cell.c

/*
 * cell.c: Cell management of the Gnumeric spreadsheet.
 *
 * Author:
 *    Miguel de Icaza 1998, 1999 (miguel@kernel.org)
 */
#include <config.h>
#include <gnome.h>
#include <locale.h>
#include "gnumeric.h"
#include "gnumeric-sheet.h"
#include "gnumeric-util.h"
#include "eval.h"
#include "format.h"
#include "color.h"
#include "cursors.h"
#include "utils.h"
#include "gnumeric-util.h"
#include <ctype.h>

static int         redraws_frozen           = 0;
static int         redraws_deep_frozen      = 0;
static GHashTable *cell_hash_queue;

static void
cell_formula_changed (Cell *cell)
{
	g_return_if_fail (cell != NULL);

	sheet_cell_formula_link (cell);

	cell_queue_recalc (cell);
}

static inline void
cell_modified (Cell *cell)
{
	Sheet *sheet = cell->sheet;

	/* Cells from the clipboard do not have a sheet attached */
	if (sheet)
		sheet->modified = TRUE;
}


/* Empty a cell's value, entered_text, and parsed_node.  */
static void
cell_cleanout (Cell *cell)
{
	if (cell->parsed_node){
		/* Clipboard cells, e.g., are not attached to a sheet.  */
		if (cell->sheet)
			sheet_cell_formula_unlink (cell);
		expr_tree_unref (cell->parsed_node);
		cell->parsed_node = NULL;
	}

	if (cell->value) {
		value_release (cell->value);
		cell->value = NULL;
	}

	if (cell->entered_text) {
		string_unref (cell->entered_text);
		cell->entered_text = NULL;
	}
}


void
cell_set_formula (Cell *cell, const char *text)
{
	ExprTree *new_expr;
	char *error_msg = _("ERROR");
	const char *desired_format = NULL;
	ParsePosition pp;

	g_return_if_fail (cell != NULL);
	g_return_if_fail (text != NULL);

	cell_modified (cell);
	new_expr = expr_parse_string (&text [1],
				      parse_pos_cell (&pp, cell),
				      &desired_format,
				      &error_msg);
	cell_cleanout (cell);

	if (new_expr == NULL){
		cell_set_rendered_text (cell, error_msg);
		cell->entered_text = string_get (text);
		/* FIXME: Supply a proper position?  */
		cell->value = value_new_error (NULL, error_msg);
		return;
	}

	if (desired_format &&
	    strcmp (cell->style->format->format, "General") == 0){
		style_format_unref (cell->style->format);
		cell->style->format = style_format_new (desired_format);
	}

	if (new_expr->oper == OPER_ARRAY){
		/* The corner sets up the entire array block */
		if (new_expr->u.array.x != 0 || new_expr->u.array.y != 0) {
			expr_tree_unref (new_expr);
			return;
		}

		/* 
		 * NOTE : The wrapper supplied by the parser will be released
		 *        and recreated.  new_expr will NOT be valid on exit
		 *        from cell_set_array_formula.
		 */
		cell->parsed_node = new_expr;
		cell_set_array_formula (cell->sheet,
					cell->row->pos, cell->col->pos,
					cell->row->pos +
					    new_expr->u.array.rows -1,
					cell->col->pos +
					    new_expr->u.array.cols -1,
					new_expr->u.array.corner.func.expr);
	} else {
		cell->parsed_node = new_expr;
		/* Until the value is recomputed, we put in this value.  */
		cell->value = value_new_error (NULL, _("Circular reference"));
		cell_formula_changed (cell);
	}
}

/*
 * cell_set_alignment:
 *
 * @cell: the cell to change the alignment of
 * @halign: the horizontal alignemnt
 * @valign: the vertical alignemnt
 * @orient: the text orientation
 *
 * This routine changes the alignment of a cell to those specified.
 */
void
cell_set_alignment (Cell *cell, int halign, int valign, int orient, int auto_return)
{
	g_return_if_fail (cell != NULL);
	g_return_if_fail (cell->style != NULL);

	if ((cell->style->halign      == halign) &&
	    (cell->style->valign      == valign) &&
	    (cell->style->fit_in_cell == auto_return) &&
	    (cell->style->orientation == orient))
		return;

	cell_modified (cell);

