path: root/calendar/gui/e-day-view-time-item.c

/*
 * EDayViewTimeItem - canvas item which displays the times down the left of
 * the EDayView.
 *
 * This program 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) version 3.
 *
 * This program 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 the program; if not, see <http://www.gnu.org/licenses/>
 *
 * Authors:
 *      Damon Chaplin <damon@ximian.com>
 *
 * Copyright (C) 1999-2008 Novell, Inc. (www.novell.com)
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <string.h>
#include <gtk/gtk.h>
#include <glib/gi18n.h>
#include "e-day-view-time-item.h"
#include "calendar-config.h"
#include <libecal/e-cal-time-util.h>
#include <widgets/e-timezone-dialog/e-timezone-dialog.h>
#include <libedataserver/e-data-server-util.h>

/* The spacing between items in the time column. GRID_X_PAD is the space down
   either side of the column, i.e. outside the main horizontal grid lines.
   HOUR_L_PAD & HOUR_R_PAD are the spaces on the left & right side of the
   big hour number (this is inside the horizontal grid lines).
   MIN_X_PAD is the spacing either side of the minute number. The smaller
   horizontal grid lines match with this.
   60_MIN_X_PAD is the space either side of the HH:MM display used when
   we are displaying 60 mins per row (inside the main grid lines).
   LARGE_HOUR_Y_PAD is the offset of the large hour string from the top of the
   row.
   SMALL_FONT_Y_PAD is the offset of the small time/minute string from the top
   of the row. */
#define E_DVTMI_TIME_GRID_X_PAD     4
#define E_DVTMI_HOUR_L_PAD      4
#define E_DVTMI_HOUR_R_PAD      2
#define E_DVTMI_MIN_X_PAD       2
#define E_DVTMI_60_MIN_X_PAD        4
#define E_DVTMI_LARGE_HOUR_Y_PAD    1
#define E_DVTMI_SMALL_FONT_Y_PAD    1

struct _EDayViewTimeItemPrivate {
    /* The parent EDayView widget. */
    EDayView *day_view;

    /* The width of the time column. */
    gint column_width;

    /* TRUE if we are currently dragging the selection times. */
    gboolean dragging_selection;

    /* The second timezone if shown, or else NULL. */
    guint second_zone_changed_id;
    icaltimezone *second_zone;
};

static void e_day_view_time_item_update (GnomeCanvasItem *item,
                         const cairo_matrix_t *i2c,
                         gint flags);
static void e_day_view_time_item_draw   (GnomeCanvasItem *item,
                         cairo_t *cr,
                         gint x,
                         gint y,
                         gint width,
                         gint height);
static GnomeCanvasItem *
        e_day_view_time_item_point  (GnomeCanvasItem *item,
                         gdouble x,
                         gdouble y,
                         gint cx,
                         gint cy);
static gint e_day_view_time_item_event  (GnomeCanvasItem *item,
                         GdkEvent *event);
static void e_day_view_time_item_increment_time
                        (gint *hour,
                         gint *minute,
                         gint time_divisions);
static void e_day_view_time_item_show_popup_menu
                        (EDayViewTimeItem *time_item,
                         GdkEvent *event);
static void e_day_view_time_item_on_set_divisions
                        (GtkWidget *item,
                         EDayViewTimeItem *time_item);
static void e_day_view_time_item_on_button_press
                        (EDayViewTimeItem *time_item,
                         GdkEvent *event);
static void e_day_view_time_item_on_button_release
                        (EDayViewTimeItem *time_item,
                         GdkEvent *event);
static void e_day_view_time_item_on_motion_notify
                        (EDayViewTimeItem *time_item,
                         GdkEvent *event);
static gint e_day_view_time_item_convert_position_to_row
                        (EDayViewTimeItem *time_item,
                         gint y);

static void edvti_second_zone_changed_cb    (GConfClient *client,
                         guint cnxn_id,
                         GConfEntry *entry,
                         gpointer user_data);

enum {
    PROP_0,
    PROP_DAY_VIEW
};

static gpointer parent_class;

static void
day_view_time_item_set_property (GObject *object,
                                 guint property_id,
                                 const GValue *value,
                                 GParamSpec *pspec)
{
    switch (property_id) {
        case PROP_DAY_VIEW:
            e_day_view_time_item_set_day_view (
                E_DAY_VIEW_TIME_ITEM (object),
                g_value_get_object (value));
            return;
    }

    G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
}

static void
day_view_time_item_get_property (GObject *object,
                                 guint property_id,
                                 GValue *value,
                                 GParamSpec *pspec)
{
    switch (property_id) {
        case PROP_DAY_VIEW:
            g_value_set_object (
                value, e_day_view_time_item_get_day_view (
                E_DAY_VIEW_TIME_ITEM (object)));
            return;
    }

