rain drop animation

src/main/scala/lc/RainDropsCaptcha.scala

@@ -6,45 +6,93 @@ import java.awt.Font
 import java.awt.Color
 import java.io.ByteArrayOutputStream
 import javax.imageio.ImageIO
+import javax.imageio.stream.ImageOutputStream;
+import javax.imageio.stream.MemoryCacheImageOutputStream;
+
+class Drop {
+  var x = 0
+  var y = 0
+  var yOffset = 0
+  var color = 0
+  var colorChange = 10
+  def mkColor = {
+    new Color(color, color,  200)
+  }
+}
 
 class RainDropsCP extends ChallengeProvider {
   private val alphabet = "abcdefghijklmnopqrstuvwxyz"
-  private val n = 8
+  private val n = 6
 
   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 width = 450
     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)
+    val imgType = BufferedImage.TYPE_INT_RGB
+    val xOffset = 1+r.nextInt(2)
+    val xBias = (height / 10) - 2
+    val drops = Array.fill[Drop](1500)( new Drop())
+    for (d <- drops) {
+      d.x = r.nextInt(width) - (xBias/2)*xOffset
+      d.yOffset = 6+r.nextInt(6)
+      d.y = r.nextInt(height)
+      d.color = r.nextInt(240)
+      if (d.color > 128) {
+        d.colorChange *= -1
+      }
     }
-    
-    // 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);
+    val ios = new MemoryCacheImageOutputStream(baos);
+    val writer = new GifSequenceWriter(ios, imgType, 100, true);
+    for(i <- 0 until 30){
+      val yOffset = 5+r.nextInt(5)
+      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
+      for (d <- drops) {
+        g.setColor(d.mkColor)
+        g.drawLine(d.x, d.y, d.x+xOffset, d.y+d.yOffset)
+        d.x += xOffset
+        d.y += d.yOffset
+        d.color += d.colorChange
+        if (d.x > width+xOffset || d.y > height+d.yOffset) {
+          d.x = r.nextInt(width) - xBias*xOffset
+          d.y = 0
+        }
+        if (d.color > 200 || d.color < 21) {
+          d.colorChange *= -1
+        }
+      }
+
+      // center the text
+      g.setFont(new Font("Sans", Font.BOLD, 70))
+      val textWidth = g.getFontMetrics().charsWidth(secret.toCharArray, 0, secret.toCharArray.length)
+      val textX = (width - textWidth)/2
+
+      // paint the top outline
+      g.setColor(Color.BLUE)
+      g.drawString(secret, textX, 69)
+      // paint the text
+      g.setColor(Color.WHITE)
+      g.drawString(secret, textX, 70)
+
+      g.dispose()
+      writer.writeToSequence(canvas)
+    }
+    writer.close
+    ios.close
+
+    // ImageIO.write(canvas,"png",baos);
     new Challenge(baos.toByteArray, "image/png", secret)
   }
   def checkAnswer(secret: String, answer: String): Boolean = {