PoC - Use Foreign Function & Memory API for GTK3 OS Support

org.eclipse.wb.os.linux/.classpath

@@ -1,7 +1,12 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <classpath>
-	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-21"/>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-24"/>
 	<classpathentry kind="con" path="org.eclipse.pde.core.requiredPlugins"/>
 	<classpathentry kind="src" path="src"/>
+	<classpathentry kind="src" path="src_java24">
+		<attributes>
+			<attribute name="release" value="24"/>
+		</attributes>
+	</classpathentry>
 	<classpathentry kind="output" path="bin"/>
 </classpath>

org.eclipse.wb.os.linux/META-INF/MANIFEST.MF

@@ -18,6 +18,8 @@ Bundle-ActivationPolicy: lazy
 Bundle-Localization: plugin
 Import-Package: org.apache.commons.io;version="[2.16.1,3.0.0)",
  org.apache.commons.lang3;version="[3.14.0,4.0.0)",
+ org.apache.commons.lang3.function;version="[3.14.0,4.0.0)",
  org.eclipse.wb.os
 Automatic-Module-Name: org.eclipse.wb.os.linux
 Provide-Capability: wbp;type=os
+Multi-Release: true

org.eclipse.wb.os.linux/build.properties

@@ -1,4 +1,5 @@
-source.. = src/
+source.. = src/,\
+           src_java24/
 output.. = bin/
 bin.includes = META-INF/,\
                .,\

org.eclipse.wb.os.linux/src_java24/org/eclipse/wb/internal/os/linux/GdkRectangle.java

@@ -0,0 +1,70 @@
+/*******************************************************************************
+ * Copyright (c) 2025 Patrick Ziegler and others.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * https://www.eclipse.org/legal/epl-2.0.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *    Patrick Ziegler - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.wb.internal.os.linux;
+
+import java.lang.foreign.Arena;
+import java.lang.foreign.MemoryLayout;
+import java.lang.foreign.MemorySegment;
+import java.lang.foreign.StructLayout;
+import java.lang.foreign.ValueLayout;
+
+/**
+ * A GdkRectangle data type for representing rectangles.
+ *
+ * GdkRectangle is identical to cairo_rectangle_t. Together with Cairo’s
+ * cairo_region_t data type, these are the central types for representing sets
+ * of pixels.
+ *
+ * The intersection of two rectangles can be computed with
+ * gdk_rectangle_intersect(); to find the union of two rectangles use
+ * gdk_rectangle_union().
+ *
+ * The cairo_region_t type provided by Cairo is usually used for managing
+ * non-rectangular clipping of graphical operations.
+ *
+ * The Graphene library has a number of other data types for regions and volumes
+ * in 2D and 3D.
+ */
+public sealed class GdkRectangle permits GtkAllocation {
+	private static final StructLayout LAYOUT = MemoryLayout.structLayout( //
+			ValueLayout.JAVA_INT.withName("x"), //
+			ValueLayout.JAVA_INT.withName("y"), //
+			ValueLayout.JAVA_INT.withName("width"), //
+			ValueLayout.JAVA_INT.withName("height"));
+
+	private final MemorySegment segment;
+
+	public GdkRectangle(Arena arena) {
+		segment = arena.allocate(LAYOUT);
+	}
+
+	public final int x() {
+		return segment.get(ValueLayout.JAVA_INT, 0);
+	}
+
+	public final int y() {
+		return segment.get(ValueLayout.JAVA_INT, 4);
+	}
+
+	public final int width() {
+		return segment.get(ValueLayout.JAVA_INT, 8);
+	}
+
+	public final int height() {
+		return segment.get(ValueLayout.JAVA_INT, 12);
+	}
+
+	public final MemorySegment segment() {
+		return segment;
+	}
+}

org.eclipse.wb.os.linux/src_java24/org/eclipse/wb/internal/os/linux/GtkAllocation.java

@@ -0,0 +1,25 @@
+/*******************************************************************************
+ * Copyright (c) 2025 Patrick Ziegler and others.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * https://www.eclipse.org/legal/epl-2.0.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *    Patrick Ziegler - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.wb.internal.os.linux;
+
+import java.lang.foreign.Arena;
+
+/**
+ * A GtkAllocation-struct of a widget represents region which has been allocated
+ * to the widget by its parent. It is a subregion of its parents allocation.
+ */
+public final class GtkAllocation extends GdkRectangle {
+	public GtkAllocation(Arena arena) {
+		super(arena);
+	}
+}

org.eclipse.wb.os.linux/src_java24/org/eclipse/wb/internal/os/linux/GtkRuntimeException.java

