Programicaly moving through list box, C, gtk4

[fik236]

Hello all,
I again need help.

I have app written in c/c++ in gtk4. In App is list box with quite a lot rows and I would like that app after pressing some letter (e.g. a) move to first row which start with this letter.

In my code I have function “keyPress” where I can recognize what letter was pressed (switch will be enhanced in real app). I can find index of row which starts with pressed letter.
But I can not find any gtk function which moves me to this row. Exists this function?

Thanks for any advice!

my testing code:

#include <gtk/gtk.h>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm> //to make string lowercases


using namespace std;

GtkWidget *lBox;

gboolean
keyPress (GtkWidget             *drawing_area,
                      guint                  keyval,
                      guint                  keycode,
                      GdkModifierType        state,
                      GtkEventControllerKey *event_controller)
{
    string comparedString;
    switch (keyval)
    {
        case GDK_KEY_a:
            std::cout << "Pressed - a" << std::endl;
            comparedString = "a";
            break;
        case GDK_KEY_b:
            std::cout << "Pressed - b" << std::endl;
            comparedString = "b";
            break;
        case GDK_KEY_c:
            std::cout << "Pressed - c" << std::endl;
            comparedString = "c";
            break;
        case GDK_KEY_d:
            std::cout << "Pressed - d" << std::endl;
            comparedString = "d";
            break;
        case GDK_KEY_e:
            std::cout << "Pressed - e" << std::endl;
            comparedString = "e";
            break;
    }

    int index = 0;
    GtkListBoxRow* testedRow;
    string rowText;
    //loop for finding row begining with pressed letter
    while ( (testedRow = gtk_list_box_get_row_at_index (GTK_LIST_BOX(lBox),index++)) != NULL ) {
        rowText = gtk_label_get_text(GTK_LABEL(gtk_list_box_row_get_child (GTK_LIST_BOX_ROW(testedRow))));

        transform(rowText.begin(), rowText.end(), rowText.begin(),[](unsigned char c){ return tolower(c); });
        //cout << "row" << index << ": " << rowText << " -find result=" << rowText.find(comparedString) << endl;
        if (rowText.find(comparedString) == 0)
        {
            break;
        }
    }

    if (testedRow == NULL)
    {
        cout << "this letter is not in listbox" << endl;
    }
    else
    {
        cout << "fist row with letter " << comparedString << " is at row " << index << endl;


        //FOCUS at row index
    }

    return TRUE;
}

static void appActivate (GApplication *app, gpointer user_data) {
    GtkWidget *win = gtk_application_window_new (GTK_APPLICATION (app));
    gtk_window_set_default_size (GTK_WINDOW (win), 400, 300);

    GtkWidget  *hBox = gtk_box_new (GTK_ORIENTATION_HORIZONTAL,10);
    gtk_box_set_homogeneous(GTK_BOX(hBox),true);
    gtk_window_set_child (GTK_WINDOW (win), hBox);

    GtkWidget *skrollBox = gtk_scrolled_window_new();
    gtk_box_append (GTK_BOX (hBox), skrollBox);

    lBox = gtk_list_box_new();
    gtk_scrolled_window_set_child(GTK_SCROLLED_WINDOW (skrollBox), lBox);
    gtk_list_box_set_selection_mode (GTK_LIST_BOX(lBox), GTK_SELECTION_MULTIPLE);

    //prepare many rows in list box
    vector<string> startLetter = {"x", "a", "r" ,"B", "g", "c"};
    for ( unsigned int x =0; x < startLetter.size(); ++x )
    {
        for (int i = 0; i < 40; i++) {
            string  jmeno = startLetter.at(x) + "test " + to_string(i);
            GtkWidget* lab = gtk_label_new(jmeno.c_str());
            gtk_list_box_append(GTK_LIST_BOX(lBox),  lab);
        }
    }

    //key shortcut
    GtkEventController *event_controller = gtk_event_controller_key_new ();
    g_signal_connect_object (event_controller, "key-pressed", G_CALLBACK (keyPress), NULL, G_CONNECT_SWAPPED);
    gtk_widget_add_controller (GTK_WIDGET (win), event_controller);
    //end - key shortcut

    gtk_widget_show (win);
}


int main(int argc, char **argv) {
    GtkApplication *app;
    app = gtk_application_new ("testing.app", G_APPLICATION_FLAGS_NONE);
    g_signal_connect (app, "activate", G_CALLBACK (appActivate), NULL);
    return g_application_run (G_APPLICATION (app), NULL, NULL);
    g_object_unref (app);

    return 0;
}

[otrocodigo]

If what you want is to highlight a row of the ListBox you can apply select_row.

Another option (which I don’t know if it’s useful for your project) is to set a GtkListBoxFilterFunc with set_filter_func to display, for example, all rows starting with ‘a’ or the key you press.

[fik236]

thank you for reply.
I do not neet selecting but I would like to list box alone scroll down to show certain row

[HighKingofMelons (Mikkel Hansen)]

It sounds like using GtkWidget.grab_focus() on the row you are interested in would do what you want.

[otrocodigo]

I understand, what you need is to change the GtkAdjustment value of the listbox to position it at the row.

[otrocodigo]

Changing the focus does not move the scrolled

[fik236]

thank you! it is working, I added into function keyPress:

else
    {
        cout << "fist row with letter " << comparedString << " is at row " << index << endl;

        //FOCUS at row index

        gtk_widget_grab_focus(GTK_WIDGET(testedRow));
    }

and list box is moved to the first row which start with pressed letter.
Thank you