Gtk3 窗口背景图像

Question

我在 gtk+-3.0.12 中使用 C 语言（截至 9/10/2011 的最新稳定版本） 如何在顶部窗口上创建 png 背景图像，并仍然在窗口上放置其他小部件（如按钮）？我尝试了以下操作，但图像是在按钮上绘制的。

/*
* Compile with: 
* gcc -Wextra -o cairo6 `pkg-config --cflags --libs gtk+-3.0` cairo6.c
*/

#include <gtk/gtk.h>
static cairo_surface_t *surface = NULL;
cairo_surface_t *image;

static gboolean
on_expose_event (GtkWidget *widget, GdkEventExpose *event, gpointer data)
{
  cairo_t *cr;
  surface = gdk_window_create_similar_surface (gtk_widget_get_window (widget),
                           CAIRO_CONTENT_COLOR,
                           gtk_widget_get_allocated_width (widget),
                           gtk_widget_get_allocated_height (widget));

cr = gdk_cairo_create ( gtk_widget_get_window (GTK_WIDGET(widget)) );
cairo_set_source_surface (cr, image, 0, 0);
cairo_paint (cr);
cairo_destroy (cr);

return TRUE;
}

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

window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
image = cairo_image_surface_create_from_png("bdrop.png"); //Supply your own image here
g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);
gtk_widget_set_app_paintable(window, FALSE);
gtk_window_set_position (GTK_WINDOW(window), GTK_WIN_POS_CENTER);
gtk_window_set_default_size (GTK_WINDOW(window), 800, 480);

GtkWidget *ebox = gtk_event_box_new ();
GtkWidget *button;
button = gtk_button_new_with_label("QUIT");
gtk_widget_set_halign (GTK_WIDGET(button),GTK_ALIGN_CENTER);
gtk_widget_set_valign (GTK_WIDGET(button),GTK_ALIGN_CENTER);
gtk_container_add (GTK_CONTAINER(ebox), button);
g_signal_connect (button, "clicked", G_CALLBACK (gtk_main_quit), NULL);

gtk_container_add (GTK_CONTAINER(window), ebox);
g_signal_connect(ebox,"draw", G_CALLBACK (on_expose_event),NULL);

gtk_widget_show_all (window);

gtk_main();
cairo_surface_destroy (image);
return 0;
}

Answer 1

检查下面的代码是否适合您：

#include <gtk/gtk.h>

int main( int argc, char *argv[])
{
    GtkWidget *window;
    GtkWidget *layout;
    GtkWidget *image;
    GtkWidget *button;

    gtk_init(&argc, &argv);

    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_default_size(GTK_WINDOW(window), 290, 200);
    gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);

    layout = gtk_layout_new(NULL, NULL);
    gtk_container_add(GTK_CONTAINER (window), layout);
    gtk_widget_show(layout);

    image = gtk_image_new_from_file("/home/my_background_image.jpg");
    gtk_layout_put(GTK_LAYOUT(layout), image, 0, 0);

    button = gtk_button_new_with_label("Button");
    gtk_layout_put(GTK_LAYOUT(layout), button, 150, 50);
    gtk_widget_set_size_request(button, 80, 35);

    g_signal_connect_swapped(G_OBJECT(window), "destroy",
    G_CALLBACK(gtk_main_quit), NULL);

    gtk_widget_show_all(window);

    gtk_main();

    return 0;
}

Answer 2

/*
* #include<string.h> for the strlen() function...
*/
void set_window_background(gchar *__imgPath__)
{
/*
* Malloc a buffer to store the css data and fill it with css code
*/
gchar *css=(gchar *)malloc((strlen(__imgPath__)+55)*sizeof(gchar));
sprintf(css,"GtkWindow{\nbackground-image: url('%s');\n}\n",__imgPath__);
/*
* Create a css provider and add pass css data to it
*/
GtkCssProvider *provider = gtk_css_provider_new();
gtk_css_provider_load_from_data(provider,css, -1, NULL);
/*
* Bind the css provider for the current display
*/
GdkDisplay *display = gdk_display_get_default();
GdkScreen *screen = gdk_display_get_default_screen (display);
gtk_style_context_add_provider_for_screen(screen,
                                      GTK_STYLE_PROVIDER (provider),
                                      GTK_STYLE_PROVIDER_PRIORITY_APPLICATION
                                     );
/*
* Free the used memory...
*/
g_object_unref(provider);
g_free(css);
}