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return function(parent, dir)
local lgi = require 'lgi'
local Gtk = lgi.Gtk
local Gdk = lgi.Gdk
local Pango = lgi.Pango
local window = Gtk.Window {
title = "Hypertext",
default_width = 450,
default_height = 450,
Gtk.ScrolledWindow {
Gtk.TextView {
id = 'textview',
wrap_mode = 'WORD',
},
},
}
-- Sample hypertext content.
local content = {
intro = [[
Some text to show that simple [hypertext hypertext] can easily be realized with [tags tags].
]],
hypertext = [[
*hypertext:*
machine-readable text that is not sequential but is organized so that related items of information are connected.
[intro Go back]
]],
tags = [[
A tag is an attribute that can be applied to some range of text. For example, a tag might be called "bold" and make the text inside the tag bold. However, the tag concept is more general than that; tags don't have to affect appearance. They can instead affect the behavior of mouse and key presses, "lock" a range of text so the user can't edit it, or countless other things.
[intro Go back]
]],
}
local active_links
local handlers = {
['^([^%[%*]+)'] =
-- Plaintext.
function(text)
return text
end,
['^%[(%w+) ([^%]]+)%]'] =
-- Link.
function(link, text)
local tag = Gtk.TextTag {
foreground = 'blue',
underline = Pango.Underline.SINGLE,
}
active_links[tag] = link
return text, tag
end,
['^%*([^%*]+)%*'] =
-- Bold text.
function(text)
return text, Gtk.TextTag {
weight = Pango.Weight.BOLD,
}
end,
}
local function fill_page(page)
local buffer = window.child.textview.buffer
buffer.text = ''
active_links = {}
if not page then return end
local iter = buffer:get_iter_at_offset(0)
local pos = 1
repeat
for pattern, handler in pairs(handlers) do
local start, stop, m1, m2 = page:find(pattern, pos)
if start then
-- Extract next part of the text.
local text, tag = handler(m1, m2)
-- Add text into the buffer.
start = iter:get_offset()
buffer:insert(iter, text, -1)
-- Apply tag, if available.
if tag then
buffer.tag_table:add(tag)
buffer:apply_tag(tag, buffer:get_iter_at_offset(start), iter)
end
-- Prepare for the next iteration.
pos = stop + 1
break
end
end
until pos >= #page
end
local cursors = {
[true] = Gdk.Cursor.new('HAND2'),
[false] = Gdk.Cursor.new('XTERM'),
}
local hovering = false
local function set_cursor_if_appropriate(view, x, y)
local tags = view:get_iter_at_location(x, y):get_tags()
local should_hover = false
for i = 1, #tags do
if active_links[tags[i]] then
should_hover = true
break
end
end
if hovering ~= should_hover then
hovering = should_hover
view:get_window('TEXT'):set_cursor(cursors[hovering])
end
end
local textview = window.child.textview
function textview:on_motion_notify_event(event)
set_cursor_if_appropriate(
self, self:window_to_buffer_coords('WIDGET', event.x, event.y))
return false
end
function textview:on_visibility_notify_event(event)
local x, y = self.window:get_pointer()
if x and y then
set_cursor_if_appropriate(
self, self:window_to_buffer_coords('WIDGET', x, y))
end
return false
end
local function follow_if_link(view, iter)
for _, tag in ipairs(iter:get_tags()) do
if active_links[tag] then
fill_page(content[active_links[tag]])
break
end
end
end
function textview:on_event_after(event)
if event.type == 'BUTTON_RELEASE' and event.button.button == 1 then
-- Don't follow link if anything is selected.
local start, stop = self.buffer:get_selection_bounds()
if not start or not stop or start:get_offset() == stop:get_offset() then
follow_if_link(self, self:get_iter_at_location(
self:window_to_buffer_coords(
'WIDGET', event.button.x, event.button.y)))
end
end
end
function textview:on_key_press_event(event)
if event.keyval == Gdk.KEY_Return or event.keyval == Gdk.KEY_KP_Enter then
follow_if_link(
self, self.buffer:get_iter_at_mark(self.buffer:get_insert()))
end
return false
end
-- Initially fill the intro page.
fill_page(content.intro)
window:show_all()
return window
end,
"Text Widget/Hypertext",
table.concat {
[[Usually, tags modify the appearance of text in the view, ]],
[[e.g. making it bold or colored or underlined. But tags are not ]],
[[restricted to appearance. They can also affect the behavior of ]],
[[mouse and key presses, as this demo shows.]],
}
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