Figured out what to do about containers in GTK+ and applied it to Group.

newctrl/container_unix.c

@@ -0,0 +1,102 @@
+// +build !windows,!darwin
+
+// 13 august 2014
+
+#include "gtk_unix.h"
+#include "_cgo_export.h"
+
+#define GOCONTAINER_TYPE (goContainer_get_type())
+#define GOCONTAINER(obj) (G_TYPE_CHECK_INSTANCE_CAST((obj), GOCONTAINER_TYPE, goContainer))
+#define IS_GOCONTAINER(obj) (G_TYPE_CHECK_INSTANCE_TYPE((obj), GOCONTAINER_TYPE))
+#define GOCONTAINER_CLASS(class) (G_TYPE_CHECK_CLASS_CAST((class), GOCONTAINER_TYPE, goContainerClass))
+#define IS_GOCONTAINER_CLASS(class) (G_TYPE_CHECK_CLASS_TYPE((class), GOCONTAINER_TYPE))
+#define GOCONTAINER_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS((obj), GOCONTAINER_TYPE, goContainerClass))
+
+typedef struct goContainer goContainer;
+typedef struct goContainerClass goContainerClass;
+
+struct goContainer {
+	GtkContainer parent_instance;
+	void *gocontainer;
+	GPtrArray *children;		// for forall()
+};
+
+struct goContainerClass {
+	GtkContainerClass parent_class;
+};
+
+G_DEFINE_TYPE(goContainer, goContainer, GTK_TYPE_CONTAINER)
+
+static void goContainer_init(goContainer *c)
+{
+	c->children = g_ptr_array_new();
+	gtk_widget_set_has_window(GTK_WIDGET(c), FALSE);
+}
+
+static void goContainer_dispose(GObject *obj)
+{
+	g_ptr_array_unref(GOCONTAINER(obj)->children);
+	G_OBJECT_CLASS(goContainer_parent_class)->dispose(obj);
+}
+
+static void goContainer_finalize(GObject *obj)
+{
+	G_OBJECT_CLASS(goContainer_parent_class)->finalize(obj);
+}
+
+static void goContainer_add(GtkContainer *container, GtkWidget *widget)
+{
+	gtk_widget_set_parent(widget, GTK_WIDGET(container));
+	g_ptr_array_add(GOCONTAINER(container)->children, widget);
+}
+
+static void goContainer_remove(GtkContainer *container, GtkWidget *widget)
+{
+	gtk_widget_unparent(widget);
+	g_ptr_array_remove(GOCONTAINER(container)->children, widget);
+}
+
+static void goContainer_size_allocate(GtkWidget *widget, GtkAllocation *allocation)
+{
+	gtk_widget_set_allocation(widget, allocation);
+}
+
+struct forall {
+	GtkCallback callback;
+	gpointer data;
+};
+
+static void doforall(gpointer obj, gpointer data)
+{
+	struct forall *s = (struct forall *) data;
+
+	(*(s->callback))(GTK_WIDGET(obj), s->data);
+}
+
+static void goContainer_forall(GtkContainer *container, gboolean includeInternals, GtkCallback callback, gpointer data)
+{
+	struct forall s;
+
+	s.callback = callback;
+	s.data = data;
+	g_ptr_array_foreach(GOCONTAINER(container)->children, doforall, &s);
+}
+
+static void goContainer_class_init(goContainerClass *class)
+{
+	G_OBJECT_CLASS(class)->dispose = goContainer_dispose;
+	G_OBJECT_CLASS(class)->finalize = goContainer_finalize;
+	GTK_WIDGET_CLASS(class)->size_allocate = goContainer_size_allocate;
+	GTK_CONTAINER_CLASS(class)->add = goContainer_add;
+	GTK_CONTAINER_CLASS(class)->remove = goContainer_remove;
+	GTK_CONTAINER_CLASS(class)->forall = goContainer_forall;
+}
+
+GtkWidget *newContainer(void *gocontainer)
+{
+	goContainer *c;
+
+	c = (goContainer *) g_object_new(GOCONTAINER_TYPE, NULL);
+	c->gocontainer = gocontainer;
+	return GTK_WIDGET(c);
+}

newctrl/container_unix.go

@@ -37,10 +37,17 @@ func (c *container) parent() *controlParent {
 	return &controlParent{c.container}
 }
 
