Added methods to copy a pixel by changing one component.

buildSrc/src/main/kotlin/Libs.kt

@@ -1,12 +1,12 @@
 object Libs {
 
-   const val kotlinVersion = "1.5.20"
+   const val kotlinVersion = "1.6.10"
 
    const val org = "com.sksamuel.scrimage"
 
 
    object TwelveMonkeys {
-      private const val Version = "3.7.0"
+      private const val Version = "3.8.2"
       const val imageIoCore = "com.twelvemonkeys.imageio:imageio-core:$Version"
       const val jpeg = "com.twelvemonkeys.imageio:imageio-jpeg:$Version"
       const val pcx = "com.twelvemonkeys.imageio:imageio-pcx:$Version"
@@ -23,10 +23,10 @@ object Libs {
    }
 
    object Kotest {
-      private const val version = "4.6.3"
-      const val assertions = "io.kotest:kotest-assertions-core-jvm:$version"
-      const val api = "io.kotest:kotest-framework-api:$version"
-      const val junit5 = "io.kotest:kotest-runner-junit5-jvm:$version"
+      private const val version = "5.1.0"
+      const val assertions = "io.kotest:kotest-assertions-core:$version"
+      const val datatest = "io.kotest:kotest-framework-datatest:$version"
+      const val junit5 = "io.kotest:kotest-runner-junit5:$version"
    }
 
    object Drewnoaks {

scrimage-core/src/main/java/com/sksamuel/scrimage/AwtImage.java

@@ -11,9 +11,7 @@
 import com.sksamuel.scrimage.scaling.ScrimageNearestNeighbourScale;
 import com.sksamuel.scrimage.subpixel.LinearSubpixelInterpolator;
 
-import java.awt.Color;
-import java.awt.Graphics2D;
-import java.awt.Point;
+import java.awt.*;
 import java.awt.image.BufferedImage;
 import java.awt.image.DataBuffer;
 import java.awt.image.DataBufferInt;
@@ -31,7 +29,9 @@
 
 /**
  * Wraps an AWT BufferedImage with some basic helper functions related to sizes, pixels etc.
+ *
  * It also includes methods to write out the image.
+ *
  * None of the operations in this class will mutate the underlying awt buffer.
  */
 public class AwtImage {
@@ -562,8 +562,9 @@ public boolean hasAlpha() {
    /**
     * Returns true if this image supports transparency/alpha in its underlying data model.
     */
+   @Deprecated()
    public boolean hasTransparency() {
-      return awt().getColorModel().hasAlpha();
+      return hasAlpha();
    }
 
    /**
@@ -612,4 +613,16 @@ public WriteContext forWriter(ImageWriter writer) {
    public ByteArrayInputStream stream(ImageWriter writer) throws IOException {
       return forWriter(writer).stream();
    }
+
+   /**
+    * Returns a copy of this image with the backing image type set to the given value.
+    */
+   public AwtImage clone(int imageType) {
+      if (imageType <= 0) throw new IllegalArgumentException("Image type must be > 0");
+      BufferedImage target = new BufferedImage(awt.getWidth(null), awt.getHeight(null), imageType);
+      Graphics g2 = target.getGraphics();
+      g2.drawImage(awt, 0, 0, null);
+      g2.dispose();
+      return new AwtImage(target);
+   }
 }

scrimage-core/src/main/java/com/sksamuel/scrimage/ImmutableImage.java

@@ -130,11 +130,7 @@ public static ImmutableImage fromAwt(BufferedImage awt, int type) {
       if (imageType == 0) {
          imageType = BufferedImage.TYPE_INT_ARGB;
       }
-      BufferedImage target = new BufferedImage(awt.getWidth(null), awt.getHeight(null), imageType);
-      Graphics g2 = target.getGraphics();
-      g2.drawImage(awt, 0, 0, null);
-      g2.dispose();
-      return new ImmutableImage(target, ImageMetadata.empty);
+      return wrapAwt(new AwtImage(awt).clone(imageType).awt());
    }
 
