mirror of https://github.com/fltk/fltk
912 lines
26 KiB
HTML
912 lines
26 KiB
HTML
<HTML>
|
|
<HEAD>
|
|
<TITLE>4 - Designing a Simple Text Editor</TITLE>
|
|
</HEAD>
|
|
<BODY>
|
|
|
|
<H1 ALIGN="RIGHT"><A NAME="editor">4 - Designing a Simple Text Editor</A></H1>
|
|
|
|
<P>This chapter takes you through the design of a simple
|
|
FLTK-based text editor.
|
|
|
|
<H2>Determining the Goals of the Text Editor</H2>
|
|
|
|
<P>Since this will be the first big project you'll be doing with FLTK,
|
|
lets define what we want our text editor to do:
|
|
|
|
<OL>
|
|
|
|
<LI>Provide a menubar/menus for all functions.</LI>
|
|
<LI>Edit a single text file, possibly with multiple views.</LI>
|
|
<LI>Load from a file.</LI>
|
|
<LI>Save to a file.</LI>
|
|
<LI>Cut/copy/delete/paste functions.</LI>
|
|
<LI>Search and replace functions.</LI>
|
|
<LI>Keep track of when the file has been changed.</LI>
|
|
|
|
</OL>
|
|
|
|
<!-- NEED 4in -->
|
|
|
|
<H2>Designing the Main Window</H2>
|
|
|
|
<P>Now that we've outlined the goals for our editor, we can begin with
|
|
the design of our GUI. Obviously the first thing that we need is a
|
|
window, which we'll place inside a class called <TT>EditorWindow</TT>:
|
|
|
|
<UL><PRE>
|
|
class EditorWindow : public Fl_Double_Window {
|
|
public:
|
|
EditorWindow(int w, int h, const char* t);
|
|
~EditorWindow();
|
|
|
|
Fl_Window *replace_dlg;
|
|
Fl_Input *replace_find;
|
|
Fl_Input *replace_with;
|
|
Fl_Button *replace_all;
|
|
Fl_Return_Button *replace_next;
|
|
Fl_Button *replace_cancel;
|
|
|
|
Fl_Text_Editor *editor;
|
|
char search[256];
|
|
};
|
|
</PRE></UL>
|
|
|
|
<H2>Variables</H2>
|
|
|
|
<P>Our text editor will need some global variables to keep track of
|
|
things:
|
|
|
|
<UL><PRE>
|
|
int changed = 0;
|
|
char filename[256] = "";
|
|
Fl_Text_Buffer *textbuf;
|
|
</PRE></UL>
|
|
|
|
<P>The <TT>textbuf</TT> variable is the text editor buffer for
|
|
our window class described previously. We'll cover the other
|
|
variables as we build the application.</P>
|
|
|
|
<H2>Menubars and Menus</H2>
|
|
|
|
<P>The first goal requires us to use a menubar and menus that
|
|
define each function the editor needs to perform. The <A
|
|
href="Fl_Menu_Item.html"><TT>Fl_Menu_Item</TT></A> structure is
|
|
used to define the menus and items in a menubar:</P>
|
|
|
|
<UL><PRE>
|
|
Fl_Menu_Item menuitems[] = {
|
|
{ "&File", 0, 0, 0, FL_SUBMENU },
|
|
{ "&New File", 0, (Fl_Callback *)new_cb },
|
|
{ "&Open File...", FL_CTRL + 'o', (Fl_Callback *)open_cb },
|
|
{ "&Insert File...", FL_CTRL + 'i', (Fl_Callback *)insert_cb, 0, FL_MENU_DIVIDER },
|
|
{ "&Save File", FL_CTRL + 's', (Fl_Callback *)save_cb },
|
|
