rain drop single frame

src/main/scala/lc/RainDropsCaptcha.scala

@@ -0,0 +1,53 @@
+package lc
+
+import java.awt.image.BufferedImage
+import java.awt.RenderingHints
+import java.awt.Font
+import java.awt.Color
+import java.io.ByteArrayOutputStream
+import javax.imageio.ImageIO
+
+class RainDropsCP extends ChallengeProvider {
+  private val alphabet = "abcdefghijklmnopqrstuvwxyz"
+  private val n = 8
+
+  def getId = "FilterChallenge"
+
+  def returnChallenge(): Challenge = {
+    val r = new scala.util.Random
+    val secret = Stream.continually(r.nextInt(alphabet.size)).map(alphabet).take(n).mkString
+    val width = 225
+    val height = 100
+
+    val canvas = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB)
+    val g = canvas.createGraphics()
+    g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON)
+
+    // clear the canvas
+    g.setColor(Color.WHITE)
+    g.fillRect(0, 0, canvas.getWidth, canvas.getHeight)
+
+    // paint the rain
+    g.setColor(Color.BLACK)
+    val xOffset = 1+r.nextInt(10)
+    val yOffset = 1+r.nextInt(10)
+    for (i <- 0 until 1000) {
+      val x = r.nextInt(width)
+      val y = r.nextInt(height)
+      g.drawLine(x, y, x+xOffset, y+yOffset)
+    }
+    
+    // paint the text
+    g.setColor(Color.WHITE)
+    g.setFont(new Font("Sans", Font.BOLD, 42))
+    g.drawString(secret, 5, 50)
+
+    g.dispose()
+    val baos = new ByteArrayOutputStream();
+    ImageIO.write(canvas,"png",baos);
+    new Challenge(baos.toByteArray, "image/png", secret)
+  }
+  def checkAnswer(secret: String, answer: String): Boolean = {
+    secret == answer
+  }
+}