	cell_queue_redraw (cell);

	cell->style->halign = halign;
	cell->style->valign = valign;
	cell->style->orientation = orient;
	cell->style->fit_in_cell = auto_return;

	cell_calc_dimensions (cell);

	cell_queue_redraw (cell);
}

void
cell_set_halign (Cell *cell, StyleHAlignFlags halign)
{
	g_return_if_fail (cell != NULL);

	if (((unsigned int)cell->style->halign) == ((unsigned int) halign))
		return;

	cell_modified (cell);

	cell_queue_redraw (cell);
	cell->style->halign = halign;

	cell_calc_dimensions (cell);
	cell_queue_redraw (cell);
}

void
cell_set_font_from_style (Cell *cell, StyleFont *style_font)
{
	g_return_if_fail (cell != NULL);
	g_return_if_fail (style_font != NULL);

	cell_modified (cell);

	cell_queue_redraw (cell);

	style_font_ref (style_font);
	style_font_unref (cell->style->font);

	cell->style->font = style_font;
	cell->style->valid_flags |= STYLE_FONT;

	cell_calc_dimensions (cell);

	cell_queue_redraw (cell);
}

void
cell_set_style (Cell *cell, Style *reference_style)
{
	g_return_if_fail (cell != NULL);
	g_return_if_fail (reference_style != NULL);

	cell_modified (cell);

	cell_queue_redraw (cell);
	style_destroy (cell->style);
	cell->style = style_duplicate (reference_style);
	if (cell->value)
		cell_render_value (cell);
	cell_calc_dimensions (cell);
	cell_queue_redraw (cell);
}

void
cell_comment_destroy (Cell *cell)
{
	CellComment *comment;
	GList *l;

	g_return_if_fail (cell != NULL);

	comment = cell->comment;
	if (!comment)
		return;
	cell->comment = NULL;

	/* Free resources */
	string_unref (comment->comment);

	if (comment->timer_tag != -1)
		gtk_timeout_remove (comment->timer_tag);

	if (comment->window)
		gtk_object_unref (GTK_OBJECT (comment->window));

	for (l = comment->realized_list; l; l = l->next)
		gtk_object_destroy (l->data);
	g_list_free (comment->realized_list);

	g_free (comment);
}

static void
cell_comment_cancel_timer (Cell *cell)
{
	if (cell->comment->timer_tag != -1){
		gtk_timeout_remove (cell->comment->timer_tag);
		cell->comment->timer_tag = -1;
	}

}

static void
cell_display_comment (Cell *cell)
{
	GtkWidget *window, *label;
	int x, y;

	g_return_if_fail (cell != NULL);

	cell_comment_cancel_timer (cell);

	window = gtk_window_new (GTK_WINDOW_POPUP);
	label = gtk_label_new (cell->comment->comment->str);
	gtk_container_add (GTK_CONTAINER (window), label);

	gdk_window_get_pointer (NULL, &x, &y, NULL);
	gtk_widget_set_uposition (window, x+10, y+10);

	gtk_widget_show_all (window);

	cell->comment->window = window;
}

static gint
cell_popup_comment (gpointer data)
{
	Cell *cell = data;

	cell->comment->timer_tag = -1;

	cell_display_comment (cell);
	return FALSE;
}

static int
cell_comment_clicked (GnomeCanvasItem *item, GdkEvent *event, Cell *cell)
{
	GnomeCanvas *canvas = item->canvas;

	switch (event->type){
	case GDK_BUTTON_RELEASE:
		if (event->button.button != 1)
			return FALSE;
		if (cell->comment->window)
			return FALSE;
		cell_display_comment (cell);
		break;

	case GDK_BUTTON_PRESS:
		if (event->button.button != 1)
			return FALSE;
		break;

	case GDK_ENTER_NOTIFY:
		cell->comment->timer_tag = gtk_timeout_add (1000, cell_popup_comment, cell);
		cursor_set_widget (canvas, GNUMERIC_CURSOR_ARROW);
		break;

	case GDK_LEAVE_NOTIFY:
		cell_comment_cancel_timer (cell);
		if (cell->comment->window){
			gtk_object_unref (GTK_OBJECT (cell->comment->window));
			cell->comment->window = NULL;
		}
		break;

