Initial data commit

Task/Color-wheel/Java/color-wheel.java

@@ -0,0 +1,80 @@
+import java.awt.*;
+import javax.swing.*;
+
+public class ColorWheel {
+    public static void main(String[] args) {
+        SwingUtilities.invokeLater(new Runnable() {
+            public void run() {
+                ColorWheelFrame frame = new ColorWheelFrame();
+                frame.setVisible(true);
+            }
+        });
+    }
+
+    private static class ColorWheelFrame extends JFrame {
+        private ColorWheelFrame() {
+            super("Color Wheel");
+            setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+            getContentPane().add(new ColorWheelPanel());
+            pack();
+        }
+    }
+
+    private static class ColorWheelPanel extends JComponent {
+        private ColorWheelPanel() {
+            setPreferredSize(new Dimension(400, 400));
+        }
+        public void paint(Graphics g) {
+            Graphics2D g2 = (Graphics2D)g;
+            int w = getWidth();
+            int h = getHeight();
+            int margin = 10;
+            int radius = (Math.min(w, h) - 2 * margin)/2;
+            int cx = w/2;
+            int cy = h/2;
+            float[] dist = {0.F, 1.0F};
+            g2.setColor(Color.BLACK);
+            g2.fillRect(0, 0, w, h);
+            for (int angle = 0; angle < 360; ++angle) {
+                Color color = hsvToRgb(angle, 1.0, 1.0);
+                Color[] colors = {Color.WHITE, color};
+                RadialGradientPaint paint = new RadialGradientPaint(cx, cy,
+                        radius, dist, colors);
+                g2.setPaint(paint);
+                g2.fillArc(cx - radius, cy - radius, radius*2, radius*2,
+                        angle, 1);
+            }
+        }
+    }
+
+    private static Color hsvToRgb(int h, double s, double v) {
+        double hp = h/60.0;
+        double c = s * v;
+        double x = c * (1 - Math.abs(hp % 2.0 - 1));
+        double m = v - c;
+        double r = 0, g = 0, b = 0;
+        if (hp <= 1) {
+            r = c;
+            g = x;
+        } else if (hp <= 2) {
+            r = x;
+            g = c;
+        } else if (hp <= 3) {
+            g = c;
+            b = x;
+        } else if (hp <= 4) {
+            g = x;
+            b = c;
+        } else if (hp <= 5) {
+            r = x;
+            b = c;
+        } else {
+            r = c;
+            b = x;
+        }
+        r += m;
+        g += m;
+        b += m;
+        return new Color((int)(r * 255), (int)(g * 255), (int)(b * 255));
+    }
+}