{ "Save File &As...", FL_CTRL + FL_SHIFT + 's', (Fl_Callback *)saveas_cb, 0, FL_MENU_DIVIDER },
|
|
{ "New &View", FL_ALT + 'v', (Fl_Callback *)view_cb, 0 },
|
|
{ "&Close View", FL_CTRL + 'w', (Fl_Callback *)close_cb, 0, FL_MENU_DIVIDER },
|
|
{ "E&xit", FL_CTRL + 'q', (Fl_Callback *)quit_cb, 0 },
|
|
{ 0 },
|
|
|
|
{ "&Edit", 0, 0, 0, FL_SUBMENU },
|
|
{ "&Undo", FL_CTRL + 'z', (Fl_Callback *)undo_cb, 0, FL_MENU_DIVIDER },
|
|
{ "Cu&t", FL_CTRL + 'x', (Fl_Callback *)cut_cb },
|
|
{ "&Copy", FL_CTRL + 'c', (Fl_Callback *)copy_cb },
|
|
{ "&Paste", FL_CTRL + 'v', (Fl_Callback *)paste_cb },
|
|
{ "&Delete", 0, (Fl_Callback *)delete_cb },
|
|
{ 0 },
|
|
|
|
{ "&Search", 0, 0, 0, FL_SUBMENU },
|
|
{ "&Find...", FL_CTRL + 'f', (Fl_Callback *)find_cb },
|
|
{ "F&ind Again", FL_CTRL + 'g', find2_cb },
|
|
{ "&Replace...", FL_CTRL + 'r', replace_cb },
|
|
{ "Re&place Again", FL_CTRL + 't', replace2_cb },
|
|
{ 0 },
|
|
|
|
{ 0 }
|
|
};
|
|
</PRE></UL>
|
|
|
|
<P>Once we have the menus defined we can create the
|
|
<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, 640, 30);
|
|
m->copy(menuitems);
|
|
</PRE></UL>
|
|
|
|
<P>We'll define the callback functions later.
|
|
|
|
<H2>Editing the Text</H2>
|
|
|
|
<P>To keep things simple our text editor will use the
|
|
<A HREF="Fl_Text_Editor.html"><TT>Fl_Text_Editor</TT></A>
|
|
widget to edit the text:
|
|
|
|
<UL><PRE>
|
|
w->editor = new Fl_Text_Editor(0, 30, 640, 370);
|
|
w->editor->buffer(textbuf);
|
|
</PRE></UL>
|
|
|
|
<P>So that we can keep track of changes to the file, we also want to add
|
|
a "modify" callback:</P>
|
|
|
|
<UL><PRE>
|
|
textbuf->add_modify_callback(changed_cb, w);
|
|
textbuf->call_modify_callbacks();
|
|
</PRE></UL>
|
|
|
|
<P>Finally, we want to use a mono-spaced font like <TT>FL_COURIER</TT>:
|
|
|
|
<UL><PRE>
|
|
w->editor->textfont(FL_COURIER);
|
|
</PRE></UL>
|
|
|
|
<H2>The Replace Dialog</H2>
|
|
|
|
<P>We can use the FLTK convenience functions for many of the
|
|
editor's dialogs, however the replace dialog needs its own
|
|
custom window. To keep things simple we will have a
|
|
"find" string, a "replace" string, and
|
|
"replace all", "replace next", and
|
|
"cancel" buttons. The strings are just
|
|
<TT>Fl_Input</TT> widgets, the "replace all" and
|
|
"cancel" buttons are <TT>Fl_Button</TT> widgets, and
|
|
the "replace next " button is a
|
|
<TT>Fl_Return_Button</TT> widget:</P>
|
|
|
|
<P ALIGN="CENTER"><IMG src="editor-replace.gif" ALT="The search and replace dialog."><BR>
|
|
<I>Figure 4-1: The search and replace dialog.</I></P>
|
|
|
|
<UL><PRE>
|
|
Fl_Window *replace_dlg = new Fl_Window(300, 105, "Replace");
|
|
Fl_Input *replace_find = new Fl_Input(70, 10, 200, 25, "Find:");
|
|
