Add initial support for picture masking.

src/main/scala/net/kogics/kojo/core/Picture.scala

@@ -218,5 +218,6 @@ trait Picture extends InputAware {
   def withZIndex(idx: Int): Picture
   def withClipping(clipShape: Shape): Picture
   def withClipping(clipPic: Picture): Picture
+  def withMask(maskPic: Picture): Picture
   def withPenCapJoin(capJoin: (Int, Int)): Picture
 }

src/main/scala/net/kogics/kojo/lite/Versions.scala

@@ -3,8 +3,8 @@ package net.kogics.kojo.lite
 object Versions {
   val KojoMajorVersion = "2.9"
   val KojoVersion = "2.9.26"
-  val KojoRevision = "r4"
-  val KojoBuildDate = "17 August 2023"
+  val KojoRevision = "r5"
+  val KojoBuildDate = "18 August 2023"
   val JavaVersion = {
     val jrv = System.getProperty("java.runtime.version")
     val arch = System.getProperty("os.arch")

src/main/scala/net/kogics/kojo/picture/package.scala

@@ -16,7 +16,9 @@ package net.kogics.kojo
 
 import java.awt.event.KeyEvent
 import java.awt.geom.GeneralPath
+import java.awt.image.BufferedImage
 import java.awt.image.BufferedImageOp
+import java.awt.image.DataBufferInt
 import java.awt.Color
 import java.awt.Font
 import java.awt.Image
@@ -30,6 +32,7 @@ import scala.swing.Graphics2D
 
 import com.jhlabs.image.LightFilter
 import com.jhlabs.image.LightFilter.Light
+import com.jhlabs.image.PointFilter
 import com.vividsolutions.jts.geom.Coordinate
 import com.vividsolutions.jts.geom.GeometryFactory
 import com.vividsolutions.jts.geom.PrecisionModel
@@ -484,7 +487,7 @@ package object picture {
   }
 
   def toShape(p: Picture): Shape = {
-    p.invisible(); p.draw()
+    p.draw()
     val coords = p.picGeom.getCoordinates
     p.erase()
     if (coords.length > 0) {
@@ -499,4 +502,48 @@ package object picture {
       throw new RuntimeException("Unable to convert picture to shape")
     }
   }
+
+  class MaskOp(maskPic: Picture) extends PointFilter {
+//    var maskImg: BufferedImage = _
+    var maskPixels: Array[Int] = _
+    var maskWidth: Int = 0
+    var maskHeight: Int = 0
+
+    def initMaskImg(): Unit = {
+      maskPic.draw()
+      val maskImg = maskPic.toImage
+      maskPic.erase()
+      maskWidth = maskImg.getWidth; maskHeight = maskImg.getHeight
+//      maskPixels = new Array[Int](maskWidth * maskHeight)
+//      maskImg.getRaster.getDataElements(0, 0, maskWidth, maskHeight, maskPixels)
+      maskPixels = maskImg.getRaster.getDataBuffer.asInstanceOf[DataBufferInt].getData
+    }
+
+    def checkSizes(src: BufferedImage): Unit = {
+      require(
+        src.getWidth <= maskWidth && src.getHeight <= maskHeight,
+        "The mask cannot be smaller than the masked pic"
+      )
+    }
+
+    override def filter(src: BufferedImage, dest: BufferedImage): BufferedImage = {
+      initMaskImg()
+      checkSizes(src)
+      super.filter(src, dest)
+    }
+
+    def filterRGB(x: Int, y: Int, pixel: Int): Int = {
+      val red = (pixel >> 16) & 0xff
+      val green = (pixel >> 8) & 0xff
+      val blue = pixel & 0xff
+
+      val maskPixel = maskPixels(x + y * maskWidth) //  maskImg.getRGB(x, y)
+      val mred = (maskPixel >> 16) & 0xff
+      val mgreen = (maskPixel >> 8) & 0xff
+      val mblue = maskPixel & 0xff
+      val mgray = (mred + mgreen + mblue) / 3
+      val outPixel = mgray << 24 | red << 16 | green << 8 | blue
+      outPixel
+    }
+  }
 }

src/main/scala/net/kogics/kojo/picture/pics.scala

@@ -462,6 +462,7 @@ trait CorePicOps2 extends GeomPolygon { self: Picture =>
   def withZIndex(zIndex: Int): Picture = PostDrawTransform { pic => pic.setZIndex(zIndex) }(this)
   def withClipping(clipShape: Shape): Picture = new ClipPic(this, clipShape)(canvas)
   def withClipping(clipPic: Picture): Picture = new ClipPicWithPic(this, clipPic)(canvas)
+  def withMask(maskPic: Picture): Picture = this.withEffect(new MaskOp(maskPic))
   def withPenCapJoin(capJoin: (Int, Int)): Picture = PostDrawTransform { pic => pic.setPenCapJoin(capJoin) }(this)
 }