[Gtk4] Fix Shell.computeSize to take header bar into account

HeaderBar is part of the regular window size  in Gtk 4 on Wayland BUT
gtk_window_get_headerbar returns 0 if it is not set by the application
but drawn internally by Gtk itself and thus it's size can not be
queried. Add a "default" GtkHeaderBar explicitly for that and take its
size into account when computing Shell size.

Author: akurtakov

bundles/org.eclipse.swt/Eclipse SWT PI/gtk/library/gtk4.c

@@ -1844,6 +1844,18 @@ JNIEXPORT jlong JNICALL GTK4_NATIVE(gtk_1gesture_1zoom_1new)
 }
 #endif
 
+#ifndef NO_gtk_1header_1bar_1new
+JNIEXPORT jlong JNICALL GTK4_NATIVE(gtk_1header_1bar_1new)
+	(JNIEnv *env, jclass that)
+{
+	jlong rc = 0;
+	GTK4_NATIVE_ENTER(env, that, gtk_1header_1bar_1new_FUNC);
+	rc = (jlong)gtk_header_bar_new();
+	GTK4_NATIVE_EXIT(env, that, gtk_1header_1bar_1new_FUNC);
+	return rc;
+}
+#endif
+
 #ifndef NO_gtk_1hsv_1to_1rgb
 JNIEXPORT void JNICALL GTK4_NATIVE(gtk_1hsv_1to_1rgb)
 	(JNIEnv *env, jclass that, jfloat arg0, jfloat arg1, jfloat arg2, jfloatArray arg3, jfloatArray arg4, jfloatArray arg5)
@@ -2509,6 +2521,18 @@ JNIEXPORT jlong JNICALL GTK4_NATIVE(gtk_1widget_1get_1first_1child)
 }
 #endif
 
+#ifndef NO_gtk_1widget_1get_1height
+JNIEXPORT jint JNICALL GTK4_NATIVE(gtk_1widget_1get_1height)
+	(JNIEnv *env, jclass that, jlong arg0)
+{
+	jint rc = 0;
+	GTK4_NATIVE_ENTER(env, that, gtk_1widget_1get_1height_FUNC);
+	rc = (jint)gtk_widget_get_height((GtkWidget *)arg0);
+	GTK4_NATIVE_EXIT(env, that, gtk_1widget_1get_1height_FUNC);
+	return rc;
+}
+#endif
+
 #ifndef NO_gtk_1widget_1get_1last_1child
 JNIEXPORT jlong JNICALL GTK4_NATIVE(gtk_1widget_1get_1last_1child)
 	(JNIEnv *env, jclass that, jlong arg0)
@@ -2598,6 +2622,18 @@ JNIEXPORT void JNICALL GTK4_NATIVE(gtk_1widget_1get_1size_1request)
 }
 #endif
 
+#ifndef NO_gtk_1widget_1get_1width
+JNIEXPORT jint JNICALL GTK4_NATIVE(gtk_1widget_1get_1width)
+	(JNIEnv *env, jclass that, jlong arg0)
+{
+	jint rc = 0;
+	GTK4_NATIVE_ENTER(env, that, gtk_1widget_1get_1width_FUNC);
+	rc = (jint)gtk_widget_get_width((GtkWidget *)arg0);
+	GTK4_NATIVE_EXIT(env, that, gtk_1widget_1get_1width_FUNC);
+	return rc;
+}
+#endif
+
 #ifndef NO_gtk_1widget_1insert_1after
 JNIEXPORT void JNICALL GTK4_NATIVE(gtk_1widget_1insert_1after)
 	(JNIEnv *env, jclass that, jlong arg0, jlong arg1, jlong arg2)
@@ -2843,6 +2879,16 @@ JNIEXPORT void JNICALL GTK4_NATIVE(gtk_1window_1set_1icon_1name)
 }
 #endif
 
+#ifndef NO_gtk_1window_1set_1titlebar
+JNIEXPORT void JNICALL GTK4_NATIVE(gtk_1window_1set_1titlebar)
+	(JNIEnv *env, jclass that, jlong arg0, jlong arg1)
+{
+	GTK4_NATIVE_ENTER(env, that, gtk_1window_1set_1titlebar_FUNC);
+	gtk_window_set_titlebar((GtkWindow *)arg0, (GtkWidget *)arg1);
+	GTK4_NATIVE_EXIT(env, that, gtk_1window_1set_1titlebar_FUNC);
+}
+#endif
+
 #ifndef NO_gtk_1window_1unminimize
 JNIEXPORT void JNICALL GTK4_NATIVE(gtk_1window_1unminimize)
 	(JNIEnv *env, jclass that, jlong arg0)

