Question

当我尝试使用Glade在Vala中将GTK IconView子类化时，出现分段错误。这是Vala中的错误，还是我做错了什么？这使用的是vala 0.42.3。也许这与IconView如何没有base()构造函数有关？（请参阅：Chain up to 'Gtk.Box.new' not supported）

test.vala：

using Gtk;

public class IconViewSubclass : Gtk.IconView {
  public IconViewSubclass() {

  }
}

public static int main(string[] args) {
  Gtk.init(ref args);
  var builder = new Builder.from_file("test.glade");
  var window = builder.get_object("window") as Window;
  var iconViewSubclass = builder.get_object("iconViewSubclass") as IconViewSubclass;
  iconViewSubclass.set_pixbuf_column(0);
  iconViewSubclass.set_text_column(1);

  window.show_all();
  Gtk.main();
  return 0;
}

test.glade：

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.22.1 -->
<interface>
  <requires lib="gtk+" version="3.20"/>
  <object class="GtkListStore" id="store">
    <columns>
      <!-- column-name pixbuf -->
      <column type="GdkPixbuf"/>
      <!-- column-name text -->
      <column type="gchararray"/>
    </columns>
  </object>
  <object class="GtkWindow" id="window">
    <property name="can_focus">False</property>
    <child>
      <placeholder/>
    </child>
    <child>
      <object class="GtkIconView" id="iconViewSubclass">
        <property name="visible">True</property>
        <property name="can_focus">True</property>
        <property name="margin">6</property>
        <property name="model">store</property>
      </object>
    </child>
  </object>
</interface>

$ valac --pkg gtk+-3.0 test.vala && ./test
Segmentation fault

Answer 1

您似乎需要使用IconViewSubclass让Gtk.Builder知道expose_object()存在。这允许在Builder UI定义文件中使用子类型。这是一个编译但不存在段错误的示例：

test.ui：

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.22.1 -->
<interface>
  <requires lib="gtk+" version="3.18"/>
  <object class="GtkWindow" id="window">
    <property name="window-position">GTK_WIN_POS_CENTER</property>
    <property name="default-height">250</property>
    <property name="default-width">250</property>
    <child>
      <placeholder/>
    </child>
    <child>
      <object class="IconViewSubclass" id="iconViewSubclass">
        <property name="visible">True</property>
        <property name="can_focus">True</property>
        <property name="margin">6</property>
      </object>
    </child>
  </object>
</interface>

和test.vala：

using Gtk;

public class IconViewSubclass : Gtk.IconView {}

public static int main(string[] args) {
  Gtk.init(ref args);
  var builder = new Builder ();
  builder.expose_object ("IconViewSubclass", new IconViewSubclass ());
  try {
    builder.add_from_file ("test.ui");
  } catch (Error error) {
    print (@"$(error.message)");
  }
  var window = builder.get_object ("window") as Window;
  var iconViewSubclass = (IconViewSubclass)builder.get_object ("iconViewSubclass");
  iconViewSubclass.set_pixbuf_column (0);
  iconViewSubclass.set_text_column (1);

  window.show_all();
  Gtk.main();
  return 0;
}

您可能想研究使用具有Vala [GtkTemplate]，[GtkChild]和[GtkCallback]属性的模板。这些属性将告诉Vala为您生成样板代码。

Answer 2

AIThomas的代码效果很好，但是，为了继续在Glade中编辑UI文件，我必须添加一个目录文件，如下所示：

<?xml version="1.0" encoding="UTF-8"?>
<glade-catalog name="test" depends="gtk+">
  <glade-widget-classes>
    <glade-widget-class name="IconViewSubclass" generic-name="iconviewsubclass" title="IconViewSubclass" parent="GtkIconView"/>
  </glade-widget-classes>
  <glade-widget-group name="test" title="test">
    <glade-widget-class-ref name="IconViewSubclass"/>
  </glade-widget-group>
</glade-catalog>

我还发现， Vala中的子类名称必须与UI XML中的小部件名称完全对应，即将IconViewSubclass中的IconViewSubclass2更改为test.vala将给您：

$ valac --pkg gtk+-3.0 test.vala && ./test
test.ui:14:1 Invalid object type 'IconViewSubclass'Segmentation fault

您还可以将名称空间用作类名的一部分，即namespace Foo { public class Bar : Baz }应该适用于UI XML文件中类型为FooBar的小部件。

如何使用Glade在Vala中继承GTK IconView

2 个答案: