From c3cde61e9879825c1547e366e2b9becedc1179e7 Mon Sep 17 00:00:00 2001
From: Michael R Sweet <michael.r.sweet@gmail.com>
Date: Sun, 9 Jun 2002 18:28:49 +0000
Subject: Add documentation for using styles in text editor.

Add placeholder for style attributes - hidden + underlined - for
future use.


git-svn-id: file:///fltk/svn/fltk/branches/branch-1.1@2301 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
---
 documentation/editor.html | 286 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 284 insertions(+), 2 deletions(-)

(limited to 'documentation/editor.html')

diff --git a/documentation/editor.html b/documentation/editor.html
index 3fb5c43b0..56de1ad71 100644
--- a/documentation/editor.html
+++ b/documentation/editor.html
@@ -105,7 +105,7 @@ Fl_Menu_Item menuitems[] = {
 <TT>Fl_Menu_Bar</TT> widget and assign the menus to it with:</P>
 
 <UL><PRE>
-Fl_Menu_Bar *m = new Fl_Menu_Bar(0, 0, 512, 30);
+Fl_Menu_Bar *m = new Fl_Menu_Bar(0, 0, 640, 30);
 m-&gt;copy(menuitems);
 </PRE></UL>
 
@@ -118,7 +118,7 @@ m-&gt;copy(menuitems);
 widget to edit the text:
 
 <UL><PRE>
-w->editor = new Fl_Text_Editor(0, 30, 512, 354);
+w->editor = new Fl_Text_Editor(0, 30, 640, 370);
 w->editor->buffer(textbuf);
 </PRE></UL>
 
@@ -598,5 +598,287 @@ The final editor window should look like the image in Figure 4-2.
 <P ALIGN="CENTER"><IMG src="editor.gif" ALT="The completed editor window."><BR>
 <I>Figure 4-2: The completed editor window</I></P>
 
