GTK+ Forums

Micah Carrick

This little example shows how you can use gtk_text_view_scroll_to_iter () to automatically scroll to the end of a GtkTextView when you insert text. This would commonly be used to implement a status log or something of that nature.

This example uses a GtkBuilder XML file created using Glade and therefore requires GTK+ 2.12 or greater.

Compile using:

Code: (Plaintext)
1	cc -Wall -g main.c -o example -export-dynamic `pkg-config --cflags --libs gtk+-2.0`

ui.xml

Code: (XML/HTML)

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<?xml version="1.0"?>
<interface>
<object class="GtkWindow" id="window">
<property name="border_width">4</property>
<signal name="destroy" handler="gtk_main_quit"/>
<child>
<object class="GtkVBox" id="vbox1">
<property name="visible">True</property>
<property name="spacing">4</property>
<child>
<object class="GtkHBox" id="hbox1">
<property name="visible">True</property>
<child>
<object class="GtkEntry" id="entry">
<property name="visible">True</property>
<property name="can_focus">True</property>
</object>
</child>
<child>
<object class="GtkButton" id="button">
<property name="visible">True</property>
<property name="can_focus">True</property>
<property name="receives_default">True</property>
<property name="label" translatable="yes">Log Message</property>
<signal name="clicked" handler="on_button_clicked"/>
</object>
<packing>
<property name="expand">False</property>
<property name="fill">False</property>
<property name="position">1</property>
</packing>
</child>
</object>
<packing>
<property name="expand">False</property>
</packing>
</child>
<child>
<object class="GtkScrolledWindow" id="scrolledwindow1">
<property name="visible">True</property>
<property name="can_focus">True</property>
<property name="extension_events">GDK_EXTENSION_EVENTS_ALL</property>
<property name="shadow_type">GTK_SHADOW_ETCHED_IN</property>
<child>
<object class="GtkTextView" id="textview">
<property name="visible">True</property>
<property name="can_focus">True</property>
</object>
</child>
</object>
<packing>
<property name="position">1</property>
</packing>
</child>
</object>
</child>
</object>
</interface>

main.c

Code: (C)

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/*
Example logging to a GtkTextView and automatically scrolling to the newly
inserted text.

Written for www.gtkforums.com by Micah Carrick

Compile using:
cc -Wall -g main.c -o example -export-dynamic `pkg-config --cflags --libs gtk+-2.0`
*/

#include <gtk/gtk.h>

/* structure to hold references to our widgets */
typedef struct
{
GtkWidget *entry;
GtkWidget *textview;
} MyWidgets;

/* call back function for when the button is pressed */
void
on_button_clicked (GtkWidget* widget, gpointer user_data)
{
MyWidgets *widgets;
gchar *message;
GtkTextBuffer *buffer;
GtkTextIter iter;

/* cast the gpointer user_data into the MyWidgets structure */
widgets = (MyWidgets *)user_data;

/* build message to log appending a new line char to the end */
message = g_strconcat (gtk_entry_get_text (GTK_ENTRY (widgets->entry)),
"\n", NULL);

/* get the text buffer */
buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (widgets->textview));

/* get end iter */
gtk_text_buffer_get_end_iter (buffer, &iter);

/* add the message to the text buffer */
gtk_text_buffer_insert (buffer, &iter, message, -1);
g_free (message);

/* scroll to end iter */
gtk_text_view_scroll_to_iter (GTK_TEXT_VIEW (widgets->textview),
&iter, 0.0, FALSE, 0, 0);
}

int
main (int argc, char *argv[])
{

GtkWidget *window;
GtkBuilder *builder;
MyWidgets *widgets;
PangoFontDescription *font_desc;
GError *err = NULL;

/* allocate space for widgets struct */
widgets = g_slice_new (MyWidgets);

/* initialize the GTK+ library */
gtk_init (&argc, &argv);

/* Build UI from xml description */
builder = gtk_builder_new ();
gtk_builder_add_from_file (builder, "ui.xml", &err);

if (err)
{
/* There was an error building the interface */
g_error (err->message);
g_error_free (err);
g_slice_free (MyWidgets, widgets);
return 1;
}

/* get widgets from GladeXML object */
window = GTK_WIDGET (gtk_builder_get_object (builder, "window"));
widgets->entry = GTK_WIDGET (gtk_builder_get_object (builder, "entry"));
widgets->textview = GTK_WIDGET (gtk_builder_get_object (builder,
"textview"));

/* connect callback functions passing MyWidgets struct as user_dada */
gtk_builder_connect_signals (builder, widgets);

/* free memory used by builder object and XML */
g_object_unref (G_OBJECT (builder));

/* use a fixed width font on the text view so the output looks proper */
font_desc = pango_font_description_from_string ("monospace 10");
gtk_widget_modify_font (widgets->textview, font_desc);
pango_font_description_free (font_desc);

/* show the main window */
gtk_widget_show (window);

gtk_main ();

/* free space for widget struct */
g_slice_free (MyWidgets, widgets);

return 0;
}