1 files changed, 79 insertions, 0 deletions
diff --git a/library/src/main/kotlin/ca/allanwang/kau/views/RippleCanvas.kt b/library/src/main/kotlin/ca/allanwang/kau/views/RippleCanvas.kt
new file mode 100644
index 0000000..2c44197
--- /dev/null
+++ b/library/src/main/kotlin/ca/allanwang/kau/views/RippleCanvas.kt
@@ -0,0 +1,79 @@
+package ca.allanwang.kau.views
+
+import android.animation.ValueAnimator
+import android.content.Context
+import android.graphics.Canvas
+import android.graphics.Color
+import android.graphics.Paint
+import android.util.AttributeSet
+import android.view.View
+
+/**
+ * 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()
+    private var baseColor = Color.TRANSPARENT
+    private val ripples: MutableList<Ripple> = mutableListOf()
+
+    init {
+        paint.isAntiAlias = true
+        paint.style = Paint.Style.FILL
+    }
+
+    override fun onDraw(canvas: Canvas) {
+        canvas.drawColor(baseColor)
+        val itr = ripples.iterator()
+        while (itr.hasNext()) {
+            val r = itr.next()
+            paint.color = r.color
+            canvas.drawCircle(r.x, r.y, r.radius, paint)
+            if (r.radius == r.maxRadius) {
+                itr.remove()
+                baseColor = r.color
+            }
+        }
+    }
+
+    fun ripple(color: Int, startX: Float = 0f, startY: Float = 0f, duration: Int = 1000) {
+        var x = startX
+        var y = startY
+        val w = width.toFloat()
+        val h = height.toFloat()
+        if (x == MIDDLE)
+            x = w / 2
+        else if (x > w) x = 0f
+        if (y == MIDDLE)
+            y = h / 2
+        else if (y > h) y = 0f
+        val maxRadius = Math.hypot(Math.max(x, w - x).toDouble(), Math.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.toLong()
+        animator.addUpdateListener { animation ->
+            ripple.radius = animation.animatedValue as Float
+            invalidate()
+        }
+        animator.start()
+    }
+
+    fun set(color: Int) {
+        baseColor = color
+        ripples.clear()
+        invalidate()
+    }
+
+    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
+    }
+}