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"""
This module manages drawing of overlayed widgets. The class responsible for
drawing management (Overlayer) and basic 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
from math import pi

from sugar import profile

# for easy profile access from cairo
color = profile.get_color().get_stroke_color()
xo_line_color = (int(color[1:3], 16)/255.0,
                 int(color[3:5], 16)/255.0,
                 int(color[5:7], 16)/255.0)
color = profile.get_color().get_fill_color()
xo_fill_color = (int(color[1:3], 16)/255.0,
                 int(color[3:5], 16)/255.0,
                 int(color[5:7], 16)/255.0)
del color

# This is the CanvasDrawable protocol. Any widget wishing to be drawn on the
# overlay must implement it. See TextBubble for a sample implementation.
#class CanvasDrawable(object):
#    """Defines the CanvasDrawable protocol"""
#    no_expose = None
#    def draw_with_context(self, context):
#        """
#            Draws the cairo widget with the passed cairo context.
#            This will be called if the widget is child of an overlayer.
#        """
#        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).

    @param overlayed widget to be overlayed. Will be resized to full size.
    """
    def __init__(self, overlayed=None):
        gtk.Layout.__init__(self)

        self._overlayed = overlayed
        if overlayed:
            self.put(overlayed, 0, 0)

        self.__realizer = self.connect_after("realize", self.__init_realized)
        self.connect("size-allocate", self.__size_allocate)
        self.show()

        self.__render_handle = None

    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).

        @param child the child to add
        @param x the horizontal coordinate for positionning
        @param y the vertical coordinate for positionning
        """
        if hasattr(child, "draw_with_context"):
            # if the widget has the CanvasDrawable protocol, use it.
            child.no_expose = True
        gtk.Layout.put(self, child, x, y)

        # be sure to redraw or the overlay may not show
        self.queue_draw()


    def __init_realized(self, widget):
        """
        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

        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()[1:]:
            if hasattr(drawn_child, "draw_with_context"):
                drawn_child.draw_with_context(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):
    """
    A CanvasDrawableWidget drawing a round textbox and a tail pointing
    to a specified widget.
    """
    def __init__(self, text, speaker=None, tailpos=(0,0)):
        """
        Creates a new cairo rendered text bubble.

        @param text the text to render in the bubble
        @param speaker the widget to compute the tail position from
        @param tailpos (optional) position relative to the bubble to use as 
            the tail position, if no speaker
        """
        gtk.Widget.__init__(self)

        # FIXME: ensure previous call does not interfere with widget stacking,
        # as using a gtk.Layout and stacking widgets may reveal a screwed up
        # order with the cairo widget on top.
        self.__label = None

        self.label = text
        self.speaker = speaker
        self.tailpos = tailpos
        self.line_width = 5
        self.padding = 20

        self._no_expose = False
        self.__exposer = None

    def draw_with_context(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.line_width
        height -= self.line_width
        #
        # TODO fetch speaker coordinates

        # draw bubble tail if present
        if self.tailpos != (0,0):
            context.move_to(xradius-width/4, yradius)
            context.line_to(self.tailpos[0], self.tailpos[1])
            context.line_to(xradius+width/4, yradius)
            context.set_line_width(self.line_width)
            context.set_source_rgb(*xo_line_color)
            context.stroke_preserve()

        # bubble border
        context.move_to(width-self.padding, 0.0)
        context.line_to(self.padding, 0.0)
        context.arc_negative(self.padding, self.padding, self.padding,
                             3*pi/2, pi)
        context.line_to(0.0, height-self.padding)
        context.arc_negative(self.padding, height-self.padding, self.padding,
                             pi, pi/2)
        context.line_to(width-self.padding, height)
        context.arc_negative(width-self.padding, height-self.padding,
                             self.padding, pi/2, 0)
        context.line_to(width, self.padding)
        context.arc_negative(width-self.padding, self.padding, self.padding,
                             0.0, -pi/2)
        context.set_line_width(self.line_width)
        context.set_source_rgb(*xo_line_color)
        context.stroke_preserve()
        context.set_source_rgb(*xo_fill_color)
        context.fill()

