88 lines
3.5 KiB
C++
88 lines
3.5 KiB
C++
//
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// Character compose processing for the Fast Light Tool Kit (FLTK).
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//
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// Copyright 1998-2010 by Bill Spitzak and others.
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//
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// This library is free software. Distribution and use rights are outlined in
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// the file "COPYING" which should have been included with this file. If this
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// file is missing or damaged, see the license at:
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//
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// https://www.fltk.org/COPYING.php
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//
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// Please see the following page on how to report bugs and issues:
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//
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// https://www.fltk.org/bugs.php
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//
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/**
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\file Fl_compose.cxx
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Utility functions to support text input.
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*/
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#include <FL/Fl.H>
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#include "Fl_Screen_Driver.H"
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#ifndef FL_DOXYGEN
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int Fl::compose_state = 0;
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#endif
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/** Any text editing widget should call this for each FL_KEYBOARD event.
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Use of this function is very simple.
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<p>If <i>true</i> is returned, then it has modified the
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Fl::event_text() and Fl::event_length() to a set of <i>bytes</i> to
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insert (it may be of zero length!). It will also set the "del"
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parameter to the number of <i>bytes</i> to the left of the cursor to
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delete, this is used to delete the results of the previous call to
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Fl::compose().
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<p>If <i>false</i> is returned, the keys should be treated as function
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keys, and del is set to zero. You could insert the text anyways, if
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you don't know what else to do.
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<p>Text editing widgets can preferentially call fl_set_spot() to indicate the window
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coordinates of the bottom of the current insertion point and the line height.
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This way, auxiliary windows that help choosing among alternative characters
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with some text input methods appear just below or above the insertion point.
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If widgets don't do that, such auxiliary windows appear at the widget's bottom.
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<p>On some platforms, text input can involve marked text, that is,
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temporary text replaced by other text during the input process. This occurs,
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e.g., under Wayland or macOS when using dead keys or when entering CJK characters.
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Text editing widgets should preferentially signal
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marked text, usually underlining it. Widgets can use
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<tt>int Fl::compose_state</tt> <i>after</i> having called Fl::compose(int&)
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to obtain the length in bytes of marked text that always finishes at the
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current insertion point. Widgets should also call
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void fl_reset_spot() when processing FL_UNFOCUS
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events. The Fl_Input and Fl_Text_Editor widgets underline marked text.
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If none of this is done by a user-defined text editing widget,
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text input will work, but will not signal to the user what text is marked.
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<p>Finally, text editing widgets should call <tt>set_flag(MAC_USE_ACCENTS_MENU);</tt>
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in their constructor if they want to use, on the macOS platform, the feature introduced with Mac OS 10.7 "Lion"
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where pressing and holding certain keys on the keyboard opens a diacritic marks popup window.
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\note For compatibility with FLTK 1.3, text editing widgets can call
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<tt>Fl::insertion_point_location(int x, int y, int height)</tt> and <tt>Fl::reset_marked_text()</tt>
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<u>only under the macOS platform</u> to indicate/reset the coordinates of the current insertion point.
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This is deprecated in version 1.4 because redundant with the platform-independent
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fl_set_spot() and fl_reset_spot() functions.
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*/
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int Fl::compose(int& del) {
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return Fl::screen_driver()->compose(del);
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}
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/**
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If the user moves the cursor, be sure to call Fl::compose_reset().
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The next call to Fl::compose() will start out in an initial state. In
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particular it will not set "del" to non-zero. This call is very fast
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so it is ok to call it many times and in many places.
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*/
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void Fl::compose_reset()
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{
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Fl::screen_driver()->compose_reset();
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}
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