tempo_lines.cc

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/*
    Copyright (C) 2002-2007 Paul Davis

    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 "pbd/compose.h"

#include "canvas/canvas.h"
#include "canvas/debug.h"

#include "ardour_ui.h"
#include "public_editor.h"
#include "rgb_macros.h"
#include "tempo_lines.h"

using namespace std;

TempoLines::TempoLines (ArdourCanvas::Container* group, double)
        : lines (group, ArdourCanvas::LineSet::Vertical)
{
        lines.set_extent (ArdourCanvas::COORD_MAX);
}

void
TempoLines::tempo_map_changed()
{
        lines.clear ();
}

void
TempoLines::show ()
{
        lines.show ();
}

void
TempoLines::hide ()
{
        lines.hide ();
}

void
TempoLines::draw_ticks (const ARDOUR::TempoMap::BBTPointList::const_iterator& b,
                        unsigned                                              divisions,
                        framecnt_t                                            leftmost_frame,
                        framecnt_t                                            frame_rate)
{
        const double   fpb  = b->tempo->frames_per_beat(frame_rate);
        const uint32_t base = ARDOUR_UI::config()->color_mod("measure line beat", "measure line beat");

        for (unsigned l = 1; l < divisions; ++l) {
                /* find the coarsest division level this tick falls on */
                unsigned level = divisions;
                for (unsigned d = divisions; d >= 4; d /= 2) {
                        if (l % (divisions / d) == 0) {
                                level = d;
                        }
                }

                /* draw line with alpha corresponding to coarsest level */
                const uint8_t    a = max(8, (int)rint(UINT_RGBA_A(base) / (0.8 * log2(level))));
                const uint32_t   c = UINT_RGBA_CHANGE_A(base, a);
                const framepos_t f = b->frame + (l * (fpb / (double)divisions));
                if (f > leftmost_frame) {
                        lines.add (PublicEditor::instance().sample_to_pixel_unrounded (f), 1.0, c);
                }
        }
}

void
TempoLines::draw (const ARDOUR::TempoMap::BBTPointList::const_iterator& begin,
                  const ARDOUR::TempoMap::BBTPointList::const_iterator& end,
                  unsigned                                              divisions,
                  framecnt_t                                            leftmost_frame,
                  framecnt_t                                            frame_rate)
{
        ARDOUR::TempoMap::BBTPointList::const_iterator i;
        double  beat_density;

        uint32_t beats = 0;
        uint32_t bars = 0;
        uint32_t color;

        /* get the first bar spacing */

        i = end;
        i--;
        bars = (*i).bar - (*begin).bar; 
        beats = distance (begin, end) - bars;

        beat_density = (beats * 10.0f) / lines.canvas()->width();

        if (beat_density > 2.0f) {
                /* if the lines are too close together, they become useless */
                lines.clear ();
                return;
        }

        /* constrain divisions to a log2 factor to cap line density */
        while (divisions > 3 && beat_density * divisions > 0.4) {
                divisions /= 2;
        }

        lines.clear ();

        if (beat_density <= 0.12 && begin != end && begin->frame > 0) {
                /* draw subdivisions of the beat before the first visible beat line */
                ARDOUR::TempoMap::BBTPointList::const_iterator prev = begin;
                --prev;
                draw_ticks(prev, divisions, leftmost_frame, frame_rate);
        }

        for (i = begin; i != end; ++i) {

                if ((*i).is_bar()) {
                        color = ARDOUR_UI::config()->color ("measure line bar");
                } else {
                        if (beat_density > 0.3) {
                                continue; /* only draw beat lines if the gaps between beats are large. */
                        }
                        color = ARDOUR_UI::config()->color_mod ("measure line beat", "measure line beat");
                }

                ArdourCanvas::Coord xpos = PublicEditor::instance().sample_to_pixel_unrounded ((*i).frame);

                lines.add (xpos, 1.0, color);

                if (beat_density <= 0.12) {
                        /* draw subdivisions of this beat */
                        draw_ticks(i, divisions, leftmost_frame, frame_rate);
                }
        }
}