	default:
		return FALSE;
	}
	return TRUE;
}

static void
cell_comment_realize (Cell *cell)
{
	GList *l;

	g_return_if_fail (cell->comment != NULL);

	sheet_cell_comment_link (cell);
	for (l = cell->sheet->sheet_views; l; l = l->next){
		SheetView *sheet_view = SHEET_VIEW (l->data);
		GnomeCanvasItem *o;

		o = sheet_view_comment_create_marker (
			sheet_view,
			cell->col->pos, cell->row->pos);
		gtk_object_ref (GTK_OBJECT (o));

		cell->comment->realized_list = g_list_prepend (
			cell->comment->realized_list, o);

		gtk_signal_connect (GTK_OBJECT (o), "event",
				    GTK_SIGNAL_FUNC (cell_comment_clicked), cell);
	}
}

static void
cell_comment_unrealize (Cell *cell)
{
	GList *l;

	g_return_if_fail (cell->comment != NULL);

	sheet_cell_comment_unlink (cell);
	for (l = cell->comment->realized_list; l; l = l->next){
		GnomeCanvasItem *o = l->data;

		gtk_object_unref (GTK_OBJECT (o));
	}
	g_list_free (cell->comment->realized_list);
	cell->comment->realized_list = NULL;
}

void
cell_realize (Cell *cell)
{
	g_return_if_fail (cell != NULL);

	if (cell->comment)
		cell_comment_realize (cell);
}

void
cell_unrealize (Cell *cell)
{
	g_return_if_fail (cell != NULL);

	if (cell->comment)
		cell_comment_unrealize (cell);
}

void
cell_set_comment (Cell *cell, const char *str)
{
	int had_comments = FALSE;

	g_return_if_fail (cell != NULL);
	g_return_if_fail (str != NULL);

	cell_modified (cell);

	cell_comment_destroy (cell);

	cell->comment = g_new (CellComment, 1);
	cell->comment->realized_list = NULL;
	cell->comment->timer_tag = -1;
	cell->comment->window = NULL;

	cell->comment->comment = string_get (str);

	if (had_comments)
		cell_queue_redraw (cell);

	if (cell->sheet)
		cell_comment_realize (cell);
}

void
cell_set_foreground (Cell *cell, gushort red, gushort green, gushort blue)
{
	g_return_if_fail (cell != NULL);

	cell_modified (cell);

	if (cell->style->valid_flags & STYLE_FORE_COLOR)
		style_color_unref (cell->style->fore_color);

	cell->style->valid_flags |= STYLE_FORE_COLOR;
	cell->style->fore_color = style_color_new (red, green, blue);

	cell_queue_redraw (cell);
}

void
cell_set_background (Cell *cell, gushort red, gushort green, gushort blue)
{
	g_return_if_fail (cell != NULL);

	cell_modified (cell);

	if (cell->style->valid_flags & STYLE_BACK_COLOR)
		style_color_unref (cell->style->back_color);

	cell->style->valid_flags |= STYLE_BACK_COLOR;
	cell->style->back_color = style_color_new (red, green, blue);

	cell_queue_redraw (cell);
}

/**
 * Null pointers unset the style.
 **/
void
cell_set_color_from_style (Cell *cell, StyleColor *foreground,
			   StyleColor *background)
{
	g_return_if_fail (cell != NULL);

	cell_modified (cell);

	if (cell->style->valid_flags & STYLE_FORE_COLOR) {
		cell->style->valid_flags ^= STYLE_FORE_COLOR;
		style_color_unref (cell->style->fore_color);
	}

	if (cell->style->valid_flags & STYLE_BACK_COLOR) {
		cell->style->valid_flags ^= STYLE_BACK_COLOR;
		style_color_unref (cell->style->back_color);
	}

	if (background) {
		cell->style->valid_flags |= STYLE_BACK_COLOR;
		style_color_ref (background);
	}
	cell->style->back_color = background;

	if (foreground) {
		cell->style->valid_flags |= STYLE_FORE_COLOR;
		style_color_ref (foreground);
	}
	cell->style->fore_color = foreground;

	cell_queue_redraw (cell);
}


void
cell_set_pattern (Cell *cell, int pattern)
{
	g_return_if_fail (cell != NULL);

	cell_modified (cell);

	cell->style->valid_flags |= STYLE_PATTERN;
	cell->style->pattern = pattern;