    G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
}

static void
day_view_time_item_dispose (GObject *object)
{
    EDayViewTimeItemPrivate *priv;

    priv = E_DAY_VIEW_TIME_ITEM (object)->priv;

    if (priv->day_view != NULL) {
        g_object_unref (priv->day_view);
        priv->day_view = NULL;
    }

    /* Chain up to parent's dispose() method. */
    G_OBJECT_CLASS (parent_class)->dispose (object);
}

static void
day_view_time_item_finalize (GObject *object)
{
    EDayViewTimeItem *time_item;

    time_item = E_DAY_VIEW_TIME_ITEM (object);

    if (time_item->priv->second_zone_changed_id)
        calendar_config_remove_notification (time_item->priv->second_zone_changed_id);
    time_item->priv->second_zone_changed_id = 0;

    /* Chain up to parent's dispose() method. */
    G_OBJECT_CLASS (parent_class)->finalize (object);
}

static void
day_view_time_item_class_init (EDayViewTimeItemClass *class)
{
    GObjectClass *object_class;
    GnomeCanvasItemClass *item_class;

    parent_class = g_type_class_peek_parent (class);
    g_type_class_add_private (class, sizeof (EDayViewTimeItemPrivate));

    object_class = G_OBJECT_CLASS (class);
    object_class->set_property = day_view_time_item_set_property;
    object_class->get_property = day_view_time_item_get_property;
    object_class->dispose = day_view_time_item_dispose;
    object_class->finalize = day_view_time_item_finalize;

    item_class = GNOME_CANVAS_ITEM_CLASS (class);
    item_class->update = e_day_view_time_item_update;
    item_class->draw = e_day_view_time_item_draw;
    item_class->point = e_day_view_time_item_point;
    item_class->event = e_day_view_time_item_event;

    g_object_class_install_property (
        object_class,
        PROP_DAY_VIEW,
        g_param_spec_object (
            "day-view",
            "Day View",
            NULL,
            E_TYPE_DAY_VIEW,
            G_PARAM_READWRITE));
}

static void
day_view_time_item_init (EDayViewTimeItem *time_item)
{
    gchar *last;

    time_item->priv = G_TYPE_INSTANCE_GET_PRIVATE (
        time_item, E_TYPE_DAY_VIEW_TIME_ITEM, EDayViewTimeItemPrivate);

    time_item->priv->dragging_selection = FALSE;
    time_item->priv->second_zone = NULL;

    last = calendar_config_get_day_second_zone ();

    if (last) {
        if (*last)
            time_item->priv->second_zone =
                icaltimezone_get_builtin_timezone (last);
        g_free (last);
    }

    time_item->priv->second_zone_changed_id =
        calendar_config_add_notification_day_second_zone (
        edvti_second_zone_changed_cb, time_item);
}

GType
e_day_view_time_item_get_type (void)
{
    static GType type = 0;

    if (G_UNLIKELY (type == 0)) {
        const GTypeInfo type_info = {
            sizeof (EDayViewTimeItemClass),
            (GBaseInitFunc) NULL,
            (GBaseFinalizeFunc) NULL,
            (GClassInitFunc) day_view_time_item_class_init,
            (GClassFinalizeFunc) NULL,
            NULL,  /* class_data */
            sizeof (EDayViewTimeItem),
            0,     /* n_preallocs */
            (GInstanceInitFunc) day_view_time_item_init,
            NULL   /* value_table */
        };

        type = g_type_register_static (
            GNOME_TYPE_CANVAS_ITEM, "EDayViewTimeItem",
            &type_info, 0);
    }

    return type;
}

static void
e_day_view_time_item_update (GnomeCanvasItem *item,
                 const cairo_matrix_t *i2c,
                 gint flags)
{
    if (GNOME_CANVAS_ITEM_CLASS (parent_class)->update)
        (* GNOME_CANVAS_ITEM_CLASS (parent_class)->update) (item, i2c, flags);

    /* The item covers the entire canvas area. */
    item->x1 = 0;
    item->y1 = 0;
    item->x2 = INT_MAX;
    item->y2 = INT_MAX;
}

/*
 * DRAWING ROUTINES - functions to paint the canvas item.
 */
static void
edvti_draw_zone (GnomeCanvasItem *canvas_item,
                 cairo_t *cr,
                 gint x,
                 gint y,
                 gint width,
                 gint height,
                 gint x_offset,
                 icaltimezone *use_zone)
{
    EDayView *day_view;
    EDayViewTimeItem *time_item;
    ECalendarView *cal_view;
    ECalModel *model;
    GtkStyle *style;
    const gchar *suffix;
    gchar buffer[64], *midnight_day = NULL, *midnight_month = NULL;
    gint time_divisions;
    gint hour, display_hour, minute, row;
    gint row_y, start_y, large_hour_y_offset, small_font_y_offset;
    gint long_line_x1, long_line_x2, short_line_x1;
    gint large_hour_x2, minute_x2;
    gint hour_width, minute_width, suffix_width;
    gint max_suffix_width, max_minute_or_suffix_width;
    PangoLayout *layout;
    PangoContext *context;
    PangoFontDescription *small_font_desc;
    PangoFontMetrics *large_font_metrics, *small_font_metrics;
    GdkColor fg, dark;
    GdkColor mb_color;

    time_item = E_DAY_VIEW_TIME_ITEM (canvas_item);
    day_view = e_day_view_time_item_get_day_view (time_item);
    g_return_if_fail (day_view != NULL);

    cal_view = E_CALENDAR_VIEW (day_view);
    model = e_calendar_view_get_model (cal_view);
    time_divisions = e_calendar_view_get_time_divisions (cal_view);

    style = gtk_widget_get_style (GTK_WIDGET (day_view));
    small_font_desc = style->font_desc;

    context = gtk_widget_get_pango_context (GTK_WIDGET (day_view));
    large_font_metrics = pango_context_get_metrics (context, day_view->large_font_desc,
                            pango_context_get_language (context));
    small_font_metrics = pango_context_get_metrics (context, small_font_desc,
                            pango_context_get_language (context));

    fg = style->fg[GTK_STATE_NORMAL];
    dark = style->dark[GTK_STATE_NORMAL];

    /* The start and end of the long horizontal line between hours. */
    long_line_x1 = (use_zone ? 0 : E_DVTMI_TIME_GRID_X_PAD) - x + x_offset;
    long_line_x2 =
        time_item->priv->column_width -
        E_DVTMI_TIME_GRID_X_PAD - x -
        (use_zone ? E_DVTMI_TIME_GRID_X_PAD : 0) + x_offset;

    if (time_divisions == 60) {
        /* The right edge of the complete time string in 60-min
           divisions, e.g. "14:00" or "2 pm". */
        minute_x2 = long_line_x2 - E_DVTMI_60_MIN_X_PAD;

        /* These aren't used for 60-minute divisions, but we initialize
           them to keep gcc happy. */
        short_line_x1 = 0;
        large_hour_x2 = 0;
    } else {
        max_suffix_width = MAX (day_view->am_string_width,
                    day_view->pm_string_width);

        max_minute_or_suffix_width = MAX (max_suffix_width,
                          day_view->max_minute_width);

        /* The start of the short horizontal line between the periods
           within each hour. */
        short_line_x1 = long_line_x2 - E_DVTMI_MIN_X_PAD * 2
            - max_minute_or_suffix_width;

        /* The right edge of the large hour string. */
        large_hour_x2 = short_line_x1 - E_DVTMI_HOUR_R_PAD;

        /* The right edge of the minute part of the time. */
        minute_x2 = long_line_x2 - E_DVTMI_MIN_X_PAD;
    }

    /* Start with the first hour & minute shown in the EDayView. */
    hour = day_view->first_hour_shown;
    minute = day_view->first_minute_shown;

    if (use_zone) {
        /* shift time with a difference between
         * local time and the other timezone */
        icaltimezone *cal_zone;
        struct icaltimetype tt;
        gint diff;
        struct tm mn;

        cal_zone = e_calendar_view_get_timezone (
            E_CALENDAR_VIEW (day_view));
        tt = icaltime_from_timet_with_zone (
            day_view->day_starts[0], 0, cal_zone);

        /* diff is number of minutes */
        diff = (icaltimezone_get_utc_offset (use_zone, &tt, NULL) -
            icaltimezone_get_utc_offset (cal_zone, &tt, NULL)
               ) / 60;

        tt = icaltime_from_timet_with_zone (day_view->day_starts[0], 0, cal_zone);
        tt.is_date = FALSE;
        icaltime_set_timezone (&tt, cal_zone);
        tt = icaltime_convert_to_zone (tt, use_zone);

        if (diff != 0) {
            /* shows the next midnight */
            icaltime_adjust (&tt, 1, 0, 0, 0);
        }

        mn = icaltimetype_to_tm (&tt);

        /* up to two characters/numbers */
        e_utf8_strftime (buffer, sizeof (buffer), "%d", &mn);
        midnight_day = g_strdup (buffer);
        /* up to three characters, abbreviated month name */
        e_utf8_strftime (buffer, sizeof (buffer), "%b", &mn);
        midnight_month = g_strdup (buffer);

        minute += (diff % 60);
        hour += (diff / 60) + (minute / 60);

        minute = minute % 60;
        if (minute < 0) {
            hour--;
            minute += 60;
        }

        hour = (hour + 48) % 24;
    }

    /* The offset of the large hour string from the top of the row. */
    large_hour_y_offset = E_DVTMI_LARGE_HOUR_Y_PAD;

