text: /* vim:noexpandtab:softtabstop=0: */
  /*
  
  MIT/X11 License
  Copyright (c) 2012 Sean Pringle <sean.pringle@gmail.com>
  
  Permission is hereby granted, free of charge, to any person obtaining
  a copy of this software and associated documentation files (the
  "Software"), to deal in the Software without restriction, including
  without limitation the rights to use, copy, modify, merge, publish,
  distribute, sublicense, and/or sell copies of the Software, and to
  permit persons to whom the Software is furnished to do so, subject to
  the following conditions:
  
  The above copyright notice and this permission notice shall be
  included in all copies or substantial portions of the Software.
  
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  
  */
  
  #define TB_AUTOHEIGHT 1<<0
  #define TB_AUTOWIDTH 1<<1
  #define TB_LEFT 1<<16
  #define TB_RIGHT 1<<17
  #define TB_CENTER 1<<18
  #define TB_EDITABLE 1<<19
  
  typedef struct {
  	unsigned long flags;
  	Window window, parent;
  	short x, y, w, h;
  	short cursor;
  	XftFont *font;
  	XftColor color_fg, color_bg;
  	char *text, *prompt;
  	XIM xim;
  	XIC xic;
  	XGlyphInfo extents;
  } textbox;
  
  void textbox_font(textbox *tb, char *font, char *fg, char *bg);
  void textbox_text(textbox *tb, char *text);
  void textbox_moveresize(textbox *tb, int x, int y, int w, int h);
  
  // Xft text box, optionally editable
  textbox* textbox_create(Window parent, unsigned long flags, short x, short y, short w, short h, char *font, char *fg, char *bg, char *text, char *prompt)
  {
  	textbox *tb = calloc(1, sizeof(textbox));
  
  	tb->flags = flags;
  	tb->parent = parent;
  
  	tb->x = x; tb->y = y; tb->w = MAX(1, w); tb->h = MAX(1, h);
  
  	XColor color; Colormap map = DefaultColormap(display, DefaultScreen(display));
  	unsigned int cp = XAllocNamedColor(display, map, bg, &color, &color) ? color.pixel: None;
  
  	tb->window = XCreateSimpleWindow(display, tb->parent, tb->x, tb->y, tb->w, tb->h, 0, None, cp);
  
  	// need to preload the font to calc line height
  	textbox_font(tb, font, fg, bg);
  
  	tb->prompt = strdup(prompt ? prompt: "");
  	textbox_text(tb, text ? text: "");
  
  	// auto height/width modes get handled here
  	textbox_moveresize(tb, tb->x, tb->y, tb->w, tb->h);
  
  	// edit mode controls
  	if (tb->flags & TB_EDITABLE)
  	{
  		tb->xim = XOpenIM(display, NULL, NULL, NULL);
  		tb->xic = XCreateIC(tb->xim, XNInputStyle, XIMPreeditNothing | XIMStatusNothing, XNClientWindow, tb->window, XNFocusWindow, tb->window, NULL);
  	}
  
  	return tb;
  }
  
  // set an Xft font by name
  void textbox_font(textbox *tb, char *font, char *fg, char *bg)
  {
  	if (tb->font) XftFontClose(display, tb->font);
  	tb->font = XftFontOpenName(display, DefaultScreen(display), font);
  
  	XftColorAllocName(display, DefaultVisual(display, DefaultScreen(display)), DefaultColormap(display, DefaultScreen(display)), fg, &tb->color_fg);
  	XftColorAllocName(display, DefaultVisual(display, DefaultScreen(display)), DefaultColormap(display, DefaultScreen(display)), bg, &tb->color_bg);
  }
  
  // outer code may need line height, width, etc
  void textbox_extents(textbox *tb)
  {
  	int length = strlen(tb->text) + strlen(tb->prompt);
  	char *line = alloca(length + 1);
  	sprintf(line, "%s%s", tb->prompt, tb->text);
  	XftTextExtents8(display, tb->font, (unsigned char*)line, length, &tb->extents);
  }
  
  // set the default text to display
  void textbox_text(textbox *tb, char *text)
  {
  	if (tb->text) free(tb->text);
  	tb->text = strdup(text);
  	tb->cursor = MAX(0, MIN(strlen(text), tb->cursor));
  	textbox_extents(tb);
  }
  