Fl_Input *replace_with = new Fl_Input(70, 40, 200, 25, "Replace:");
|
|
Fl_Button *replace_all = new Fl_Button(10, 70, 90, 25, "Replace All");
|
|
Fl_Button *replace_next = new Fl_Button(105, 70, 120, 25, "Replace Next");
|
|
Fl_Button *replace_cancel = new Fl_Button(230, 70, 60, 25, "Cancel");
|
|
</PRE></UL>
|
|
|
|
<H2>Callbacks</H2>
|
|
|
|
<P>Now that we've defined the GUI components of our editor, we
|
|
need to define our callback functions.</P>
|
|
|
|
<H3>changed_cb()</H3>
|
|
|
|
<P>This function will be called whenever the user changes any text in the
|
|
<TT>editor</TT> widget:
|
|
|
|
<UL><PRE>
|
|
void changed_cb(int, int nInserted, int nDeleted,int, const char*, void* v) {
|
|
if ((nInserted || nDeleted) && !loading) changed = 1;
|
|
EditorWindow *w = (EditorWindow *)v;
|
|
set_title(w);
|
|
if (loading) w->editor->show_insert_position();
|
|
}
|
|
</PRE></UL>
|
|
|
|
<P>The <TT>set_title()</TT> function is one that we will write to set
|
|
the changed status on the current file. We're doing it this way
|
|
because we want to show the changed status in the window's
|
|
title bar.
|
|
|
|
<H3>copy_cb()</H3>
|
|
|
|
<P>This callback function will call <A
|
|
href="Fl_Text_Editor.html#Fl_Text_Editor.kf_copy"><TT>kf_copy()</TT></A>
|
|
to copy the currently selected text to the clipboard:</P>
|
|
|
|
<UL><PRE>
|
|
void copy_cb(Fl_Widget*, void* v) {
|
|
EditorWindow* e = (EditorWindow*)v;
|
|
Fl_Text_Editor::kf_copy(0, e->editor);
|
|
}
|
|
</PRE></UL>
|
|
|
|
<H3>cut_cb()</H3>
|
|
|
|
<P>This callback function will call <A
|
|
href="Fl_Text_Editor.html#Fl_Text_Editor.kf_cut"><TT>kf_cut()</TT></A>
|
|
to cut the currently selected text to the clipboard:</P>
|
|
|
|
<UL><PRE>
|
|
void cut_cb(Fl_Widget*, void* v) {
|
|
EditorWindow* e = (EditorWindow*)v;
|
|
Fl_Text_Editor::kf_cut(0, e->editor);
|
|
}
|
|
</PRE></UL>
|
|
|
|
<H3>delete_cb()</H3>
|
|
|
|
<P>This callback function will call <A
|
|
href="Fl_Text_Buffer.html#Fl_Text_Buffer.remove_selection"><TT>remove_selection()</TT></A>
|
|
to delete the currently selected text to the clipboard:</P>
|
|
|
|
<UL><PRE>
|
|
void delete_cb(Fl_Widget*, void* v) {
|
|
textbuf->remove_selection();
|
|
}
|
|
</PRE></UL>
|
|
|
|
<H3>find_cb()</H3>
|
|
|
|
<P>This callback function asks for a search string using the <A
|
|
href="functions.html#fl_input2"><TT>fl_input()</TT></A>
|
|
convenience function and then calls the <TT>find2_cb()</TT>
|
|
function to find the string:
|
|
|
|
<UL><PRE>
|
|
void find_cb(Fl_Widget* w, void* v) {
|
|
EditorWindow* e = (EditorWindow*)v;
|
|
const char *val;
|
|
|
|
val = fl_input("Search String:", e->search);
|
|
if (val != NULL) {
|
|
// User entered a string - go find it!