    /* The offset of the small time/minute string from top of row. */
    small_font_y_offset = E_DVTMI_SMALL_FONT_Y_PAD;

    /* Calculate the minimum y position of the first row we need to draw.
       This is normally one row height above the 0 position, but if we
       are using the large font we may have to go back a bit further. */
    start_y = 0 - MAX (day_view->row_height,
               (pango_font_metrics_get_ascent (large_font_metrics) +
                pango_font_metrics_get_descent (large_font_metrics)) / PANGO_SCALE +
               E_DVTMI_LARGE_HOUR_Y_PAD);

    /* Draw the Marcus Bains Line first, so it appears under other elements. */
    if (e_day_view_marcus_bains_get_show_line (day_view)) {
        struct icaltimetype time_now;
        gint marcus_bains_y;

        cairo_save (cr);
        gdk_cairo_set_source_color (
            cr, &day_view->colors[E_DAY_VIEW_COLOR_MARCUS_BAINS_LINE]);

        if (day_view->marcus_bains_time_bar_color &&
            gdk_color_parse (
                day_view->marcus_bains_time_bar_color,
                &mb_color)) {
            gdk_cairo_set_source_color (cr, &mb_color);
        } else
            mb_color = day_view->colors[E_DAY_VIEW_COLOR_MARCUS_BAINS_LINE];

        time_now = icaltime_current_time_with_zone (
            e_calendar_view_get_timezone (
            E_CALENDAR_VIEW (day_view)));
        marcus_bains_y =
            (time_now.hour * 60 + time_now.minute) *
            day_view->row_height / time_divisions - y;
        cairo_set_line_width (cr, 1.5);
        cairo_move_to (
            cr, long_line_x1 -
            (use_zone ? E_DVTMI_TIME_GRID_X_PAD : 0),
            marcus_bains_y);
        cairo_line_to (cr, long_line_x2, marcus_bains_y);
        cairo_stroke (cr);
        cairo_restore (cr);
    } else {
        mb_color = day_view->colors[E_DAY_VIEW_COLOR_MARCUS_BAINS_LINE];

        if (day_view->marcus_bains_time_bar_color &&
            gdk_color_parse (
                day_view->marcus_bains_time_bar_color,
                &mb_color)) {
            gdk_cairo_set_source_color (cr, &mb_color);
        }
    }

    /* Step through each row, drawing the times and the horizontal lines
       between them. */
    for (row = 0, row_y = 0 - y;
         row < day_view->rows && row_y < height;
         row++, row_y += day_view->row_height) {
        gboolean show_midnight_date;

        show_midnight_date =
            use_zone && hour == 0 &&
            (minute == 0 || time_divisions == 60) &&
            midnight_day && midnight_month;

        /* If the row is above the first row we want to draw just
           increment the time and skip to the next row. */
        if (row_y < start_y) {
            e_day_view_time_item_increment_time (
                &hour, &minute, time_divisions);
            continue;
        }

        /* Calculate the actual hour number to display. For 12-hour
           format we convert 0-23 to 12-11am/12-11pm. */
        e_day_view_convert_time_to_display (day_view, hour,
                            &display_hour,
                            &suffix, &suffix_width);

        if (time_divisions == 60) {
            /* 60 minute intervals - draw a long horizontal line
               between hours and display as one long string,
               e.g. "14:00" or "2 pm". */
            cairo_save (cr);
            gdk_cairo_set_source_color (cr, &dark);
            cairo_save (cr);
            cairo_set_line_width (cr, 0.7);
            cairo_move_to (cr, long_line_x1, row_y);
            cairo_line_to (cr, long_line_x2, row_y);
            cairo_stroke (cr);
            cairo_restore (cr);

            if (show_midnight_date) {
                strcpy (buffer, midnight_day);
                strcat (buffer, " ");
                strcat (buffer, midnight_month);
            } else if (e_cal_model_get_use_24_hour_format (model)) {
                g_snprintf (buffer, sizeof (buffer), "%i:%02i",
                        display_hour, minute);
            } else {
                g_snprintf (buffer, sizeof (buffer), "%i %s",
                        display_hour, suffix);
            }

            cairo_save (cr);
            if (show_midnight_date)
                gdk_cairo_set_source_color (cr, &mb_color);
            else
                gdk_cairo_set_source_color (cr, &fg);
            layout = pango_cairo_create_layout (cr);
            pango_layout_set_text (layout, buffer, -1);
            pango_layout_get_pixel_size (layout, &minute_width, NULL);
            cairo_translate (
                cr, minute_x2 - minute_width,
                row_y + small_font_y_offset);
            pango_cairo_update_layout (cr, layout);
            pango_cairo_show_layout (cr, layout);
            cairo_restore (cr);

            g_object_unref (layout);
        } else {
            /* 5/10/15/30 minute intervals. */

