BAEL-7454 RGB conversions (#16053)

Author: mdabrowski-eu

java-numbers-2/src/main/java/com/baeldung/rbg/Rgb.java

@@ -0,0 +1,46 @@
+package com.baeldung.rbg;
+
+import java.util.Objects;
+
+public class Rgb {
+    private int alpha;
+    private int red;
+    private int green;
+    private int blue;
+
+    public Rgb(int alpha, int red, int green, int blue) {
+        this.alpha = alpha;
+        this.red = red;
+        this.green = green;
+        this.blue = blue;
+    }
+
+    public int getAlpha() {
+        return alpha;
+    }
+
+    public int getRed() {
+        return red;
+    }
+
+    public int getGreen() {
+        return green;
+    }
+
+    public int getBlue() {
+        return blue;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Rgb rgb = (Rgb) o;
+        return alpha == rgb.alpha && red == rgb.red && green == rgb.green && blue == rgb.blue;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(alpha, red, green, blue);
+    }
+}

java-numbers-2/src/main/java/com/baeldung/rbg/RgbConversions.java

@@ -0,0 +1,31 @@
+package com.baeldung.rbg;
+
+public class RgbConversions {
+
+    public static int rgbToInt(int alpha, int red, int green, int blue) {
+        alpha = clamp(alpha, 0, 255);
+        red = clamp(red, 0, 255);
+        green = clamp(green, 0, 255);
+        blue = clamp(blue, 0, 255);
+
+        return (alpha << 24) | (red << 16) | (green << 8) | blue;
+    }
+
+    public static int rgbToInt(Rgb rgb) {
+        return rgbToInt(rgb.getAlpha(), rgb.getRed(), rgb.getGreen(), rgb.getBlue());
+    }
+
+    public static Rgb intToRgb(int argb) {
+        int alpha = (argb >> 24) & 0xFF;
+        int red = (argb >> 16) & 0xFF;
+        int green = (argb >> 8) & 0xFF;
+        int blue = argb & 0xFF;
+
+        return new Rgb(alpha, red, green, blue);
+    }
+
+    private static int clamp(int value, int min, int max) {
+        return Math.max(min, Math.min(max, value));
+    }
+}
+

java-numbers-2/src/test/java/com/baeldung/rgb/RgbConversionUnitTest.java

@@ -0,0 +1,118 @@
+package com.baeldung.rgb;
+
+import com.baeldung.rbg.Rgb;
+import com.baeldung.rbg.RgbConversions;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class RgbConversionUnitTest {
+
+    @Test
+    public void whenBasicPackingAndUnpackingRgb_thenReturnInitialComponentsValues() {
+        int alpha = 255;
+        int red = 255;
+        int green = 0;
+        int blue = 0;
+
+        int rgb = (alpha << 24) | (red << 16) | (green << 8) | blue;
+
+        assertEquals(rgb, 0xFFFF0000);
+
+        int alphaReconstructed = (rgb >> 24) & 0xFF;
+        int redReconstructed = (rgb >> 16) & 0xFF;
+        int greenReconstructed = (rgb >> 8) & 0xFF;
+        int blueReconstructed = rgb & 0xFF;
+
+        assertEquals(alphaReconstructed, alpha);
+        assertEquals(redReconstructed, red);
+        assertEquals(greenReconstructed, green);
+        assertEquals(blueReconstructed, blue);
+    }
+
+    @Test
+    public void whenRgbaToIntWithoutClamping_ReturnIntegerRepresentations() {
+        // Fully opaque red
+        assertEquals(0xFFFF0000, RgbConversions.rgbToInt(255, 255, 0, 0));
+        // Fully transparent blue
+        assertEquals(0x000000FF, RgbConversions.rgbToInt(0, 0, 0, 255));
+        // 50% transparent green
+        assertEquals(0x8000FF00, RgbConversions.rgbToInt(128, 0, 255, 0));
+    }
+
+    @Test
+    public void whenRgbaToIntWithClamping_ReturnIntegerRepresentations() {
+        // Clamping for values below 0
+        assertEquals(0x00000000, RgbConversions.rgbToInt(-1, -1, -1, -1));
+        // Clamping for values above 255
+        assertEquals(0xFFFFFFFF, RgbConversions.rgbToInt(256, 256, 256, 256));
+    }
+
+    @Test
+    public void whenRgbaToIntBoundary_ReturnIntegerRepresentations() {
+        // Boundary values for each color component including alpha
+        assertEquals(0xFF000000, RgbConversions.rgbToInt(255, 0, 0, 0)); // Opaque black
+        assertEquals(0x00FFFFFF, RgbConversions.rgbToInt(0, 255, 255, 255)); // Transparent white
+    }
+
+    @Test
+    public void whenRgbaToIntAndIntToRgb_ReturnTheSameValues() {
+        Rgb rgb = new Rgb(0, 125, 125, 100);
+        assertEquals(rgb, RgbConversions.intToRgb(RgbConversions.rgbToInt(rgb)));
+    }
+
+    @Test
+    public void whenBrightnessAdjustment_ReturnChangedRgbIntegerValue() {
+        float scale = 0.8f; // darken by 20%
+
+        // initial values
+        int alpha = 0;
+        int red = 100;
+        int green = 255;
+        int blue = 100;
+
+
+        int adjustedRed = (int)(red * scale);
+        int adjustedGreen = (int)(green * scale);
+        int adjustedBlue = (int)(blue * scale);
+
+        int newArgb = (alpha << 24) | (adjustedRed << 16) | (adjustedGreen << 8) | adjustedBlue;
+
+        assertEquals(newArgb, 0x50CC50);
+    }
+
+    @Test
+    public void whenGrayscaleConversion_ReturnChangedRgbIntegerValue() {
+        float scale = 0.8f; // darken by 20%
+
+        // initial values
+        int alpha = 0;
+        int red = 100;
+        int green = 255;
+        int blue = 100;
+
+        int average = (int)(red * 0.299 + green * 0.587 + blue * 0.114);
+        int grayscaleArgb = (alpha << 24) | (average << 16) | (average << 8) | average;
+
+        assertEquals(grayscaleArgb, 0xBEBEBE);
+    }
+
+    @Test
+    public void whenInversion_ReturnChangedRgbIntegerValue() {
+        float scale = 0.8f; // darken by 20%
+
+        // initial values
+        int alpha = 0;
+        int red = 100;
+        int green = 255;
+        int blue = 100;
+
+        red = 255 - red;
+        green = 255 - green;
+        blue = 255 - blue;
+
+        int invertedArgb = (alpha << 24) | (red << 16) | (green << 8) | blue;
+
+        assertEquals(invertedArgb, 0x9B009B);
+    }
+}