array2d.h

游戏开发数据结构-Data.Structures.for.Game.Programmers

// ============================================================================
// Data Structures For Game Programmers
// Ron Penton
// Array2D.h
// This is the 2D Aray class
// ============================================================================

#ifndef ARRAY2D_H
#define ARRAY2D_H


template <class Datatype>
class Array2D
{
public:

// -------------------------------------------------------
// Name:        Array2D::Array2D
// Description: This creates the 2D array using a single
//              linear array.
// -------------------------------------------------------
    Array2D( int p_width, int p_height )
    {
        // create the new array
        m_array = new Datatype[ p_width * p_height ];

        // set the width and height
        m_width = p_width;
        m_height = p_height;
    }


// -------------------------------------------------------
// Name:        Array2D::~Array2D
// Description: This destructs the array.
// -------------------------------------------------------
    ~Array2D()
    {
        // if the array is valid, delete it.
        if( m_array != 0 )
            delete[] m_array;
        m_array = 0;
    }

 
// -------------------------------------------------------
// Name:        Array2D::Get
// Description: This retrieves the item at the given
//              index.
// -------------------------------------------------------
    Datatype& Get( int p_x, int p_y )
    {
        return m_array[ p_y * m_width + p_x ];
    }



// -------------------------------------------------------
// Name:        Array2D::Resize
// Description: This resizes the array.
// -------------------------------------------------------
    void Resize( int p_width, int p_height )
    {
        // create a new array.
        Datatype* newarray = new Datatype[ p_width * p_height ];

        if( newarray == 0 )
            return;

        // create the two coordinate variables and the two temp 
        // variables.
        int x, y, t1, t2;

        // determine the minimum of both dimensions.
        int minx = (p_width < m_width ? p_width : m_width);
        int miny = (p_height < m_height ? p_height : m_height);

        // loop through each cell and copy everything over.
        for( y = 0; y < miny; y++ )
        {
            // OPTIMISATION: pre-calculate t1 and t2
            // the standard algorithm to calculate the
            // position in a 2d array is [y * w + x].
            // however, since y * w doesn't change at all
            // in the innermost loop, we calculate it out
            // here instead.
            t1 = y * p_width;
            t2 = y * m_width;
            for( x = 0; x < minx; x++ )
            {
                // move the data to the new array.
                newarray[ t1 + x ] = m_array[ t2 + x ];
            }
        }

        // delete the old array.        
        if( m_array != 0 )
            delete[] m_array;

        // set the new array, and the width and height.
        m_array = newarray;
        m_width = p_width;
        m_height = p_height;
    }



// -------------------------------------------------------
//  Name:         Array2D::Size
//  Description:  gets the size of the array.
//  Return Value: the size of the array.
// -------------------------------------------------------
    int Size()
    {
        return m_width * m_height;
    }


// -------------------------------------------------------
//  Name:         Array2D::Width
//  Description:  gets the width of the array.
//  Return Value: the width of the array.
// -------------------------------------------------------
    int Width()
    {
        return m_width;
    }


// -------------------------------------------------------
//  Name:         Array2D::Height
//  Description:  gets the height of the array.
//  Return Value: the height of the array.
// -------------------------------------------------------
    int Height()
    {
        return m_height;
    }




// -------------------------------------------------------
// Name:        array2d::m_array
// Description: This is a pointer to the array.
// -------------------------------------------------------
 Datatype* m_array;

// -------------------------------------------------------
// Name:        array2d::m_width
// Description: the current width of the array.
// -------------------------------------------------------
 int m_width;

// -------------------------------------------------------
// Name:        array2d::m_height
// Description: the current height of the array.
// -------------------------------------------------------
 int m_height;
};




#endif