X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fbeaming-pattern.cc;h=c32666133ba84f9b5fbb244d4fd7a9d018070326;hb=5b4b0d6e9a197e8f9eb085b7c2ad78b8be3e5cfc;hp=37ef6ee614e76cf52629e7ebb073a0c88f536fc4;hpb=899b43568c8be13c53625593bc1b1099892d0048;p=lilypond.git diff --git a/lily/beaming-pattern.cc b/lily/beaming-pattern.cc index 37ef6ee614..c32666133b 100644 --- a/lily/beaming-pattern.cc +++ b/lily/beaming-pattern.cc @@ -1,30 +1,52 @@ /* beaming-info.cc -- implement Beam_rhythmic_element, Beaming_pattern + A Beaming_pattern object takes a set of stems at given moments and calculates + the pattern of their beam. That is, it works out, for each stem, how many + beams should be connected to the right and left sides of that stem. In + calculating this, Beaming_pattern takes into account + - the rhythmic position of the stems + - the options that are defined in Beaming_options + source file of the GNU LilyPond music typesetter - (c) 1999--2007 Han-Wen Nienhuys + (c) 1999--2008 Han-Wen Nienhuys */ #include "beaming-pattern.hh" #include "context.hh" +/* + Represents a stem belonging to a beam. Sometimes (for example, if the stem + belongs to a rest and stemlets aren't used) the stem will be invisible. + + The rhythmic_importance_ of an element tells us the significance of the + moment at which this element occurs. For example, an element that occurs at + a beat is more significant than one that doesn't. Smaller number are + more important. The rhythmic_importance_ is decided and filled in by + Beaming_pattern. A rhythmic_importance_ smaller than zero has extra + significance: it represents the start of a beat and therefore beams may + need to be subdivided. +*/ Beam_rhythmic_element::Beam_rhythmic_element () { start_moment_ = 0; + rhythmic_importance_ = 0; beam_count_drul_[LEFT] = 0; beam_count_drul_[RIGHT] = 0; + invisible_ = false; } -Beam_rhythmic_element::Beam_rhythmic_element (Moment m, int i) +Beam_rhythmic_element::Beam_rhythmic_element (Moment m, int i, bool inv) { start_moment_ = m; + rhythmic_importance_ = 0; beam_count_drul_[LEFT] = i; beam_count_drul_[RIGHT] = i; + invisible_ = inv; } - void Beam_rhythmic_element::de_grace () { @@ -36,73 +58,51 @@ Beam_rhythmic_element::de_grace () } int -count_factor_twos (int x) +Beam_rhythmic_element::count (Direction d) const { - int c = 0; - while (x && x % 2 == 0) - { - x /= 2; - c ++; - } - - return c; + return beam_count_drul_[d]; } -int -Beaming_pattern::best_splitpoint_index (bool *at_boundary) const +/* + Finds the appropriate direction for the flags at the given index that + hang below the neighbouring flags. If + the stem has no more flags than either of its neighbours, this returns + CENTER. +*/ +Direction +Beaming_pattern::flag_direction (Beaming_options const &options, vsize i) const { - *at_boundary = true; - for (vsize i = 1; i < infos_.size (); i++) - { - if (infos_[i].group_start_ == infos_[i].start_moment_) - return i; - } - - for (vsize i = 1; i < infos_.size (); i++) - { - if (infos_[i].beat_start_ == infos_[i].start_moment_) - return i; - } - - *at_boundary = false; - - int min_den = INT_MAX; - int min_index = -1; - - for (vsize i = 1; i < infos_.size (); i++) + // The extremal stems shouldn't be messed with, so it's appropriate to + // return CENTER here also. + if (i == 0 || i == infos_.size () - 1) + return CENTER; + + int count = infos_[i].count (LEFT); // Both directions should still be the same + int left_count = infos_[i-1].count (RIGHT); + int right_count = infos_[i+1].count (LEFT); + + // If we are told to subdivide beams and we are next to a beat, point the + // beamlet away from the beat. + if (options.subdivide_beams_) { - Moment dt = infos_[i].start_moment_ - infos_[i].beat_start_; - - /* - This is a kludge, for the most common case of 16th, 32nds - etc. What should really happen is that \times x/y should - locally introduce a voice-specific beat duration. (or - perhaps: a list of beat durations for nested tuplets.) - - */ - - dt /= infos_[i].beat_length_; - - if (dt.den () < min_den) - { - min_den = dt.den (); - min_index = i; - } + if (infos_[i].rhythmic_importance_ < 0) + return RIGHT; + else if (infos_[i+1].rhythmic_importance_ < 0) + return LEFT; } - return min_index; -} + if (count <= left_count && count <= right_count) + return CENTER; -int -Beaming_pattern::beam_extend_count (Direction d) const -{ - if (infos_.size () == 1) - return infos_[0].beam_count_drul_[d]; + // Try to avoid sticking-out flags as much as possible by pointing my flags + // at the neighbour with the most flags. + else if (right_count > left_count) + return RIGHT; + else if (left_count > right_count) + return LEFT; - Beam_rhythmic_element thisbeam = boundary (infos_, d, 0); - Beam_rhythmic_element next = boundary (infos_, d, 1); - - return min (thisbeam.beam_count_drul_[-d], next.beam_count_drul_[d]); + // If all else fails, point the beamlet away from the important moment. + return (infos_[i].rhythmic_importance_ <= infos_[i+1].rhythmic_importance_) ? RIGHT : LEFT; } void @@ -117,6 +117,8 @@ Beaming_pattern::de_grace () void Beaming_pattern::beamify (Beaming_options const &options) { + unbeam_invisible_stems (); + if (infos_.size () <= 1) return; @@ -126,15 +128,36 @@ Beaming_pattern::beamify (Beaming_options const &options) if (infos_[0].start_moment_ < Moment (0)) for (vsize i = 0; i < infos_.size (); i++) infos_[i].start_moment_ += options.measure_length_; - - Moment measure_pos (0); - - vector group_starts; - vector beat_starts; + find_rhythmic_importance (options); + + for (vsize i = 1; i < infos_.size () - 1; i++) + { + Direction non_flag_dir = other_dir (flag_direction (options, i)); + if (non_flag_dir) + { + int importance = (non_flag_dir == LEFT) + ? infos_[i].rhythmic_importance_ : infos_[i+1].rhythmic_importance_; + int count = (importance < 0 && options.subdivide_beams_) + ? 