/*
 * RenderArea.cpp
 * 
 * Copyright (C) 2008 Matthias Schiffer <matthias@gamezock.de>
 * 
 * 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 3 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, see <http://www.gnu.org/licenses/>.
 */

#include "RenderArea.h"
#include <View/View.h>
#include <iostream>
#include <cstdlib>
#include <cmath>
#include <gtkmm/toolbutton.h>
#include <gtkmm/adjustment.h>
#include <GL/gl.h>

namespace ZoomEdit {
namespace Gui {

GdkGLConfig *RenderArea::glconfig = 0;

RenderArea::RenderArea(BaseObjectType *cobject, const Glib::RefPtr<Gnome::Glade::Xml> &xml)
: Gtk::DrawingArea(cobject), view(0), xCenter(0), yCenter(0), zoomLevel(0), scale(100) {
  if(!glconfig) {
    glconfig = gdk_gl_config_new_by_mode((GdkGLConfigMode)(GDK_GL_MODE_RGB | GDK_GL_MODE_DOUBLE));
    if(!glconfig) glconfig = gdk_gl_config_new_by_mode(GDK_GL_MODE_RGB); // Hmm, can't find double buffered config
    if(!glconfig) {
      std::cerr << "*** No appropriate OpenGL-capable visual found." << std::endl;
      std::exit(1);
    }
  }
  
  signal_realize().connect(sigc::mem_fun(this, &RenderArea::onRealize));
  signal_configure_event().connect(sigc::mem_fun(this, &RenderArea::onConfigureEvent));
  signal_expose_event().connect(sigc::mem_fun(this, &RenderArea::onExposeEvent));
  signal_scroll_event().connect(sigc::mem_fun(this, &RenderArea::onScrollEvent));
  
  Gtk::ToolButton *button;
  xml->get_widget("ToolButtonZoomIn", button);
  button->signal_clicked().connect(sigc::bind(sigc::mem_fun(this, &RenderArea::zoom), 2, 0.5f, 0.5f));
  
  xml->get_widget("ToolButtonZoomOut", button);
  button->signal_clicked().connect(sigc::bind(sigc::mem_fun(this, &RenderArea::zoom), -2, 0.5f, 0.5f));
  
  xml->get_widget("Hscrollbar", hScrollbar);
  hScrollbar->signal_value_changed().connect(sigc::mem_fun(this, &RenderArea::updateScrolling));
  
  xml->get_widget("Vscrollbar", vScrollbar);
  vScrollbar->signal_value_changed().connect(sigc::mem_fun(this, &RenderArea::updateScrolling));
  
  gtk_widget_set_gl_capability(GTK_WIDGET(cobject), glconfig, 0, TRUE, GDK_GL_RGBA_TYPE);
}

void RenderArea::onRealize() {
  if(!gdkGLBegin())
    return;
  
  glClearColor(0, 0, 0, 0);
  
  glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  glEnable(GL_BLEND);
  
  glEnable(GL_LINE_SMOOTH);
  glEnable(GL_POINT_SMOOTH);
  
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  
  gdkGLEnd();
}

bool RenderArea::onConfigureEvent(GdkEventConfigure*) {
  updateViewport();
  return true;
}

bool RenderArea::onExposeEvent(GdkEventExpose*) {
  if(!gdkGLBegin())
    return false;
  
  glClear(GL_COLOR_BUFFER_BIT);
  
  glMatrixMode(GL_MODELVIEW);
  glPushMatrix();
  
  glScalef(scale, scale, 1);
  glTranslatef(-xCenter, -yCenter, 0);
  
  if(view)
    view->render(this);
  
  glMatrixMode(GL_MODELVIEW);
  glPopMatrix();
  
  gdkSwapBuffers();
  gdkGLEnd();
  
  return true;
}

bool RenderArea::onScrollEvent(GdkEventScroll *event) {
  switch(event->direction) {
    case GDK_SCROLL_UP:
      zoom(1, event->x/get_width(), event->y/get_height());
      return true;
    case GDK_SCROLL_DOWN:
      zoom(-1, event->x/get_width(), event->y/get_height());
      return true;
    default:
      return false;
  }
}

void RenderArea::zoom(int zoom, float x, float y) {
  zoomLevel = std::max(std::min(zoomLevel + zoom, 50), -100);
  scale = 100*std::pow(1.1f, zoomLevel);
  
  updateScrollbars(x, y);
}

void RenderArea::updateViewport() {
  if(!gdkGLBegin())
    return;
  
  glViewport(0, 0, get_width(), get_height());
  
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  
  if(get_width() != 0 && get_height() != 0)
    glScalef(2.0f/get_width(), -2.0f/get_height(), 1);
  
  gdkGLEnd();
  
  updateScrollbars();
}

void RenderArea::updateScrollbars(float x, float y) {
  float minX, maxX, minY, maxY;
  const gdouble width = getViewWidth(), height = getViewHeight();
  gdouble lower, upper, pageSize, value;
  
  if(!view)
    return;
  
  view->getBounds(&minX, &maxX, &minY, &maxY);
  float xVal = std::max(std::fabs(minX), std::fabs(maxX));
  float yVal = std::max(std::fabs(minY), std::fabs(maxY));
  
  get_window()->freeze_updates();
  
  lower = hScrollbar->get_adjustment()->get_lower();
  upper = hScrollbar->get_adjustment()->get_upper();
  pageSize = hScrollbar->get_adjustment()->get_page_size();
  
  hScrollbar->get_adjustment()->set_lower(-xVal + width/2);
  hScrollbar->get_adjustment()->set_upper(xVal + width/2);
  hScrollbar->get_adjustment()->set_page_size(width);
  
  if(pageSize > (upper-lower) && width < 2*xVal)
    value = 0;
  else
    value = hScrollbar->get_value() + (x-0.5)*(pageSize-width);
  
  hScrollbar->set_value(std::max(std::min(value, xVal - width/2), -xVal + width/2));
  
  lower = vScrollbar->get_adjustment()->get_lower();
  upper = vScrollbar->get_adjustment()->get_upper();
  pageSize = vScrollbar->get_adjustment()->get_page_size();
  
  vScrollbar->get_adjustment()->set_lower(-yVal + height/2);
  vScrollbar->get_adjustment()->set_upper(yVal + height/2);
  vScrollbar->get_adjustment()->set_page_size(height);
  
  if(pageSize > (upper-lower) && height < 2*yVal)
    value = 0;
  else
    value = vScrollbar->get_value() + (y-0.5)*(pageSize-height);
  
  vScrollbar->set_value(std::max(std::min(value, yVal - height/2), -yVal + height/2));
  
  get_window()->thaw_updates();
  
  updateScrolling();
}

void RenderArea::updateScrolling() {
  const float imageWidth = hScrollbar->get_adjustment()->get_upper()-hScrollbar->get_adjustment()->get_lower();
  const float imageHeight = vScrollbar->get_adjustment()->get_upper()-vScrollbar->get_adjustment()->get_lower();
  
  if(hScrollbar) {
    if(imageWidth < getViewWidth())
      xCenter = 0;
    else
      xCenter = hScrollbar->get_value();
  }
  
  if(vScrollbar) {
    if(imageHeight < getViewHeight())
      yCenter = 0;
    else 
      yCenter = vScrollbar->get_value();
  }
  
  queue_draw();
}

}
}