MIDIPianoRollView

Customisable UIScrollView subclass for rendering/editing MIDI notes on a piano roll view.

Demo

Requirements

• iOS 9.0+
• Swift 4.2+
• Xcode 10.0+

Usage

Create a MIDIPianoRollView either from storyboard (subclass from UIScrollView) or programmatically.

MIDIPianoRollView.Keys

• An enum that represents the data source of the piano roll's keys.
• It can be either
  • A range of UInt8 MIDI notes like 30...50 (30th note to 50th note)
  • A Scale of notes between specified octave range
  • Or custom unordered pitches.

MIDIPianoRollView.Bars

• An enum that represents the bar count on the piano roll.
• It can be either
  • A fixed value by .fixed(barCount)
  • Or .auto that auto-caluclating bar count by the data source.

MIDIPianoRollNote

• Set the notes data source array in order to pop the notes.
• It is a [MIDIPianoRollNote] array that has the start position, duration, midi note and velocity data for each note.

MIDIPianoRollPosition

• This represents the both position and duration values for the notes on the piano roll. Contains bar, beat, subbeat and cent values.
• Each of them are Int and confomrs to Comparable, Equatable, Codable and custom + and - operatros.
• Each bar has a number of beats that the piano roll's timesingature has.
• Each beat has 4 subbeats.
• Each subbeat has 240 cents for fine tuning.

MIDIPianoRollCellView

• Each cell on the piano roll is a subclass of the MIDIPianoRollCellView.
• You can basically create your custom cell view by subclassing it.

MIDIPianoRollRowView

• Each key view on the right side of the piano roll is a subclass of MIDIPianoRollRowView.
• You can create your custom sublass may be with some piano key images and render it on the piano roll.

MIDIPianoRollMeasureView

• Measure is a custom view with bunch of CALayers that rendering the position texts and guide lines.
• You can set grid line width and colors.
• You can set measure position label font and text colors.
• If you don't want to render measure, then you can set the isMeasureEnabled property to false.

MIDIPianoRollView.ZoomLevel

• Zoom level represents the currently rendering beat value on the piano roll.
• It has a customisable minZoomLevel and maxZoomLevel range.
• Each zoom level have note rate, for example,
  • .halfNotes means a bar have 2 beats with 2 half notes,
  • .quarterNotes means a bar have 4 beats with 4 quarter notes.
• If isZoomingEnabled is set true, then you can horizontally pinch-to-zoom in or out between customisable minBeatWidth and maxBeatWidth values to set current beatWidth.
• When a beatWidth hits the limit, the zoom level advances the next level depending on the zooming in or out.
• You can disable this behaviour by setting isZoomingEnabled property to false.
• The same behavior also controls the row height zooming. If you vertically pinch-to-zoom, then current rowHeight will scale between minRowHeight and maxRowHeight properties.

MIDIPianoRollView.GridLine

• Contains line properties for grid line styling.
• You can set each line's width, color or dash pattern styling.

Editing

• You can enter the cell editing mode by setting isEditing property to true.
• When you are in the edit mode, you can not scroll the view but you can pan the cells to move or resize.
• You can enable/disable the multiple editing by setting the isMultipleEditingEnabled property to true.
  • When it's enabled, you can drag your finger to render a multiple selection view to select all cells that under the drag-to-select box.
  • Then you can move or resize the selected cells.
• When editing is done, piano roll will informs its delegate.

MIDIPianoRollViewDelegate

• Informs the delegate when the cell is edited.
• You can update your notes data source in the delegate calls.

  func midiPianoRollView(_ midiPianoRollView: MIDIPianoRollView,
                         didMove cellView: MIDIPianoRollCellView,
                         to newPosition: MIDIPianoRollPosition,
                         pitch: UInt8)

• Informs delegate about that the cell is moved a new position and/or row.
• You can use the pitch value to determine which row is the cell moved.

func midiPianoRollView(_ midiPianoRollView: MIDIPianoRollView,
                         didResize cellView: MIDIPianoRollCellView,
                         to newDuration: MIDIPianoRollPosition)

• Informs delegate about that the cell's duration changed.
• Called when cell is resized.

func midiPianoRollViewMultipleEditingDraggingView(_ midiPianoRollView: MIDIPianoRollView) -> UIView?

• Return a custom UIView if you want to render your custom drag-to-select view.

Example Project

• Check out the example project for getting more information about the implementation.

Documentation

You can find the documentation here.