winamp/Src/Wasabi/api/config/items/attrhandler.h

//!##  An object to multiplex the callbacks of multiple attributes.
#ifndef _ATTRHANDLER_H
#define _ATTRHANDLER_H

// This class is meant to be subclassed.  The methods you must provide
// are given as pure virtuals.  See ExampleAttrib for more details, and
// an example subclass that you can copy for your own use.

#include "attrcb.h"
#include "attribs.h"
#include <bfc/map.h>

//
// Forward References
class WAComponentClient;
class Attribute;


//
// Class Definition
template <class TCallback>
class AttrHandler {
protected:
  // Heh, oops.  Can't have one AttrCallback handle lots of different attribs, anymore.  I fix.
  class AttrHandlerChild : public AttrCallback {
    public:
      AttrHandlerChild(AttrHandler *_parent) : AttrCallback() {
        ASSERT(_parent != NULL);
        recursion = 0;
        callback = NULL;
        parent = _parent;
      }

      // Here is where we split out the different value types
      virtual void onValueChange(Attribute *attr) {
        if (!recursion) {
          // protect our programmers from stack overflow, please.
          recursion = 1;
          if ((callback != NULL) && (parent != NULL)) {
            int id;
            // find the id from the map (friendly)
            int success = parent->attribmap.getItem(attr,&id);
            if (success) {
              // and send it to the proper handling function (poorman's RTTI)
              switch (attr->getAttributeType()) {
                case AttributeType::INT:
                  callback->onIntChange(id,*static_cast<_int *>(attr));
                break;
                case AttributeType::BOOL:
                  callback->onBoolChange(id, *static_cast<_bool *>(attr));
                break;
                case AttributeType::FLOAT:
                  callback->onFloatChange(id, *static_cast<_float *>(attr));
                break;
                case AttributeType::STRING:
                  callback->onStringChange(id, *static_cast<_string *>(attr));
                break;
              }
            }
          }
          recursion = 0;
        }
      }

      virtual void bindCallbackObj(TCallback *callbackobj) {
        // Be advised, this may be null.  That's okay, we test for it above.
        callback = callbackobj;
      }
    private:
      int recursion;
      TCallback *callback;
      AttrHandler *parent;
  };

public:
  AttrHandler() {
    component = NULL;
    callback = NULL;
  }

  // Call this method to bind your component (in your component's constructor)
  virtual void bindComponent(WAComponentClient *parentcomponent) {
    component = parentcomponent;
  }

  // Call this method to bind your callback object (usually your window in its constructor)
  virtual void bindCallbackObj(TCallback *callbackobj) {
    // Bind ourselves.
    callback = callbackobj;

    // Then go through and rebind any children.
    int i, num = attrchildren.getNumItems();
    for (i = 0; i < num; i++) {
      AttrHandlerChild *child = attrchildren.enumItem(i);
      child->bindCallbackObj(callback);
    }
  }

  // Call this method to register each attribute.
  virtual void registerAttribute(Attribute *attr, int id) {
    ASSERTPR(component != NULL, "BIND YOUR COMPONENT before registering Attributes to a Handler.");
    // register the attrib with a child object as its callback
    AttrHandlerChild *child = new AttrHandlerChild(this);
    attrchildren.addItem(child);
    component->registerAttribute(attr, child);
    // and save its id mapping
    attribmap.addItem(attr, id);
  }

#if 0  
  // Your callback object (probably your primary window class) must implement
  // its own versions of these methods here.  They will be called by the 
  // switch statement below.
  virtual void onIntChange(int id, int *attr);
  virtual void onBoolChange(int id, bool *attr);
  virtual void onFloatChange(int id, double *attr);
  virtual void onStringChange(int id, const char *attr);
#endif

  
private:
  friend AttrHandlerChild;
  TCallback *callback;
  WAComponentClient *component;
  Map< Attribute *, int >  attribmap;
  PtrList<AttrHandlerChild>  attrchildren;
};

#endif  // _ATTRHANDLER_H