	cell_queue_redraw (cell);
}

/**
 * cell_set_border:
 * @cell: the cell
 * @border_type: an array containing the borders for the cell
 * @border_color: an array of StyleColors with the
 * NB. don't unref the StyleColor *s you pass.
 */
void
cell_set_border (Cell *cell,
		 StyleBorderType  const border_type[4],
		 StyleColor      *border_color[4])
{
	g_return_if_fail (cell != NULL);

	cell_modified (cell);

  	if (cell->style->valid_flags & STYLE_BORDER)
		style_border_unref (cell->style->border);

	cell->style->valid_flags |= STYLE_BORDER;
	cell->style->border = style_border_new (border_type, border_color);

	cell_queue_redraw (cell);
}

/*
 * cell_set_rendered_text
 * @cell:          the cell we will modify
 * @rendered_text: the text we will display
 *
 * This routine sets the rendered text field of the cell
 * it recomputes the bounding box for the cell as well
 */
void
cell_set_rendered_text (Cell *cell, const char *rendered_text)
{
	String *oldtext;

	g_return_if_fail (cell != NULL);
	g_return_if_fail (rendered_text != NULL);

	cell_modified (cell);

	oldtext = cell->text;
	cell->text = string_get (rendered_text);
	if (oldtext)
		string_unref (oldtext);

	cell_calc_dimensions (cell);
}

/*
 * cell_render_value
 * @cell: The cell whose value needs to be rendered
 *
 * The value of the cell is formated according to the format style
 */
void
cell_render_value (Cell *cell)
{
	StyleColor *color;
	char *str;

	g_return_if_fail (cell != NULL);
	g_return_if_fail (cell->value != NULL);

	if (cell->render_color){
		style_color_unref (cell->render_color);
		cell->render_color = NULL;
	}

	str = format_value (cell->style->format, cell->value, &color);
	cell->render_color = color;

	cell_set_rendered_text (cell, str);
	g_free (str);
}

/*
 * Sets the value for a cell:
 *
 * This is kind of an internal function and should be only called by
 * routines that know what they are doing.  These are the important
 * differences from cell_set_value:
 *
 *    - It does not queue redraws (so you have to queue the redraw yourself
 *      or queue a full redraw).
 *
 *    - It does not queue any recomputations.  You have to queue the recompute
 *      yourself.
 */
void
cell_set_value_simple (Cell *cell, Value *v)
{
	g_return_if_fail (cell);
	g_return_if_fail (v);

	cell_modified (cell);
	cell_cleanout (cell);

	cell->value = v;
	cell_render_value (cell);
}

/*
 * cell_set_value
 *
 * Changes the value of a cell
 */
void
cell_set_value (Cell *cell, Value *v)
{
	g_return_if_fail (cell);
	g_return_if_fail (v);

	cell_queue_redraw (cell);

	cell_set_value_simple (cell, v);
	cell_content_changed (cell);

	cell_queue_redraw (cell);
}

/*
 * Sets the text for a cell:
 *
 * This is kind of an internal function and should be only called by
 * routines that know what they are doing.  These are the important
 * differences from cell_set_text:
 *
 *    - It does not queue redraws (so you have to queue the redraw yourself
 *      or queue a full redraw).
 *
 *    - It does not queue any recomputations.  You have to queue the recompute
 *      yourself.
 */
void
cell_set_text_simple (Cell *cell, const char *text)
{
	g_return_if_fail (cell != NULL);
	g_return_if_fail (text != NULL);

	cell_modified (cell);
	cell_cleanout (cell);

 	if (text [0] == '=' && text [1] != 0){
		cell_set_formula (cell, text);
	} else {
		char *end;
		long l;
		int  set=0;

		l = strtol (text, &end, 10);
		if (l != LONG_MAX && l != LONG_MIN &&
		    text != end && (l == (int)l)) {
			/* Allow and ignore spaces at the end of integers.  */
			while (*end == ' ')
				end++;
			if (*end == 0) {
				cell->value = value_new_int (l);
				set = 1;
			}
		}
		
		if (!set) {
			double d;
			d = strtod (text, &end);
			if (text != end && *end == 0) {
				/* It is a floating point number.  */
				cell->value = value_new_float ((float_t)d);
			} else {
				/* It is text.  */
				cell->value = value_new_string (text);
			}
		}

		cell_render_value (cell);
	}
}

/*
 * cell_content_changed:
 *
 * Call this routine if you modify the contents of a cell
 * to trigger a recompute on any dependencies
 */
void
cell_content_changed (Cell *cell)
{
	GList   *deps;

	g_return_if_fail (cell != NULL);

