A reminder using GTK shaped window

26 Apr 2007

The GNU/Linux User Group Catania meets the last thursday of every month. Usually a reminder is sent to mailing list by someone, but the other day a friend of mine started a «reminder contest».

I could not miss it! :)

I wanted something unusual to set the timer, so I decided to use the Heaviside step function:

def u(t):
    if t < 0: return 0
    else: return 1

Obviously not a single unit step! :)

def setTimer(t):
    return u(t) - 0.5 * u(t-TOTAL_HOURS-3) - 0.25 * u(t-TOTAL_HOURS-1)

In this manner the reminder is more dynamic: I use the return value to change the display's frequency.

It's time to write the GUI part!

A shaped window is simply a pixmap where the background pixels are transparent.

An image is worth a thousand words.

Yes, the pizza is our window :)

class PReminder:

    def __init__(self):
        self.window = gtk.Window(gtk.WINDOW_POPUP)
        self.window.set_events(
            self.window.get_events() | gtk.gdk.BUTTON_PRESS_MASK)
        self.window.connect("button_press_event", self.hide)

        # [...]

Using gtk.WINDOW_POPUP makes the window a popup so it will not have a titlebar. In addiction, the button_press_event signal is attached to self.hide callback to hide the reminder:

    def hide(self, *args):
        self.window.hide()
        if self.timerShow:
            gobject.source_remove(self.timerShow)

To masks out everything except for the image we have to use gtk.gdk.Window.shape_combine_mask:

self.window.shape_combine_mask(self.mask, 0, 0)

Changing the window itself as the time for the appointment approaches, can be useful.

    def draw(self):
        w = self.width, self.pangolayout.get_pixel_size()[0]
        offset = (max(w) - min(w)) / 2.

        if self.width < self.pangolayout.get_pixel_size()[0]:
            offset = -offset

        self.mask.draw_rectangle(self.bmgc,
                                True,
                                0, 0,
                                self.pieces * self.pixelpiece,
                                self.height)
        textwidth = self.pangolayout.get_pixel_size()[0]
        self.pixmap.draw_layout(self.bgc,
                                int(offset),
                                int(self.height / 2.),
                                self.pangolayout)
        self.mask.draw_layout(self.wmgc,
                            int(offset),
                            int(self.height / 2.),
                            self.pangolayout)

        self.image = gtk.Image()
        self.image.set_from_pixmap(self.pixmap, self.mask)
        self.image.show()

        self.window.shape_combine_mask(self.mask, 0, 0)

We have to change only the mask to obtain the desired effect.

Checking for last thursday of every month can be done in few line of code using dateutil:

    lastThursday = rrule.rrule(rrule.MONTHLY,
                                byweekday=rrule.TH(-1),
                                count=1)[0].date()

The complete checking method:

    def check(self):
        today = datetime.today()
        lastThursday = rrule.rrule(rrule.MONTHLY,
                                    byweekday=rrule.TH(-1),
                                    count=1)[0].date()

        if today.date() == lastThursday:
            now = today.time()
            if START_CHECK_HOUR <= now <= FINISH_CHECK_HOUR:
                timerModulator = setTimer(now.hour - START_CHECK_HOUR.hour)
                timer = int(timerModulator * 60 * 60 * 1000)
                self.setText(DIPLAYING_TEXT)
                self.setPiece(now.hour - START_CHECK_HOUR.hour)

                self.show()
                self.timerShow = gobject.timeout_add(AUTO_HIDE_AFTER * 1000,
                                                        self.hide)
        else:
            timer = CHECK_TIMER * 1000

        self.timerID = gobject.timeout_add(timer, self.check)

You can download the complete source code here: preminder-0.1.zip.