            if (minute == 0) {
                /* On the hour - draw a long horizontal line
                   before the hour and display the hour in the
                   large font. */

                cairo_save (cr);
                gdk_cairo_set_source_color (cr, &dark);
                if (show_midnight_date)
                    strcpy (buffer, midnight_day);
                else
                    g_snprintf (buffer, sizeof (buffer), "%i",
                            display_hour);

                cairo_set_line_width (cr, 0.7);
                cairo_move_to (cr, long_line_x1, row_y);
                cairo_line_to (cr, long_line_x2, row_y);
                cairo_stroke (cr);
                cairo_restore (cr);

                cairo_save (cr);
                if (show_midnight_date)
                    gdk_cairo_set_source_color (cr, &mb_color);
                else
                    gdk_cairo_set_source_color (cr, &fg);
                layout = pango_cairo_create_layout (cr);
                pango_layout_set_text (layout, buffer, -1);
                pango_layout_set_font_description (layout, day_view->large_font_desc);
                pango_layout_get_pixel_size (layout, &hour_width, NULL);
                cairo_translate (
                    cr, large_hour_x2 - hour_width,
                    row_y + large_hour_y_offset);
                pango_cairo_update_layout (cr, layout);
                pango_cairo_show_layout (cr, layout);
                cairo_restore (cr);

                g_object_unref (layout);
            } else {
                /* Within the hour - draw a short line before
                   the time. */
                cairo_save (cr);
                gdk_cairo_set_source_color (cr, &dark);
                cairo_set_line_width (cr, 0.7);
                cairo_move_to (cr, short_line_x1, row_y);
                cairo_line_to (cr, long_line_x2, row_y);
                cairo_stroke (cr);
                cairo_restore (cr);
            }

            /* Normally we display the minute in each
               interval, but when using 30-minute intervals
               we don't display the '30'. */
            if (time_divisions != 30 || minute != 30) {
                /* In 12-hour format we display 'am' or 'pm'
                   instead of '00'. */
                if (show_midnight_date)
                    strcpy (buffer, midnight_month);
                else if (minute == 0
                    && !e_cal_model_get_use_24_hour_format (model)) {
                    strcpy (buffer, suffix);
                } else {
                    g_snprintf (buffer, sizeof (buffer),
                            "%02i", minute);
                }

                cairo_save (cr);
                if (show_midnight_date)
                    gdk_cairo_set_source_color (cr, &mb_color);
                else
                    gdk_cairo_set_source_color (cr, &fg);
                layout = pango_cairo_create_layout (cr);
                pango_layout_set_text (layout, buffer, -1);
                pango_layout_set_font_description (layout, day_view->small_font_desc);
                pango_layout_get_pixel_size (layout, &minute_width, NULL);
                cairo_translate (
                    cr, minute_x2 - minute_width,
                    row_y + small_font_y_offset);
                pango_cairo_update_layout (cr, layout);
                pango_cairo_show_layout (cr, layout);
                cairo_restore (cr);

                g_object_unref (layout);
            }
        }

        e_day_view_time_item_increment_time (&hour, &minute,
                             time_divisions);
    }

    pango_font_metrics_unref (large_font_metrics);
    pango_font_metrics_unref (small_font_metrics);

    g_free (midnight_day);
    g_free (midnight_month);
}

static void
e_day_view_time_item_draw (GnomeCanvasItem *canvas_item,
                           cairo_t *cr,
                           gint x,
                           gint y,
                           gint width,
                           gint height)
{
    EDayViewTimeItem *time_item;

    time_item = E_DAY_VIEW_TIME_ITEM (canvas_item);
    g_return_if_fail (time_item != NULL);

    edvti_draw_zone (canvas_item, cr, x, y, width, height, 0, NULL);

    if (time_item->priv->second_zone)
        edvti_draw_zone (
            canvas_item, cr, x, y, width, height,
            time_item->priv->column_width,
            time_item->priv->second_zone);
}

/* Increment the time by the 5/10/15/30/60 minute interval.
   Note that time_divisions is never > 60, so we never have to
   worry about adding more than 60 minutes. */
static void
e_day_view_time_item_increment_time (gint   *hour,
                     gint   *minute,
                     gint    time_divisions)
{
    *minute += time_divisions;
    if (*minute >= 60) {
        *minute -= 60;
        /* Currently we never wrap around to the next day, but
           we may do if we display extra timezones. */
        *hour = (*hour + 1) % 24;
    }
}

static GnomeCanvasItem *
e_day_view_time_item_point (GnomeCanvasItem *item, double x, double y,
                gint cx, gint cy)
{
    return item;
}

static gint
e_day_view_time_item_event (GnomeCanvasItem *item,
                GdkEvent *event)
{
    EDayViewTimeItem *time_item;

