Added example of dynamically setting style buffer with text editor.

This example greatly simplifies the test/editor example to focus on
just the mechanics of dynamic style buffer manipulation via the
add_modify_callback().


git-svn-id: file:///fltk/svn/fltk/branches/branch-1.4@13034 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

examples/Makefile

@@ -31,6 +31,7 @@ ALL = clipboard$(EXEEXT) \
       SVG_File_Surface$(EXEEXT) \
       textdisplay-with-colors$(EXEEXT) \
       texteditor-simple$(EXEEXT) \
+      texteditor-with-dynamic-colors$(EXEEXT) \
       tree-simple$(EXEEXT) \
       tree-as-container$(EXEEXT) \
       tree-custom-draw-items$(EXEEXT) \

examples/texteditor-with-dynamic-colors.cxx

@@ -0,0 +1,138 @@
+//
+// "$Id$"
+//
+//      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:
+//
+//     http://www.fltk.org/COPYING.php
+//
+// Please report all bugs and problems on the following page:
+//
+//     http://www.fltk.org/str.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());
+}
+
+//
+// End of "$Id$".
+//