path: root/src/sugar/tutorius/overlayer.py

"""
This guy manages drawing of overlayed widgets. The class responsible for drawing
management (Overlayer) and overlayable widgets are defined here.
"""
# Copyright (C) 2009, Tutorius.org
#
# 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 gobject
import gtk
import cairo
import pangocairo

class CanvasDrawable(object):
    """Defines the CanvasDrawable protocol"""
    should_expose = None
    def drawWithContext(self, context): pass


class Overlayer(gtk.Layout):
    """
    This guy manages drawing of overlayed widgets. Those can be standard GTK
    widgets or special "cairoDrawable" widgets which support the defined
    interface (see the put method).
    """
    def __init__(self):
        gtk.Layout.__init__(self)

        # no overlayed child yet
        self.__overlayed = None

##        win.connect("expose-event", self.__transparent_overlay)
        self.__realizer = self.connect("expose-event", self.__init_realized)
        self.connect("size-allocate", self.__size_allocate)
        self.show()

##        win.show_all()

##        win.connect_after("expose-event", self.__expose_overlay)

    def reparent(self, parent):
        """Reparent this widget as child of parent instead."""
        self.__realizer = self.connect("expose-event", self.__init_realized)
        gtk.Layout.reparent(self, parent)

    def inject(self, child):
        """
        Insert this widget at "child" level so that it can overlay "child".
        """
        assert not self.__overlayed, "trying to reinject while already injected"
        parent = child.parent
        self.__overlayed = child
        child.reparent(self)
        parent.add(self)
        self.__realizer = parent.connect("expose-event", self.__init_realized)

    def put(self, child, x, y):
        """
        Adds a child widget to be overlayed. This can be, overlay widgets or
        normal GTK widgets (though normal widgets will alwas appear under
        cairo widgets due to the rendering chain).
        """
        if hasattr(child, "should_expose"):
            # if the widget has the CanvasDrawable protocol, use it.
            # protocol is defined as
            # should_expose property with setter to flag as not drawn using
            #               expose-events
            # drawWithContext(context) method to pass a context to draw with.
            child.should_expose = True
        gtk.Layout.put(self, child, x, y)

    def eject(self):
        """
        Remove this widget from the widget hierarchy without affecting its
        children.
        """
        parent = self.parent
        parent.disconnect(self.__render_handle)
        assert hasattr(parent, "remove"), "parent should be a container"
        self.parent.remove(self)
        self.__overlayed.reparent(parent)
        self.__overlayed = None

    def __init_realized(self, widget, event):
        """
        Initializer to set once widget is realized.
        Since an expose event is signaled only to realized widgets, we set this
        callback for the first expose run. It should also be called after
        beign reparented to ensure the window used for drawing is set up.
        """
        assert hasattr(self.window, "set_composited"), \
            "compositing not supported or widget not realized."
        self.disconnect(self.__realizer)
        del self.__realizer

        # use RGBA on overlayer so that when we paint we don't cover what's
        # under
        screen = self.get_screen()
        rgba_map = screen.get_rgba_colormap()
        self.set_colormap(rgba_map) # will fail if already realized
        # app paintable will ensure that what we draw isn't erased by gtk
        self.parent.set_app_paintable(True)

        # the parent is composited, so we can access gtk's rendered buffer
        # and overlay over. If we don't composite, we won't be able to read
        # pixels and background will be black.
        self.window.set_composited(True)
        self.__render_handle = self.parent.connect_after("expose-event", \
            self.__expose_overlay)

    def __expose_overlay(self, widget, event):
        """expose event handler to draw the thing."""
        #get our child (in this case, the event box)
        child = widget.get_child()

        #create a cairo context to draw to the window
        ctx = widget.window.cairo_create()

        #the source data is the (composited) event box
        ctx.set_source_pixmap(child.window,
                              child.allocation.x,
                              child.allocation.y)

        #draw no more than our expose event intersects our child
##        region = gtk.gdk.region_rectangle(child.allocation)
##        rect = gtk.gdk.region_rectangle(event.area)
##        region.intersect(rect)
##        ctx.region (region)
##        ctx.clip()

        ctx.set_operator(cairo.OPERATOR_OVER)
        # has to be blended and a 1.0 alpha would not make it blend
        ctx.paint_with_alpha(0.99)

        #draw overlay
        for drawn_child in self.get_children():
            if hasattr(drawn_child, "drawWithContext"):
                drawn_child.drawWithContext(ctx)


    def __size_allocate(self, widget, allocation):
        """set size allocation (actual gtk widget size) and propagate it to overlayed child"""
        self.allocation = allocation
        # One may wonder why using size_request instead of size_allocate;
        # Since widget is laid out in a Layout box, the Layout will honor the
        # requested size. Using size_allocate could make a nasty nested loop in
        # some cases.
        self.__overlayed.set_size_request(allocation.width, allocation.height)


class TextBubble(gtk.Widget):
    def __init__(self, text, speaker=None, tailpos=None):
        """
        Creates a new cairo rendered text bubble.