1 : min (infos_[i].count (non_flag_dir), + infos_[i+non_flag_dir].count (-non_flag_dir)); + + infos_[i].beam_count_drul_[non_flag_dir] = count; + } + } +} + +void +Beaming_pattern::find_rhythmic_importance (Beaming_options const &options) +{ + Moment measure_pos (0); SCM grouping = options.grouping_; - while (measure_pos <= infos_.back ().start_moment_) + vsize i = 0; + + // Mark the importance of stems that start at a beat or a beat group. + while (i < infos_.size ()) { + // If a beat grouping is not specified, default to 2 beats per group. int count = 2; if (scm_is_pair (grouping)) { @@ -142,85 +165,69 @@ Beaming_pattern::beamify (Beaming_options const &options) grouping = scm_cdr (grouping); } - group_starts.push_back (measure_pos); - for (int i = 0; i < count; i++) + // Mark the start of this beat group + if (infos_[i].start_moment_ == measure_pos) + infos_[i].rhythmic_importance_ = -2; + + // Mark the start of each beat up to the end of this beat group. + for (int beat = 1; beat <= count; beat++) { - beat_starts.push_back (measure_pos + options.beat_length_ * i); + Moment next_measure_pos = measure_pos + options.beat_length_; + + while (i < infos_.size () && infos_[i].start_moment_ < next_measure_pos) + { + Moment dt = infos_[i].start_moment_ - measure_pos; + + // The rhythmic importance of a stem between beats depends on its fraction + // of a beat: those stems with a lower denominator are deemed more + // important. + // FIXME: This is not the right way to do things for tuplets. For example, + // in an 8th-note triplet with a quarter-note beat, 1/3 of a beat should be + // more important than 1/2. + if (infos_[i].rhythmic_importance_ >= 0) + infos_[i].rhythmic_importance_ = (dt / options.beat_length_).den (); + + i++; + } + + measure_pos = next_measure_pos; + if (i < infos_.size () && infos_[i].start_moment_ == measure_pos) + infos_[i].rhythmic_importance_ = -1; } - measure_pos += options.beat_length_ * count; - } - - vsize j = 0; - vsize k = 0; - for (vsize i = 0; i < infos_.size (); i++) - { - while (j + 1 < group_starts.size () - && group_starts[j+1] <= infos_[i].start_moment_) - j++; - - if (j < group_starts.size ()) - infos_[i].group_start_ = group_starts[j]; - - infos_[i].beat_length_ = options.beat_length_; - while (k + 1 < beat_starts.size () - && beat_starts[k+1] <= infos_[i].start_moment_) - k++; - - if (k < beat_starts.size ()) - infos_[i].beat_start_ = beat_starts[k]; } - - beamify (options.subdivide_beams_); } +/* + Invisible stems should be treated as though they have the same number of + beams as their least-beamed neighbour. Here we go through the stems and + modify the invisible stems to satisfy this requirement. +*/ void -Beaming_pattern::beamify (bool subdivide_beams) +Beaming_pattern::unbeam_invisible_stems () { - if (infos_.size () <= 1) - return; - - Drul_array splits; - - bool at_boundary = false; - int m = best_splitpoint_index (&at_boundary); - - splits[LEFT].infos_ = vector (infos_.begin (), - infos_.begin () + m); - splits[RIGHT].infos_ = vector (infos_.begin () + m, - infos_.end ()); - - Direction d = LEFT; - - do - { - splits[d].beamify (subdivide_beams); - } - while (flip (&d) != LEFT); - - int middle_beams = ((at_boundary && subdivide_beams) - ? 1 - : min (splits[RIGHT].beam_extend_count (LEFT), - splits[LEFT].beam_extend_count (RIGHT))); - - do - { - if (splits[d].infos_.size () != 1) - boundary (splits[d].infos_, -d, 0).beam_count_drul_[-d] = middle_beams; - } - while (flip (&d) != LEFT); - - infos_ = splits[LEFT].infos_; - infos_.insert (infos_.end (), - splits[RIGHT].infos_.begin (), - splits[RIGHT].infos_.end ()); + for (vsize i = 1; i < infos_.size (); i++) + if (infos_[i].invisible_) + { + int b = min (infos_[i].count (LEFT), infos_[i-1].count (LEFT)); + infos_[i].beam_count_drul_[LEFT] = b; + infos_[i].beam_count_drul_[RIGHT] = b; + } + + for (vsize i = infos_.size (); i--;) + if (infos_[i].invisible_) + { + int b = min (infos_[i].count (LEFT), infos_[i+1].count (LEFT)); + infos_[i].beam_count_drul_[LEFT] = b; + infos_[i].beam_count_drul_[RIGHT] = b; + } } void -Beaming_pattern::add_stem (Moment m, int b) +Beaming_pattern::add_stem (Moment m, int b, bool invisible) { - infos_.push_back (Beam_rhythmic_element (m, b)); + infos_.push_back (Beam_rhythmic_element (m, b, invisible)); } Beaming_pattern::Beaming_pattern ()