gtk2/gtk/gtktextutil.c

/* GTK - The GIMP Toolkit
 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library. If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * Modified by the GTK+ Team and others 1997-2001.  See the AUTHORS
 * file for a list of people on the GTK+ Team.  See the ChangeLog
 * files for a list of changes.  These files are distributed with
 * GTK+ at ftp://ftp.gtk.org/pub/gtk/. 
 */

#include "config.h"

#include "gtktextview.h"
#include "gtktextutil.h"

#define GTK_TEXT_USE_INTERNAL_UNSUPPORTED_API

#include "gtktextdisplay.h"
#include "gtktextbuffer.h"
#include "gtkmenuitem.h"
#include "gtkintl.h"

#define DRAG_ICON_MAX_WIDTH 250
#define DRAG_ICON_MAX_HEIGHT 250
#define DRAG_ICON_MAX_LINES 7
#define ELLIPSIS_CHARACTER "\xe2\x80\xa6"

typedef struct _GtkUnicodeMenuEntry GtkUnicodeMenuEntry;
typedef struct _GtkTextUtilCallbackInfo GtkTextUtilCallbackInfo;

struct _GtkUnicodeMenuEntry {
  const char *label;
  gunichar ch;
};

struct _GtkTextUtilCallbackInfo
{
  GtkTextUtilCharChosenFunc func;
  gpointer data;
};

static const GtkUnicodeMenuEntry bidi_menu_entries[] = {
  { N_("LRM _Left-to-right mark"), 0x200E },
  { N_("RLM _Right-to-left mark"), 0x200F },
  { N_("LRE Left-to-right _embedding"), 0x202A },
  { N_("RLE Right-to-left e_mbedding"), 0x202B },
  { N_("LRO Left-to-right _override"), 0x202D },
  { N_("RLO Right-to-left o_verride"), 0x202E },
  { N_("PDF _Pop directional formatting"), 0x202C },
  { N_("ZWS _Zero width space"), 0x200B },
  { N_("ZWJ Zero width _joiner"), 0x200D },
  { N_("ZWNJ Zero width _non-joiner"), 0x200C }
};

static GtkTextUtilCallbackInfo *
callback_info_new (GtkTextUtilCharChosenFunc  func,
                   gpointer                   data)
{
  GtkTextUtilCallbackInfo *info;

  info = g_slice_new (GtkTextUtilCallbackInfo);

  info->func = func;
  info->data = data;

  return info;
}

static void
callback_info_free (GtkTextUtilCallbackInfo *info)
{
  g_slice_free (GtkTextUtilCallbackInfo, info);
}

static void
activate_cb (GtkWidget *menu_item,
             gpointer   data)
{
  GtkUnicodeMenuEntry *entry;
  GtkTextUtilCallbackInfo *info = data;
  char buf[7];
  
  entry = g_object_get_data (G_OBJECT (menu_item), "gtk-unicode-menu-entry");

  buf[g_unichar_to_utf8 (entry->ch, buf)] = '\0';
  
  (* info->func) (buf, info->data);
}

/*
 * _gtk_text_util_append_special_char_menuitems
 * @menushell: a #GtkMenuShell
 * @callback:  call this when an item is chosen
 * @data: data for callback
 * 
 * Add menuitems for various bidi control characters  to a menu;
 * the menuitems, when selected, will call the given function
 * with the chosen character.
 *
 * This function is private/internal in GTK 2.0, the functionality may
 * become public sometime, but it probably needs more thought first.
 * e.g. maybe there should be a way to just get the list of items,
 * instead of requiring the menu items to be created.
 */
void
_gtk_text_util_append_special_char_menuitems (GtkMenuShell              *menushell,
                                              GtkTextUtilCharChosenFunc  func,
                                              gpointer                   data)
{
  int i;

  for (i = 0; i < G_N_ELEMENTS (bidi_menu_entries); i++)
    {
      GtkWidget *menuitem;
      GtkTextUtilCallbackInfo *info;

      info = callback_info_new (func, data);

      menuitem = gtk_menu_item_new_with_mnemonic (_(bidi_menu_entries[i].label));
      g_object_set_data (G_OBJECT (menuitem), I_("gtk-unicode-menu-entry"),
                         (gpointer)&bidi_menu_entries[i]);