|
|
strcpy(e->search, val);
|
|
find2_cb(w, v);
|
|
}
|
|
</PRE></UL>
|
|
|
|
<H3>find2_cb()</H3>
|
|
|
|
<P>This function will find the next occurrence of the search
|
|
string. If the search string is blank then we want to pop up the
|
|
search dialog:
|
|
|
|
<UL><PRE>
|
|
void find2_cb(Fl_Widget* w, void* v) {
|
|
EditorWindow* e = (EditorWindow*)v;
|
|
if (e->search[0] == '\0') {
|
|
// Search string is blank; get a new one...
|
|
find_cb(w, v);
|
|
return;
|
|
}
|
|
|
|
int pos = e->editor->insert_position();
|
|
int found = textbuf->search_forward(pos, e->search, &pos);
|
|
if (found) {
|
|
// Found a match; select and update the position...
|
|
textbuf->select(pos, pos+strlen(e->search));
|
|
e->editor->insert_position(pos+strlen(e->search));
|
|
e->editor->show_insert_position();
|
|
}
|
|
else fl_alert("No occurrences of \'%s\' found!", e->search);
|
|
}
|
|
</PRE></UL>
|
|
|
|
<P>If the search string cannot be found we use the <A
|
|
href="functions.html#fl_alert"><TT>fl_alert()</TT></A>
|
|
convenience function to display a message to that effect.
|
|
|
|
<H3>new_cb()</H3>
|
|
<P>This callback function will clear the editor widget and current
|
|
filename. It also calls the <TT>check_save()</TT> function to give the
|
|
user the opportunity to save the current file first as needed:
|
|
|
|
<UL><PRE>
|
|
void new_cb(Fl_Widget*, void*) {
|
|
if (!check_save()) return;
|
|
|
|
filename[0] = '\0';
|
|
textbuf->select(0, textbuf->length());
|
|
textbuf->remove_selection();
|
|
changed = 0;
|
|
textbuf->call_modify_callbacks();
|
|
}
|
|
</PRE></UL>
|
|
|
|
<H3>open_cb()</H3>
|
|
|
|
<P>This callback function will ask the user for a filename and then load
|
|
the specified file into the input widget and current filename. It also
|
|
calls the <TT>check_save()</TT> function to give the user the
|
|
opportunity to save the current file first as needed:
|
|
|
|
<UL><PRE>
|
|
void open_cb(Fl_Widget*, void*) {
|
|
if (!check_save()) return;
|
|
|
|
char *newfile = fl_file_chooser("Open File?", "*", filename);
|
|
if (newfile != NULL) load_file(newfile, -1);
|
|
}
|
|
</PRE></UL>
|
|
|
|
<P>We call the <TT>load_file()</TT> function to actually load the file.
|
|
|
|
<H3>paste_cb()</H3>
|
|
|
|
<P>This callback function will call <A
|
|
href="Fl_Text_Editor.html#Fl_Text_Editor.kf_paste"><TT>kf_paste()</TT></A>
|
|
to paste the clipboard at the current position:</P>
|
|
|
|
<UL><PRE>
|
|
void paste_cb(Fl_Widget*, void* v) {
|
|
EditorWindow* e = (EditorWindow*)v;
|
|
Fl_Text_Editor::kf_paste(0, e->editor);
|
|
}
|
|
</PRE></UL>
|
|
|
|
<H3>quit_cb()</H3>
|
|
|
|
<P>The quit callback will first see if the current file has been
|
|
modified, and if so give the user a chance to save it. It then exits
|
|
from the program:
|
|
|
|
<UL><PRE>
|
|
void quit_cb(Fl_Widget*, void*) {
|
|
if (changed && !check_save())
|
|
return;
|
|
|
|
exit(0);
|
|
}
|
|
</PRE></UL>
|
|
|
|
<H3>replace_cb()</H3>
|
|
|
|
<P>The replace callback just shows the replace dialog:
|
|
|
|
<UL><PRE>
|
|
void replace_cb(Fl_Widget*, void* v) {
|
|
EditorWindow* e = (EditorWindow*)v;
|
|
e->replace_dlg->show();
|
|
}
|
|
</PRE></UL>
|
|
|
|
<H3>replace2_cb()</H3>
|
|
|
|
<P>This callback will replace the next occurence of the replacement
|
|
string. If nothing has been entered for the replacement string, then
|
|
the replace dialog is displayed instead:
|
|
|
|
<UL><PRE>
|
|
void replace2_cb(Fl_Widget*, void* v) {
|
|
EditorWindow* e = (EditorWindow*)v;
|
|
const char *find = e->replace_find->value();
|
|
const char *replace = e->replace_with->value();
|
|
|
|
if (find[0] == '\0') {
|
|
// Search string is blank; get a new one...
