xorrectangle.h

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/*
 Copyright (C) 2001-2006, William Joseph.
 All Rights Reserved.

 This file is part of GtkRadiant.

 GtkRadiant 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.

 GtkRadiant 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 GtkRadiant; if not, write to the Free Software
 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#if !defined (INCLUDED_XORRECTANGLE_H)
#define INCLUDED_XORRECTANGLE_H

#include <gtk/gtkwidget.h>
#include "math/FloatTools.h"

class Rectangle
{
    public:
        Rectangle () :
            x(0), y(0), w(0), h(0)
        {
        }
        Rectangle (float _x, float _y, float _w, float _h) :
            x(_x), y(_y), w(_w), h(_h)
        {
        }
        float x;
        float y;
        float w;
        float h;
};

struct Coord2D
{
        float x, y;
        Coord2D (float _x, float _y) :
            x(_x), y(_y)
        {
        }
};

inline Coord2D coord2d_device2screen (const Coord2D& coord, unsigned int width, unsigned int height)
{
    return Coord2D(((coord.x + 1.0f) * 0.5f) * width, ((coord.y + 1.0f) * 0.5f) * height);
}

inline Rectangle rectangle_from_area (const float min[2], const float max[2], unsigned int width, unsigned int height)
{
    Coord2D botleft(coord2d_device2screen(Coord2D(min[0], min[1]), width, height));
    Coord2D topright(coord2d_device2screen(Coord2D(max[0], max[1]), width, height));
    return Rectangle(botleft.x, botleft.y, topright.x - botleft.x, topright.y - botleft.y);
}

class XORRectangle
{
        Rectangle m_rectangle;

        GtkWidget* m_widget;
        GdkGC* m_gc;

        bool initialised () const
        {
            return m_gc != 0;
        }
        void lazy_init ()
        {
            if (!initialised()) {
                m_gc = gdk_gc_new(m_widget->window);

                GdkColor color = { 0, 0xffff, 0xffff, 0xffff, };
                GdkColormap* colormap = gdk_window_get_colormap(m_widget->window);
                gdk_colormap_alloc_color(colormap, &color, FALSE, TRUE);
                gdk_gc_copy(m_gc, m_widget->style->white_gc);
                gdk_gc_set_foreground(m_gc, &color);
                gdk_gc_set_background(m_gc, &color);

                gdk_gc_set_function(m_gc, GDK_INVERT);
            }
        }
        void draw () const
        {
            const int x = float_to_integer(m_rectangle.x);
            const int y = float_to_integer(m_rectangle.y);
            const int w = float_to_integer(m_rectangle.w);
            const int h = float_to_integer(m_rectangle.h);
            gdk_draw_rectangle(m_widget->window, m_gc, FALSE, x, -(h) - (y - m_widget->allocation.height), w, h);
        }

    public:
        XORRectangle (GtkWidget* widget) :
            m_widget(widget), m_gc(0)
        {
        }
        ~XORRectangle ()
        {
            if (initialised()) {
                gdk_gc_unref(m_gc);
            }
        }
        void set (Rectangle rectangle)
        {
            if (GTK_WIDGET_REALIZED(m_widget)) {
                lazy_init();
                draw();
                m_rectangle = rectangle;
                draw();
            }
        }
};

#endif