bundles/org.eclipse.swt/Eclipse SWT PI/gtk/library/gtk4_stats.h

@@ -151,6 +151,7 @@ typedef enum {
 	gtk_1gesture_1rotate_1new_FUNC,
 	gtk_1gesture_1set_1sequence_1state_FUNC,
 	gtk_1gesture_1zoom_1new_FUNC,
+	gtk_1header_1bar_1new_FUNC,
 	gtk_1hsv_1to_1rgb_FUNC,
 	gtk_1icon_1paintable_1get_1file_FUNC,
 	gtk_1icon_1theme_1get_1for_1display_FUNC,
@@ -204,13 +205,15 @@ typedef enum {
 	gtk_1widget_1class_1add_1binding_1signal_FUNC,
 	gtk_1widget_1get_1clipboard_FUNC,
 	gtk_1widget_1get_1first_1child_FUNC,
+	gtk_1widget_1get_1height_FUNC,
 	gtk_1widget_1get_1last_1child_FUNC,
 	gtk_1widget_1get_1native_FUNC,
 	gtk_1widget_1get_1next_1sibling_FUNC,
 	gtk_1widget_1get_1prev_1sibling_FUNC,
 	gtk_1widget_1get_1receives_1default_FUNC,
 	gtk_1widget_1get_1root_FUNC,
 	gtk_1widget_1get_1size_1request_FUNC,
+	gtk_1widget_1get_1width_FUNC,
 	gtk_1widget_1insert_1after_FUNC,
 	gtk_1widget_1insert_1before_FUNC,
 	gtk_1widget_1measure_FUNC,
@@ -232,5 +235,6 @@ typedef enum {
 	gtk_1window_1set_1child_FUNC,
 	gtk_1window_1set_1default_1widget_FUNC,
 	gtk_1window_1set_1icon_1name_FUNC,
+	gtk_1window_1set_1titlebar_FUNC,
 	gtk_1window_1unminimize_FUNC,
 } GTK4_FUNCS;

bundles/org.eclipse.swt/Eclipse SWT PI/gtk/org/eclipse/swt/internal/gtk4/GTK4.java

@@ -464,6 +464,11 @@ public class GTK4 {
 	/** @param window cast=(GtkWindow *) */
 	public static final native long gtk_window_get_titlebar(long window);
 
+	/** @param window cast=(GtkWindow *)
+	 *  @param titlebar cast=(GtkWidget *)
+	 **/
+	public static final native void gtk_window_set_titlebar(long window, long titlebar);
+
 	/** @param window cast=(GtkWindow *) */
 	public static final native void gtk_window_present(long window) ;
 
@@ -1064,4 +1069,16 @@ public class GTK4 {
 	 */
 	public static final native long gtk_gesture_get_last_updated_sequence(long gesture);
 
+	/**
+	 * @param widget cast=(GtkWidget *)
+	 */
+	public static final native int gtk_widget_get_width(long widget);
+
+	/**
+	 * @param widget cast=(GtkWidget *)
+	 */
+	public static final native int gtk_widget_get_height(long widget);
+
+	public static final native long gtk_header_bar_new();
+
 }

bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Shell.java

@@ -728,6 +728,14 @@ Rectangle computeTrimInPixels (int x, int y, int width, int height) {
 		trim.y -= menuBarHeight;
 		trim.height += menuBarHeight;
 	}
+	if (GTK.GTK4 && OS.isWayland()) {
+		long titlebar = GTK4.gtk_window_get_titlebar(shellHandle);
+		if (titlebar != 0) {
+			int titleBarHeight = GTK4.gtk_widget_get_height (titlebar);
+			trim.y -= titleBarHeight;
+			trim.height += titleBarHeight;
+		}
+	}
 	return trim;
 }
 
@@ -743,6 +751,15 @@ void createHandle (int index) {
 			if (GTK.GTK4) {
 				// TODO: GTK4 need to handle for GTK_WINDOW_POPUP type
 				shellHandle = GTK4.gtk_window_new();
+				if (OS.isWayland()) {
+					long headerbar = GTK4.gtk_window_get_titlebar(shellHandle);
+					if (headerbar == 0) {
+					    // Force-install a headerbar if none exists in order to be able to qurey its size later
+						// If none set by the app gtk_window_get_titlebar returns 0 but Gtk still draws one internally
+					    long hb = GTK4.gtk_header_bar_new();
+					    GTK4.gtk_window_set_titlebar(shellHandle, hb);
+					}
+				}
 			} else {
 				shellHandle = GTK3.gtk_window_new(type);
 			}