      g_signal_connect_data (menuitem, "activate",
                             G_CALLBACK (activate_cb),
                             info, (GClosureNotify) callback_info_free, 0);

      gtk_widget_show (menuitem);
      gtk_menu_shell_append (menushell, menuitem);
    }
}

static void
append_n_lines (GString *str, const gchar *text, GSList *lines, gint n_lines)
{
  PangoLayoutLine *line;
  gint i;

  for (i = 0; i < n_lines; i++)
    {
      line = lines->data;
      g_string_append_len (str, &text[line->start_index], line->length);
      lines = lines->next;
    }
}

static void
limit_layout_lines (PangoLayout *layout)
{
  const gchar *text;
  GString     *str;
  GSList      *lines, *elem;
  gint         n_lines;

  n_lines = pango_layout_get_line_count (layout);
  
  if (n_lines >= DRAG_ICON_MAX_LINES)
    {
      text  = pango_layout_get_text (layout);
      str   = g_string_new (NULL);
      lines = pango_layout_get_lines_readonly (layout);

      /* get first lines */
      elem = lines;
      append_n_lines (str, text, elem,
                      DRAG_ICON_MAX_LINES / 2);

      g_string_append (str, "\n" ELLIPSIS_CHARACTER "\n");

      /* get last lines */
      elem = g_slist_nth (lines, n_lines - DRAG_ICON_MAX_LINES / 2);
      append_n_lines (str, text, elem,
                      DRAG_ICON_MAX_LINES / 2);

      pango_layout_set_text (layout, str->str, -1);
      g_string_free (str, TRUE);
    }
}

/**
 * _gtk_text_util_create_drag_icon:
 * @widget: #GtkWidget to extract the pango context
 * @text: a #gchar to render the icon
 * @len: length of @text, or -1 for NUL-terminated text
 *
 * Creates a drag and drop icon from @text.
 *
 * Returns: a #cairo_surface_t to use as DND icon
 */
cairo_surface_t *
_gtk_text_util_create_drag_icon (GtkWidget *widget,
                                 gchar     *text,
                                 gsize      len)
{
  GtkStyleContext *style_context;
  cairo_surface_t *surface;
  PangoContext *context;
  PangoLayout  *layout;
  cairo_t      *cr;
  gint          pixmap_height, pixmap_width;
  gint          layout_width, layout_height;
  GdkRGBA       color;

  g_return_val_if_fail (widget != NULL, NULL);
  g_return_val_if_fail (text != NULL, NULL);

  context = gtk_widget_get_pango_context (widget);
  layout  = pango_layout_new (context);

  pango_layout_set_text (layout, text, len);
  pango_layout_set_wrap (layout, PANGO_WRAP_WORD_CHAR);
  pango_layout_get_size (layout, &layout_width, &layout_height);

  layout_width = MIN (layout_width, DRAG_ICON_MAX_WIDTH * PANGO_SCALE);
  pango_layout_set_width (layout, layout_width);

  limit_layout_lines (layout);

  /* get again layout extents, they may have changed */
  pango_layout_get_size (layout, &layout_width, &layout_height);

  pixmap_width  = layout_width  / PANGO_SCALE;
  pixmap_height = layout_height / PANGO_SCALE;

  surface = gdk_window_create_similar_surface (gtk_widget_get_window (widget),
                                               CAIRO_CONTENT_COLOR_ALPHA,
                                               pixmap_width, pixmap_height);
  cr = cairo_create (surface);

  style_context = gtk_widget_get_style_context (widget);
  gtk_style_context_get_color (style_context,
                               &color);
  gdk_cairo_set_source_rgba (cr, &color);
  pango_cairo_show_layout (cr, layout);

  cairo_destroy (cr);
  g_object_unref (layout);

  return surface;
}

static void
set_attributes_from_style (GtkStyleContext   *context,
                           GtkTextAttributes *values)
{
  const GdkRGBA black = { 0, };

  if (!values->appearance.bg_rgba)
    values->appearance.bg_rgba = gdk_rgba_copy (&black);
  if (!values->appearance.fg_rgba)
    values->appearance.fg_rgba = gdk_rgba_copy (&black);