    time_item = E_DAY_VIEW_TIME_ITEM (item);

    switch (event->type) {
    case GDK_BUTTON_PRESS:
        if (event->button.button == 1) {
            e_day_view_time_item_on_button_press (time_item, event);
        } else if (event->button.button == 3) {
            e_day_view_time_item_show_popup_menu (time_item, event);
            return TRUE;
        }
        break;
    case GDK_BUTTON_RELEASE:
        if (event->button.button == 1)
            e_day_view_time_item_on_button_release (time_item,
                                event);
        break;

    case GDK_MOTION_NOTIFY:
        e_day_view_time_item_on_motion_notify (time_item, event);
        break;

    default:
        break;
    }

    return FALSE;
}

static void
edvti_second_zone_changed_cb (GConfClient *client,
                              guint cnxn_id,
                              GConfEntry *entry,
                              gpointer user_data)
{
    EDayViewTimeItem *time_item = user_data;
    EDayView *day_view;
    gchar *location;

    g_return_if_fail (user_data != NULL);
    g_return_if_fail (E_IS_DAY_VIEW_TIME_ITEM (time_item));

    location = calendar_config_get_day_second_zone ();
    time_item->priv->second_zone =
        location ? icaltimezone_get_builtin_timezone (location) : NULL;
    g_free (location);

    day_view = e_day_view_time_item_get_day_view (time_item);
    gtk_widget_set_size_request (
        day_view->time_canvas,
        e_day_view_time_item_get_column_width (time_item), -1);
    gtk_widget_queue_draw (day_view->time_canvas);
}

static void
edvti_on_select_zone (GtkWidget *item,
                      EDayViewTimeItem *time_item)
{
    calendar_config_select_day_second_zone ();
}

static void
edvti_on_set_zone (GtkWidget *item,
                   EDayViewTimeItem *time_item)
{
    if (!gtk_check_menu_item_get_active (GTK_CHECK_MENU_ITEM (item)))
        return;

    calendar_config_set_day_second_zone (
        g_object_get_data (G_OBJECT (item), "timezone"));
}

static void
e_day_view_time_item_show_popup_menu (EDayViewTimeItem *time_item,
                                      GdkEvent *event)
{
    static gint divisions[] = { 60, 30, 15, 10, 5 };
    EDayView *day_view;
    ECalendarView *cal_view;
    GtkWidget *menu, *item, *submenu;
    gchar buffer[256];
    GSList *group = NULL, *recent_zones, *s;
    gint current_divisions, i;
    icaltimezone *zone;

    day_view = e_day_view_time_item_get_day_view (time_item);
    g_return_if_fail (day_view != NULL);

    cal_view = E_CALENDAR_VIEW (day_view);
    current_divisions = e_calendar_view_get_time_divisions (cal_view);

    menu = gtk_menu_new ();

    /* Make sure the menu is destroyed when it disappears. */
    g_signal_connect (
        menu, "selection-done",
        G_CALLBACK (gtk_widget_destroy), NULL);

    for (i = 0; i < G_N_ELEMENTS (divisions); i++) {
        g_snprintf (buffer, sizeof (buffer),
        /* TO TRANSLATORS: %02i is the number of minutes; this is a context menu entry
         * to change the length of the time division in the calendar day view, e.g.
         * a day is displayed in 24 "60 minute divisions" or 48 "30 minute divisions"
         */
                _("%02i minute divisions"), divisions[i]);
        item = gtk_radio_menu_item_new_with_label (group, buffer);
        group = gtk_radio_menu_item_get_group (GTK_RADIO_MENU_ITEM (item));
        gtk_widget_show (item);
        gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);

        if (current_divisions == divisions[i])
            gtk_check_menu_item_set_active (GTK_CHECK_MENU_ITEM (item), TRUE);

        g_object_set_data (G_OBJECT (item), "divisions",
                   GINT_TO_POINTER (divisions[i]));

        g_signal_connect (item, "toggled",
                  G_CALLBACK (e_day_view_time_item_on_set_divisions), time_item);
    }

    item = gtk_separator_menu_item_new ();
    gtk_widget_show (item);
    gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);

    submenu = gtk_menu_new ();
    item = gtk_menu_item_new_with_label (_("Show the second time zone"));
    gtk_widget_show (item);
    gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);
    gtk_menu_item_set_submenu (GTK_MENU_ITEM (item), submenu);

    zone = e_calendar_view_get_timezone (E_CALENDAR_VIEW (day_view));
    if (zone)
        item = gtk_menu_item_new_with_label (icaltimezone_get_display_name (zone));
    else
        item = gtk_menu_item_new_with_label ("---");
    gtk_widget_set_sensitive (item, FALSE);
    gtk_menu_shell_append (GTK_MENU_SHELL (submenu), item);