+<H2>Advanced Features</H2>
+
+<P>Now that we've implemented the basic functionality, it is
+time to show off some of the advanced features of the
+<CODE>Fl_Text_Editor</CODE> widget.
+
+<H3>Syntax Highlighting</H3>
+
+<P>The <CODE>Fl_Text_Editor</CODE> widget supports highlighting
+of text with different fonts, colors, and sizes. The
+implementation is based on the excellent <A
+HREF="http://www.nedit.org/">NEdit</A> text editor core, which
+uses a parallel "style" buffer which tracks the font, color, and
+size of the text that is drawn.
+
+<P>Styles are defined using the
+<CODE>Fl_Text_Display::Style_Table_Entry</CODE> structure
+defined in <CODE>&lt;FL/Fl_Text_Display.H></CODE>:
+
+<UL><PRE>
+struct Style_Table_Entry {
+  Fl_Color color;
+  Fl_Font  font;
+  int      size;
+  unsigned attr;
+};
+</PRE></UL>
+
+<P>The <CODE>color</CODE> member sets the color for the text,
+the <CODE>font</CODE> member sets the FLTK font index to use,
+and the <CODE>size</CODE> member sets the pixel size of the
+text. The <CODE>attr</CODE> member is currently not used.
+
+<P>For our text editor we'll define 7 styles for plain code,
+comments, keywords, and preprocessor directives:
+
+<UL><PRE>
+Fl_Text_Display::Style_Table_Entry styletable[] = {     // Style table
+  { FL_BLACK,      FL_COURIER,        FL_NORMAL_SIZE }, // A - Plain
+  { FL_DARK_GREEN, FL_COURIER_ITALIC, FL_NORMAL_SIZE }, // B - Line comments
+  { FL_DARK_GREEN, FL_COURIER_ITALIC, FL_NORMAL_SIZE }, // C - Block comments
+  { FL_BLUE,       FL_COURIER,        FL_NORMAL_SIZE }, // D - Strings
+  { FL_DARK_RED,   FL_COURIER,        FL_NORMAL_SIZE }, // E - Directives
+  { FL_DARK_RED,   FL_COURIER_BOLD,   FL_NORMAL_SIZE }, // F - Types
+  { FL_BLUE,       FL_COURIER_BOLD,   FL_NORMAL_SIZE }  // G - Keywords
+};
+</PRE></UL>
+
+<P>You'll notice that the comments show a letter next to each
+style - each style in the style buffer is referenced using a
+character starting with the letter 'A'.
+
+<P>You call the <CODE>highlight_data()</CODE> method to associate the
+style data and buffer with the text editor widget:
+
+<UL><PRE>
+Fl_Text_Buffer *stylebuf;
+
+w->editor->highlight_data(stylebuf, styletable,
+                          sizeof(styletable) / sizeof(styletable[0]),
+                          'A', style_unfinished_cb, 0);
+</PRE></UL>
+
+<P>Finally, you need to add a callback to the main text buffer so
+that changes to the text buffer are mirrored in the style buffer:
+
+<UL><PRE>
+textbuf->add_modify_callback(style_update, w->editor);
+</PRE></UL>
+
+<P>The <CODE>style_update()</CODE> function, like the <CODE>change_cb()</CODE>
+function described earlier, is called whenever text is added or removed from
+the text buffer. It mirrors the changes in the style buffer and then updates
+the style data as necessary:
+
+<UL><PRE>
+//
+// 'style_update()' - Update the style buffer...
+//
+
+void
+style_update(int        pos,          // I - Position of update
+             int        nInserted,    // I - Number of inserted chars
+             int        nDeleted,     // I - Number of deleted chars
+             int        nRestyled,    // I - Number of restyled chars
+             const char *deletedText, // I - Text that was deleted
+             void       *cbArg) {     // I - Callback data
+  int  start,                         // Start of text
+       end;                           // End of text
+  char last,                          // Last style on line
+       *style,                        // Style data
+       *text;                         // Text data
+
+
+  // If this is just a selection change, just unselect the style buffer...
+  if (nInserted == 0 &amp;&amp; nDeleted == 0) {
+    stylebuf->unselect();
+    return;
+  }
+
+  // Track changes in the text buffer...
+  if (nInserted > 0) {
+    // Insert characters into the style buffer...
+    style = new char[nInserted + 1];
+    memset(style, 'A', nInserted);
+    style[nInserted] = '\0';
+
+    stylebuf->replace(pos, pos + nDeleted, style);
+    delete[] style;
+  } else {
+    // Just delete characters in the style buffer...
+    stylebuf->remove(pos, pos + nDeleted);
+  }
+
+  // Select the area that was just updated to avoid unnecessary
+  // callbacks...
+  stylebuf->select(pos, pos + nInserted - nDeleted);
+
+  // Re-parse the changed region; we do this by parsing from the
+  // beginning of the line of the changed region to the end of
+  // the line of the changed region...  Then we check the last
+  // style character and keep updating if we have a multi-line
+  // comment character...
+  start = textbuf->line_start(pos);
+  end   = textbuf->line_end(pos + nInserted - nDeleted);
+  text  = textbuf->text_range(start, end);
+  style = stylebuf->text_range(start, end);
+  last  = style[end - start - 1];
+
+  style_parse(text, style, end - start);
+
+  stylebuf->replace(start, end, style);
+  ((Fl_Text_Editor *)cbArg)->redisplay_range(start, end);
+
+  if (last != style[end - start - 1]) {
+    // The last character on the line changed styles, so reparse the
+    // remainder of the buffer...
+    free(text);
+    free(style);
+
+    end   = textbuf->length();
+    text  = textbuf->text_range(start, end);
+    style = stylebuf->text_range(start, end);
+
+    style_parse(text, style, end - start);
+
+    stylebuf->replace(start, end, style);
+    ((Fl_Text_Editor *)cbArg)->redisplay_range(start, end);
+  }
+
+  free(text);
+  free(style);
+}
+</PRE></UL>
+
+<P>The <CODE>style_parse()</CODE> function scans a copy of the
+text in the buffer and generates the necessary style characters
+for display. It assumes that parsing begins at the start of a line:
+
+<UL><PRE>
+//
+// 'style_parse()' - Parse text and produce style data.
+//
+
+void
+style_parse(const char *text,
+            char       *style,
+            int        length) {
+  char             current;
+  int             col;
+  int             last;
+  char             buf[255],
+             *bufptr;
+  const char *temp;
+
+  for (current = *style, col = 0, last = 0; length > 0; length --, text ++) {
+    if (current == 'A') {
+      // Check for directives, comments, strings, and keywords...
+      if (col == 0 &amp;&amp; *text == '#') {
+        // Set style to directive
+        current = 'E';
+      } else if (strncmp(text, "//", 2) == 0) {
+        current = 'B';
+      } else if (strncmp(text, "/*", 2) == 0) {
+        current = 'C';
+      } else if (strncmp(text, "\\\"", 2) == 0) {
+        // Quoted quote...
+        *style++ = current;
+        *style++ = current;
+        text ++;
+        length --;
+        col += 2;
+        continue;
+      } else if (*text == '\"') {
+        current = 'D';
+      } else if (!last &amp;&amp; islower(*text)) {
+        // Might be a keyword...
+        for (temp = text, bufptr = buf;
+             islower(*temp) &amp;&amp; bufptr &lt; (buf + sizeof(buf) - 1);
+             *bufptr++ = *temp++);
+
+        if (!islower(*temp)) {
+          *bufptr = '\0';
+
+          bufptr = buf;
+
+          if (bsearch(&amp;bufptr, code_types,
+                      sizeof(code_types) / sizeof(code_types[0]),
+                      sizeof(code_types[0]), compare_keywords)) {
+            while (text &lt; temp) {
+              *style++ = 'F';
+              text ++;
+              length --;
+              col ++;
+            }
+
+            text --;
+            length ++;
+            last = 1;
+            continue;
+          } else if (bsearch(&amp;bufptr, code_keywords,
+                             sizeof(code_keywords) / sizeof(code_keywords[0]),
+                             sizeof(code_keywords[0]), compare_keywords)) {
+            while (text &lt; temp) {
+              *style++ = 'G';
+              text ++;
+              length --;
+              col ++;
+            }
+
+            text --;
+            length ++;
+            last = 1;
+            continue;
+          }
+        }
+      }
+    } else if (current == 'C' &amp;&amp; strncmp(text, "*/", 2) == 0) {
+      // Close a C comment...
+      *style++ = current;
+      *style++ = current;
+      text ++;
+      length --;
+      current = 'A';
+      col += 2;
+      continue;
+    } else if (current == 'D') {
+      // Continuing in string...
+      if (strncmp(text, "\\\"", 2) == 0) {
+        // Quoted end quote...
+        *style++ = current;
+        *style++ = current;
+        text ++;
+        length --;
+        col += 2;
+        continue;
+      } else if (*text == '\"') {
+        // End quote...
+        *style++ = current;
+        col ++;
+        current = 'A';
+        continue;
+      }
+    }
+
+    // Copy style info...
+    if (current == 'A' &amp;&amp; (*text == '{' || *text == '}')) *style++ = 'G';
+    else *style++ = current;
+    col ++;
+
+    last = isalnum(*text) || *text == '.';
+
+    if (*text == '\n') {
+      // Reset column and possibly reset the style
+      col = 0;
+      if (current == 'B' || current == 'E') current = 'A';
+    }
+  }
+}
+</PRE></UL>
+
+
 </BODY>
 </HTML>
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