8332895: Support interpolation for backgrounds and borders

build.gradle

@@ -4363,6 +4363,7 @@ task javadoc(type: Javadoc, dependsOn: createMSPfile) {
     options.tags("apiNote:a:API Note:")
     options.tags("implSpec:a:Implementation Requirements:")
     options.tags("implNote:a:Implementation Note:")
+    options.tags("interpolationType:a:Interpolation type:")
     options.tags("param")
     options.tags("return")
     options.tags("throws")

modules/javafx.base/src/main/java/com/sun/javafx/UnmodifiableArrayList.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,6 +26,8 @@
 package com.sun.javafx;
 
 import java.util.AbstractList;
+import java.util.List;
+import java.util.Objects;
 import java.util.RandomAccess;
 
 /**
@@ -60,4 +62,68 @@ public UnmodifiableArrayList(T[] elements, int size) {
     @Override public int size() {
         return size;
     }
+
+    /**
+     * Converts the specified list into an unmodifiable list that does not contain {@code null} values.
+     * The returned list is a copy of, and not a wrapper around the specified list.
+     *
+     * @param <T> the type of elements in the list
+     * @param list the list, not {@code null}
+     * @return an unmodifiable list that does not contain null values
+     */
+    public static <T> UnmodifiableArrayList<T> copyOfNullFiltered(List<T> list) {
+        Objects.requireNonNull(list, "list cannot be null");
+
+        int index = 0;
+        int numNonNullValues = 0;
+
+        @SuppressWarnings("unchecked")
+        T[] newValues = (T[])new Object[list.size()];
+
+        if (list instanceof RandomAccess) {
+            // Prevents the iterator allocation for random-access lists.
+            for (int i = 0, max = list.size(); i < max; ++i) {
+                T value = list.get(i);
+                if (value != null) {
+                    newValues[index++] = value;
+                    ++numNonNullValues;
+                }
+            }
+        } else {
+            for (T value : list) {
+                if (value != null) {
+                    newValues[index++] = value;
+                    ++numNonNullValues;
+                }
+            }
+        }
+
+        return new UnmodifiableArrayList<>(newValues, numNonNullValues);
+    }
+
+    /**
+     * Converts the specified array into an unmodifiable list that does not contain {@code null} values.
+     * The returned list is a copy of, and not a wrapper around the specified array.
+     *
+     * @param <T> the type of elements in the array
+     * @param elements the array, not {@code null}
+     * @return an unmodifiable list that does not contain null values
+     */
+    public static <T> UnmodifiableArrayList<T> copyOfNullFiltered(T[] elements) {
+        Objects.requireNonNull(elements, "elements cannot be null");
+
+        int numNonNullValues = 0;
+
+        @SuppressWarnings("unchecked")
+        T[] newValues = (T[])new Object[elements.length];
+
+        for (int i = 0, j = 0; i < elements.length; ++i) {
+            if (elements[i] != null) {
+                newValues[j++] = elements[i];
+                ++numNonNullValues;
+            }
+        }
+
+        return new UnmodifiableArrayList<>(newValues, numNonNullValues);
+    }
 }

modules/javafx.base/src/test/addExports

@@ -1,4 +1,5 @@
 #
+--add-exports javafx.base/com.sun.javafx=ALL-UNNAMED
 --add-exports javafx.base/com.sun.javafx.binding=ALL-UNNAMED
 --add-exports javafx.base/com.sun.javafx.collections=ALL-UNNAMED
 --add-exports javafx.base/com.sun.javafx.event=ALL-UNNAMED

