How to auto-scroll a gtk.scrolledwindow?

Question

I have a treeview-widget inside a ScrolledWindow, which is populated during runtime. I want the ScrolledWindow to auto-scroll to the end of the list. I "solved" the problem, by adjusting the vadjustment of the ScrolledWindow, everytime a row is inserted into the treeview. e.g:

if new_line_in_row:
   adj = self.scrolled_window.get_vadjustment()
   adj.set_value( adj.upper - adj.page_size )

If i run the code in an interactive ipython session and set the value by myself, everything works as expected.

If i run the code with the default python interpreter, the auto-scroll doesn't work all the time. I debugged the code and the problem seems be, that the adjustment values have some kind of "lag" and are only changed after some period of time.

My question is: how do I scroll, reliably, to maximum position of the ScrolledWindow? is a special signal generated which i can use? or is there a better way to set the adjustment-value?

Good question. I have wanted to know this for a _long_ time. It came out of [this question](http://stackoverflow.com/questions/2659026/painting-on-gtkscrolledwindow-or-gtkeventbox), which I even offered a bounty of 150 on but didn't get the answer I hoped. — ptomato, Mar 07 '11 at 22:05

score 29 · Accepted Answer · answered Mar 08 '11 at 16:34

After widening my search-radius, i found a ruby-related answer. since the problem is gtk-related, it should be able to be solved in any language like this:

you connect the widget which changes, in my case the treeview, with gtk.widget's 'size-allocate' signal and set the gtk.scrolledwindow value to "upper - page_size". example:

self.treeview.connect('size-allocate', self.treeview_changed)

...

def treeview_changed(self, widget, event, data=None):
    adj = self.scrolled_window.get_vadjustment()
    adj.set_value( adj.upper - adj.page_size )

link to the original post at ruby-forum.com:

hint hint

the member variables seem to be hidden now. use get_upper() and get_page_size() instead — Fookatchu, Oct 31 '13 at 09:57

score 8 · Answer 2 · edited Dec 16 '14 at 15:11

8

Python Gtk 3 version:

adj.set_value(adj.get_upper() - adj.get_page_size())

edited Dec 16 '14 at 15:11

BlackVegetable

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answered Dec 16 '14 at 01:10

Federico

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This does not work in eg. a gtk.treeview: `adj`'s values are updated later, so mostly, the last added row will not appear. – jcoppens Jul 13 '17 at 15:19

score 8 · Answer 3 · answered Jan 15 '12 at 06:52

8

fookatchu's answer can be improved so that the callback could be used by multiple widgets:

def treeview_changed( self, widget, event, data=None ):
    adj = widget.get_vadjustment()
    adj.set_value( adj.upper - adj.pagesize )

answered Jan 15 '12 at 06:52

Chuck R

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ddubson · Answer 4 · 2020-06-20T20:46:01.607

The accepted answer has helped me figure out a Rust solution in gtk-rs to the auto-scroll to end of content issue.

Here's a Rust snippet that might help others:

// Imports used for reference
use gtk::{TextBuffer, TextView, TextBufferBuilder, ScrolledWindow, ScrolledWindowBuilder};

// The text buffer where the text is appended later
let text_buffer: TextBuffer = TextBufferBuilder::new().build();

// The containing text view that holds the text buffer
let text_view: TextView = TextView::new_with_buffer(&text_buffer);

// The scrolled window container with fixed height/width that holds the text view
let scrolled_window: ScrolledWindow = ScrolledWindowBuilder::new()
        .min_content_height(400)
        .min_content_width(600)
        .child(&text_view)
        .build();

// Have the text view connect to signal "size-allocate"
text_view.connect_size_allocate(clone!(@weak scrolled_window => move |_,_| {
   let adj = scrolled_window.get_vadjustment().unwrap();
   adj.set_value(adj.get_upper() - adj.get_page_size());
}));

// ...
// Later on, fill buffer with some text.
text_buffer.insert(&mut text_buffer.get_end_iter(), "This is my text I'm adding");

Just a note that this doesn't work with Gtk4 because the `size-allocate` signal was removed. — Herohtar, Dec 15 '21 at 05:34

score 2 · Answer 5 · answered Feb 18 '22 at 20:45

None of the suggested solutions worked for me, but I was able to get the desired behavior doing this (using GTk4 bindings for Go):

adj := scrolledWindow.VAdjustment()
adj.SetUpper(adj.Upper() + adj.PageSize())
adj.SetValue(adj.Upper())

The other solutions would move the scrolled window (mine contained a list box) down to the 2nd-to-last item, but not show the last item. The way it was acting made me think that the upper limit needed to be increased, so I tried increasing it by page-size then setting the scroll value to the new upper limit.

FWIW that also works for GTK3, thank for the answer! – Jayson Reis Jul 19 '23 at 17:37 — Jayson Reis, Jul 19 '23 at 17:37

score 0 · Answer 6 · answered Apr 25 '20 at 12:16

Still need the callback (I used a textView rather than treeView):

textView = Gtk.TextView()
scrolledWindow = Gtk.ScrolledWindow()

def textViewChanged( self, widget ):
    adjustment = scrolledWindow.get_vadjustment()
    adjustment.set_value( adjustment.get_upper() - adjustment.get_page_size() )

textView.connect( "size-allocate", textViewChanged )

How to auto-scroll a gtk.scrolledwindow?

6 Answers6