如何在C中用GTK3创建自定义小部件？

Question

你知道如何在GTK 3中创建自定义小部件吗？我试图在C中继承GtkDrawingArea几个小时.Gnome.org仅提供了关于如何子类化G_OBJECT的简明教程.我的问题是,G_Object/ GTK没有查看我的自定义StrokerNodalContainer为的一个子类GtkWidget与铸造时GTK_WIDGET,甚至强硬我的定义struct包含了这样一行:

GtkDrawingArea parent_instance;

它说 :

invalid cast from 'StrokerNodalContainer' to 'GtkWidget'

如果您怀疑其他可能有问题,请输入完整的代码.它是最小的所以我没有看到外部代码搞乱的任何理由.

司炉,nodalcontainer.h

#ifndef __STROKER_NODALCONTAINER_H__
#define __STROKER_NODALCONTAINER_H__

#ifndef NO_INCLUDE_WITHIN_HEADERS
#include <gtk/gtk.h>
#endif

#define STROKER_TYPE_NODAL_CONTAINER                  (stroker_nodal_container_get_type ())
#define STROKER_NODAL_CONTAINER(obj)                  (G_TYPE_CHECK_INSTANCE_CAST ((obj), STROKER_TYPE_NODAL_CONTAINER, StrokerNodalContainer))
#define STROKER_NODAL_CONTAINER_CLASS(klass)          (G_TYPE_CHECK_CLASS_CAST  ((klass), STROKER_TYPE_NODAL_CONTAINER, StrokerNodalContainerClass))
#define STROKER_IS_NODAL_CONTAINER(obj)               (G_TYPE_CHECK_INSTANCE_TYPE ((obj), STROKER_TYPE_NODAL_CONTAINER))
#define STROKER_IS_NODAL_CONTAINER_CLASS(klass)       (G_TYPE_CHECK_CLASS_TYPE  ((klass), STROKER_TYPE_NODAL_CONTAINER))
#define STROKER_NODAL_CONTAINER_GET_CLASS(obj)        (G_TYPE_INSTANCE_GET_CLASS  ((obj), STROKER_TYPE_NODAL_CONTAINER, StrokerNodalContainerClass))

typedef struct _StrokerNodalContainer      StrokerNodalContainer;
typedef struct _StrokerNodalContainerClass StrokerNodalContainerClass;

struct _StrokerNodalContainer
{
    GtkDrawingArea parent_instance;
};

struct _StrokerNodalContainerClass
{
    GtkDrawingAreaClass parent_class;
};

GType stroker_nodal_container_get_type(void);

//StrokerNodalContainer* stroker_nodalcontainer_new(void);

#endif /* __STROKER_NODALCONTAINER_H__ */

司炉,nodalcontainer.c

#include <gtk/gtk.h>
#include "stroker-nodalcontainer.h"

G_DEFINE_TYPE( StrokerNodalContainer, stroker_nodal_container, G_TYPE_OBJECT )

static void stroker_nodal_container_class_init( StrokerNodalContainerClass* klass )
    {}

static void stroker_nodal_container_init( StrokerNodalContainer* self )
{
    GdkRGBA c;
    GtkWidget *widget;

    gdk_rgba_parse(&c, "blue");
    widget = GTK_WIDGET(self);

    gtk_widget_override_background_color( widget, GTK_STATE_FLAG_NORMAL, &c );
}

main.c中

#include <stdlib.h>
#include <stdio.h>
#include <gtk/gtk.h>
#include <cairo/cairo.h>

#include "stroker-nodalcontainer.h"

int main(int argc, char *argv[])
{
    GtkWidget *window;
    GtkWidget *nodalWidget;

    gtk_init( &argc, &argv );

    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title (GTK_WINDOW (window), "Stroker");
    g_signal_connect( window, "destroy", G_CALLBACK (gtk_main_quit), NULL );
    gtk_container_set_border_width( GTK_CONTAINER(window), 10 );
    gtk_widget_show (window);

    nodalWidget = g_object_new(STROKER_TYPE_NODAL_CONTAINER,NULL);
    gtk_container_add( GTK_CONTAINER(window), nodalWidget );
    gtk_widget_show (nodalWidget);

    gtk_main();


    return EXIT_SUCCESS;
}

感谢您的任何帮助 !

Answer 1

错误信息可能是因为这个：

G_DEFINE_TYPE( StrokerNodalContainer, stroker_nodal_container, G_TYPE_OBJECT )

如果您查看G_DEFINE_TYPE()的文档，您会看到第三个参数应该是父类型：您可能需要GTK_TYPE_DRAWING_AREA在这里。