@@ -0,0 +1,26 @@
+/*******************************************************************************
+ * Copyright (c) 2025 Patrick Ziegler and others.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * https://www.eclipse.org/legal/epl-2.0.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *    Patrick Ziegler - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.wb.internal.os.linux;
+
+import org.eclipse.wb.os.OSRuntimeException;
+
+/**
+ * Wrapper for all exceptions thrown while accessing native code.
+ */
+public class GtkRuntimeException extends OSRuntimeException {
+	private static final long serialVersionUID = 1L;
+
+	public GtkRuntimeException(Throwable t) {
+		super(t);
+	}
+}

org.eclipse.wb.os.linux/src_java24/org/eclipse/wb/internal/os/linux/GtkWidget.java

@@ -0,0 +1,57 @@
+/*******************************************************************************
+ * Copyright (c) 2025 Patrick Ziegler and others.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * https://www.eclipse.org/legal/epl-2.0.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *    Patrick Ziegler - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.wb.internal.os.linux;
+
+import org.eclipse.wb.internal.core.utils.reflect.ReflectionUtils;
+
+import org.eclipse.swt.widgets.Shell;
+import org.eclipse.swt.widgets.Widget;
+
+/**
+ * GtkWidget is the base class all widgets in GTK+ derive from. It manages the
+ * widget lifecycle, states and style.
+ */
+public record GtkWidget(long handle) {
+
+	public GtkWidget(Widget widget) {
+		this(getHandle(widget));
+	}
+
+	/**
+	 * @return the handle value of the {@link Widget} using reflection.
+	 */
+	private static long getHandle(Widget widget) {
+		long widgetHandle = getHandleValue(widget, "fixedHandle");
+		if (widgetHandle == 0) {
+			// may be null, roll back to "handle"
+			if (widget instanceof Shell) {
+				widgetHandle = getHandleValue(widget, "shellHandle");
+			} else {
+				widgetHandle = getHandleValue(widget, "handle");
+			}
+		}
+		return widgetHandle;
+	}
+
+	/**
+	 * @return the widget as native pointer for native handles. Note: returns 0 if
+	 *         handle cannot be obtained.
+	 */
+	private static long getHandleValue(Object widget, String fieldName) {
+		if (ReflectionUtils.getFieldObject(widget, fieldName) instanceof Long longValue) {
+			return longValue;
+		}
+		// field might be shadowed (e.g. in ImageBasedFrame)
+		return 0L;
+	}
+}

org.eclipse.wb.os.linux/src_java24/org/eclipse/wb/internal/os/linux/Native.java

@@ -0,0 +1,54 @@
+/*******************************************************************************
+ * Copyright (c) 2025 Patrick Ziegler and others.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * https://www.eclipse.org/legal/epl-2.0.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *    Patrick Ziegler - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.wb.internal.os.linux;
+
+import org.apache.commons.lang3.function.FailableRunnable;
+import org.apache.commons.lang3.function.FailableSupplier;
+
+import java.lang.foreign.FunctionDescriptor;
+import java.lang.foreign.Linker;
+import java.lang.foreign.MemorySegment;
+import java.lang.foreign.SymbolLookup;
+import java.lang.invoke.MethodHandle;
+
+public class Native {
+
+	protected static class NativeHolder {
+		private static final Linker LINKER = Linker.nativeLinker();
+
+		protected static MethodHandle createHandle(SymbolLookup sl, String name, FunctionDescriptor descriptor) {
+			MemorySegment symbol = sl.find(name).orElseThrow(UnsatisfiedLinkError::new);
+			return LINKER.downcallHandle(symbol, descriptor);
+		}
+	}
+
+	protected static Object callSafe(FailableSupplier<Object, Throwable> s) {
+		try {
+			return s.get();
+		} catch (Error e) {
+			throw e;
+		} catch (Throwable t) {
+			throw new GtkRuntimeException(t);
+		}
+	}
+
+	protected static void runSafe(FailableRunnable<Throwable> r) {
+		try {
+			r.run();
+		} catch (Error e) {
+			throw e;
+		} catch (Throwable t) {
+			throw new GtkRuntimeException(t);
+		}
+	}
+}