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return function(parent, dir)
local lgi = require 'lgi'
local GLib = lgi.GLib
local Gtk = lgi.Gtk
local window = Gtk.Window {
title = "Automatic scrolling",
default_width = 600,
default_height = 400,
Gtk.Box {
orientation = 'HORIZONTAL',
spacing = 6,
homogeneous = true,
Gtk.ScrolledWindow {
Gtk.TextView {
id = 'view1',
expand = true,
}
},
Gtk.ScrolledWindow {
Gtk.TextView {
id = 'view2',
expand = true,
}
},
},
}
for i = 1, 2 do
local view = window.child['view' .. i]
local buffer = view.buffer
local timer
if i == 1 then
-- If we want to scroll to the end, including horizontal
-- scrolling, then we just create a mark with right gravity at
-- the end of the buffer. It will stay at the end unless
-- explicitely moved with Gtk.TextBuffer.move_mark().
local mark = buffer:create_mark(nil, buffer:get_end_iter(), false)
local count = 0
timer = GLib.timeout_add(
GLib.PRIORITY_DEFAULT, 50,
function()
-- Insert to the 'end' mark.
buffer:insert(buffer:get_iter_at_mark(mark),
'\n' .. (' '):rep(count)
.. "Scroll to end scroll to end scroll to end "
.."scroll to end ",
-1)
-- Scroll so that the mark is visible onscreen.
view:scroll_mark_onscreen(mark)
-- Move to the next column, or if we got too far, scroll
-- back to left again.
count = (count <= 150) and (count + 1) or 0
return true
end)
else
-- If we want to scroll to the bottom, but not scroll
-- horizontally, then an end mark won't do the job. Just use
-- Gtk.TextView.scroll_mark_onscreen() explicitely when
-- needed.
local count = 0
local mark = buffer:create_mark(nil, buffer:get_end_iter(), true)
timer = GLib.timeout_add(
GLib.PRIORITY_DEFAULT, 100,
function()
-- Insert some text into the buffer.
local iter = buffer:get_end_iter()
buffer:insert(iter,
'\n' .. (' '):rep(count)
.. "Scroll to bottom scroll to bottom scroll to bottom "
.."scroll to bottom ",
-1)
-- Move the iterator to the beginning of line, so we don't
-- scroll in horizontal direction.
iter:set_line_offset(0)
-- Place mark at iter.
buffer:move_mark(mark, iter)
-- Scroll the mark onscreen.
view:scroll_mark_onscreen(mark)
-- Move to the next column, or if we got too far, scroll
-- back to left again.
count = (count <= 40) and (count + 1) or 0
return true
end)
end
-- Make sure that the timer is destroyed when the view is destroyed too.
function view:on_destroy()
GLib.source_remove(timer)
end
end
window:show_all()
return window
end,
"Text Widget/Automatic scrolling",
table.concat {
[[This example demonstrates how to use the gravity of Gtk.TextMarks ]],
[[to keep a text view scrolled to the bottom when appending text.]]
}
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