modules/javafx.base/src/test/java/test/com/sun/javafx/UnmodifiableArrayListTest.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package test.com.sun.javafx;
+
+import com.sun.javafx.UnmodifiableArrayList;
+import org.junit.jupiter.api.Test;
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class UnmodifiableArrayListTest {
+
+    @Test
+    void testCopyOfNullFilteredList_nullList() {
+        assertThrows(NullPointerException.class, () -> UnmodifiableArrayList.copyOfNullFiltered((List<?>)null));
+    }
+
+    @Test
+    void testCopyOfNullFilteredList_nullArray() {
+        assertThrows(NullPointerException.class, () -> UnmodifiableArrayList.copyOfNullFiltered((Object[])null));
+    }
+
+    @Test
+    void testCopyOfNullFilteredList_randomAccess() {
+        var list = new ArrayList<String>();
+        list.add("a");
+        list.add(null);
+        list.add("b");
+        list.add(null);
+
+        assertEquals(List.of("a", "b"), UnmodifiableArrayList.copyOfNullFiltered(list));
+    }
+
+    @Test
+    void testCopyOfNullFilteredList_nonRandomAccess() {
+        var list = new LinkedList<String>();
+        list.add("a");
+        list.add(null);
+        list.add("b");
+        list.add(null);
+
+        assertEquals(List.of("a", "b"), UnmodifiableArrayList.copyOfNullFiltered(list));
+    }
+
+    @Test
+    void testCopyOfNullFilteredArray() {
+        var list = new String[4];
+        list[0] = "a";
+        list[1] = null;
+        list[2] = "b";
+        list[3] = null;
+
+        assertEquals(List.of("a", "b"), UnmodifiableArrayList.copyOfNullFiltered(list));
+    }
+}

modules/javafx.graphics/src/main/java/com/sun/javafx/scene/paint/PaintUtils.java

@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package com.sun.javafx.scene.paint;
+
+import javafx.animation.Interpolatable;
+import javafx.scene.paint.Color;
+import javafx.scene.paint.LinearGradient;
+import javafx.scene.paint.Paint;
+import javafx.scene.paint.RadialGradient;
+import javafx.scene.paint.Stop;
+import java.util.List;
+
+public final class PaintUtils {
+
+    private PaintUtils() {}
+
+    /**
+     * Interpolates between potentially different types of paint.
+     * <p>
+     * In addition to homogeneous interpolations between paints of the same type, the following
+     * heterogeneous interpolations are supported:
+     * <ul>
+     *     <li>Color ↔ LinearGradient
+     *     <li>Color ↔ RadialGradient
+     * </ul>
+     * If a paint is not interpolatable, {@code startValue} is returned for {@code t < 0.5},
+     * and {@code endValue} is returned otherwise.
+     */
+    @SuppressWarnings({"rawtypes", "unchecked"})
+    public static Paint interpolate(Paint startValue, Paint endValue, double t) {
+        if (startValue instanceof Color start) {
+            if (endValue instanceof Color end) {
+                return start.interpolate(end, t);
+            }
+
+            if (endValue instanceof LinearGradient end) {
+                return newSolidGradient(end, start).interpolate(end, t);
+            }
+
+            if (endValue instanceof RadialGradient end) {
+                return newSolidGradient(end, start).interpolate(end, t);
+            }
+        }
+
+        if (startValue instanceof LinearGradient start) {
+            if (endValue instanceof LinearGradient end) {
+                return start.interpolate(end, t);
+            }
+
+            if (endValue instanceof Color end) {
+                return start.interpolate(newSolidGradient(start, end), t);
+            }
+        }
+
+        if (startValue instanceof RadialGradient start) {
+            if (endValue instanceof RadialGradient end) {
+                return start.interpolate(end, t);
+            }
+
+            if (endValue instanceof Color end) {
+                return start.interpolate(newSolidGradient(start, end), t);
+            }
+        }
+
+        if (startValue instanceof Interpolatable start
+                && endValue instanceof Interpolatable end
+                && startValue.getClass().isInstance(endValue)) {
+            return (Paint)start.interpolate(end, t);
+        }
+
+        return t < 0.5 ? startValue : endValue;
+    }
+
+    /**
+     * Creates a new linear gradient that consists of two stops with the same color.
+     */
+    public static LinearGradient newSolidGradient(LinearGradient source, Color color) {
+        return new LinearGradient(
+                source.getStartX(), source.getStartY(),
+                source.getEndX(), source.getEndY(),
+                source.isProportional(),
+                source.getCycleMethod(),
+                List.of(new Stop(0, color), new Stop(1, color)));
+    }
+
+    /**
+     * Creates a new radial gradient that consists of two stops with the same color.
+     */
+    public static RadialGradient newSolidGradient(RadialGradient source, Color color) {
+        return new RadialGradient(
+                source.getFocusAngle(), source.getFocusDistance(),
+                source.getCenterX(), source.getCenterY(),
+                source.getRadius(),
+                source.isProportional(),
+                source.getCycleMethod(),
+                List.of(new Stop(0, color), new Stop(1, color)));
+    }
+}