gxcolourmap.h

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//
// Copyright (C) 2017 Graeme Walker
// 
// 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/>.
// ===
///
/// \file gxcolourmap.h
///

#ifndef GX_COLOURMAP_H
#define GX_COLOURMAP_H

#include "gdef.h"
#include "gxdef.h"
#include "gxdrawable.h"
#include <vector>

namespace GX
{
    class ColourMap ;
    class Display ;
    class Window ;
}

/// \class GX::ColourMap
/// A colourmap class that provides pixel values for a set of mapped colours. 
/// The map can be for 16 colours or 256 greys. The first colour (0) is black, 
/// and the last (15/255) is white.
/// 
class GX::ColourMap
{
public:
    explicit ColourMap( Display & , bool greyscale256 = false ) ;
        ///< Constructor for a colourmap for the default visual
        ///< providing 16 colours or 256 grey levels. The 
        ///< implementation creates a temporary window.

    ColourMap( Display & , GX::Window & w , ::Visual * v ) ;
        ///< Constructor for a colourmap for a specific visual. 
        ///< The display reference is kept. The window is only 
        ///< used to determine the screen.

    ~ColourMap() ;
        ///< Destructor.

    ::Colormap x() ;
        ///< Returns the X colourmap id. See XCreateColormap(3).

    unsigned long get( int index ) const ;
        ///< Gets the pixel value for the given index value.

    unsigned int size() const ;
        ///< Returns 16 for colours or 256 for greyscale.

    int find( unsigned long ) const ;
        ///< Does a reverse lookup to return the index value
        ///< for the given pixel value.

private:
    ColourMap( const ColourMap & ) ;
    void operator=( const ColourMap & ) ;
    void create( Display & , ::Window , ::Visual * v , bool ) ;
    void setGrey256() ;
    void setColour16() ;
    void addColour16(int,int,int) ;

private:
    Display & m_display ;
    ::Colormap m_x ;
    std::vector<unsigned long> m_map ;
    unsigned int m_size ;
} ;

inline
unsigned long GX::ColourMap::get( int index ) const
{
    //index = index % m_size ;
    return m_map[static_cast<size_t>(index)] ;
}

#endif