path: root/widgets/misc/e-clipped-label.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */

/* 
 * Author : 
 *  Damon Chaplin <damon@ximian.com>
 *
 * Copyright 1999, Ximian, Inc.
 *
 * This program is free software; you can redistribute it and/or 
 * modify it under the terms of version 2 of the GNU General Public 
 * License as published by the Free Software Foundation.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 */

/*
 * This is similar to GtkLabel but clips itself and displays '...' if it
 * can't fit inside its allocated area. The intended use is for inside buttons
 * that are a fixed size. The GtkLabel would normally display only the middle
 * part of the text, which doesn't look very good. This only supports one line
 * of text (so no wrapping/justification), without underlined characters.
 */

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

#include "e-clipped-label.h"

#include <math.h>
#include <string.h>

#include <glib.h>
#include <gdk/gdki18n.h>
#include <glib/gi18n.h>


static void e_clipped_label_class_init (EClippedLabelClass *class);
static void e_clipped_label_init (EClippedLabel *label);
static void e_clipped_label_size_request (GtkWidget      *widget,
                      GtkRequisition *requisition);
static void e_clipped_label_size_allocate (GtkWidget *widget,
                       GtkAllocation *allocation);
static gint e_clipped_label_expose (GtkWidget      *widget,
                    GdkEventExpose *event);
static void e_clipped_label_recalc_chars_displayed (EClippedLabel *label);
static void e_clipped_label_finalize               (GObject *object);

static void build_layout (EClippedLabel *label, const char *text);

static GtkMiscClass *parent_class;

/* This is the string to draw when the label is clipped, e.g. '...'. */
static gchar *e_clipped_label_ellipsis;

/* Flags used in chars_displayed field. Must be negative. */
#define E_CLIPPED_LABEL_NEED_RECALC     -1
#define E_CLIPPED_LABEL_SHOW_ENTIRE_LABEL   -2


GtkType
e_clipped_label_get_type (void)
{
    static GtkType e_clipped_label_type = 0;

    if (!e_clipped_label_type){
        GtkTypeInfo e_clipped_label_info = {
            "EClippedLabel",
            sizeof (EClippedLabel),
            sizeof (EClippedLabelClass),
            (GtkClassInitFunc) e_clipped_label_class_init,
            (GtkObjectInitFunc) e_clipped_label_init,
            NULL, /* reserved 1 */
            NULL, /* reserved 2 */
            (GtkClassInitFunc) NULL
        };

        parent_class = g_type_class_ref(GTK_TYPE_MISC);
        e_clipped_label_type = gtk_type_unique (GTK_TYPE_MISC,
                            &e_clipped_label_info);
    }

    return e_clipped_label_type;
}


static void
e_clipped_label_class_init (EClippedLabelClass *class)
{
    GObjectClass *object_class;
    GtkWidgetClass *widget_class;

    object_class = (GObjectClass *) class;
    widget_class = (GtkWidgetClass *) class;

    /* Method override */
    widget_class->size_request  = e_clipped_label_size_request;
    widget_class->size_allocate = e_clipped_label_size_allocate;
    widget_class->expose_event  = e_clipped_label_expose;

    object_class->finalize          = e_clipped_label_finalize;

    e_clipped_label_ellipsis = _("...");
}


static void
e_clipped_label_init (EClippedLabel *label)
{
    GTK_WIDGET_SET_FLAGS (label, GTK_NO_WINDOW);

    label->label = NULL;
    label->chars_displayed = E_CLIPPED_LABEL_NEED_RECALC;
}


/**
 * e_clipped_label_new:
 *
 * @text: The label text.
 * @Returns: A new #EClippedLabel.
 *
 * Creates a new #EClippedLabel with the given text.
 **/
GtkWidget *
e_clipped_label_new (const gchar *text,
             PangoWeight font_weight,
             gfloat font_size)
{
    GtkWidget *label;
    EClippedLabel *clipped;

    label = g_object_new (e_clipped_label_get_type (), NULL);

    clipped = E_CLIPPED_LABEL (label);

    clipped->font_size = font_size;
    clipped->font_weight = font_weight;
    clipped->layout = NULL;