    item = gtk_separator_menu_item_new ();
    gtk_menu_shell_append (GTK_MENU_SHELL (submenu), item);

    group = NULL;
    item = gtk_radio_menu_item_new_with_label (group, C_("cal-second-zone", "None"));
    group = gtk_radio_menu_item_get_group (GTK_RADIO_MENU_ITEM (item));
    if (!time_item->priv->second_zone)
        gtk_check_menu_item_set_active (GTK_CHECK_MENU_ITEM (item), TRUE);
    gtk_menu_shell_append (GTK_MENU_SHELL (submenu), item);
    g_signal_connect (item, "toggled", G_CALLBACK (edvti_on_set_zone), time_item);

    recent_zones = calendar_config_get_day_second_zones ();
    for (s = recent_zones; s != NULL; s = s->next) {
        zone = icaltimezone_get_builtin_timezone (s->data);
        if (!zone)
            continue;

        item = gtk_radio_menu_item_new_with_label (
            group, icaltimezone_get_display_name (zone));
        group = gtk_radio_menu_item_get_group (GTK_RADIO_MENU_ITEM (item));
        /* both comes from builtin, thus no problem to compare pointers */
        if (zone == time_item->priv->second_zone)
            gtk_check_menu_item_set_active (GTK_CHECK_MENU_ITEM (item), TRUE);
        gtk_menu_shell_append (GTK_MENU_SHELL (submenu), item);
        g_object_set_data_full (
            G_OBJECT (item), "timezone",
            g_strdup (s->data), g_free);
        g_signal_connect (
            item, "toggled",
            G_CALLBACK (edvti_on_set_zone), time_item);
    }
    calendar_config_free_day_second_zones (recent_zones);

    item = gtk_separator_menu_item_new ();
    gtk_menu_shell_append (GTK_MENU_SHELL (submenu), item);

    item = gtk_menu_item_new_with_label (_("Select..."));
    g_signal_connect (item, "activate", G_CALLBACK (edvti_on_select_zone), time_item);
    gtk_menu_shell_append (GTK_MENU_SHELL (submenu), item);

    gtk_widget_show_all (submenu);

    gtk_menu_popup (GTK_MENU (menu), NULL, NULL, NULL, NULL,
            event->button.button, event->button.time);
}

static void
e_day_view_time_item_on_set_divisions (GtkWidget *item,
                       EDayViewTimeItem *time_item)
{
    EDayView *day_view;
    ECalendarView *cal_view;
    gint divisions;

    day_view = e_day_view_time_item_get_day_view (time_item);
    g_return_if_fail (day_view != NULL);

    if (!gtk_check_menu_item_get_active (GTK_CHECK_MENU_ITEM (item)))
        return;

    divisions = GPOINTER_TO_INT (g_object_get_data (G_OBJECT (item), "divisions"));

    cal_view = E_CALENDAR_VIEW (day_view);
    e_calendar_view_set_time_divisions (cal_view, divisions);
}

static void
e_day_view_time_item_on_button_press (EDayViewTimeItem *time_item,
                      GdkEvent *event)
{
    GdkWindow *window;
    EDayView *day_view;
    GnomeCanvas *canvas;
    gint row;

    day_view = e_day_view_time_item_get_day_view (time_item);
    g_return_if_fail (day_view != NULL);

    canvas = GNOME_CANVAS_ITEM (time_item)->canvas;

    row = e_day_view_time_item_convert_position_to_row (time_item,
                                event->button.y);

    if (row == -1)
        return;

    if (!gtk_widget_has_focus (GTK_WIDGET (day_view)))
        gtk_widget_grab_focus (GTK_WIDGET (day_view));

    window = gtk_layout_get_bin_window (GTK_LAYOUT (canvas));

    if (gdk_pointer_grab (window, FALSE,
                  GDK_POINTER_MOTION_MASK
                  | GDK_BUTTON_RELEASE_MASK,
                  NULL, NULL, event->button.time) == 0) {
        e_day_view_start_selection (day_view, -1, row);
        time_item->priv->dragging_selection = TRUE;
    }
}

static void
e_day_view_time_item_on_button_release (EDayViewTimeItem *time_item,
                    GdkEvent *event)
{
    EDayView *day_view;

    day_view = e_day_view_time_item_get_day_view (time_item);
    g_return_if_fail (day_view != NULL);

    if (time_item->priv->dragging_selection) {
        gdk_pointer_ungrab (event->button.time);
        e_day_view_finish_selection (day_view);
        e_day_view_stop_auto_scroll (day_view);
    }

    time_item->priv->dragging_selection = FALSE;
}

static void
e_day_view_time_item_on_motion_notify (EDayViewTimeItem *time_item,
                       GdkEvent *event)
{
    EDayView *day_view;
    GnomeCanvas *canvas;
    gdouble window_y;
    gint y, row;

    if (!time_item->priv->dragging_selection)
        return;

    day_view = e_day_view_time_item_get_day_view (time_item);
    g_return_if_fail (day_view != NULL);

    canvas = GNOME_CANVAS_ITEM (time_item)->canvas;

    y = event->motion.y;
    row = e_day_view_time_item_convert_position_to_row (time_item, y);

    if (row != -1) {
        gnome_canvas_world_to_window (canvas, 0, event->motion.y,
                          NULL, &window_y);
        e_day_view_update_selection (day_view, -1, row);
        e_day_view_check_auto_scroll (day_view, -1, (gint) window_y);
    }
}