        # bubble painting. Redrawing the inside after the tail will combine
        if self.tailpos != (0,0):
            context.move_to(xradius-width/4, yradius)
            context.line_to(self.tailpos[0], self.tailpos[1])
            context.line_to(xradius+width/4, yradius)
            context.set_line_width(self.line_width)
            context.set_source_rgb(*xo_fill_color)
            context.fill()

        context.set_source_rgb(1.0, 1.0, 1.0)
        pangoctx = pangocairo.CairoContext(context)
        self._text_layout.set_markup(self.__label)
        text_size = self._text_layout.get_pixel_size()
        pangoctx.move_to(
            int((self.allocation.width-text_size[0])/2),
            int((self.allocation.height-text_size[1])/2))
        pangoctx.show_layout(self._text_layout)

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

    def do_realize(self):
        """ Setup gdk window creation. """
        self.set_flags(gtk.REALIZED | gtk.NO_WINDOW)
        self.window = self.get_parent_window()
        if not self._no_expose:
            self.__exposer = self.connect_after("expose-event", \
                                                self.__on_expose)

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

        self.draw_with_context(ctx)

        return True

    def _set_label(self, value):
        """Sets the label and flags the widget to be redrawn."""
        self.__label = "<b>%s</b>"%value
        if not self.parent:
            return
        ctx = self.parent.window.cairo_create()
        pangoctx = pangocairo.CairoContext(ctx)
        self._text_layout = pangoctx.create_layout()
        self._text_layout.set_markup(value)
        del pangoctx, ctx#, surf

    def do_size_request(self, requisition):
        """Fill requisition with size occupied by the widget."""
        ctx = self.parent.window.cairo_create()
        pangoctx = pangocairo.CairoContext(ctx)
        self._text_layout = pangoctx.create_layout()
        self._text_layout.set_markup(self.__label)

        width, height = self._text_layout.get_pixel_size()
        requisition.width = int(width+2*self.padding)
        requisition.height = int(height+2*self.padding)

    def do_size_allocate(self, allocation):
        """Save zone allocated to the widget."""
        self.allocation = allocation

    def _get_label(self):
        """Getter method for the label property"""
        return self.__label[3:-4]

    def _set_no_expose(self, value):
        """setter for no_expose property"""
        self._no_expose = value
        if not (self.flags() and gtk.REALIZED):
            return

        if self.__exposer and value:
            self.parent.disconnect(self.__exposer)
            self.__exposer = None
        elif (not self.__exposer) and (not value):
            self.__exposer = self.parent.connect_after("expose-event",
                self.__on_expose)

    def _get_no_expose(self):
        """getter for no_expose property"""
        return self._no_expose

    no_expose = property(fset=_set_no_expose, fget=_get_no_expose,
        doc="Whether the widget should handle exposition events or not.")

    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)

class Rectangle(gtk.Widget):
    """
    A CanvasDrawableWidget drawing a rectangle over a specified widget.
    """
    def __init__(self, widget, color):
        """
        Creates a new Rectangle

        @param widget the widget to cover
        @param color the color of the rectangle, as a 4-tuple RGBA
        """
        gtk.Widget.__init__(self)

        self.covered = widget
        self.color = color

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

    def draw_with_context(self, context):
        """
        Draw using the passed cairo context instead of creating a new cairo
        context. This eases blending between multiple cairo-rendered
        widgets.
        """
        if self.covered is None:
            # nothing to hide, no coordinates, no drawing
            return
        mask_alloc = self.covered.get_allocation()
        x, y = self.covered.translate_coordinates(self.parent, 0, 0)

        context.rectangle(x, y, mask_alloc.width, mask_alloc.height)
        context.set_source_rgba(*self.color)
        context.fill()

    def do_realize(self):
        """ Setup gdk window creation. """
        self.set_flags(gtk.REALIZED | gtk.NO_WINDOW)

        self.window = self.get_parent_window()
        if not isinstance(self.parent, Overlayer):
            assert False, "%s should not realize" % type(self).__name__
            print "Danger, Will Robinson! Rectangle parent is not Overlayer"

    def __on_expose(self, widget, event):
        """Redraw event callback."""
        assert False, "%s wasn't meant to be exposed by gtk" % \
                      type(self).__name__
        ctx = self.window.cairo_create()

