1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *  textbox.c -- implements the text box
4  *
5  *  ORIGINAL AUTHOR: Savio Lam (lam836@cs.cuhk.hk)
6  *  MODIFIED FOR LINUX KERNEL CONFIG BY: William Roadcap (roadcap@cfw.com)
7  */
8 
9 #include "dialog.h"
10 
11 static int hscroll;
12 static int begin_reached, end_reached, page_length;
13 static const char *buf, *page;
14 static size_t start, end;
15 
16 /*
17  * Go back 'n' lines in text. Called by dialog_textbox().
18  * 'page' will be updated to point to the desired line in 'buf'.
19  */
20 static void back_lines(int n)
21 {
22 	int i;
23 
24 	begin_reached = 0;
25 	/* Go back 'n' lines */
26 	for (i = 0; i < n; i++) {
27 		if (*page == '\0') {
28 			if (end_reached) {
29 				end_reached = 0;
30 				continue;
31 			}
32 		}
33 		if (page == buf) {
34 			begin_reached = 1;
35 			return;
36 		}
37 		page--;
38 		do {
39 			if (page == buf) {
40 				begin_reached = 1;
41 				return;
42 			}
43 			page--;
44 		} while (*page != '\n');
45 		page++;
46 	}
47 }
48 
49 /*
50  * Return current line of text. Called by dialog_textbox() and print_line().
51  * 'page' should point to start of current line before calling, and will be
52  * updated to point to start of next line.
53  */
54 static char *get_line(void)
55 {
56 	int i = 0;
57 	static char line[MAX_LEN + 1];
58 
59 	end_reached = 0;
60 	while (*page != '\n') {
61 		if (*page == '\0') {
62 			end_reached = 1;
63 			break;
64 		} else if (i < MAX_LEN)
65 			line[i++] = *(page++);
66 		else {
67 			/* Truncate lines longer than MAX_LEN characters */
68 			if (i == MAX_LEN)
69 				line[i++] = '\0';
70 			page++;
71 		}
72 	}
73 	if (i <= MAX_LEN)
74 		line[i] = '\0';
75 	if (!end_reached)
76 		page++;		/* move past '\n' */
77 
78 	return line;
79 }
80 
81 /*
82  * Print a new line of text.
83  */
84 static void print_line(WINDOW *win, int row, int width)
85 {
86 	char *line;
87 
88 	line = get_line();
89 	line += MIN(strlen(line), hscroll);	/* Scroll horizontally */
90 	wmove(win, row, 0);	/* move cursor to correct line */
91 	waddch(win, ' ');
92 	waddnstr(win, line, MIN(strlen(line), width - 2));
93 
94 	/* Clear 'residue' of previous line */
95 	wclrtoeol(win);
96 }
97 
98 /*
99  * Print a new page of text.
100  */
101 static void print_page(WINDOW *win, int height, int width)
102 {
103 	int i, passed_end = 0;
104 
105 	page_length = 0;
106 	for (i = 0; i < height; i++) {
107 		print_line(win, i, width);
108 		if (!passed_end)
109 			page_length++;
110 		if (end_reached && !passed_end)
111 			passed_end = 1;
112 	}
113 	wnoutrefresh(win);
114 }
115 
116 /*
117  * Print current position
118  */
119 static void print_position(WINDOW *win)
120 {
121 	int percent;
122 
123 	wattrset(win, dlg.position_indicator.atr);
124 	wbkgdset(win, dlg.position_indicator.atr & A_COLOR);
125 	percent = (page - buf) * 100 / strlen(buf);
126 	wmove(win, getmaxy(win) - 3, getmaxx(win) - 9);
127 	wprintw(win, "(%3d%%)", percent);
128 }
129 
130 /*
131  * refresh window content
132  */
133 static void refresh_text_box(WINDOW *dialog, WINDOW *box, int boxh, int boxw,
134 			     int cur_y, int cur_x)
135 {
136 	start = page - buf;
137 
138 	print_page(box, boxh, boxw);
139 	print_position(dialog);
140 	wmove(dialog, cur_y, cur_x);	/* Restore cursor position */
141 	wrefresh(dialog);
142 
143 	end = page - buf;
144 }
145 
146 /*
147  * Display text from a file in a dialog box.