-//export containerResizing
-func containerResizing(data unsafe.Pointer, r *C.GtkAllocation) {
-	c := (*container)(data)
-	c.resize(int(r.x), int(r.y), int(r.width), int(r.height))
+func (c *container) allocation(margined bool) C.GtkAllocation {
+	var a C.GtkAllocation
+
+	C.gtk_widget_get_allocation(c.widget, &a)
+	if margined {
+		a.x += C.gint(gtkXMargin)
+		a.y += C.gint(gtkYMargin)
+		a.width -= C.gint(gtkXMargin) * 2
+		a.height -= C.gint(gtkYMargin) * 2
+	}
+	return a
 }
 
 const (
@@ -53,9 +60,6 @@ const (
 func (w *window) beginResize() (d *sizing) {
 	d = new(sizing)
 	if spaced {
-		d.xmargin = gtkXMargin
-		d.ymargintop = gtkYMargin
-		d.ymarginbottom = d.ymargintop
 		d.xpadding = gtkXPadding
 		d.ypadding = gtkYPadding
 	}

newctrl/group_unix.go

@@ -0,0 +1,88 @@
+// +build !windows,!darwin
+
+// 15 august 2014
+
+package ui
+
+import (
+	"unsafe"
+)
+
+// #include "gtk_unix.h"
+import "C"
+
+type group struct {
+	*controlSingleWidget
+	gcontainer *C.GtkContainer
+	frame      *C.GtkFrame
+
+	child			Control
+	container		*container
+
+	margined		bool
+}
+
+func newGroup(text string, control Control) Group {
+	ctext := togstr(text)
+	defer freegstr(ctext)
+	widget := C.gtk_frame_new(ctext)
+	g := &group{
+		controlSingleWidget:	newControlSingleWidget(widget),
+		gcontainer: (*C.GtkContainer)(unsafe.Pointer(widget)),
+		frame:      (*C.GtkFrame)(unsafe.Pointer(widget)),
+		child:	control,
+	}
+
+	// with GTK+, groupboxes by default have frames and slightly x-offset regular text
+	// they should have no frame and fully left-justified, bold text
+	var yalign C.gfloat
+
+	// preserve default y-alignment
+	C.gtk_frame_get_label_align(g.frame, nil, &yalign)
+	C.gtk_frame_set_label_align(g.frame, 0, yalign)
+	C.gtk_frame_set_shadow_type(g.frame, C.GTK_SHADOW_NONE)
+	label := (*C.GtkLabel)(unsafe.Pointer(C.gtk_frame_get_label_widget(g.frame)))
+	// this is the boldness level used by GtkPrintUnixDialog
+	// (it technically uses "bold" but see pango's pango-enum-types.c for the name conversion; GType is weird)
+	bold := C.pango_attr_weight_new(C.PANGO_WEIGHT_BOLD)
+	boldlist := C.pango_attr_list_new()
+	C.pango_attr_list_insert(boldlist, bold)
+	C.gtk_label_set_attributes(label, boldlist)
+	C.pango_attr_list_unref(boldlist) // thanks baedert in irc.gimp.net/#gtk+
+
+	g.container = newContainer(control)
+	g.child.setParent(g.container.parent())
+	g.container.setParent(&controlParent{g.gcontainer})
+
+	g.fresize = g.resize
+
+	return g
+}
+
+func (g *group) Text() string {
+	return fromgstr(C.gtk_frame_get_label(g.frame))
+}
+
+func (g *group) SetText(text string) {
+	ctext := togstr(text)
+	defer freegstr(ctext)
+	C.gtk_frame_set_label(g.frame, ctext)
+}
+
+func (g *group) Margined() bool {
+	return g.margined
+}
+
+func (g *group) SetMargined(margined bool) {
+	g.margined = margined
+}
+
+func (g *group) resize(x int, y int, width int, height int, d *sizing) {
+	// first, chain up to change the GtkFrame and its child container
+	// TODO use a variable for this
+	g.containerSingleWidget.resize(x, y, width, height, d)
+
+	// now that the container has the correct size, we can resize the child
+	a := g.container.allocation(g.margined)
+	g.child.resize(int(a.x), int(a.y), int(a.width), int(a.height), d)
+}