forked from KolibriOS/kolibrios
101 lines
3.6 KiB
C
101 lines
3.6 KiB
C
/*
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* This file is part of libdom.
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* Licensed under the MIT License,
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* http://www.opensource.org/licenses/mit-license.php
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* Copyright 2009 Bo Yang <struggleyb.nku@gmail.com>
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*/
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#ifndef dom_events_document_event_h_
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#define dom_events_document_event_h_
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#include <stdbool.h>
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#include <dom/core/exceptions.h>
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#include <dom/core/string.h>
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struct dom_event;
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struct dom_document;
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typedef struct dom_document dom_document_event;
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/**
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* The callback function which is used to process the default action of any
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* event.
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*
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* As ::dom_default_action_phase defines, we have three points in our
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* implementation where these kinds of callbacks get invoked.
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*
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* When the implementation start to dispatch certain event, it firstly invoke
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* the following callback, which should process the event before the normal
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* event flow.
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*
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* Take a MousePressed event on a check box object as example:
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* 1. The 'pressed' event is generated by OS and catched by our UI code;
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* 2. The UI code dispatch the event to DOM;
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* 3. DOM trys to dispatch the event as what the spec said;
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* 4. Before the real event flow happens, DOM get the
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* dom_default_action_callback function from the
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* dom_events_default_action_fetcher with param
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* DOM_DEFAULT_ACTION_STARTED, and then call it;
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* 5. The callback function invoke some System-denpendent API to make the
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* checkbox checked and then return;
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* 6. Normal event flow goes on.
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* 7. When the implementation reach the end of the event flow, it check whether
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* the event's default action is prevented, if it is, then go to step 8,
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* else go to step 9.
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* 8. The event's default action get prevented, DOM get the
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* dom_default_action_callback function from the
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* dom_events_default_action_fetcher with param
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* DOM_DEFAULT_ACTION_PREVENTED, and then call it.
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* 8. The event's default action does not get prevented, DOM get the
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* dom_default_action_callback function from the
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* dom_events_default_action_fetcher with param
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* DOM_DEFAULT_ACTION_END, and then call it.
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*
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* @note: the point here is that we want the UI related stuff to be done
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* within the default action code. The DOM only take care of the content tree
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* and the event flow itself.
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*/
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typedef void (*dom_default_action_callback)(struct dom_event *evt, void *pw);
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/**
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* The default action phase
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*
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* @note: we define the following three values to fetch three different types
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* of dom_default_action_callback function and their private data.
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*/
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typedef enum {
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DOM_DEFAULT_ACTION_STARTED = 0,
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DOM_DEFAULT_ACTION_PREVENTED,
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DOM_DEFAULT_ACTION_END
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} dom_default_action_phase;
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/**
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* The default action fetcher
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*
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* \param type The type of the event
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* \param phase The phase of the default action callback
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* \param pw The return private data of the callback function
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* \return a callback function, NULL if there is none.
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*/
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typedef dom_default_action_callback (*dom_events_default_action_fetcher)
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(dom_string *type, dom_default_action_phase phase,
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void **pw);
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dom_exception _dom_document_event_create_event(dom_document_event *de,
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dom_string *type, struct dom_event **evt);
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#define dom_document_event_create_event(d, t, e) \
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_dom_document_event_create_event((dom_document_event *) (d), \
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(dom_string *) (t), (struct dom_event **) (e))
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dom_exception _dom_document_event_can_dispatch(dom_document_event *de,
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dom_string *namespace, dom_string *type,
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bool* can);
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#define dom_document_event_can_dispatch(d, n, t, c) \
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_dom_document_event_can_dispatch((dom_document_event *) (d), \
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(dom_string *) (n), (dom_string *) (t),\
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(bool *) (c))
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#endif
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