How to decrease the width of a GtkEntry in Gtk3.0?

Question

I have a GTK program with 2 GtkButtons and one GtkEntry. I would like to dynamically resize the width of the entry by clicking a button to increase/decrease it. The program I have so far is able to dynamically increase the size of the entry, but is unable to decrease it.

Is it possible to do so for GTK entries?

#include <gtk/gtk.h>


#define INITIAL_WIDTH 200
#define WIDTH_STEP 20

// Function to increase the width of GtkEntry
static void increase_size(GtkWidget *widget, GtkWidget *entry) {
    GtkAllocation allocation;
    gtk_widget_get_allocation(entry, &allocation);

    int new_width = allocation.width + WIDTH_STEP;
    gtk_widget_set_size_request(entry, new_width, -1); // -1 keeps the default height
}

// Function to decrease the width of GtkEntry
static void decrease_size(GtkWidget *widget, GtkWidget *entry) {
    GtkAllocation allocation;
    gtk_widget_get_allocation(entry, &allocation);

    int new_width = allocation.width - WIDTH_STEP;
    if (new_width < 1) new_width = 1; // Ensure width does not become negative or zero
    gtk_widget_set_size_request(entry, new_width, -1); // -1 keeps the default height
}

int main(int argc, char *argv[]) {
    GtkWidget *window;
    GtkWidget *vbox;
    GtkWidget *entry;
    GtkWidget *button_box;
    GtkWidget *plus_button;
    GtkWidget *minus_button;

    // Initialize GTK
    gtk_init(&argc, &argv);

    // Create a new window
    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title(GTK_WINDOW(window), "Resize GtkEntry with Buttons");
    gtk_window_set_default_size(GTK_WINDOW(window), 400, 200);

    // Create a vertical box
    vbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, 6);
    gtk_container_add(GTK_CONTAINER(window), vbox);

    // Create a new GtkEntry
    entry = gtk_entry_new();
    gtk_entry_set_text(GTK_ENTRY(entry), "Resize me with buttons!");
    gtk_widget_set_size_request(entry, INITIAL_WIDTH, -1); // Set initial width
    gtk_box_pack_start(GTK_BOX(vbox), entry, TRUE, TRUE, 0);

    // Create a button box to hold the plus and minus buttons
    button_box = gtk_button_box_new(GTK_ORIENTATION_HORIZONTAL);
    gtk_box_pack_start(GTK_BOX(vbox), button_box, FALSE, FALSE, 0);

    // Create plus and minus buttons
    plus_button = gtk_button_new_with_label("Increase Size");
    minus_button = gtk_button_new_with_label("Decrease Size");

    // Add buttons to the button box
    gtk_container_add(GTK_CONTAINER(button_box), plus_button);
    gtk_container_add(GTK_CONTAINER(button_box), minus_button);

    // Connect button signals to respective handlers
    g_signal_connect(plus_button, "clicked", G_CALLBACK(increase_size), entry);
    g_signal_connect(minus_button, "clicked", G_CALLBACK(decrease_size), entry);

    // Connect the destroy event to exit the GTK main loop
    g_signal_connect(window, "destroy", G_CALLBACK(gtk_main_quit), NULL);

    // Show all widgets
    gtk_widget_show_all(window);

    // Enter the GTK main loop
    gtk_main();

    return 0;
}

Add a padding widget (with horizontal auto grow) on the right of your entry - you will see the decreasing entry. Currently - it is almost a direct child of window widget and it has its own rules (auto squeeze is not one of them). — White Owl
– White Owl, Commented Aug 29, 2024 at 22:00

BobMorane · Accepted Answer · 2024-08-29 22:22:57Z

1

After having resized the entry, you need to shrink the window as well:

// Function to decrease the width of GtkEntry 
static void decrease_size(GtkWidget *widget, GtkWidget *entry) { 
    // Resize entry: 
    GtkAllocation entry_allocation; 
    gtk_widget_get_allocation(entry, &entry_allocation); 
 
    int new_width = entry_allocation.width - WIDTH_STEP; 
    if (new_width < 1) new_width = 1; // Ensure width does not become negative or zero 
    gtk_widget_set_size_request(entry, new_width, -1); // -1 keeps the default height 
  
    // Shrink surrounding window: 
    GtkWidget* window = gtk_widget_get_toplevel(entry); 
    GtkAllocation window_allocation;

    gtk_widget_get_allocation(window, &window_allocation); 
    gtk_window_resize(GTK_WINDOW(window), 1, window_allocation.height); // One to fit down. 
}

answered Aug 29, 2024 at 22:22

BobMorane

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2 Comments

BobMorane Over a year ago

@codeology Did this answer solve your problem?

codeology Over a year ago

Unfortunately for the purposes of my task, I cannot resize the window. Your answer certainly solves what I had asked here though.

BobMorane · Accepted Answer · 2024-09-04 11:28:44Z

0

If you do not want the window to shrink as the entry does, you can simply disable the default alignement, which is set to GTK_ALIGN_FILL;

// Function to decrease the width of GtkEntry
static void decrease_size(GtkWidget *widget, GtkWidget *entry) {
    // Make sure the entry does not fill its container, i.e. the window.
    gtk_widget_set_halign(entry, GTK_ALIGN_START);

    GtkAllocation entry_allocation;
    gtk_widget_get_allocation(entry, &entry_allocation);
 
    int new_width = entry_allocation.width - WIDTH_STEP;
    if (new_width < 1) new_width = 1; // Ensure width does not become negative or zero
    gtk_widget_set_size_request(entry, new_width, -1); // -1 keeps the default height
}

edited Sep 4, 2024 at 11:28

answered Sep 3, 2024 at 15:27

BobMorane

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1 Comment

BobMorane Over a year ago

@codeology Did this new answer solve your problem?

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