Ichthyostega
5127414773
- allow tab specification to be elided - simple comparisons between UI coordinates - local query predicates
141 lines
4.3 KiB
C++
141 lines
4.3 KiB
C++
/*
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CMD-CONTEXT.hpp - interface to access command context binding services within the UI
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Copyright (C) Lumiera.org
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2017, Hermann Vosseler <Ichthyostega@web.de>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of
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the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/** @file cmd-context.hpp
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** Abstraction: support for binding command invocation into an UI context.
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** The interact::CmdContext front-end is used when commands need to be bound to a whole context
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** of UI elements rather than to a specific widget -- especially for picking up command arguments
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** from interaction state found within that context. To invoke a command, typically it is necessary
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** to prepare a _command instance_ and to pick up and bind _command arguments._ In most cases, this
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** can be done directly, using a fixed command-ID and locally known argument values. But in the
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** aforementioned special situation, we have to deal with ongoing user interactions, which might
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** span several widgets, where some interaction events just happen to make invocation of a specific
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** command viable. The prototypical example is when some element is dragged around, and, depending
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** on the vicinity, might cause quite different actions when dropped. Such behaviour can be achieved
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** with the help of an intermediary, known as ["interaction state manager"](\ref InteractionState).
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** The command context accessor allows to discover a specific InteractionState instance, which
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** - is responsible for the specific command to be invoked
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** - can handle context information related to a specific _control system_ (e.g mouse, keyboard,
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** hardware controller, pen)
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** - might handle changing contextual state and thus decide if a command can be invoked
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** From the InteractionState instance, it is possible to retrieve a notification when a specific,
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** context-bound command becomes executable by picking up suitable parameter values from this context.
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**
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** @todo as of 3/2017 this is a early design draft and WIP-WIP-WIP
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** @todo after initial design draft, postponed as of 10/2017
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**
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** @see CmdContext_test
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** @see ////TODO_test usage example
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**
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*/
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#ifndef GUI_INTERACT_CMD_CONTEXT_H
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#define GUI_INTERACT_CMD_CONTEXT_H
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#include "lib/error.hpp"
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//#include "gui/ctrl/bus-term.hpp"
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//#include "lib/idi/entry-id.hpp"
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#include "lib/hash-indexed.hpp"
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#include "lib/symbol.hpp"
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//#include "lib/util.hpp"
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#include <boost/noncopyable.hpp>
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#include <string>
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namespace gui {
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namespace interact {
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// using lib::HashVal;
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using lib::hash::LuidH;
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using lib::Symbol;
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// using util::isnil;
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using std::string;
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/**
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* Abstract foundation of UI state tracking components.
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* @todo write type comment...
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*/
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class CmdContext
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: boost::noncopyable
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{
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public:
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~CmdContext(); ///< @todo do we need a VTable / virtual dtor?
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/* === access front-end === */
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static CmdContext& of (Symbol cmdID, string ctxID);
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struct Resolver;
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protected:
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private:
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};
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/**
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* Helper for dynamic command argument resolution.
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*/
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struct CmdContext::Resolver
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{
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/** query current interaction state to resolve the element in question
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* @return hash-ID to indicate the element or scope
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*/
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operator LuidH ();
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enum Spec {
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HERE,
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RECENT
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};
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friend Resolver
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scope (Spec scopeSpec)
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{
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return Resolver{scopeSpec};
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}
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friend Resolver
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element (Spec elementSpec)
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{
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return Resolver{elementSpec};
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}
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private:
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const Spec spec = HERE;
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Resolver(Spec s)
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: spec(s)
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{ }
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};
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}} // namespace gui::interact
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#endif /*GUI_INTERACT_CMD_CONTEXT_H*/
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