GtkComboBox 與 GtkTreeStore

接續 GtkComboBox 與 GtkListStore，有了其中的觀念，接下來要使用GtkTreeStore就不是難事了，只是多了父子關係的部份。

若想要製作有階層的樹狀結構，則要搭配GtkTreeStore來使用，主要的差別在於，GtkTreeStroe具 有父子節點關係，也因此在加入子節點時，必須指明父節點為誰，加入節點可以使用gtk_tree_store_append()函式，設定節點資料可以使 用gtk_tree_store_set()函式：

void gtk_tree_store_append(GtkTreeStore *tree_store,
GtkTreeIter *iter,
GtkTreeIter *parent); void gtk_tree_store_set(GtkTreeStore *tree_store, GtkTreeIter *iter, ...);

使用gtk_tree_store_append()時若無父節點，則第三個參數設定為NULL，表示這是最上層節點，也因此，您必須有兩個GtkTreeIter，一個指向目前GtkTreeStore中的父節點位置，一個用以指向子節點位置。 下面這個程式改寫 GtkComboBox 與 GtkListStore，使其具有子階層，在GtkComboBox中會以子選單方式呈現，子選單的內容是亂數選取決定的，程式的改寫主要都是在Model的建立部份：

• gtk_combo_box_with_tree_demo.c

#include <gtk/gtk.h>

enum {
    PIXBUF_COL,
    TEXT_COL
};

GtkTreeModel* createModel() {
    const gchar *files[] = {"caterpillar.jpg", "momor.jpg",
                            "hamimi.jpg", "bush.jpg"};
    gchar *stocks[] = {
        GTK_STOCK_DIALOG_WARNING,
        GTK_STOCK_STOP,
        GTK_STOCK_NEW,
        GTK_STOCK_CLEAR,
        GTK_STOCK_OPEN    
    };

    gchar *stockNames[] = {
        "WARNING",
        "STOP",
        "NEW",
        "GTK_STOCK_CLEAR",
        "GTK_STOCK_OPEN"
    };

    GtkWidget *cellView;
    GdkPixbuf *pixbuf;
    GtkTreeIter iter1, iter2;
    GtkTreeStore *store;
    gint i, j, s;

    store = gtk_tree_store_new(2, GDK_TYPE_PIXBUF, G_TYPE_STRING);
    cellView = gtk_cell_view_new();
    for(i = 0; i < 4; i++) {
        pixbuf = gdk_pixbuf_new_from_file(files[i], NULL);
        gtk_tree_store_append(store, &iter1, NULL);
        gtk_tree_store_set(store, &iter1,
                           PIXBUF_COL, pixbuf,
                           TEXT_COL, files[i],
		           -1);
        gdk_pixbuf_unref(pixbuf);

        for(j = 0; j < 3; j++) {
            s = rand() % 5;
            pixbuf = gtk_widget_render_icon(cellView, stocks[s],
					   GTK_ICON_SIZE_BUTTON, NULL);
            gtk_tree_store_append(store, &iter2, &iter1);
            gtk_tree_store_set(store, &iter2, 
                               PIXBUF_COL, pixbuf,
                               TEXT_COL, stockNames[s],
                              -1);
             gdk_pixbuf_unref(pixbuf);
        }
    }

    return GTK_TREE_MODEL(store);
}

gboolean combo_changed(GtkComboBox *comboBox, GtkLabel *label) {
    GtkTreeModel *model = gtk_combo_box_get_model(comboBox);
    GtkTreeIter iter;
    gchar *active;
    gtk_combo_box_get_active_iter(comboBox, &iter);
    gtk_tree_model_get(model, &iter,
                       1, &active,
                       -1);

    gtk_label_set_text(label, active);
}

int main(int argc, char *argv[]) {
    GtkWidget *window;
    GtkWidget *comboBox;
    GtkCellRenderer *renderer;
    GtkWidget *label;
    GtkWidget *vbox;

    gtk_init(&argc, &argv);

    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title(GTK_WINDOW(window), "GtkComboBox");
    gtk_window_set_default_size(GTK_WINDOW(window), 200, 50);

    comboBox = gtk_combo_box_new_with_model(createModel());
    gtk_combo_box_set_active(GTK_COMBO_BOX(comboBox), 0);
    renderer = gtk_cell_renderer_pixbuf_new();
    gtk_cell_layout_pack_start(GTK_CELL_LAYOUT(comboBox), renderer, FALSE);
    gtk_cell_layout_set_attributes(GTK_CELL_LAYOUT(comboBox), renderer,
				   "pixbuf", PIXBUF_COL, 
				   NULL);
    renderer = gtk_cell_renderer_text_new();
    gtk_cell_layout_pack_start(GTK_CELL_LAYOUT(comboBox), renderer, FALSE);
    gtk_cell_layout_set_attributes(GTK_CELL_LAYOUT(comboBox), renderer,
				   "text", TEXT_COL,
				   NULL);    

    label = gtk_label_new("caterpillar.jpg");
    vbox = gtk_vbox_new(TRUE, 5);

    gtk_box_pack_start(GTK_BOX(vbox), comboBox, TRUE, TRUE, 5);
    gtk_box_pack_start(GTK_BOX(vbox), label, TRUE, TRUE, 5);
    gtk_container_add(GTK_CONTAINER(window), vbox);

    g_signal_connect(GTK_OBJECT(comboBox), "changed",
                     G_CALLBACK(combo_changed), label);

    g_signal_connect(GTK_OBJECT(window), "destroy",
                     G_CALLBACK(gtk_main_quit), NULL);

    gtk_widget_show_all(window);

    gtk_main();

    return 0;
}

一個執行的結果如下所示：