/* Returns the row corresponding to the y position, or -1. */
static gint
e_day_view_time_item_convert_position_to_row (EDayViewTimeItem *time_item,
                          gint y)
{
    EDayView *day_view;
    gint row;

    day_view = e_day_view_time_item_get_day_view (time_item);
    g_return_val_if_fail (day_view != NULL, -1);

    if (y < 0)
        return -1;

    row = y / day_view->row_height;
    if (row >= day_view->rows)
        return -1;

    return row;
}

EDayView *
e_day_view_time_item_get_day_view (EDayViewTimeItem *time_item)
{
    g_return_val_if_fail (E_IS_DAY_VIEW_TIME_ITEM (time_item), NULL);

    return time_item->priv->day_view;
}

void
e_day_view_time_item_set_day_view (EDayViewTimeItem *time_item,
                                   EDayView *day_view)
{
    g_return_if_fail (E_IS_DAY_VIEW_TIME_ITEM (time_item));
    g_return_if_fail (E_IS_DAY_VIEW (day_view));

    if (time_item->priv->day_view != NULL)
        g_object_unref (time_item->priv->day_view);

    time_item->priv->day_view = g_object_ref (day_view);

    g_object_notify (G_OBJECT (time_item), "day-view");
}

/* Returns the minimum width needed for the column, by adding up all the
   maximum widths of the strings. The string widths are all calculated in
   the style_set handlers of EDayView and EDayViewTimeCanvas. */
gint
e_day_view_time_item_get_column_width (EDayViewTimeItem *time_item)
{
    EDayView *day_view;
    GtkStyle *style;
    gint digit, large_digit_width, max_large_digit_width = 0;
    gint max_suffix_width, max_minute_or_suffix_width;
    gint column_width_default, column_width_60_min_rows;

    day_view = e_day_view_time_item_get_day_view (time_item);
    g_return_val_if_fail (day_view != NULL, 0);

    style = gtk_widget_get_style (GTK_WIDGET (day_view));
    g_return_val_if_fail (style != NULL, 0);

    /* Find the maximum width a digit can have. FIXME: We could use pango's
     * approximation function, but I worry it won't be precise enough. Also
     * it needs a language tag that I don't know where to get. */
    for (digit = '0'; digit <= '9'; digit++) {
        PangoLayout *layout;
        gchar digit_str[2];

        digit_str[0] = digit;
        digit_str[1] = '\0';

        layout = gtk_widget_create_pango_layout (GTK_WIDGET (day_view), digit_str);
        pango_layout_set_font_description (layout, day_view->large_font_desc);
        pango_layout_get_pixel_size (layout, &large_digit_width, NULL);

        g_object_unref (layout);

        max_large_digit_width = MAX (max_large_digit_width,
                         large_digit_width);
    }

    /* Calculate the width of each time column, using the maximum of the
       default format with large hour numbers, and the 60-min divisions
       format which uses small text. */
    max_suffix_width = MAX (day_view->am_string_width,
                day_view->pm_string_width);

    max_minute_or_suffix_width = MAX (max_suffix_width,
                      day_view->max_minute_width);

    column_width_default = max_large_digit_width * 2
        + max_minute_or_suffix_width
        + E_DVTMI_MIN_X_PAD * 2
        + E_DVTMI_HOUR_L_PAD
        + E_DVTMI_HOUR_R_PAD
        + E_DVTMI_TIME_GRID_X_PAD * 2;

    column_width_60_min_rows = day_view->max_small_hour_width
        + day_view->colon_width
        + max_minute_or_suffix_width
        + E_DVTMI_60_MIN_X_PAD * 2
        + E_DVTMI_TIME_GRID_X_PAD * 2;

    time_item->priv->column_width =
        MAX (column_width_default, column_width_60_min_rows);

    if (time_item->priv->second_zone)
        return (2 * time_item->priv->column_width) -
            E_DVTMI_TIME_GRID_X_PAD;

    return time_item->priv->column_width;
}

icaltimezone *
e_day_view_time_item_get_second_zone (EDayViewTimeItem *time_item)
{
    g_return_val_if_fail (E_IS_DAY_VIEW_TIME_ITEM (time_item), NULL);

    return time_item->priv->second_zone;
}