gecko/content/canvas/src/CanvasUtils.h

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
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 * The Original Code is mozilla.org code.
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 * The Initial Developer of the Original Code is
 *   Vladimir Vukicevic <vladimir@pobox.com>
 * Portions created by the Initial Developer are Copyright (C) 2009
 * the Initial Developer. All Rights Reserved.
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#ifndef _CANVASUTILS_H_
#define _CANVASUTILS_H_

#include "prtypes.h"

class nsHTMLCanvasElement;
class nsIPrincipal;

namespace mozilla {

class CanvasUtils {
public:
    // Check that the rectangle [x,y,w,h] is a subrectangle of [0,0,realWidth,realHeight]

    static PRBool CheckSaneSubrectSize(PRInt32 x, PRInt32 y, PRInt32 w, PRInt32 h,
                                       PRInt32 realWidth, PRInt32 realHeight)
    {
        if (w <= 0 || h <= 0 || x < 0 || y < 0)
            return PR_FALSE;

        if (x >= realWidth  || w > (realWidth - x) ||
            y >= realHeight || h > (realHeight - y))
            return PR_FALSE;

        return PR_TRUE;
    }

    // Flag aCanvasElement as write-only if drawing an image with aPrincipal
    // onto it would make it such.

    static void DoDrawImageSecurityCheck(nsHTMLCanvasElement *aCanvasElement,
                                         nsIPrincipal *aPrincipal,
                                         PRBool forceWriteOnly);

    static void LogMessage (const nsCString& errorString);
    static void LogMessagef (const char *fmt, ...);

private:
    // this can't be instantiated
    CanvasUtils() { }
};

}

#endif /* _CANVASUTILS_H_ */