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import android.content.Context
import android.graphics.Canvas
import android.graphics.Color
import android.graphics.Paint
import android.util.AttributeSet
import android.view.View
import androidx.annotation.ColorInt
import java.lang.Math.pow
import kotlin.math.cos
import kotlin.math.sqrt
private const val N = 12
private const val W = 44f
private const val H = W * 3
private const val PERIOD = 5000
private const val PI = Math.PI.toFloat()
private const val TWO_PI = 2 * PI
private val LIGHT = Color.parseColor("#EAEAEA")
private val DARK = Color.parseColor("#222222")
class CrossesSquaresView(context: Context, attrs: AttributeSet?) : View(context, attrs) {
private val paint = Paint(Paint.ANTI_ALIAS_FLAG)
private val t: Float
get() = (System.currentTimeMillis() % PERIOD) / PERIOD.toFloat()
override fun onDraw(canvas: Canvas) {
super.onDraw(canvas)
val t = t
canvas.drawBackground(
if (t * 3 < 1) {
LIGHT
} else if (t * 3 < 2) {
DARK
} else {
val t = t * 3f - 2f
if (t > .5f) DARK else LIGHT
}
)
canvas.save()
canvas.translate(width / 2f, height / 2f)
when {
t * 3 < 1 -> {
val t = t * 3f
for (i in -N..N) {
for (j in -N..N) {
val tt = ease(t, 3f)
canvas.save()
canvas.translate(i * H - j * W * tt, j * H + i * W * tt)
canvas.rotate(90 * tt)
canvas.drawCross(DARK)
canvas.restore()
}
}
}
t * 3 < 2 -> {
val t = t * 3f - 1f
canvas.save()
canvas.scale(-1f, 1f)
for (i in -N..N) {
for (j in -N..N) {
val tt = 1f - ease(t, 3f)
canvas.save()
canvas.translate((i + .5f) * H + (j + .5f) * W * tt, (j + .5f) * H - (i + .5f) * W * tt)
canvas.rotate(-90f * tt)
canvas.drawCross(LIGHT)
canvas.restore()
}
}
canvas.restore()
}
else -> {
val t = t * 3f - 2f
paint.color = if (t > .5f) LIGHT else DARK
for (i in -N..N) {
for (j in -N..N) {
canvas.save()
val tt = ease(t, 3f)
canvas.translate(
(i + .5f * if (t > .5f) 1f else 0f) * H,
(j + .5f * if (t > .5f) 1f else 0f) * H
)
canvas.rotate(90 * tt)
val s = map(cos(TWO_PI * tt), 1f, -1f, 1f, sqrt(2f) * 3f / 4f)
canvas.scale(s, s)
canvas.drawRect(-W, -W, W, W, paint)
canvas.restore()
}
}
}
}
canvas.restore()
postInvalidateOnAnimation()
}
private fun Canvas.drawBackground(@ColorInt color: Int) {
paint.color = color
drawRect(0f, 0f, width.toFloat(), height.toFloat(), paint)
}
private fun Canvas.drawCross(@ColorInt color: Int) {
paint.color = color
drawRect(-W / 2f, -H / 2f, W / 2f, H / 2f, paint)
drawRect(-H / 2f, -W / 2f, H / 2f, W / 2f, paint)
}
}
private fun map(value: Float, start1: Float, stop1: Float, start2: Float, stop2: Float): Float {
return start2 + (stop2 - start2) * ((value - start1) / (stop1 - start1))
}
private fun ease(p: Float, g: Float): Float {
return if (p < 0.5f) {
0.5f * pow(2.0 * p, g.toDouble()).toFloat()
} else {
1f - 0.5f * pow(2.0 * (1f - p), g.toDouble()).toFloat()
}
}
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