    build_layout (clipped, e_clipped_label_ellipsis);
    pango_layout_get_pixel_size (clipped->layout, &clipped->ellipsis_width, NULL);

    if (text && *text)
        e_clipped_label_set_text (clipped, text);

    return label;
}

static void
build_layout (EClippedLabel *label, const char *text)
{
    if (!label->layout) {
        GtkStyle *style = gtk_widget_get_style (GTK_WIDGET (label));
        PangoFontDescription *desc = pango_font_description_copy (style->font_desc);

        label->layout = gtk_widget_create_pango_layout (GTK_WIDGET (label), text);

        pango_font_description_set_size (desc, pango_font_description_get_size (desc) * label->font_size);
        
        pango_font_description_set_weight (desc, label->font_weight);
        pango_layout_set_font_description (label->layout, desc);
        pango_font_description_free (desc);
    }

    pango_layout_set_text (label->layout, text, -1);
}

static void
e_clipped_label_size_request (GtkWidget      *widget,
                  GtkRequisition *requisition)
{
    EClippedLabel *label;
    int height;
    int width;

    g_return_if_fail (E_IS_CLIPPED_LABEL (widget));
    g_return_if_fail (requisition != NULL);
  
    label = E_CLIPPED_LABEL (widget);

    pango_layout_get_pixel_size (label->layout, &width, &height);

    requisition->width = 0;
    requisition->height = height + 2 * GTK_MISC (widget)->ypad;
}


static void
e_clipped_label_size_allocate (GtkWidget *widget,
                   GtkAllocation *allocation)
{
    EClippedLabel *label;

    label = E_CLIPPED_LABEL (widget);

    widget->allocation = *allocation;

    /* Flag that we need to recalculate how many characters to display. */
    label->chars_displayed = E_CLIPPED_LABEL_NEED_RECALC;
}


static gint
e_clipped_label_expose (GtkWidget      *widget,
            GdkEventExpose *event)
{
    EClippedLabel *label;
    GtkMisc *misc;
    gint x;
    PangoRectangle rect;

    g_return_val_if_fail (E_IS_CLIPPED_LABEL (widget), FALSE);
    g_return_val_if_fail (event != NULL, FALSE);
  
    label = E_CLIPPED_LABEL (widget);
    misc = GTK_MISC (widget);

    /* If the label isn't visible or has no text, just return. */
    if (!GTK_WIDGET_VISIBLE (widget) || !GTK_WIDGET_MAPPED (widget)
        || !label->label || (*label->label == '\0'))
        return TRUE;

    /* Recalculate the number of characters displayed, if necessary. */
    if (label->chars_displayed == E_CLIPPED_LABEL_NEED_RECALC)
        e_clipped_label_recalc_chars_displayed (label);

    /*
     * GC Clipping
     */
    gdk_gc_set_clip_rectangle (widget->style->white_gc,
                   &event->area);
    gdk_gc_set_clip_rectangle (widget->style->fg_gc[widget->state],
                   &event->area);

    pango_layout_get_pixel_extents (label->layout, &rect, NULL);

    if (label->chars_displayed == E_CLIPPED_LABEL_SHOW_ENTIRE_LABEL) {
        x = floor (widget->allocation.x + (gint)misc->xpad
               + (((gint)widget->allocation.width - 
                   (gint)label->label_width - 2 * (gint)misc->xpad)
                  * misc->xalign) + 0.5);

        gdk_draw_layout (widget->window, widget->style->fg_gc[widget->state],
                 x, label->label_y, label->layout);
    } else {
        int layout_width;

        x = widget->allocation.x + (gint)misc->xpad;

        /* trim the layout to the number of characters we're displaying */
        pango_layout_set_text (label->layout, label->label, label->chars_displayed);

        /* draw it */
        gdk_draw_layout (widget->window, widget->style->fg_gc[widget->state],
                 x, label->label_y, label->layout);

        pango_layout_get_pixel_size (label->layout, &layout_width, NULL);

        /* offset the X position for the ellipsis */
        x = widget->allocation.x + (gint)misc->xpad
            + label->ellipsis_x;

