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path: root/canvas.py
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# Copyright (C) 2009, Tomeu Vizoso
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

import logging

import gobject
import gtk

from sugar import dispatch

class Canvas(gtk.DrawingArea):

    __gtype_name__ = 'MindMapCanvas'
    
    def __init__(self):
        self._elements = []
        self._pressed_button = None
        self._press_start_x = None
        self._press_start_y = None
        self._last_clicked_element = None
        self._dragging = False

        gobject.GObject.__init__(self)

        self.dragging_started = dispatch.Signal()
        self.dragging_motion = dispatch.Signal()
        self.dragging_finished = dispatch.Signal()

        self.add_events(gtk.gdk.BUTTON_PRESS_MASK |
                        gtk.gdk.BUTTON_RELEASE_MASK |
                        gtk.gdk.POINTER_MOTION_MASK |
                        gtk.gdk.POINTER_MOTION_HINT_MASK)

        self.connect('expose-event', self.__expose_event_cb)
        self.connect('button-press-event', self.__button_press_event_cb)
        self.connect('button-release-event', self.__button_release_event_cb)
        self.connect('motion-notify-event', self.__motion_notify_event_cb)

    def __expose_event_cb(self, widget, event):
        context = self.window.cairo_create()

        rect = self.get_allocation()
        rect.x = 0
        rect.y = 0

        context.rectangle(event.area.x, event.area.y,
                          event.area.width, event.area.height)
        context.clip()

        context.set_source_rgb(1.0, 1.0, 1.0)
        context.paint()

        for element in self._elements:
            rect = element.get_rect()
            if rect.intersect(event.area):
                context.save()

                context.rectangle(rect.x, rect.y, rect.width, rect.height)
                context.clip()

                element.draw(context)

                context.restore()

        return False

    def get_element_at(self, x, y):
        for element in self._elements:
            rect = element.get_rect()
            if (x >= rect.x and x <= rect.x + rect.width) and \
                    (y >= rect.y and y <= rect.y + rect.height):
                return element
        return None

    def _invalidate(self, x, y, width, height):
        if self.window is None:
            return
        rect = gtk.gdk.Rectangle(x, y, width, height)
        self.window.invalidate_rect(rect, True)
        self.window.process_updates(True)

    def add_element(self, element):
        element.invalidated.connect(self.__element_invalidated_cb)
        self._elements.append(element)
        rect = element.get_rect()
        self._invalidate(rect.x, rect.y, rect.width, rect.height)

    def remove_all_elements(self):
        rect = gtk.gdk.Rectangle(0, 0, 0, 0)
        for element in self._elements:
            rect.union(element.get_rect())

        self._invalidate(rect.x, rect.y, rect.width, rect.height)

        self._elements = []

    def get_elements(self):
        return self._elements

    def __element_invalidated_cb(self, **kwargs):
        element = kwargs['sender']

        rect = element.previous_rect
        self._invalidate(rect.x, rect.y, rect.width, rect.height)

        rect = element.get_rect()
        self._invalidate(rect.x, rect.y, rect.width, rect.height)

    def __button_press_event_cb(self, widget, event):
        logging.debug('button_press_event_cb')

        if event.button == 1 and event.type == gtk.gdk.BUTTON_PRESS:
            self._last_clicked_element = self.get_element_at(event.x, event.y)
            logging.debug('button_press_event_cb %r' % self._last_clicked_element)
            if self._last_clicked_element is not None:
                self._pressed_button = event.button
                self._press_start_x = event.x
                self._press_start_y = event.y

        return False

    def __button_release_event_cb(self, widget, event):
        logging.debug('button_release_event_cb')
        if self._dragging:
            self.dragging_finished.send(self, position=(event.x, event.y),
                                        element=self._last_clicked_element)
            self._cleanup_drag()
            return True

        return False

    def _cleanup_drag(self):
        self._last_clicked_element = None
        self._pressed_button = None
        self._press_start_x = None
        self._press_start_y = None
        self._dragging = False

    def __motion_notify_event_cb(self, widget, event):
        if self._last_clicked_element is None:
            for element in self._elements:
                rect = element.get_rect()
                if (event.x >= rect.x and event.x <= rect.x + rect.width) and \
                        (event.y >= rect.y and event.y <= rect.y + rect.height):
                    element.hovering = True
                else:
                    element.hovering = False
            return False

        # if the mouse button is not pressed, no drag should occurr
        if not event.state & gtk.gdk.BUTTON1_MASK:
            self._cleanup_drag()
            return False

        if event.is_hint:
            x, y, state_ = event.window.get_pointer()
        else:
            x = event.x
            y = event.y

        if self._dragging:
            self.dragging_motion.send(self, position=(x, y))
            return False

        logging.debug('motion_notify_event_cb')

        if self.drag_check_threshold(int(self._press_start_x),
                                     int(self._press_start_y),
                                     int(x),
                                     int(y)):
            self._dragging = True
            self.dragging_started.send(self, position=(x, y),
                                       element=self._last_clicked_element)

        return False

class CanvasElement(object):
    def __init__(self):
        self.invalidated = dispatch.Signal()
        self.previous_rect = gtk.gdk.Rectangle(0, 0, 0, 0)
        self._hovering = False

    def draw(self, context):
        self.previous_rect = self.get_rect()

    def invalidate(self):
        self.invalidated.send(self)

    def get_rect(self):
        pass

    def set_hovering(self, hovering):
        if self._hovering != hovering:
            self._hovering = hovering
            self.invalidate()

    def get_hovering(self):
        return self._hovering

    hovering = property(get_hovering, set_hovering)