|
|
e->replace_dlg->show();
|
|
return;
|
|
}
|
|
|
|
e->replace_dlg->hide();
|
|
|
|
int pos = e->editor->insert_position();
|
|
int found = textbuf->search_forward(pos, find, &pos);
|
|
|
|
if (found) {
|
|
// Found a match; update the position and replace text...
|
|
textbuf->select(pos, pos+strlen(find));
|
|
textbuf->remove_selection();
|
|
textbuf->insert(pos, replace);
|
|
textbuf->select(pos, pos+strlen(replace));
|
|
e->editor->insert_position(pos+strlen(replace));
|
|
e->editor->show_insert_position();
|
|
}
|
|
else fl_alert("No occurrences of \'%s\' found!", find);
|
|
}
|
|
</PRE></UL>
|
|
|
|
<H3>replall_cb()</H3>
|
|
|
|
<P>This callback will replace all occurences of the search
|
|
string in the file:
|
|
|
|
<UL><PRE>
|
|
void replall_cb(Fl_Widget*, void* v) {
|
|
EditorWindow* e = (EditorWindow*)v;
|
|
const char *find = e->replace_find->value();
|
|
const char *replace = e->replace_with->value();
|
|
|
|
find = e->replace_find->value();
|
|
if (find[0] == '\0') {
|
|
// Search string is blank; get a new one...
|
|
e->replace_dlg->show();
|
|
return;
|
|
}
|
|
|
|
e->replace_dlg->hide();
|
|
|
|
e->editor->insert_position(0);
|
|
int times = 0;
|
|
|
|
// Loop through the whole string
|
|
for (int found = 1; found;) {
|
|
int pos = e->editor->insert_position();
|
|
found = textbuf->search_forward(pos, find, &pos);
|
|
|
|
if (found) {
|
|
// Found a match; update the position and replace text...
|
|
textbuf->select(pos, pos+strlen(find));
|
|
textbuf->remove_selection();
|
|
textbuf->insert(pos, replace);
|
|
e->editor->insert_position(pos+strlen(replace));
|
|
e->editor->show_insert_position();
|
|
times++;
|
|
}
|
|
}
|
|
|
|
if (times) fl_message("Replaced %d occurrences.", times);
|
|
else fl_alert("No occurrences of \'%s\' found!", find);
|
|
}
|
|
</PRE></UL>
|
|
|
|
<H3>replcan_cb()</H3>
|
|
|
|
<P>This callback just hides the replace dialog:
|
|
|
|
<UL><PRE>
|
|
void replcan_cb(Fl_Widget*, void* v) {
|
|
EditorWindow* e = (EditorWindow*)v;
|
|
e->replace_dlg->hide();
|
|
}
|
|
</PRE></UL>
|
|
|
|
<H3>save_cb()</H3>
|
|
|
|
<P>This callback saves the current file. If the current filename is
|
|
blank it calls the "save as" callback:
|
|
|
|
<UL><PRE>
|
|
void save_cb(void) {
|
|
if (filename[0] == '\0') {
|
|
// No filename - get one!
