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//
// How to use Fl_Text_Editor with dynamic colors. -erco 08/29/2018
// Originally posted on fltk.general.
//
// Shows how to use the add_modify_callback() to dynamically apply colors
// to text while the user types. For demonstration purposes, we trivially
// color the digits 0-4 in green, 5-9 in red, and all else in black.
//
// The text buffer and style buffer are two parallel character arrays;
// chars in the *text* buffer are the text in the editor, and
// chars in the *style* buffer represent coloring + font information
// for the corresponding character in the text buffer.
//
// In this example, a style buffer table sets up these style buffer
// characters: 'A' to be black text, 'B' to be green, and 'C' for red.
// The style buffer uses the same font + font sizes, so the font sizes
// remain the same when colors are changed.
//
// Copyright 2018 Greg Ercolano.
// Copyright 1998-2018 by Bill Spitzak and others.
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file. If this
// file is missing or damaged, see the license at:
//
// https://www.fltk.org/COPYING.php
//
// Please see the following page on how to report bugs and issues:
//
// https://www.fltk.org/bugs.php
//
#include <FL/Fl.H>
#include <FL/Fl_Window.H>
#include <FL/Fl_Text_Editor.H>
// Custom class to demonstrate a specialized text editor
class MyEditor : public Fl_Text_Editor {
Fl_Text_Buffer *tbuff; // text buffer
Fl_Text_Buffer *sbuff; // style buffer
// Modify callback handler
void ModifyCallback(int pos, // position of update
int nInserted, // number of inserted chars
int nDeleted, // number of deleted chars
int, // number of restyled chars (unused here)
const char*) { // text deleted (unused here)
// Nothing inserted or deleted?
if (nInserted == 0 && nDeleted == 0) return;
// Characters inserted into tbuff?
// Insert same number of chars into style buffer..
//
if (nInserted > 0) {
char *style = new char[nInserted + 1]; // temp buffer
memset(style, 'A', nInserted); // init style to "A"s
style[nInserted] = '\0'; // terminate string
sbuff->insert(pos, style); // insert "A"s into style buffer
delete[] style; // done with temp buffer..
}
// Characters deleted from tbuff?
// Delete same number of chars from style buffer..
//
if ( nDeleted > 0 ) {
sbuff->remove(pos, pos + nDeleted);
return; // nothing more to do; deleting won't affect our single char coloring
}
// Focus on characters inserted
int start = pos;
int end = pos + nInserted;
//DEBUG fprintf(stderr, "add_modify_callback(): start/end=%d/%d, text='%.*s'\n", start, end, (end-start), tbuff->address(start));
// SIMPLE EXAMPLE:
// Color the digits 0-4 in green, 5-9 in red.
//
for ( int i=start; i<end; i++ ) {
unsigned int c = tbuff->char_at(i);
if ( strchr("01234", c) ) sbuff->replace(i, i+1, "B"); // style 'B' (green)
else if ( strchr("56789", c) ) sbuff->replace(i, i+1, "C"); // style 'C' (red)
else sbuff->replace(i, i+1, "A"); // style 'A' (black)
}
}
static void ModifyCallback_STATIC(int pos, // position of update
int nInserted, // number of inserted chars
int nDeleted, // number of deleted chars
int nRestyled, // number of restyled chars
const char *deletedText, // text deleted
void *cbarg) { // callback data
MyEditor *med = (MyEditor*)cbarg;
med->ModifyCallback(pos, nInserted, nDeleted, nRestyled, deletedText);
}
public:
MyEditor(int X,int Y,int W,int H) : Fl_Text_Editor(X,Y,W,H) {
// Style table for the respective styles
static const Fl_Text_Editor::Style_Table_Entry stable[] = {
// FONT COLOR FONT FACE FONT SIZE
// --------------- ----------- --------------
{ FL_BLACK, FL_COURIER, 14 }, // A - Black
{ FL_DARK_GREEN, FL_COURIER, 14 }, // B - Green
{ FL_RED, FL_COURIER, 14 }, // C - Red
};
tbuff = new Fl_Text_Buffer(); // text buffer
sbuff = new Fl_Text_Buffer(); // style buffer
buffer(tbuff);
int stable_size = sizeof(stable)/sizeof(stable[0]);
highlight_data(sbuff, stable, stable_size, 'A', 0, 0);
tbuff->add_modify_callback(ModifyCallback_STATIC, (void*)this);
}
void text(const char* val) {
tbuff->text(val);
}
};
int main() {
Fl_Window *win = new Fl_Window(720, 480, "Text Editor With Dynamic Coloring");
MyEditor *med = new MyEditor(10,10,win->w()-20,win->h()-20);
// Initial text in editor.
med->text("In this editor, digits 0-4 are shown in green, 5-9 shown in red.\n"
"So here's some numbers 0123456789.\n"
"Coloring is handled automatically by the add_modify_callback().\n"
"\n"
"You can type here to test. ");
win->resizable(med);
win->show();
return(Fl::run());
}
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