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/*
* Copyright 2018 Allan Wang
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package ca.allanwang.kau.ui.views
import android.animation.Animator
import android.animation.AnimatorListenerAdapter
import android.animation.ArgbEvaluator
import android.animation.ValueAnimator
import android.content.Context
import android.graphics.Canvas
import android.graphics.Color
import android.graphics.Paint
import android.graphics.PorterDuff
import android.graphics.PorterDuffXfermode
import android.util.AttributeSet
import android.view.View
import kotlin.math.hypot
import kotlin.math.max
/**
* Created by Allan Wang on 2016-11-17.
*
* Canvas drawn ripples that keep the previous color
* Extends to view dimensions
* Supports multiple ripples from varying locations
*/
class RippleCanvas @JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0
) : View(context, attrs, defStyleAttr) {
private val paint: Paint = Paint().apply {
isAntiAlias = true
style = Paint.Style.FILL
}
private val eraser: Paint = Paint().apply {
style = Paint.Style.FILL
xfermode = PorterDuffXfermode(PorterDuff.Mode.CLEAR)
}
private var baseColor = Color.TRANSPARENT
private val ripples: MutableList<Ripple> = mutableListOf()
/**
* Draw ripples one at a time in the order given
* To support transparent ripples, we simply erase the overlapping base before adding a new circle
*/
override fun onDraw(canvas: Canvas) {
paint.color = baseColor
canvas.drawRect(0f, 0f, width.toFloat(), height.toFloat(), paint)
val itr = ripples.iterator()
while (itr.hasNext()) {
val r = itr.next()
paint.color = r.color
canvas.drawCircle(r.x, r.y, r.radius, eraser)
canvas.drawCircle(r.x, r.y, r.radius, paint)
if (r.radius == r.maxRadius) {
itr.remove()
baseColor = r.color
}
}
}
/**
* Creates a ripple effect from the given starting values
*/
fun ripple(
color: Int,
startX: Float = 0f,
startY: Float = 0f,
duration: Long = 600L,
callback: (() -> Unit)? = null
) {
val w = width.toFloat()
val h = height.toFloat()
val x = when (startX) {
MIDDLE -> w / 2
END -> w
else -> startX
}
val y = when (startY) {
MIDDLE -> h / 2
END -> h
else -> startY
}
val maxRadius = hypot(max(x, w - x).toDouble(), max(y, h - y).toDouble()).toFloat()
val ripple = Ripple(color, x, y, 0f, maxRadius)
ripples.add(ripple)
val animator = ValueAnimator.ofFloat(0f, maxRadius)
animator.duration = duration
animator.addUpdateListener { animation ->
ripple.radius = animation.animatedValue as Float
invalidate()
}
if (callback != null) {
animator.addListener(object : AnimatorListenerAdapter() {
override fun onAnimationCancel(animation: Animator?) = callback()
override fun onAnimationEnd(animation: Animator?) = callback()
})
}
animator.start()
}
/**
* Sets a color directly; clears ripple queue if it exists
*/
fun set(color: Int) {
baseColor = color
ripples.clear()
invalidate()
}
override fun setBackgroundColor(color: Int) = set(color)
/**
* Sets a color directly but with a transition
*/
fun fade(color: Int, duration: Long = 300L) {
ripples.clear()
val animator = ValueAnimator.ofObject(ArgbEvaluator(), baseColor, color)
animator.duration = duration
animator.addUpdateListener { animation ->
baseColor = animation.animatedValue as Int
invalidate()
}
animator.start()
}
internal class Ripple(
val color: Int,
val x: Float,
val y: Float,
var radius: Float,
val maxRadius: Float
)
companion object {
const val MIDDLE = -1.0f
const val END = -2.0f
}
}
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