|
|
saveas_cb();
|
|
return;
|
|
}
|
|
else save_file(filename);
|
|
}
|
|
</PRE></UL>
|
|
|
|
<P>The <TT>save_file()</TT> function saves the current file to the
|
|
specified filename.
|
|
|
|
<H3>saveas_cb()</H3>
|
|
|
|
<P>This callback asks the user for a filename and saves the current file:
|
|
|
|
<UL><PRE>
|
|
void saveas_cb(void) {
|
|
char *newfile;
|
|
|
|
newfile = fl_file_chooser("Save File As?", "*", filename);
|
|
if (newfile != NULL) save_file(newfile);
|
|
}
|
|
</PRE></UL>
|
|
|
|
<P>The <TT>save_file()</TT> function saves the current file to the
|
|
specified filename.
|
|
|
|
<H2>Other Functions</H2>
|
|
|
|
<P>Now that we've defined the callback functions, we need our support
|
|
functions to make it all work:
|
|
|
|
<H3>check_save()</H3>
|
|
|
|
<P>This function checks to see if the current file needs to be saved. If
|
|
so, it asks the user if they want to save it:
|
|
|
|
<UL><PRE>
|
|
int check_save(void) {
|
|
if (!changed) return 1;
|
|
|
|
int r = fl_choice("The current file has not been saved.\n"
|
|
"Would you like to save it now?",
|
|
"Cancel", "Save", "Discard");
|
|
|
|
if (r == 1) {
|
|
save_cb(); // Save the file...
|
|
return !changed;
|
|
}
|
|
|
|
return (r == 2) ? 1 : 0;
|
|
}
|
|
</PRE></UL>
|
|
|
|
<H3>load_file()</H3>
|
|
|
|
<P>This function loads the specified file into the <TT>textbuf</TT> class:
|
|
|
|
<UL><PRE>
|
|
int loading = 0;
|
|
void load_file(char *newfile, int ipos) {
|
|
loading = 1;
|
|
int insert = (ipos != -1);
|
|
changed = insert;
|
|
if (!insert) strcpy(filename, "");
|
|
int r;
|
|
if (!insert) r = textbuf->loadfile(newfile);
|
|
else r = textbuf->insertfile(newfile, ipos);
|
|
if (r)
|
|
fl_alert("Error reading from file \'%s\':\n%s.", newfile, strerror(errno));
|
|
else
|
|
if (!insert) strcpy(filename, newfile);
|
|
loading = 0;
|
|
textbuf->call_modify_callbacks();
|
|
}
|
|
</PRE></UL>
|
|
|
|
<P>When loading the file we use the <A
|
|
href="Fl_Text_Buffer.html#Fl_Text_Buffer.loadfile"><TT>loadfile()</TT></A>
|
|
method to "replace" the text in the buffer, or the <A
|
|
href="Fl_Text_Buffer.html#Fl_Text_Buffer.insertfile"><TT>insertfile()</TT></A>
|
|
method to insert text in the buffer from the named file.
|
|
|
|
<H3>save_file()</H3>
|
|
|
|
<P>This function saves the current buffer to the specified file:
|
|
|
|
<UL><PRE>
|
|
void save_file(char *newfile) {
|
|
if (textbuf->savefile(newfile))
|
|
fl_alert("Error writing to file \'%s\':\n%s.", newfile, strerror(errno));
|
|
else
|
|
strcpy(filename, newfile);
|
|
changed = 0;
|
|
textbuf->call_modify_callbacks();
|
|
}
|
|
</PRE></UL>
|
|
|
|
<H3>set_title()</H3>
|
|
|
|
<P>This function checks the <TT>changed</TT> variable and updates the
|
|
window label accordingly:
|
|
<UL><PRE>
|
|
void set_title(Fl_Window* w) {
|
|
if (filename[0] == '\0') strcpy(title, "Untitled");
|
|
else {
|
|
char *slash;
|
|
slash = strrchr(filename, '/');
|
|
#ifdef WIN32
|
|
if (slash == NULL) slash = strrchr(filename, '\\');
|
|
#endif
|
|
if (slash != NULL) strcpy(title, slash + 1);
|
|
else strcpy(title, filename);
|
|
}
|
|
|
|
if (changed) strcat(title, " (modified)");
|
|
|
|
w->label(title);
|
|
}
|
|
</PRE></UL>
|
|
|
|
<H2>The main() Function</H2>
|
|
|
|
<P>Once we've created all of the support functions, the only thing left
|
|
is to tie them all together with the <TT>main()</TT> function.