        self.draw_with_context(ctx)

        return True

    def do_size_request(self, requisition):
        """Fill requisition with size occupied by the masked widget."""
        # This is a bit pointless, as this will always ignore allocation and
        # be rendered directly on overlay, but for sanity, let's put some values
        # in there.
        if not self.covered:
            requisition.width = 0
            requisition.height = 0
            return

        masked_alloc = self.covered.get_allocation()
        requisition.width = masked_alloc.width
        requisition.height = masked_alloc.height

    def do_size_allocate(self, allocation):
        """Save zone allocated to the widget."""
        self.allocation = allocation

    def _set_no_expose(self, value):
        """setter for no_expose property"""
        if self.__exposer and value:
            self.disconnect(self.__exposer)
            self.__exposer = None
        elif (not self.__exposer) and (not value):
            self.__exposer = self.connect("expose-event", self.__on_expose)

    def _get_no_expose(self):
        """getter for no_expose property"""
        return not self.__exposer

    no_expose = property(fset=_set_no_expose, fget=_get_no_expose,
        doc="Whether the widget should handle exposition events or not.")
gobject.type_register(Rectangle)

class Mask(gtk.EventBox):
    """
    A CanvasDrawableWidget drawing a rectangle over a specified widget.
    """
    def __init__(self, catch_events=False, pass_thru=()):
        """
        Creates a new Rectangle

        @param catch_events whether the Mask should catch events
        @param pass_thru the widgets that "punch holes" through this Mask.
            Events will pass through to those widgets.
        """
        gtk.EventBox.__init__(self)
        self.no_expose = True # ignored
        self._catch_events = False
        self.catch_events = catch_events
        self.pass_thru = list(pass_thru)

    def __del__(self):
        for widget in self.pass_thru:
            widget.drag_unhighlight()

    def mask(self, widget):
        """
        Remove the widget from the unmasked list.
        @param widget a widget to remask
        """
        assert widget in self.pass_thru, \
            "trying to mask already masked widget"
        self.pass_thru.remove(widget)
        widget.drag_unhighlight()

    def unmask(self, widget):
        """
        Add to the unmasked list the widget passed.
        A hole will be punched through the mask at that widget's position.
        @param widget a widget to unmask
        """
        if widget not in self.pass_thru:
            widget.drag_highlight()
            self.pass_thru.append(widget)


    def set_catch_events(self, do_catch):
        """Sets whether the mask catches events of widgets under it"""
        if bool(self._catch_events) ^ bool(do_catch):
            if do_catch:
                self._catch_events = True
                self.grab_add()
            else:
                self.grab_remove()
                self._catch_events = False

    def get_catch_events(self):
        """Gets whether the mask catches events of widgets under it"""
        return bool(self._catch_handle)

    catch_events = property(fset=set_catch_events, fget=get_catch_events)

    def draw_with_context(self, context):
        """
        Draw using the passed cairo context instead of creating a new cairo
        context. This eases blending between multiple cairo-rendered
        widgets.
        """
        # Fill parent container
        mask_alloc = self.parent.get_allocation()
        oldrule = context.get_fill_rule()
        context.set_fill_rule(cairo.FILL_RULE_EVEN_ODD)
        x, y = self.translate_coordinates(self.parent, 0, 0)

        context.rectangle(x, y, mask_alloc.width, mask_alloc.height)
        for hole in self.pass_thru:
            alloc = hole.get_allocation()
            x, y = hole.translate_coordinates(self.parent, 0, 0)
            context.rectangle(x, y, alloc.width, alloc.height)
        context.set_source_rgba(0, 0, 0, 0.7)
        context.fill()
        context.set_fill_rule(oldrule)

    def do_size_request(self, requisition):
        """Fill requisition with size occupied by the masked widget."""
        # This is required for the event box to span across all the parent.
        alloc = self.parent.get_allocation()
        requisition.width = alloc.width
        requisition.height = alloc.height

    def do_size_allocate(self, allocation):
        """Save zone allocated to the widget."""
        self.allocation = allocation

gobject.type_register(Mask)


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