  // set an input prompt for edit mode
  void textbox_prompt(textbox *tb, char *text)
  {
  	if (tb->prompt) free(tb->prompt);
  	tb->prompt = strdup(text);
  	textbox_extents(tb);
  }
  
  // within the parent. handled auto width/height modes
  void textbox_moveresize(textbox *tb, int x, int y, int w, int h)
  {
  	if (tb->flags & TB_AUTOHEIGHT)
  		h = tb->font->ascent + tb->font->descent;
  
  	if (tb->flags & TB_AUTOWIDTH)
  		w = tb->extents.width;
  
  	if (x != tb->x || y != tb->y || w != tb->w || h != tb->h)
  	{
  		tb->x = x; tb->y = y; tb->w = MAX(1, w); tb->h = MAX(1, h);
  		XMoveResizeWindow(display, tb->window, tb->x, tb->y, tb->w, tb->h);
  	}
  }
  
  void textbox_show(textbox *tb)
  {
  	XMapWindow(display, tb->window);
  }
  
  void textbox_hide(textbox *tb)
  {
  	XUnmapWindow(display, tb->window);
  }
  
  // will also unmap the window if still displayed
  void textbox_free(textbox *tb)
  {
  	if (tb->flags & TB_EDITABLE)
  	{
  		XDestroyIC(tb->xic);
  		XCloseIM(tb->xim);
  	}
  
  	if (tb->text) free(tb->text);
  	if (tb->prompt) free(tb->prompt);
  	if (tb->font) XftFontClose(display, tb->font);
  
  	XDestroyWindow(display, tb->window);
  	free(tb);
  }
  
  void textbox_draw(textbox *tb)
  {
  	int i;
  	XGlyphInfo extents;
  
  	GC context    = XCreateGC(display, tb->window, 0, 0);
  	Pixmap canvas = XCreatePixmap(display, tb->window, tb->w, tb->h, DefaultDepth(display, DefaultScreen(display)));
  	XftDraw *draw = XftDrawCreate(display, canvas, DefaultVisual(display, DefaultScreen(display)), DefaultColormap(display, DefaultScreen(display)));
  
  	// clear canvas
  	XftDrawRect(draw, &tb->color_bg, 0, 0, tb->w, tb->h);
  
  	char *line   = tb->text,
  		*text   = tb->text ? tb->text: "",
  		*prompt = tb->prompt ? tb->prompt: "";
  
  	int text_len    = strlen(text);
  	int length      = text_len;
  	int line_height = tb->font->ascent + tb->font->descent;
  	int line_width  = 0;
  
  	int cursor_x      = 0;
  	int cursor_offset = 0;
  	int cursor_width  = MAX(2, line_height/10);
  
  	if (tb->flags & TB_EDITABLE)
  	{
  		int prompt_len = strlen(prompt);
  		length = text_len + prompt_len;
  		cursor_offset = MIN(tb->cursor + prompt_len, length);
  
  		line = alloca(length + 10);
  		sprintf(line, "%s%s", prompt, text);
  
  		// replace spaces so XftTextExtents8 includes their width
  		for (i = 0; i < length; i++) if (isspace(line[i])) line[i] = '_';
  
  		// calc cursor position
  		XftTextExtents8(display, tb->font, (unsigned char*)line, cursor_offset, &extents);
  		cursor_x = extents.width;
  
  		// restore correct text string with spaces
  		sprintf(line, "%s%s", prompt, text);
  	}
  
  	// calc full input text width
  	XftTextExtents8(display, tb->font, (unsigned char*)line, length, &extents);
  	line_width = extents.width;
  
  	int x = 0, y = tb->font->ascent;
  	if (tb->flags & TB_RIGHT)  x = tb->w - line_width;
  	if (tb->flags & TB_CENTER) x = (tb->w - line_width) / 2;
  
  	// draw the text, including any prompt in edit mode
  	XftDrawString8(draw, &tb->color_fg, tb->font, x, y, (unsigned char*)line, length);
  
