emscale.cc

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/*
    Copyright (C) 2014 Paul Davis, Robin Gareus

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <algorithm>
#include <gdk/gdk.h>
#include <pangomm/layout.h>

#include "gtkmm2ext/emscale.h"

#include "i18n.h"

using namespace Gtkmm2ext;

std::map<std::string,EmScale> EmScale::_emscales;

EmScale::EmScale (const Pango::FontDescription& fd)
        : _font (fd)
        , _char_pixel_width (-1)
        , _char_pixel_height (-1)
        , _char_avg_pixel_width (-1)
{
}

void
EmScale::recalc_char_pixel_geometry ()
{
        if (_char_pixel_height > 0 && _char_pixel_width > 0) {
                return;
        }

        Glib::RefPtr<Pango::Context> pc = Glib::wrap (gdk_pango_context_get_for_screen (gdk_screen_get_default()));
        Glib::RefPtr<Pango::Layout> layout = Pango::Layout::create (pc);

        layout->set_font_description (_font);

        int w, h;
        std::string x = _("ABCDEFGHIJLKMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789");
        layout->set_text (x);
        layout->get_pixel_size (w, h);
        _char_pixel_height = std::max(4, h);
        // number of actual chars in the string (not bytes)
        // Glib to the rescue.
        Glib::ustring gx(x);
        _char_avg_pixel_width = w / (float)gx.size();
        _char_pixel_width = std::max(4, (int) ceil (_char_avg_pixel_width));
}

EmScale&
EmScale::by_font (const Pango::FontDescription& fd)
{
        std::map<std::string,EmScale>::iterator i = _emscales.find (fd.to_string());

        if (i == _emscales.end()) {
                i = _emscales.insert (std::make_pair (fd.to_string(), EmScale (fd))).first;
        }

        return i->second;
}