        @param text the text to render in the bubble
        @param speaker the widget to associate with the bubble tail
        @param tailpos an optional position for the tail if no speaker
        """
        gtk.Widget.__init__(self)

        ##self.set_app_paintable(True) # else may be blank
         # FIXME ensure previous call does not interfere with widget stacking
        self.label = text
        self.speaker = speaker
        self.tailpos = tailpos
        self.lineWidth = 5

        self.connect("expose-event", self.__on_expose)

    def drawWithContext(self, context):
        """
        Draw using the passed cairo context instead of creating a new cairo
        context. This eases blending between multiple cairo-rendered
        widgets.
        """
        context.translate(self.allocation.x, self.allocation.y)
        width = self.allocation.width
        height = self.allocation.height
        xradius = width/2
        yradius = height/2
        width -= self.lineWidth
        height -= self.lineWidth

        # TODO fetch speaker coordinates

        # draw bubble tail
        if self.tailpos:
##            speaker_alloc = self.speaker.get_allocation()
            context.move_to(xradius-40, yradius)
            context.line_to(self.tailpos[0], self.tailpos[1])
##            context.line_to(speaker_alloc.x-self.allocation.x,
##                speaker_alloc.y - self.allocation.y)
            context.line_to(xradius+40, yradius)
            context.set_source_rgb(1.0, 1.0, 0.0)
            context.fill_preserve()
            context.set_line_width(self.lineWidth)
            context.set_source_rgb(0.0, 0.0, 0.0)
            context.stroke()

        # bubble
        context.move_to(self.lineWidth, yradius)
        context.curve_to(self.lineWidth, self.lineWidth,
            self.lineWidth, self.lineWidth, xradius, self.lineWidth)
        context.curve_to(width, self.lineWidth,
            width, self.lineWidth, width, yradius)
        context.curve_to(width, height, width, height, xradius, height)
        context.curve_to(self.lineWidth, height,
            self.lineWidth, height, self.lineWidth, yradius)
        context.set_source_rgb(1.0, 1.0, 0.0)
        context.fill_preserve()
        context.set_line_width(self.lineWidth)
        context.set_source_rgb(0.0, 0.0, 0.0)
        context.stroke()

        # text
        # FIXME create layout in realize method
        pangoctx = pangocairo.CairoContext(context)
        text_layout = pangoctx.create_layout()
        text_layout.set_text(self.__label)
        pangoctx.move_to(int((self.allocation.width-self.__text_dimentions[0])/2),
            int((self.allocation.height-self.__text_dimentions[1])/2))
        pangoctx.show_layout(text_layout)

        # work done. Be kind to next cairo widgets and reset matrix.
        context.identity_matrix()

    def do_realize(self):
        self.set_flags(gtk.REALIZED | gtk.NO_WINDOW)
        self.window = self.get_parent_window()

    def __on_expose(self, widget, event):
        """Redraw event callback."""
        # TODO
        ctx = self.window.cairo_create()

        # set drawing region. Useless since this widget has its own window.
##        region = gtk.gdk.region_rectangle(self.allocation)
##        region.intersect(gtk.gdk.region_rectangle(event.area))
##        ctx.region(region)
##        ctx.rectangle(event.area.x, event.area.y, event.area.width, event.area.height)
##        ctx.clip()

        ##import pdb; pdb.set_trace()
        ##ctx.set_operator(cairo.OPERATOR_CLEAR)
        ##ctx.paint()
        ##ctx.set_operator(cairo.OPERATOR_OVER)

        self.drawWithContext(ctx)

        return True

    def _set_label(self, value):
        """Sets the label and flags the widget to be redrawn."""
        # yes we use the setter
        self.__label = value
        # FIXME hack to calculate size. necessary because may not have been
        # realized
        surf = cairo.SVGSurface("/dev/null", 0, 0)
        ctx = cairo.Context(surf)
        pangoctx = pangocairo.CairoContext(ctx)
        text_layout = pangoctx.create_layout()
        text_layout.set_text(value)
        self.__text_dimentions = text_layout.get_pixel_size()
        del text_layout, pangoctx, ctx, surf

    def do_size_request(self, requisition):
        width, height = self.__text_dimentions

        # FIXME bogus values follows
        requisition.width = int(width+30)
        requisition.height = int(height+40)

    def do_size_allocate(self, allocation):
        self.allocation = allocation

    def _get_label(self):
        """Getter method for the label property"""
        return self.__label

    def _set_will_expose(self, value):
        """setter for will_expose property"""
        if self.__exposer and not value:
            self.disconnect(self.__exposer)
        elif not (self.__exposer or value):
            self.__exposer = self.connect(self.__on_expose)

    should_expose = property(fset=_set_will_expose)

    label = property(fget=_get_label, fset=_set_label,\
        doc="Text label which is to be painted on the top of the widget")

gobject.type_register(TextBubble)


# vim:set ts=4 sts=4 sw=4 et: