ladybird/Applications/Piano/RollWidget.h
William McPherson 72cbbd5297 Piano: New timing system and zoomable piano roll
This patch allows roll notes to be of different sizes. This necessitates
a new internal representation of time. BPM and time signatures are
mostly implemented but not exposed.

Roll notes are now sample-accurate and the grid is aligned to 60 BPM
4/4. The roll is divided by the time signature raised to some power of
2, giving the musical divisions of (in the case of 4/4) 16, 32, 64 etc.

Before, our timing was derived from the buffer size and we relied on
that to implement delay. Delay has been rewritten to be sample-granular.
It's now exposed as the proper "divisions of a beat".
Something to be wary of is that the last buffer in the loop is also used
for the start of the next loop. In other words, we loop mid-buffer. This
means we write WAVs with a tiny bit of silence due to breaking the loop
after filling half a buffer.

The data structure for the roll is an array of SinglyLinkedLists of
RollNotes. Separating by pitch (via the array layout) makes insertion
much simpler and faster. Using sorted lists (and thus
SinglyLinkedListIterators) to do lookups is very quick as you know the
sample of the next note and can just compare it to the current sample. I
implemented this with HashMaps and the cost of lookups was abysmal. I
also tried a single SinglyLinkedList and the insertion code got even
more complicated than it already is.
2020-02-27 10:21:13 +01:00

54 lines
2.0 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2019-2020, William McPherson <willmcpherson2@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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#pragma once
#include "Music.h"
#include <LibGUI/ScrollableWidget.h>
class AudioEngine;
class RollWidget final : public GUI::ScrollableWidget {
C_OBJECT(RollWidget)
public:
virtual ~RollWidget() override;
private:
explicit RollWidget(AudioEngine&);
virtual void paint_event(GUI::PaintEvent&) override;
virtual void mousedown_event(GUI::MouseEvent& event) override;
virtual void mousewheel_event(GUI::MouseEvent&) override;
AudioEngine& m_audio_engine;
int m_roll_width;
int m_num_notes;
double m_note_width;
int m_zoom_level { 1 };
};