	/* Queue all of the dependencies for this cell */
	deps = cell_get_dependencies (cell->sheet,
				      cell->col->pos,
				      cell->row->pos);
	if (deps)
		cell_queue_recalc_list (deps, TRUE);
}


/*
 * cell_set_text
 *
 * Changes the content of a cell
 */
void
cell_set_text (Cell *cell, const char *text)
{
	g_return_if_fail (cell != NULL);
	g_return_if_fail (text != NULL);

	if (cell->parsed_node != NULL && cell->parsed_node->oper == OPER_ARRAY) {
		gnumeric_no_modify_array_notice (cell->sheet->workbook);
		return;
	}

	cell_queue_redraw (cell);

	cell_set_text_simple (cell, text);
	cell_content_changed (cell);

	cell_queue_redraw (cell);
}

/**
 * cell_set_formula_tree_simple:
 * @cell:    the cell to set the formula to
 * @formula: an expression tree with the formula
 *
 * This is an internal function.  It should be only called by routines that
 * know what they are doing.  These are the important differences from
 * cell_set_formula:
 *
 *   - It does not queue redraws (so you have to queue the redraw yourself
 *     or queue a full redraw).
 *
 *   - It does not queue any recomputations.  You have to queue the
 *     recompute yourself.
 */
void
cell_set_formula_tree_simple (Cell *cell, ExprTree *formula)
{
	g_return_if_fail (cell != NULL);
	g_return_if_fail (formula != NULL);

	/* Ref before unref.  Repeat after me.  */
	expr_tree_ref (formula);

	cell_modified (cell);
	cell_cleanout (cell);

	cell->parsed_node = formula;
	/* Until the value is recomputed, we put in this value.  */
	cell->value = value_new_error (NULL, _("Circular reference"));
	cell_formula_changed (cell);
}

/**
 * cell_set_array_formula:
 * @sheet:   The sheet to set the formula to.
 * @row_a:   The top row in the destination region.
 * @col_a:   The left column in the destination region.
 * @row_b:   The bottom row in the destination region.
 * @col_b:   The right column in the destination region.
 * @formula: an expression tree with the formula
 *
 * Uses cell_set_formula_tree_simple to store the formula as an 
 * 'array-formula'.  The supplied expression is wrapped in an array
 * operator for each cell in the range and scheduled for recalc.  The
 * upper left corner is handled as a special case and care is taken to
 * out it at the head of the recalc queue.
 */
void
cell_set_array_formula (Sheet *sheet,
			int row_a, int col_a, int row_b, int col_b,
			ExprTree *formula)
{
	int const num_rows = 1 + row_b - row_a;
	int const num_cols = 1 + col_b - col_a;
	int x, y;
	Cell * const corner = sheet_cell_fetch (sheet, col_a, row_a);
	Cell * cell = NULL;
	ExprTree *wrapper;

	g_return_if_fail (num_cols > 0);
	g_return_if_fail (num_rows > 0);
	g_return_if_fail (formula != NULL);
	g_return_if_fail (corner != NULL);

	wrapper = expr_tree_array_formula (0, 0, num_rows, num_cols);
	wrapper->u.array.corner.func.value = NULL;
	wrapper->u.array.corner.func.expr = formula;
	expr_tree_ref (formula);
	cell_set_formula_tree_simple (corner, wrapper);
	expr_tree_unref (wrapper);

	/* The corner must be 1st on the recalc list, queue it later */
	cell_unqueue_from_recalc (corner);

	for (x = 0; x < num_cols; ++x)
		for (y = 0; y < num_rows; ++y) {
			if (x == 0 && y == 0)
				continue;
			cell = sheet_cell_fetch (sheet, col_a+x,row_a+y);
			wrapper = expr_tree_array_formula (x, y,
							   num_rows, num_cols);
			wrapper->u.array.corner.cell = corner;
			cell_set_formula_tree_simple (cell, wrapper);
			expr_tree_unref (wrapper);
		}

