GTK3 在按钮标签中换行

Question

作为this question 的后续/简化，我正在尝试使 GTK3 按钮对象内的文本自动环绕。

所以;

btn = gtk_button_new();
gtk_button_set_label (GTK_BUTTON(btn), "A very long label that should wrap");

不换行 - 按钮只是伸展到适合（此处是不需要的行为）。

但是：

label = gtk_button_get_label(GTK_BUTTON(dbp->btn));
if (GTK_IS_LABEL (label))
{
     g_message("Is label");
     gtk_label_set_ellipsize(GTK_LABEL(label),PANGO_ELLIPSIZE_END);
     gtk_label_set_line_wrap(GTK_LABEL(label), TRUE);
     gtk_label_set_max_width_chars(GTK_LABEL(label), 14);
}

这会在第一行引发编译错误，鉴于 gtk_button_get_label 返回的是 gchar 字符串而不是实际的标签小部件，您可能会期望出现这种错误。

warning: assignment to ‘GtkWidget *’ {aka ‘struct _GtkWidget *’} from incompatible pointer type ‘const gchar *’ {aka ‘const char *’} [-Wincompatible-pointer-types]
    label = gtk_button_get_label(GTK_BUTTON(btn));

所以，看起来我们可以很好地将标签小部件包裹在其他任何地方，但不能包裹按钮标签。任何人都可以填补这块缺失的部分吗？

Answer 1

是python，不过翻译成C也不难。 正如我前面提到的，GtkLabel 是一个GtkBin，它创建了一些子小部件：容器、图像、标签。你必须递归它的孩子并找到一个标签，然后你才能设置它的 ellipsize 参数。

import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk, GdkPixbuf
from gi.repository import GObject as g
from gi.repository import Pango

def find_label(widget):
    # check if we've found a label
    #   there are convinient macros in C:
    #   is_label = GTK_IS_LABEL(widget) in this case
    if g.type_is_a(widget, Gtk.Label):
        return widget
    # if a container (or it's subclass)
    if g.type_is_a(widget, Gtk.Container):
        children = widget.get_children()
        for i in children:
            r = find_label(i)
            if r is not None:
                return r

def set_text_and_ellipsize(button, text):
    button.set_label(text)
    b = find_label(button)
    # In case we fail...
    if b is None:
        return
    # setting ellipsize
    b.set_ellipsize(Pango.EllipsizeMode.END)

# called on entry's text changed event
def text_changed(*args):
    text = entry.get_text()
    print(text)
    # initiates recreation of child GtkLabel widget
    set_text_and_ellipsize(button1, text)
    set_text_and_ellipsize(button2, text)
    set_text_and_ellipsize(button3, text)


win = Gtk.Window.new(Gtk.WindowType.TOPLEVEL)
grid = Gtk.Grid.new()
button1 = Gtk.Button.new()
button2 = Gtk.Button.new()
button3 = Gtk.Button.new()
entry = Gtk.Entry.new()
win.add(grid)
grid.add(button1)
grid.add(button2)
grid.add(button3)
grid.add(entry)
entry.connect("changed", text_changed)

win.show_all()
Gtk.main()