[gparted] Set the xalign property for Gtk::Labels (!40)

[Mike Fleetwood <mfleetwo src gnome org>]

commit 12f08d38b8b215afd07733e6da87e9728aa480d6
Author: Luca Bacci <luca bacci982 gmail com>
Date:   Fri May 3 15:42:45 2019 +0200

    Set the xalign property for Gtk::Labels (!40)
    
    With the same case as from the previous commit, the very long "Mounted
    on ..." text is now wrapped, but the text may not be left justified.
    Slowly adjust the dialog width and see how the text wrapping is updated
    to fit the size adjustment but the text is centred rather than left
    justified.
    
    This is because setting the halign property to Gtk::ALIGN_START does not
    guarantee left alignment of text for wrapped or ellipsized Gtk::Labels.
    
    Use the xalign property instead.
    
    To set the xalign property there is a method in the GtkMisc (Gtk::Misc)
    base class:
    
      gtk_misc_set_alignment (Gtk::Misc::set_alignment)
    
    However, GtkMisc (Gtk::Misc) was deprecated in Gtk 3.14 (Gtkmm 3.14)
    and in Gtk 3.16 (gtkmm 3.16) set_alignment() was replaced with the
    introduction of two new methods:
    
      gtk_label_set_xalign (Gtk::Label::set_xalign)
      gtk_label_set_yalign (Gtk::Label::set_yalign)
    
    Add a check for Gtkmm method Gtk::Label::set_xalign() in configure.ac
    and use it when available.
    
    References:
    
    [1] Gtk3 Reference Documentation - gtk_misc_set_alignment()
        https://developer.gnome.org/gtk3/stable/GtkMisc.html#gtk-misc-set-alignment
        "gtk_misc_set_alignment has been deprecated since version 3.14 and
        should not be used in newly-written code. Use GtkWidget's alignment
        ("halign" and "valign") and margin properties or GtkLabel's
        "xalign" and "yalign" properties."
    
    [2] Gtkmm 3.16 Gtk::Misc Class Reference, set_alignment() method
        https://developer.gnome.org/gtkmm/3.16/classGtk_1_1Misc.html#a52b2675874cf46a3097938756b9fe9e8
    
    [3] GNOME BugZilla - EmptyBoxes: instructions_label's alignment is off
        https://bugzilla.gnome.org/show_bug.cgi?id=735841
    
    [4] Gtk commit from 2014-09-16:
        GtkLabel: add x/yalign properties
        https://gitlab.gnome.org/GNOME/gtk/commit/d39424fc
    
    [5] Gtk3 Reference Documentation - gtk_label_set_xalign()
        https://developer.gnome.org/gtk3/stable/GtkLabel.html#gtk-label-set-xalign
    
    [6] Gtkmm 3.16 Gtk::Label Class Reference, set_xalign() method
        https://developer.gnome.org/gtkmm/3.16/classGtk_1_1Label.html#acee7d4e87d7cc14080a7b8ded5f84e5e
    
    Closes !40 - Limit wrapping labels

 configure.ac    | 12 ++++++++++++
 include/Utils.h |  2 +-
 src/Utils.cc    | 10 ++++++++--
 3 files changed, 21 insertions(+), 3 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 63fd222e..58f4f3a5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -242,6 +242,18 @@ if test "x$need_cxx_compile_stdcxx_11" = xyes; then
 fi
 
 
+dnl Check for gtkmm >= 3.16 to determine availability of Gtk::Label::set_xalign().
+AC_MSG_CHECKING([for Gtk::Label::set_xalign() method])
+PKG_CHECK_EXISTS(
+       [gtkmm-3.0 >= 3.16.0],
+       [AC_DEFINE([HAVE_LABEL_SET_XALIGN], 1,
+                  [Define to 1 if gtkmm provides Gtk::Label::set_xalign() method.])
+        AC_MSG_RESULT([yes])
+       ],
+       [AC_MSG_RESULT([no])]
+)
+
+
 dnl Check for gtkmm >= 3.22 to determine availability of Gtk::ScrolledWindow::set_propagate_natural_width().
 AC_MSG_CHECKING([for Gtk::ScrolledWindow::set_propagate_natural_width() method])
 PKG_CHECK_EXISTS(
diff --git a/include/Utils.h b/include/Utils.h
index 2b8406ea..ab0d7b3d 100644
--- a/include/Utils.h
+++ b/include/Utils.h
@@ -128,7 +128,7 @@ public:
                                    , bool use_markup = true
                                    , bool wrap = false
                                    , bool selectable = false
-                                   , Gtk::Align yalign = Gtk::ALIGN_CENTER
+                                   , Gtk::Align valign = Gtk::ALIGN_CENTER
                                    ) ;
        static Gtk::Image* mk_image(const Gtk::StockID& stock_id, Gtk::IconSize icon_size);
        static Glib::RefPtr<Gdk::Pixbuf> mk_pixbuf(Gtk::Widget& widget,
diff --git a/src/Utils.cc b/src/Utils.cc
index 09f06647..c746b15b 100644
--- a/src/Utils.cc
+++ b/src/Utils.cc
@@ -62,11 +62,17 @@ Gtk::Label * Utils::mk_label( const Glib::ustring & text
                             , bool use_markup
                             , bool wrap
                             , bool selectable
-                            , Gtk::Align yalign
+                            , Gtk::Align valign
                             )
 {
-       Gtk::Label * label = manage(new Gtk::Label(text, Gtk::ALIGN_START, yalign));
+       Gtk::Label *label = manage(new Gtk::Label(text));
 
+#if HAVE_LABEL_SET_XALIGN
+       label->set_xalign(0.0);
+#else
+       label->set_alignment(0.0, 0.5);
+#endif
+       label->set_valign(valign);
        label ->set_use_markup( use_markup ) ;
        if (wrap)
        {