  	// draw the cursor
  	if (tb->flags & TB_EDITABLE)
  		XftDrawRect(draw, &tb->color_fg, cursor_x, 2, cursor_width, line_height-4);
  
  	// flip canvas to window
  	XCopyArea(display, canvas, tb->window, context, 0, 0, tb->w, tb->h, 0, 0);
  
  	XFreeGC(display, context);
  	XftDrawDestroy(draw);
  	XFreePixmap(display, canvas);
  }
  
  // cursor handling for edit mode
  void textbox_cursor(textbox *tb, int pos)
  {
  	tb->cursor = MAX(0, MIN(strlen(tb->text), pos));
  }
  
  // move right
  void textbox_cursor_inc(textbox *tb)
  {
  	textbox_cursor(tb, tb->cursor+1);
  }
  
  // move left
  void textbox_cursor_dec(textbox *tb)
  {
  	textbox_cursor(tb, tb->cursor-1);
  }
  
  // beginning of line
  void textbox_cursor_home(textbox *tb)
  {
  	tb->cursor = 0;
  }
  
  // end of line
  void textbox_cursor_end(textbox *tb)
  {
  	tb->cursor = strlen(tb->text);
  }
  
  // insert text
  void textbox_insert(textbox *tb, int pos, char *str)
  {
  	int len = strlen(tb->text), slen = strlen(str);
  	pos = MAX(0, MIN(len, pos));
  	// expand buffer
  	tb->text = realloc(tb->text, len + slen + 1);
  	// move everything after cursor upward
  	char *at = tb->text + pos;
  	memmove(at + slen, at, len - pos + 1);
  	// insert new str
  	memmove(at, str, slen);
  	textbox_extents(tb);
  }
  
  // remove text
  void textbox_delete(textbox *tb, int pos, int dlen)
  {
  	int len = strlen(tb->text);
  	pos = MAX(0, MIN(len, pos));
  	// move everything after pos+dlen down
  	char *at = tb->text + pos;
  	memmove(at, at + dlen, len - pos);
  	textbox_extents(tb);
  }
  
  // insert one character
  void textbox_cursor_ins(textbox *tb, char c)
  {
  	char tmp[2] = { c, 0 };
  	textbox_insert(tb, tb->cursor, tmp);
  	textbox_cursor_inc(tb);
  }
  
  // delete on character
  void textbox_cursor_del(textbox *tb)
  {
  	textbox_delete(tb, tb->cursor, 1);
  }
  
  // back up and delete one character
  void textbox_cursor_bkspc(textbox *tb)
  {
  	if (tb->cursor > 0)
  	{
  		textbox_cursor_dec(tb);
  		textbox_cursor_del(tb);
  	}
  }
  
  // handle a keypress in edit mode
  // 0 = unhandled
  // 1 = handled
  // -1 = handled and return pressed (finished)
  int textbox_keypress(textbox *tb, XEvent *ev)
  {
  	KeySym key; Status stat;
  	char pad[32]; int len;
  
  	if (!(tb->flags & TB_EDITABLE)) return 0;
  
  	len = XmbLookupString(tb->xic, &ev->xkey, pad, sizeof(pad), &key, &stat);
  	pad[len] = 0;
  
  	if (key == XK_Left)
  	{
  		textbox_cursor_dec(tb);
  		return 1;
  	}
  	else
  	if (key == XK_Right)
  	{
  		textbox_cursor_inc(tb);
  		return 1;
  	}
  	else
  	if (key == XK_Home)
  	{
  		textbox_cursor_home(tb);
  		return 1;
  	}
  	else
  	if (key == XK_End)
  	{
  		textbox_cursor_end(tb);
  		return 1;
  	}
  	else
  	if (key == XK_Delete)
  	{
  		textbox_cursor_del(tb);
  		return 1;
  	}
  	else
  	if (key == XK_BackSpace)
  	{
  		textbox_cursor_bkspc(tb);
  		return 1;
  	}
  	else
  	if (key == XK_Return)
  	{
  		return -1;
  	}
  	else
  	if (!iscntrl(*pad))
  	{
  		textbox_insert(tb, tb->cursor, pad);
  		textbox_cursor_inc(tb);
  		return 1;
  	}
  	return 0;
  }
  