148  *
149  * keys is a null-terminated array
150  */
151 int dialog_textbox(const char *title, const char *tbuf, int initial_height,
152 		   int initial_width, int *_vscroll, int *_hscroll,
153 		   int (*extra_key_cb)(int, size_t, size_t, void *), void *data)
154 {
155 	int i, x, y, cur_x, cur_y, key = 0;
156 	int height, width, boxh, boxw;
157 	WINDOW *dialog, *box;
158 	bool done = false;
159 
160 	begin_reached = 1;
161 	end_reached = 0;
162 	page_length = 0;
163 	hscroll = 0;
164 	buf = tbuf;
165 	page = buf;	/* page is pointer to start of page to be displayed */
166 
167 	if (_vscroll && *_vscroll) {
168 		begin_reached = 0;
169 
170 		for (i = 0; i < *_vscroll; i++)
171 			get_line();
172 	}
173 	if (_hscroll)
174 		hscroll = *_hscroll;
175 
176 do_resize:
177 	getmaxyx(stdscr, height, width);
178 	if (height < TEXTBOX_HEIGTH_MIN || width < TEXTBOX_WIDTH_MIN)
179 		return -ERRDISPLAYTOOSMALL;
180 	if (initial_height != 0)
181 		height = initial_height;
182 	else
183 		if (height > 4)
184 			height -= 4;
185 		else
186 			height = 0;
187 	if (initial_width != 0)
188 		width = initial_width;
189 	else
190 		if (width > 5)
191 			width -= 5;
192 		else
193 			width = 0;
194 
195 	/* center dialog box on screen */
196 	x = (getmaxx(stdscr) - width) / 2;
197 	y = (getmaxy(stdscr) - height) / 2;
198 
199 	draw_shadow(stdscr, y, x, height, width);
200 
201 	dialog = newwin(height, width, y, x);
202 	keypad(dialog, TRUE);
203 
204 	/* Create window for box region, used for scrolling text */
205 	boxh = height - 4;
206 	boxw = width - 2;
207 	box = subwin(dialog, boxh, boxw, y + 1, x + 1);
208 	wattrset(box, dlg.dialog.atr);
209 	wbkgdset(box, dlg.dialog.atr & A_COLOR);
210 
211 	keypad(box, TRUE);
212 
213 	/* register the new window, along with its borders */
214 	draw_box(dialog, 0, 0, height, width,
215 		 dlg.dialog.atr, dlg.border.atr);
216 
217 	wattrset(dialog, dlg.border.atr);
218 	mvwaddch(dialog, height - 3, 0, ACS_LTEE);
219 	for (i = 0; i < width - 2; i++)
220 		waddch(dialog, ACS_HLINE);
221 	wattrset(dialog, dlg.dialog.atr);
222 	wbkgdset(dialog, dlg.dialog.atr & A_COLOR);
223 	waddch(dialog, ACS_RTEE);
224 
225 	print_title(dialog, title, width);
226 
227 	print_button(dialog, " Exit ", height - 2, width / 2 - 4, TRUE);
228 	wnoutrefresh(dialog);
229 	getyx(dialog, cur_y, cur_x);	/* Save cursor position */
230 
231 	/* Print first page of text */
232 	attr_clear(box, boxh, boxw, dlg.dialog.atr);
233 	refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);
234 
235 	while (!done) {
236 		key = wgetch(dialog);
237 		switch (key) {
238 		case 'E':	/* Exit */
239 		case 'e':
240 		case 'X':
241 		case 'x':
242 		case 'q':
243 		case '\n':
244 			done = true;
245 			break;
246 		case 'g':	/* First page */
247 		case KEY_HOME:
248 			if (!begin_reached) {
249 				begin_reached = 1;
250 				page = buf;
251 				refresh_text_box(dialog, box, boxh, boxw,
252 						 cur_y, cur_x);
253 			}
254 			break;
255 		case 'G':	/* Last page */
256 		case KEY_END:
257 
258 			end_reached = 1;
259 			/* point to last char in buf */
260 			page = buf + strlen(buf);
261 			back_lines(boxh);
262 			refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);
263 			break;
264 		case 'K':	/* Previous line */
265 		case 'k':
266 		case KEY_UP:
267 			if (begin_reached)
268 				break;
269 
270 			back_lines(page_length + 1);
271 			refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);
272 			break;
273 		case 'B':	/* Previous page */
274 		case 'b':
275 		case 'u':
276 		case KEY_PPAGE:
277 			if (begin_reached)
278 				break;
279 			back_lines(page_length + boxh);
280 			refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);
281 			break;
282 		case 'J':	/* Next line */
283 		case 'j':
284 		case KEY_DOWN:
285 			if (end_reached)
286 				break;
287 
288 			back_lines(page_length - 1);
289 			refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);
290 			break;
291 		case KEY_NPAGE:	/* Next page */
292 		case ' ':
293 		case 'd':
294 			if (end_reached)
295 				break;
296 
297 			begin_reached = 0;
298 			refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);
299 			break;
300 		case '0':	/* Beginning of line */
301 		case 'H':	/* Scroll left */
302 		case 'h':
303 		case KEY_LEFT:
304 			if (hscroll <= 0)
305 				break;
306 
307 			if (key == '0')
308 				hscroll = 0;
309 			else
310 				hscroll--;
311 			/* Reprint current page to scroll horizontally */
312 			back_lines(page_length);
313 			refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);
314 			break;
315 		case 'L':	/* Scroll right */
316 		case 'l':
317 		case KEY_RIGHT:
318 			if (hscroll >= MAX_LEN)
319 				break;
320 			hscroll++;
321 			/* Reprint current page to scroll horizontally */
322 			back_lines(page_length);
323 			refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);
324 			break;
325 		case KEY_ESC:
326 			if (on_key_esc(dialog) == KEY_ESC)
327 				done = true;
328 			break;
329 		case KEY_RESIZE:
330 			back_lines(height);
331 			delwin(box);
332 			delwin(dialog);
333 			on_key_resize();
334 			goto do_resize;
335 		default:
336 			if (extra_key_cb && extra_key_cb(key, start, end, data)) {
337 				done = true;
338 				break;
339 			}
340 		}
341 	}
342 	delwin(box);
343 	delwin(dialog);
344 	if (_vscroll) {
345 		const char *s;
346 
347 		s = buf;
348 		*_vscroll = 0;
349 		back_lines(page_length);
350 		while (s < page && (s = strchr(s, '\n'))) {
351 			(*_vscroll)++;
352 			s++;
353 		}
354 	}
355 	if (_hscroll)
356 		*_hscroll = hscroll;
357 	return key;
358 }
359