	/* Put the corner at the head of the recalc list */
	cell_queue_recalc (corner);
}

void
cell_set_formula_tree (Cell *cell, ExprTree *formula)
{
	g_return_if_fail (cell != NULL);

	cell_queue_redraw (cell);

	cell_set_formula_tree_simple (cell, formula);
	cell_content_changed (cell);

	cell_queue_redraw (cell);
}

/**
 * cell_copy:
 * @cell: existing cell to duplicate
 *
 * Makes a copy of a Cell.
 *
 * Returns a copy of the cell.
 */
Cell *
cell_copy (const Cell *cell)
{
	Cell *new_cell;

	g_return_val_if_fail (cell != NULL, NULL);

	new_cell = g_new (Cell, 1);

	/* bitmap copy first */
	*new_cell = *cell;

	new_cell->flags &= ~CELL_QUEUED_FOR_RECALC;

	/* now copy properly the rest */
	if (new_cell->parsed_node)
		expr_tree_ref (new_cell->parsed_node);

	if (new_cell->text)
		string_ref (new_cell->text);

	if (new_cell->entered_text)
		string_ref (new_cell->entered_text);

	if (new_cell->style)
		new_cell->style = style_duplicate (new_cell->style);

	if (new_cell->render_color)
		style_color_ref (new_cell->render_color);

	if (new_cell->value)
		new_cell->value = value_duplicate (new_cell->value);

	if (cell->comment) {
		new_cell->comment = NULL;
		cell_set_comment (new_cell, cell->comment->comment->str);
	}

	return new_cell;
}

void
cell_destroy (Cell *cell)
{
	g_return_if_fail (cell != NULL);

	if (cell_hash_queue && g_hash_table_lookup (cell_hash_queue, cell)) {
		g_warning ("FIXME: Deleting cell %s which was queued for redraw",
			   cell_name (cell->col->pos, cell->row->pos));
		g_hash_table_remove (cell_hash_queue, cell);
	}

	cell_modified (cell);
	cell_cleanout (cell);

	if (cell->render_color)
		style_color_unref (cell->render_color);
	cell->render_color = (void *)0xdeadbeef;

	cell_comment_destroy (cell);

	if (cell->text)
		string_unref (cell->text);
	cell->text = (void *)0xdeadbeef;

	style_destroy (cell->style);
	cell->style = (void *)0xdeadbeef;

	g_free (cell);
}

void
cell_freeze_redraws (void)
{
	redraws_frozen++;
	if (redraws_frozen == 1)
		cell_hash_queue = g_hash_table_new (g_direct_hash, g_direct_equal);
}

static void
call_cell_queue_redraw (gpointer key, gpointer value, gpointer user_data)
{
	cell_queue_redraw (value);
}

void
cell_thaw_redraws (void)
{
	redraws_frozen--;
	if (redraws_frozen < 0){
		g_warning ("unbalanced freeze/thaw\n");
		return;
	}
	if (redraws_frozen == 0){
		g_hash_table_foreach (cell_hash_queue, call_cell_queue_redraw, NULL);
		g_hash_table_destroy (cell_hash_queue);
		cell_hash_queue = NULL;
	}
}
void
cell_deep_freeze_redraws (void)
{
	redraws_deep_frozen++;
}

void
cell_deep_thaw_redraws (void)
{
	redraws_deep_frozen--;
	if (redraws_frozen < 0)
		g_warning ("unbalanced deep freeze/thaw\n");
}

static void
queue_cell (Cell *cell)
{
	if (g_hash_table_lookup (cell_hash_queue, cell))
		return;
	g_hash_table_insert (cell_hash_queue, cell, cell);
}

void
cell_queue_redraw (Cell *cell)
{
	/* You wake up dead after a deep freeze */
	if (redraws_deep_frozen > 0)
		return;

	g_return_if_fail (cell != NULL);

	if (redraws_frozen){
		queue_cell (cell);
		return;
	}

	sheet_redraw_cell_region (cell->sheet,
				  cell->col->pos, cell->row->pos,
				  cell->col->pos, cell->row->pos);
}

