimationEnd")
}
override fun onAnimationCancel(p0: Animator?) {
Log.d("animator","onAnimationCancel")
}
override fun onAnimationRepeat(p0: Animator?) {
Log.d("animator","onAnimationRepeat")
}
})
}
完整代码
package com.tx.txcustomview.view
import android.animation.Animator
import android.animation.ValueAnimator
import android.content.Context
import android.graphics.*
import android.util.AttributeSet
import android.util.Log
import android.view.MotionEvent
import android.view.animation.LinearInterpolator
/**
* create by xu.tian
* @date 2021/9/14
*/
class CustomSwitch(context: Context?, attrs: AttributeSet?) : androidx.appcompat.widget.AppCompatCheckBox(
context!!, attrs) {
// 初始化画笔
var paint = Paint()
// 定义绘制背景的路径
var path = Path()
// 定义动画
private lateinit var animator : ValueAnimator
init {
paint.isAntiAlias = true
setLayerType(LAYER_TYPE_SOFTWARE,null)
}
// 控件的宽
var w = 0f
// 控件的高
var h = 0f
// 圆形按钮的半径
var radius = 0f
// 圆形按钮的中心的x坐标
var centerX = 0f
// 圆形按钮中心的y坐标
var centerY = 0f
// 底层的颜色背景
var color = Color.rgb(255,255,255)
// 当前状态的圆形按钮的中心的x坐标
var currentCenterX = 0f
// 动画执行时间
var animatorDuration = 500L
// 定义的未选中时的阴影偏移量
var shadowOffSet = 10f
// 绘制的当前状态的阴影偏移量
var currentShadow = 10f
override fun onDraw(canvas: Canvas) {
drawBg(canvas)
drawSwitch(canvas)
}
override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
super.onSizeChanged(w, h, oldw, oldh)
this.w = w.toFloat()
this.h= h.toFloat()
radius = (w/4).toFloat()
centerX = radius
centerY = (h/2).toFloat()
currentCenterX = centerX
initPath()
initAnimator()
}
override fun onTouchEvent(event: MotionEvent?): Boolean {
when (event?.action){
MotionEvent.ACTION_UP -> {
isChecked = !isChecked
startAnim()
}
}
return true
}
/**
* 绘制背景
*/
private fun drawBg(canvas: Canvas){
paint.style = Paint.Style.FILL
paint.setShadowLayer(5f,2f,2f,Color.BLACK)
paint.color = Color.WHITE
canvas.drawPath(path,paint)
paint.color = this.color
canvas.drawPath(path,paint)
}
/**
* 初始化绘制背景的路径
*/
private fun initPath(){
path.moveTo(radius,centerY-radius)
path.lineTo(radius*3,centerY-radius)
var rightRect = RectF()
rightRect.left = radius*2
rightRect.top = centerY-radius
rightRect.right = radius*4
rightRect.bottom = centerY+radius
path.arcTo(rightRect,-90f,180f)
path.lineTo(radius,centerY+radius)
var leftRect = RectF()
leftRect.left = 0f
leftRect.top = centerY-radius
leftRect.right = radius*2
leftRect.bottom = centerY+radius
path.arcTo(leftRect,90f,180f)
}
/**
* 绘制中心的圆形按钮
*/
private fun drawSwitch(canvas: Canvas){
paint.shader = null
paint.color = Color.WHITE
paint.style = Paint.Style.FILL
paint.strokeWidth = 5f
paint.setShadowLayer(10f,currentShadow,shadowOffSet,Color.parseColor("#DDA69E9E"))
canvas.drawCircle(centerX,centerY,radius/10*9,paint)
}
/**
* 初始化动画
*/
private fun initAnimator(){
animator = ValueAnimator.ofFloat(0f,100f)
animator.duration = animatorDuration
animator.interpolator = LinearInterpolator()
animator.addUpdateListener { valueAnimator ->
var currentValue = valueAnimator.animatedValue as Float
Log.d("animator","currentValue $currentValue")
if (isChecked){
centerX = (3*radius-currentCenterX)*(currentValue/100f)+currentCenterX
color = Color.argb((currentValue/100f*255).toInt(),0,255,0)
currentShadow = (shadowOffSet-20*((currentValue/100f)))
}else{
centerX = currentCenterX - (currentCenterX-radius)*(currentValue/100f)
color = Color.argb((255-currentValue/100f*255).toInt(),0,255,0)
currentShadow = 20*((currentValue/100f))-shadowOffSet
}
postInvalidate()
}
animator.addListener(object : Animator.AnimatorListener{
override fun onAnimationStart(p0: Animator?) {
Log.d("animator","onAnimationStart")
}
override fun onAnimationEnd(p0: Animator?) {
currentCenterX = centerX
Log.d("animator","onAnimationEnd")
}
override fun onAnimationCancel(p0: Animator?) {
Log.d("animator","onAnimationCancel")
}
override fun onAnimationRepeat(p0: Animator?) {
Log.d("animator","onAnimationRepeat")
}
})
}
/**
* 开始执行动画
*/
private fun startAnim(){
animator.start()
}
/**
* remove view时取消动画,防止内存泄漏
*/
override fun onDetachedFromWindow() {
super.onDetachedFromWindow()
animator.cancel()
}
}
总结
今天的开关就写到这里了，整体来说实现这个开关还是比较简单的，下篇再见了~