// src/cairo_widget.cc - Copyright 2005, 2006, University
//               of Padova, dept. of Pure and Applied
//               Mathematics
//
// This file is part of SGPEMv2.
//
// This 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.
//
// SGPEMv2 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 SGPEMv2; if not, write to the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

#include "cairo_elements.hh"
#include "cairo_widget.hh"

#include "backend/history.hh"
#include "backend/simulation.hh"

#include <gdkmm/window.h>

#include <cassert>
#include <memory>


using namespace sgpem;


CairoWidget::CairoWidget()
  : Glib::ObjectBase("sgpem_CairoWidget"),
		Gtk::Widget(), _h(1), _buf(NULL)
{
  set_flags(Gtk::NO_WINDOW);
  // Register this observer:
  Simulation::get_instance().get_history().attach(*this);
}
 

CairoWidget::~CairoWidget()
{
  Simulation::get_instance().get_history().detach(*this);
}


void 
CairoWidget::update(const History& history)
{
  // get_window() returns a null pointer
  // if the widget has not been realized
	if(!is_realized())
    return; // Nowhere to draw to.

  // Determine the final height before to start drawing
  unsigned int w = get_allocation().get_width();
  _h = calc_height(history);

  _buf = Gdk::Pixmap::create(get_window(), w, _h);

  // Draw the widget background as the first thing.
  // I've seen this is how it's done in the very Gtk+ toolkit
  // for the GtkProgressBar widget.
  GtkStyle* gStyle = get_style()->gobj(); 
  gtk_paint_box(gStyle, _buf->gobj(), 
                GTK_STATE_NORMAL, GTK_SHADOW_ETCHED_IN, 
                NULL, this->gobj(), "through",
                0, 0, w, _h);  

  cairo_t* ctx = gdk_cairo_create(_buf->gobj());

  // do the drawing...
  draw_widget(ctx);

  cairo_scale(ctx, w, _h);

  // manually force an expose_event?
  cairo_destroy(ctx);

  queue_draw();
}


void 
CairoWidget::on_realize()
{
  if(is_realized()) return;

  Gtk::Widget::on_realize();
  ensure_style();

  GdkWindowAttr attributes;
  memset(&attributes, 0, sizeof(attributes));

	Gtk::Allocation alloc = get_allocation();

	attributes.x = alloc.get_x();
	attributes.y = alloc.get_y();
	attributes.width = alloc.get_width();
	attributes.height = alloc.get_height();
	attributes.wclass = GDK_INPUT_OUTPUT;
  attributes.event_mask = get_events() | GDK_EXPOSURE_MASK;
  attributes.window_type = GDK_WINDOW_CHILD;
  attributes.visual = get_visual()->gobj();
  attributes.colormap = get_colormap()->gobj();

  static const gint attributes_mask = Gdk::WA_X | Gdk::WA_Y | Gdk::WA_WMCLASS 
    | Gdk::WA_VISUAL | Gdk::WA_COLORMAP;

	Glib::RefPtr<Gdk::Window> window = Gdk::Window::create(get_parent_window(),
																												 &attributes,
																												 attributes_mask);

  unset_flags(Gtk::NO_WINDOW);
	set_window(window);
	window->set_user_data(gobj());
  
  // Not sure if the following line is needed:
  gtk_style_attach(get_style()->gobj(), window->gobj());
	get_style()->set_background(window, Gtk::STATE_ACTIVE);
}

void
CairoWidget::on_size_request(Gtk::Requisition* requisition)
{
  // FIXME: take correct measures, consider also using a viewport(?)
  *requisition = Gtk::Requisition();
	requisition->width = get_allocation().get_width();
	requisition->height = _h;
}


void
CairoWidget::on_size_allocate(const Gtk::Allocation& allocation)
{
	set_allocation(allocation);
	
	if(is_realized())
		get_window()->move_resize(allocation.get_x(), allocation.get_y(),
															allocation.get_width(), allocation.get_height());
}


bool 
CairoWidget::on_expose_event(GdkEventExpose* event)
{
  if(event == NULL || event->count > 0) 
    return false;

  // calculated dinamically:
  int w = get_allocation().get_width();
  set_size_request(w, _h);
  
  // Clip to redraw only the smallest possible area
  // Use double buffering or we're CPU-dead
  // Copy from the buffer to the screen
  if(_buf)
    get_window()->draw_drawable(get_style()->get_black_gc(), _buf, 
                                event->area.x, event->area.y, 
                                event->area.x, event->area.y,
                                event->area.width, event->area.height);
  
  return true;
}


bool 
CairoWidget::on_button_press_event(GdkEventButton* event)
{
  // Not here. Yet.
  return false;
}