/*
 * cell_set_format_simple:
 *
 * This routine is similar to cell_set_format, but it does not queue
 * any redraws, nor expects the cell to have a value.
 *
 * Make sure you queue a draw in the future for this cell.
 */
void
cell_set_format_simple (Cell *cell, const char *format)
{
	g_return_if_fail (cell != NULL);
	g_return_if_fail (format != NULL);

	if (strcmp (format, cell->style->format->format) == 0)
		return;

	/* Change the format */
	cell_modified (cell);
	style_format_unref (cell->style->format);
	cell->style->format = style_format_new (format);
	cell->flags |= CELL_FORMAT_SET;
}

/*
 * cell_set_format:
 *
 * Changes the format for CELL to be FORMAT.  FORMAT should be
 * a number display format as specified on the manual
 */
void
cell_set_format (Cell *cell, const char *format)
{
	g_return_if_fail (cell != NULL);

	cell_set_format_simple (cell, format);

	/* re-render the cell text */
	cell_render_value (cell);
	cell_queue_redraw (cell);
}

void
cell_set_format_from_style (Cell *cell, StyleFormat *style_format)
{
	g_return_if_fail (cell != NULL);
	g_return_if_fail (cell->value);
	g_return_if_fail (style_format != NULL);

	cell_modified (cell);
	cell_queue_redraw (cell);

	/* Change the format */
	style_format_ref (style_format);
	style_format_unref (cell->style->format);

	cell->style->format = style_format;
	cell->style->valid_flags |= STYLE_FORMAT;
	cell->flags |= CELL_FORMAT_SET;

	/* re-render the cell text */
	cell_render_value (cell);
	cell_queue_redraw (cell);
}

void
cell_comment_reposition (Cell *cell)
{
	GList *l;

	g_return_if_fail (cell != NULL);
	g_return_if_fail (cell->comment != NULL);

	for (l = cell->comment->realized_list; l; l = l->next){
		GnomeCanvasItem *o = l->data;
		SheetView *sheet_view = GNUMERIC_SHEET (o->canvas)->sheet_view;

		sheet_view_comment_relocate (sheet_view, cell->col->pos, cell->row->pos, o);
	}
}

/*
 * cell_relocate:
 * @cell:     The cell that is changing position
 * @col_diff: The column delta.
 * @row_diff: The row delta .
 *
 * This routine is used to move a cell to a different location:
 *
 * Auxiliary items canvas items attached to the cell are moved.
 */
void
cell_relocate (Cell *cell, int col_diff, int row_diff)
{
	g_return_if_fail (cell != NULL);

	/* 1. Tag the cell as modified */
	cell_modified (cell);

	/* 2. If the cell contains a formula, relocate the formula */
	if (cell->parsed_node){
		EvalPosition pos;
		ExprTree * newtree;
		sheet_cell_formula_unlink (cell);

		/*
		 * WARNING WARNING WARNING
		 *
		 * This will only work if the new array cell has already
		 * been inserted.
		 *
		 * WARNING WARNING WARNING
		 */
		/* If cell was part of an array, reset the corner pointer */
		if (cell->parsed_node->oper == OPER_ARRAY) {
			int const x = cell->parsed_node->u.array.x;
			int const y = cell->parsed_node->u.array.y;
			if (x != 0 || y != 0)
				cell->parsed_node->u.array.corner.cell =
					sheet_cell_get (cell->sheet,
							cell->col->pos - x,
							cell->row->pos - y);
		}

		newtree = expr_relocate (cell->parsed_node,
					 eval_pos_cell (&pos, cell),
					 col_diff, row_diff);

		if (newtree) {
			expr_tree_ref (newtree);
			expr_tree_unref (cell->parsed_node);
			cell->parsed_node = newtree;
		}

		/* The following call also relinks the cell.  */
		cell_formula_changed (cell);
	}

	/* 3. Move any auxiliary canvas items */
	if (cell->comment)
		cell_comment_reposition (cell);
}

/*
 * This routine drops the formula and just keeps the value
 */
void
cell_make_value (Cell *cell)
{
	g_return_if_fail (cell != NULL);
	g_return_if_fail (cell->parsed_node != NULL);

	/* FIXME: does this work at all?  -- MW */
	cell_modified (cell);
}

int
cell_get_horizontal_align (const Cell *cell)
{
	g_return_val_if_fail (cell != NULL, HALIGN_LEFT);

	if (cell->style->halign == HALIGN_GENERAL){