UI_OHEventHandler.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * NAME:        UI_OHEventHandler.h ( UI Library, C++)
 *
 * COMMENTS:
 *              This is the base class for the various types of event
 *              handlers. Typically gadgets will derive from this
 *              (or some subclass of this class) and redefine how
 *              its virtual methods work.
 *              
 *              For full documentation, please refer to DOCS/index.html
 */

#ifndef __UI_EventHandler__
#define __UI_EventHandler__

#include "UI_API.h"
#include "UI_Object.h"
class UI_Value;

#include "UI_OHTriggerObject.h"

class UI_API UI_OHEventHandler
{
public:
                         UI_OHEventHandler(UI_OHTriggerObject &);
    virtual             ~UI_OHEventHandler();
    virtual const char  *ohClassName() const { return "UI_OHEventHandler"; }

    // You call ohRequestDeferredUpdate in response to an event that
    // should cause an Update. When the time is right, UI will call
    // ohHandleDeferredUpdate for you. You should override 
    // ohHandleDeferredUpdate to do the "Update" computation. If you
    // think that the "Update" should cause you gadget to Redraw, then
    // call ohRequestDeferredRedraw. That in turn, will call
    // ohHandleDeferredRedraw.
    //
    // Note: OH_OpEventHandler overrides ohHandleDeferredUpdate already
    //       and calls ohHandleDeferredNodeUpdate that can be overridden.

    virtual void         ohRequestDeferredUpdate();
    virtual void         ohHandleDeferredUpdate();
    virtual void         ohRequestDeferredRedraw();
    virtual void         ohHandleDeferredRedraw();

    // These two should only called by UI_TriggerObject. You should typically
    // only override ohHandleTimeChange, and then only if you've called 
    // ohAddTimeInterest.
    virtual void         ohHandleTrigger();
    virtual void         ohHandleTimeChange(UI_Event *);

    // The following Time functions are provided purely for convenience.
    // Their functioning is completely independent of the rest of this
    // class.
    void                 ohAddTimeInterest()
                            { myOHtriggerObject.addTimeInterest(); }
    void                 ohRemoveTimeInterest()
                            { myOHtriggerObject.removeTimeInterest(); }

    // ohGetTimeValue returns nullptr if you haven't set a time interest
    UI_Value*            ohGetTimeValue()
                            { return myOHtriggerObject.getTimeValue(); }

    // ohGetTime returns 0 if you haven't set a time interest
    fpreal               ohGetTime() const
                            { return myOHtriggerObject.getTime(); }

    void                 ohAllowNestedRedraws() { myOHAllowNestedRedraws=true; }

protected:
    virtual void         ohRequestTrigger();

    bool                 ohUpdatePending() const { return myOHupdatePending; }

private:
    UI_OHTriggerObject  &myOHtriggerObject;

    bool                 myOHtriggerPending;
    bool                 myOHupdatePending;
    bool                 myOHredrawPending;
    bool                 myOHAllowNestedRedraws;
};

#endif