G_GNUC_BEGIN_IGNORE_DEPRECATIONS
  gtk_style_context_get_background_color (context, values->appearance.bg_rgba);
G_GNUC_END_IGNORE_DEPRECATIONS
  gtk_style_context_get_color (context, values->appearance.fg_rgba);

  if (values->font)
    pango_font_description_free (values->font);

  gtk_style_context_get (context, "font", &values->font, NULL);
}

cairo_surface_t *
_gtk_text_util_create_rich_drag_icon (GtkWidget     *widget,
                                      GtkTextBuffer *buffer,
                                      GtkTextIter   *start,
                                      GtkTextIter   *end)
{
  GtkAllocation      allocation;
  cairo_surface_t   *surface;
  gint               layout_width, layout_height;
  GtkTextBuffer     *new_buffer;
  GtkTextLayout     *layout;
  GtkTextAttributes *style;
  PangoContext      *ltr_context, *rtl_context;
  GtkTextIter        iter;
  cairo_t           *cr;

  g_return_val_if_fail (GTK_IS_WIDGET (widget), NULL);
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), NULL);
  g_return_val_if_fail (start != NULL, NULL);
  g_return_val_if_fail (end != NULL, NULL);

  new_buffer = gtk_text_buffer_new (gtk_text_buffer_get_tag_table (buffer));
  gtk_text_buffer_get_start_iter (new_buffer, &iter);

  gtk_text_buffer_insert_range (new_buffer, &iter, start, end);

  gtk_text_buffer_get_start_iter (new_buffer, &iter);

  layout = gtk_text_layout_new ();

  ltr_context = gtk_widget_create_pango_context (widget);
  pango_context_set_base_dir (ltr_context, PANGO_DIRECTION_LTR);
  rtl_context = gtk_widget_create_pango_context (widget);
  pango_context_set_base_dir (rtl_context, PANGO_DIRECTION_RTL);

  gtk_text_layout_set_contexts (layout, ltr_context, rtl_context);

  g_object_unref (ltr_context);
  g_object_unref (rtl_context);

  style = gtk_text_attributes_new ();

  gtk_widget_get_allocation (widget, &allocation);
  layout_width = allocation.width;

  set_attributes_from_style (gtk_widget_get_style_context (widget), style);

  if (GTK_IS_TEXT_VIEW (widget))
    {
      layout_width = layout_width
        - gtk_text_view_get_border_window_size (GTK_TEXT_VIEW (widget), GTK_TEXT_WINDOW_LEFT)
        - gtk_text_view_get_border_window_size (GTK_TEXT_VIEW (widget), GTK_TEXT_WINDOW_RIGHT);
    }

  style->direction = gtk_widget_get_direction (widget);
  style->wrap_mode = GTK_WRAP_WORD_CHAR;

  gtk_text_layout_set_default_style (layout, style);
  gtk_text_attributes_unref (style);

  gtk_text_layout_set_buffer (layout, new_buffer);
  gtk_text_layout_set_cursor_visible (layout, FALSE);
  gtk_text_layout_set_screen_width (layout, layout_width);

  gtk_text_layout_validate (layout, DRAG_ICON_MAX_HEIGHT);
  gtk_text_layout_get_size (layout, &layout_width, &layout_height);

  layout_width = MIN (layout_width, DRAG_ICON_MAX_WIDTH);
  layout_height = MIN (layout_height, DRAG_ICON_MAX_HEIGHT);

  surface = gdk_window_create_similar_surface (gtk_widget_get_window (widget),
                                               CAIRO_CONTENT_COLOR_ALPHA,
                                               layout_width, layout_height);

  cr = cairo_create (surface);

  gtk_text_layout_draw (layout, widget, cr, NULL);

  cairo_destroy (cr);
  g_object_unref (layout);
  g_object_unref (new_buffer);

  return surface;
}

static gint
layout_get_char_width (PangoLayout *layout)
{
  gint width;
  PangoFontMetrics *metrics;
  const PangoFontDescription *font_desc;
  PangoContext *context = pango_layout_get_context (layout);