|
|
The <TT>main()</TT> function creates a new text buffer, creates a
|
|
new view (window) for the text, shows the window, loads the file on
|
|
the command-line (if any), and then enters the FLTK event loop:
|
|
|
|
<UL><PRE>
|
|
int main(int argc, char **argv) {
|
|
textbuf = new Fl_Text_Buffer;
|
|
|
|
Fl_Window* window = new_view();
|
|
|
|
window->show(1, argv);
|
|
|
|
if (argc > 1) load_file(argv[1], -1);
|
|
|
|
return Fl::run();
|
|
}
|
|
</PRE></UL>
|
|
|
|
<H2>Compiling the Editor</H2>
|
|
|
|
<P>The complete source for our text editor can be found in the <TT>test/editor.cxx</TT> source file. Both the Makefile and Visual C++
|
|
workspace include the necessary rules to build the editor. You can
|
|
also compile it using a standard compiler with:
|
|
|
|
<UL><PRE>
|
|
CC -o editor editor.cxx -lfltk -lXext -lX11 -lm
|
|
</PRE></UL>
|
|
|
|
<P>or by using the <TT>fltk-config</TT> script with:
|
|
|
|
<UL><PRE>
|
|
fltk-config --compile editor.cxx
|
|
</PRE></UL>
|
|
|
|
<P>As noted in <A href="basics.html">Chapter 1</A>, you may need to
|
|
include compiler and linker options to tell them where to find the FLTK
|
|
library. Also, the <TT>CC</TT> command may also be called <TT>gcc</TT>
|
|
or <TT>c++</TT> on your system.
|
|
|
|
<P>Congratulations, you've just built your own text editor!</P>
|
|
|
|
<H2>The Final Product</H2>
|
|
|
|
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><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 && 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 && *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 && islower(*text)) {
|
|
// Might be a keyword...
|
|
for (temp = text, bufptr = buf;
|
|
islower(*temp) && bufptr < (buf + sizeof(buf) - 1);
|
|
*bufptr++ = *temp++);
|
|
|
|
if (!islower(*temp)) {
|
|
*bufptr = '\0';
|
|
|
|
bufptr = buf;
|
|
|
|
if (bsearch(&bufptr, code_types,
|
|
sizeof(code_types) / sizeof(code_types[0]),
|
|
sizeof(code_types[0]), compare_keywords)) {
|
|
while (text < temp) {
|
|
*style++ = 'F';
|
|
text ++;
|
|
length --;
|
|
col ++;
|
|
}
|
|
|
|
text --;
|
|
length ++;
|
|
last = 1;
|
|
continue;
|
|
} else if (bsearch(&bufptr, code_keywords,
|
|
sizeof(code_keywords) / sizeof(code_keywords[0]),
|
|
sizeof(code_keywords[0]), compare_keywords)) {
|
|
while (text < temp) {
|
|
*style++ = 'G';
|
|
text ++;
|
|
length --;
|
|
col ++;
|
|
}
|
|
|
|
text --;
|
|
length ++;
|
|
last = 1;
|
|
continue;
|
|
}
|
|
}
|
|
}
|
|
} else if (current == 'C' && 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' && (*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>
|