xrb_pal.hpp

// ///////////////////////////////////////////////////////////////////////////
// xrb_pal.hpp by Victor Dods, created 2009/08/15
// ///////////////////////////////////////////////////////////////////////////
// Unless a different license was explicitly granted in writing by the
// copyright holder (Victor Dods), this software is freely distributable under
// the terms of the GNU General Public License, version 2.  Any works deriving
// from this work must also be released under the GNU GPL.  See the included
// file LICENSE for details.
// ///////////////////////////////////////////////////////////////////////////

#if !defined(_XRB_PAL_HPP_)
#define _XRB_PAL_HPP_

#include "xrb.hpp"

#include "xrb_screencoord.hpp"

namespace Xrb
{

class Event;
class Font;
class Screen;
class Texture;

// Platform Abstraction Layer interface.  at most one instance of this
// interface will ever exist at one time (it is used as a singleton).
class Pal
{
public:

    enum Status { SUCCESS = 0, FAILURE = 1 };

    virtual ~Pal () { }

    // for pre-video-mode setup (e.g. starting the millisecond timer).
    virtual Status Initialize () = 0;
    // for post-video-mode shutdown.
    virtual void Shutdown () = 0;

    virtual Status InitializeVideo (Uint16 width, Uint16 height, Uint8 bit_depth, bool fullscreen) = 0;
    virtual void ShutdownVideo () = 0;

    virtual void SetWindowCaption (char const *window_caption) = 0;
    // TODO: grab/release method and show/hide cursor method

    // returns the number of milliseconds since the Pal instance was
    // initialized.  due to the size of a 32-bit int, this value will
    // wrap about every 49 days
    virtual Uint32 CurrentTime () = 0;

    // block the the process for at least the specified number of
    // milliseconds, but possibly longer due to OS process scheduling.
    virtual void Sleep (Uint32 milliseconds_to_sleep) = 0;

    // called once, immediately after the game loop is done rendering
    // (could be used for video buffer swapping for example).
    virtual void FinishFrame () = 0;

    // return the next queued (input) event.  should return NULL if no
    // events are available, otherwise should new-up and return the
    // appropriate Xrb::Event (it will be deleted by XRB).
    virtual Event *PollEvent (Screen const *screen, Float time) = 0;

    // should return NULL if the load failed
    virtual Texture *LoadImage (char const *image_path) = 0;
    // return value should indicate status
    virtual Status SaveImage (char const *image_path, Texture const &texture) = 0;

    // should return NULL if the load failed
    virtual Font *LoadFont (char const *font_path, ScreenCoord pixel_height) = 0;
}; // end of class Pal

} // end of namespace Xrb

#endif // !defined(_XRB_PAL_HPP_)

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