  font_desc = pango_layout_get_font_description (layout);
  if (!font_desc)
    font_desc = pango_context_get_font_description (context);

  metrics = pango_context_get_metrics (context, font_desc, NULL);
  width = pango_font_metrics_get_approximate_char_width (metrics);
  pango_font_metrics_unref (metrics);

  return width;
}

/*
 * _gtk_text_util_get_block_cursor_location
 * @layout: a #PangoLayout
 * @index: index at which cursor is located
 * @pos: cursor location
 * @at_line_end: whether cursor is drawn at line end, not over some
 * character
 *
 * Returns: whether cursor should actually be drawn as a rectangle.
 *     It may not be the case if character at index is invisible.
 */
gboolean
_gtk_text_util_get_block_cursor_location (PangoLayout    *layout,
					  gint            index,
					  PangoRectangle *pos,
					  gboolean       *at_line_end)
{
  PangoRectangle strong_pos, weak_pos;
  PangoLayoutLine *layout_line;
  gboolean rtl;
  gint line_no;
  const gchar *text;

  g_return_val_if_fail (layout != NULL, FALSE);
  g_return_val_if_fail (index >= 0, FALSE);
  g_return_val_if_fail (pos != NULL, FALSE);

  pango_layout_index_to_pos (layout, index, pos);

  if (pos->width != 0)
    {
      /* cursor is at some visible character, good */
      if (at_line_end)
	*at_line_end = FALSE;
      if (pos->width < 0)
	{
	  pos->x += pos->width;
	  pos->width = -pos->width;
	}
      return TRUE;
    }

  pango_layout_index_to_line_x (layout, index, FALSE, &line_no, NULL);
  layout_line = pango_layout_get_line_readonly (layout, line_no);
  g_return_val_if_fail (layout_line != NULL, FALSE);

  text = pango_layout_get_text (layout);

  if (index < layout_line->start_index + layout_line->length)
    {
      /* this may be a zero-width character in the middle of the line,
       * or it could be a character where line is wrapped, we do want
       * block cursor in latter case */
      if (g_utf8_next_char (text + index) - text !=
	  layout_line->start_index + layout_line->length)
	{
	  /* zero-width character in the middle of the line, do not
	   * bother with block cursor */
	  return FALSE;
	}
    }

  /* Cursor is at the line end. It may be an empty line, or it could
   * be on the left or on the right depending on text direction, or it
   * even could be in the middle of visual layout in bidi text. */

  pango_layout_get_cursor_pos (layout, index, &strong_pos, &weak_pos);

  if (strong_pos.x != weak_pos.x)
    {
      /* do not show block cursor in this case, since the character typed
       * in may or may not appear at the cursor position */
      return FALSE;
    }

  /* In case when index points to the end of line, pos->x is always most right
   * pixel of the layout line, so we need to correct it for RTL text. */
  if (layout_line->length)
    {
      if (layout_line->resolved_dir == PANGO_DIRECTION_RTL)
	{
	  PangoLayoutIter *iter;
	  PangoRectangle line_rect;
	  gint i;
	  gint left, right;
	  const gchar *p;

	  p = g_utf8_prev_char (text + index);

	  pango_layout_line_index_to_x (layout_line, p - text, FALSE, &left);
	  pango_layout_line_index_to_x (layout_line, p - text, TRUE, &right);
	  pos->x = MIN (left, right);

	  iter = pango_layout_get_iter (layout);
	  for (i = 0; i < line_no; i++)
	    pango_layout_iter_next_line (iter);
	  pango_layout_iter_get_line_extents (iter, NULL, &line_rect);
	  pango_layout_iter_free (iter);

          rtl = TRUE;
	  pos->x += line_rect.x;
	}
      else
	rtl = FALSE;
    }
  else
    {
      PangoContext *context = pango_layout_get_context (layout);
      rtl = pango_context_get_base_dir (context) == PANGO_DIRECTION_RTL;
    }

  pos->width = layout_get_char_width (layout);

  if (rtl)
    pos->x -= pos->width - 1;

  if (at_line_end)
    *at_line_end = TRUE;

  return pos->width != 0;
}