    /**
@@ -239,7 +235,7 @@ public static ImmutableImage create(int width, int height, int type) {
       BufferedImage target = new BufferedImage(width, height, type);
       return new ImmutableImage(target, ImageMetadata.empty);
    }
-   
+
    /**
     * Create a new ImmutableImage that is the given dimension with no initialization.
     * This will usually result in a default black background (all pixel data defaulting to zeroes)

scrimage-core/src/main/java/com/sksamuel/scrimage/pixels/Pixel.java

@@ -70,6 +70,51 @@ public int toARGBInt() {
       return argb;
    }
 
+   /**
+    * Returns a copy of this pixel, with the same red, green, blue values, but with alpha
+    * set to the given value.
+    */
+   public Pixel alpha(int a) {
+      return new Pixel(x, y, red(), green(), blue(), a);
+   }
+
+   /**
+    * Returns a copy of this pixel, with the same red, green, blue values, but with alpha
+    * set to fully opaque (255).
+    */
+   public Pixel noalpha() {
+      return alpha(255);
+   }
+
+   /**
+    * Returns a copy of this pixel, with the same red, green, blue values, but with alpha
+    * set to fully transparent (0).
+    */
+   public Pixel fullalpha() {
+      return alpha(0);
+   }
+
+   /**
+    * Returns a copy of this pixel with the red component set to the given value.
+    */
+   public Pixel red(int r) {
+      return new Pixel(x, y, r, green(), blue(), alpha());
+   }
+
+   /**
+    * Returns a copy of this pixel with the green component set to the given value.
+    */
+   public Pixel green(int g) {
+      return new Pixel(x, y, red(), g, blue(), alpha());
+   }
+
+   /**
+    * Returns a copy of this pixel with the blue component set to the given value.
+    */
+   public Pixel blue(int b) {
+      return new Pixel(x, y, red(), green(), b, alpha());
+   }
+
    /**
     * Returns this pixel as an array of ARGB values.
     */

scrimage-tests/src/test/kotlin/com/sksamuel/scrimage/core/AnglesTest.kt

@@ -1,8 +1,8 @@
 package com.sksamuel.scrimage.core
 
 import com.sksamuel.scrimage.angles.Degrees
-import io.kotest.core.datatest.forAll
 import io.kotest.core.spec.style.FunSpec
+import io.kotest.datatest.withData
 import io.kotest.matchers.doubles.plusOrMinus
 import io.kotest.matchers.shouldBe
 
@@ -12,7 +12,7 @@ class AnglesTest : FunSpec() {
       data class DegreeConversion(val input: Int, val output: Double)
 
       context("degrees to rads") {
-         forAll(
+         withData(
             DegreeConversion(45, 0.785398),
             DegreeConversion(180, 3.14159),
             DegreeConversion(360, 6.28319),

scrimage-tests/src/test/kotlin/com/sksamuel/scrimage/core/Issue239Test.kt

@@ -0,0 +1,24 @@
+package com.sksamuel.scrimage.core
+
+import com.sksamuel.scrimage.ImmutableImage
+import com.sksamuel.scrimage.MutableImage
+import io.kotest.core.spec.style.FunSpec
+import java.awt.image.BufferedImage
+
+class Issue239Test : FunSpec({
+
+   // https://github.com/sksamuel/scrimage/issues/239
+   test("Pixels with alpha 0 turns black #239") {
+      val image = ImmutableImage.loader().fromResource("/issue239.jpg")
+      val mutImage = MutableImage(image.copy(BufferedImage.TYPE_INT_ARGB).awt())
+      for (pixel in mutImage.pixels()) {
+         if (pixel.red() > 240 && pixel.green() > 240 && pixel.blue() > 240) {
+            val newPixel = pixel.fullalpha().red(125).blue(0).green(0)
+            mutImage.setPixel(newPixel)
+         }
+      }
+
+      // issue was that the source image did not have alpha enabled
+   }
+
+})