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# Copyright (c) 2015-2016 Ruby-GNOME2 Project Team
# This program is licenced under the same licence as Ruby-GNOME2.
#
=begin
= Theming/Multiple Backgrounds
Gtk themes are written using CSS. Every widget is build of multiple items
that you can style very similarly to a regular website.
=end
class CssMultiplebgsDemo
def initialize(main_window)
@window = Gtk::Window.new(:toplevel)
@window.screen = main_window.screen
@window.title = "Mutiple Backgrounds"
@window.transient_for = main_window
@window.set_default_size(400, 300)
container = Gtk::Overlay.new
container.add_events([:enter_notify_mask, :leave_notify_mask,
:pointer_motion_mask])
@window.add(container)
da = initialize_drawing_area
container.add(da)
button = initialize_bricks_button
container.add_overlay(button)
paned = Gtk::Paned.new(:vertical)
container.add_overlay(paned)
css = "/css_multiplebgs/css_multiplebgs.css"
@default_css = Gio::Resources.lookup_data(css)
# Need a filler so we get a handle
child = Gtk::Box.new(:vertical, 0)
paned.add(child)
initialize_text_buffer
container = Gtk::ScrolledWindow.new
paned.add(container)
child = Gtk::TextView.new(@text)
container.add(child)
initialize_provider
apply_style(@window, @provider)
end
def run
if !@window.visible?
@window.show_all
else
@window.destroy
end
@window
end
private
def apply_style(widget, provider)
style_context = widget.style_context
style_context.add_provider(provider, Gtk::StyleProvider::PRIORITY_USER)
return unless widget.respond_to?(:children)
widget.children.each do |child|
apply_style(child, provider)
end
end
def initialize_drawing_area
da = Gtk::DrawingArea.new
da.name = "canvas"
da.signal_connect "draw" do |widget, cr|
context = widget.style_context
Gtk.render_background(context, cr, 0, 0, widget.allocated_width,
widget.allocated_height)
Gtk.render_frame(context, cr, 0, 0, widget.allocated_width,
widget.allocated_height)
false
end
da
end
def initialize_bricks_button
button = Gtk::Button.new
button.add_events([:enter_notify_mask, :leave_notify_mask,
:pointer_motion_mask])
button.name = "bricks-button"
button.halign = :center
button.valign = :center
button.set_size_request(250, 84)
button
end
def initialize_text_buffer
@text = Gtk::TextBuffer.new
@text.create_tag("warning", "underline" => Pango::UNDERLINE_SINGLE)
@text.create_tag("error", "underline" => Pango::UNDERLINE_ERROR)
@text.text = @default_css
text_buffer_signal_connect_changed
end
def text_buffer_signal_connect_changed
@text.signal_connect "changed" do |buffer|
buffer.remove_all_tags(buffer.start_iter, buffer.end_iter)
modified_text = buffer.get_text(buffer.start_iter,
buffer.end_iter,
false)
begin
@provider.load_from_data(modified_text)
rescue
@provider.load_from_data(@default_css)
end
Gtk::StyleContext.reset_widgets
end
end
def initialize_provider
@provider = Gtk::CssProvider.new
@provider.load_from_data(@default_css)
provider_signal_connect_parsing_error
end
def provider_signal_connect_parsing_error
@provider.signal_connect "parsing-error" do |_css_provider, section, error|
start_i = @text.get_iter_at(:line => section.start_line,
:index => section.start_position)
end_i = @text.get_iter_at(:line => section.end_line,
:index => section.end_position)
tag = error == Gtk::CssProviderError::DEPRECATED ? "warning" : "error"
@text.apply_tag_by_name(tag, start_i, end_i)
end
end
end
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