        /* then draw the ellipsis */
        pango_layout_set_text (label->layout, e_clipped_label_ellipsis, strlen (e_clipped_label_ellipsis));

        gdk_draw_layout (widget->window, widget->style->fg_gc[widget->state],
                 x, label->label_y, label->layout);
        
        /* then reset the layout to our original label text */
        pango_layout_set_text (label->layout, label->label, -1);
    }

    gdk_gc_set_clip_mask (widget->style->white_gc, NULL);
    gdk_gc_set_clip_mask (widget->style->fg_gc[widget->state], NULL);

    return TRUE;
}


static void
e_clipped_label_finalize (GObject *object)
{
    EClippedLabel *label;

    g_return_if_fail (E_IS_CLIPPED_LABEL (object));

    label = E_CLIPPED_LABEL(object);

    g_free (label->label);

    g_object_unref (label->layout);

    (* G_OBJECT_CLASS (parent_class)->finalize) (object);
}


/**
 * e_clipped_label_get_text:
 *
 * @label: An #EClippedLabel.
 * @Return: The label text.
 *
 * Returns the label text, or NULL.
 **/
gchar*
e_clipped_label_get_text (EClippedLabel *label)
{
    g_return_val_if_fail (E_IS_CLIPPED_LABEL (label), NULL);

    return label->label;
}


/**
 * e_clipped_label_set_text:
 *
 * @label: An #EClippedLabel.
 * @text: The new label text.
 *
 * Sets the label text.
 **/
void
e_clipped_label_set_text (EClippedLabel *label,
              const gchar *text)
{
    g_return_if_fail (E_IS_CLIPPED_LABEL (label));

    if (label->label != text || !label->label || !text
        || strcmp (label->label, text)) {
        g_free (label->label);
        label->label = NULL;

        if (text)
            label->label = g_strdup (text);

        build_layout (label, text);

        /* Reset the number of characters displayed, so it is
           recalculated when needed. */
        label->chars_displayed = E_CLIPPED_LABEL_NEED_RECALC;

        /* We don't queue a resize, since the label should not affect
           the widget size, but we queue a draw. */
        gtk_widget_queue_draw (GTK_WIDGET (label));
    }
}


static void
e_clipped_label_recalc_chars_displayed (EClippedLabel *label)
{
    gint max_width, width;
    GSList *lines;
    PangoLayoutLine *line;
    int index;
    PangoRectangle rect;
    GtkWidget *widget = GTK_WIDGET (label);
    GtkMisc *misc = GTK_MISC (label);
        
    max_width = GTK_WIDGET (label)->allocation.width
        - 2 * GTK_MISC (label)->xpad;

    if (!label->label) {
        label->chars_displayed = 0;
        return;
    }

    /* See if the entire label fits in the allocated width. */
    pango_layout_set_text (label->layout, label->label, -1);

    pango_layout_get_pixel_extents (label->layout, &rect, NULL);

    label->label_y = floor (widget->allocation.y + (gint)misc->ypad 
                + (((gint)widget->allocation.height - 2 * (gint)misc->ypad
                    + (gint)PANGO_ASCENT (rect) - PANGO_DESCENT(rect))
                   * misc->yalign) + 0.5);

    pango_layout_get_pixel_size (label->layout, &label->label_width, NULL);
    if (label->label_width <= max_width) {
        label->chars_displayed = E_CLIPPED_LABEL_SHOW_ENTIRE_LABEL;
        return;
    }

    label->chars_displayed = 0;
    label->ellipsis_x = 0;

    if (max_width <= 0)
        return;

    max_width -= label->ellipsis_width;

    lines = pango_layout_get_lines (label->layout);
    line = lines->data;

    if (!pango_layout_line_x_to_index (line,
                       max_width * PANGO_SCALE,
                       &index,
                       NULL)) {
        return;
    }

    label->chars_displayed = index;

    pango_layout_set_text (label->layout, label->label, label->chars_displayed);
    pango_layout_get_pixel_size (label->layout, &width, NULL);

    label->ellipsis_x = width;
}