oop - 如何使用 Glade 在 Vala 中子类化 GTK IconView

Question

当我尝试使用 Glade 在 Vala 中子类化 GTK IconView 时，我遇到了段错误。这是 Vala 中的错误，还是我只是做错了什么？这是使用 vala 0.42.3。也许这与 IconView 没有 base() 构造函数有关？ (参见:Chain up to 'Gtk.Box.new' not supported)

测试.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;
}

测试.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

看起来您需要使用 expose_object() 让 Gtk.Builder 知道 IconViewSubclass 存在。这允许在 Builder UI 定义文件中使用子类型。这是一个编译但没有段错误的示例:

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。