bitmapcachekey.cpp

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// $Id: bitmapcachekey.cpp 1282 2006-06-09 09:46:49Z alex $
// BitmapCacheKey.cpp: implementation of the CBitmapCacheKey class.
//
/* @@tag:xara-cn@@ DO NOT MODIFY THIS LINE
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 */

#include "camtypes.h"

//#include "bitmapcachekey.h" - in camtypes.h [AUTOMATICALLY REMOVED]

// Construction/Destruction

CBitmapCacheKey::CBitmapCacheKey()
{
    memset(&pOwner, 0, sizeof(CBitmapCacheKey)-((LPBYTE)&pOwner-(LPBYTE)this));
    pOwner = NULL;
    dPixelWidth = 0;
    nOption = 0;
}

CBitmapCacheKey::CBitmapCacheKey(LPVOID pNewOwner, double dNewPixelWidth, UINT32 nNewOption)
{
    memset(&pOwner, 0, sizeof(CBitmapCacheKey)-((LPBYTE)&pOwner-(LPBYTE)this));
    pOwner = pNewOwner;
    dPixelWidth = dNewPixelWidth;
    nOption = nNewOption;
}

// Copy constructor
// Required by CTypedPtrMap
CBitmapCacheKey::CBitmapCacheKey(const CBitmapCacheKey& key)
{
    memset(&pOwner, 0, sizeof(CBitmapCacheKey)-((LPBYTE)&pOwner-(LPBYTE)this));
    pOwner = key.pOwner;
    dPixelWidth = key.dPixelWidth;
    nOption = key.nOption;
}

CBitmapCacheKey::~CBitmapCacheKey()
{

}




/********************************************************************************************

>   CBitmapCacheKey::operator==()
    Author:     Phil_Martin (Xara Group Ltd) <camelotdev@xara.com>
    Created:    10/06/2004
    Inputs:     -
    Outputs:    -
    Returns:    TRUE if this key is exactly the same the the specified key
    Purpose:    Test whether this object has been constructed correctly
                Required by CTypedPtrMap
    Errors:     -
    SeeAlso:    -

********************************************************************************************/
bool CBitmapCacheKey::operator==(const CBitmapCacheKey& key) const
{
    return (pOwner == key.pOwner &&
            dPixelWidth == key.dPixelWidth &&
            nOption == key.nOption
            );
}




/********************************************************************************************

>   BOOL CBitmapCacheKey::IsValid() const
    Author:     Phil_Martin (Xara Group Ltd) <camelotdev@xara.com>
    Created:    10/06/2004
    Inputs:     -
    Outputs:    -
    Returns:    TRUE if this key is valid
                FALSE otherwise
    Purpose:    Test whether this object has been constructed correctly
    Errors:     -
    SeeAlso:    -

********************************************************************************************/
BOOL CBitmapCacheKey::IsValid() const
{
    return (pOwner!=NULL && dPixelWidth!=0);
}




/********************************************************************************************

>   UINT32 CBitmapCacheKey::Hash() const
    Author:     Phil_Martin (Xara Group Ltd) <camelotdev@xara.com>
    Created:    10/06/2004
    Inputs:     -
    Outputs:    -
    Returns:    UINT32 containing hashed value of all the bytes in this object
    Purpose:    Compute a Hash value to allow this object to be used as the key into
                a Hash Table
    Errors:     -
    SeeAlso:    -

********************************************************************************************/
UINT32 CBitmapCacheKey::Hash() const
{
    UINT32 nHash = 0;
    //LPBYTE pThis = (LPBYTE)this;
    LPBYTE pThis = (LPBYTE)&pOwner;
    // Can't use sizeof class because that includes alignment bytes which contain random values
    //const INT32 bytesize = sizeof(CBitmapCacheKey);
    const size_t bytesize = sizeof(CBitmapCacheKey)-((LPBYTE)&pOwner-(LPBYTE)this);

    for(unsigned i=0; i<bytesize; i++)
    {
        nHash = (nHash<<5)+nHash + *pThis++;
    }

    return nHash;
}

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