drag move charm #1

When we want to move a window on the desktop, we grab the title bar of the window, move it with keeping on grabbing, and release it. Thus we can do it with title bar, but cannot otherwise.

In the graphics-dojo's example "drag move charm", we can move the window not only with grabbing title bar, but also with grabbing top level widget. I learn this example and start to write by QtRuby like below:

require 'Qt4'

class DragMoveData
attr_accessor :moving, :start_drag
alias :moving? :moving
end

class DragMoveCharm < Qt::Object

def initialize parent = nil
super
@drag_move_data = {}
end

def activate_on widget
unless @drag_move_data.include?(widget)
data = DragMoveData.new
data.start_drag = Qt::Point.new(0, 0)
data.moving = false
@drag_move_data[widget] = data
widget.install_event_filter(self)
end
end

def deactivate_from widget
@drag_move_data.delete(widget)
widget.remove_event_filter(self)
end

protected
def event_filter(widget, event)
consumed = widget.is_a?(Qt::Widget)
if consumed
type = event.type
case(type)
when Qt::Event::MouseButtonPress,
Qt::Event::MouseButtonRelease,
Qt::Event::MouseMove
consumed = event.kind_of?(Qt::MouseEvent) &&
event.modifiers == Qt::NoModifier &&
@drag_move_data.include?(widget)
if consumed
data = @drag_move_data[widget]
case(type)
when Qt::Event::MouseButtonPress
consumed = event.button == Qt::LeftButton
if consumed
data.start_drag = event.global_pos
data.moving = true
end
when Qt::Event::MouseButtonRelease
data.start_drag = Qt::Point.new(0, 0)
data.moving = false
consumed = false
when Qt::Event::MouseMove
consumed = data.moving?
if consumed
pos = event.global_pos
widget.move(widget.pos + pos - data.start_drag)
data.start_drag = pos;
end
end
end
else
consumed = false
end
end
consumed
end

alias :eventFilter :event_filter
end

and main codes to execute above classes:

require 'dragmovecharm'
require 'qtwebkit'

def image_show
Qt::Label.new do
self.text = "<img src='#{::File.dirname($PROGRAM_NAME)}/pudding.jpg'>"
self.adjust_size
self.window_title = 'Drag to move around'
show
end
end

def mini_browser
Qt::Dialog.new do
self.layout = Qt::VBoxLayout.new do
self.set_contents_margins(3, 15, 3, 3)
end
self.window_flags = Qt::FramelessWindowHint
self.size_grip_enabled = true
self.window_title = 'Drag to move around'
show

tab = Qt::TabWidget.new(self) do
search = Qt::WebView.new(self)
search.load(Qt::Url.new('http://www.google.com/m?hl=en'))
search.set_focus
self.add_tab(search, 'Search')
news = Qt::WebView.new(self)
news.load(Qt::Url.new('http://www.google.com/m/news?source=mobileproducts'))
self.add_tab(news, 'News')
bbc = Qt::WebView.new(self)
bbc.load(Qt::Url.new('http://news.bbc.co.uk/text_only.stm'))
self.add_tab(bbc, 'BBC')
fb = Qt::WebView.new(self)
fb.load(Qt::Url.new('http://iphone.facebook.com'))
self.add_tab(fb, 'Facebook')
end

self.layout.add_widget(tab)
self.resize(350, 500)
(tab.document_mode = true) if Qt::version >= '4.5'
end
end

Qt::Application.new(ARGV) do
charm = DragMoveCharm.new
charm.activate_on(image_show)
charm.activate_on(mini_browser)
exec
end

Run these codes, 2 charms(widgets) is shown successfully.

But, these can only be moved with grabbing title bar. These yet cannot be moved with grabbing top level widget. to be continued...