Juce Attachments

This proposal features three Attachments for the
juce::AudioProcessorValueTreeState class

• SbRadioGroupAttachment (to be used with the custom SbRadioGroup component)
• LabelAttachment
• ComboBoxAttachment (based on the existing version)

These attachments make use of the user defined valueToTextFunction and
textToValueFunction when set as the last 2 parameters from the
createAndAddParameter function.

These functions are used to create an updated text entry from a new parameter
value and to evaluate text entries in the label or ComboBox editor. The
SbRadioGroupAttachment will populate the RadioGroup with ToggleButtons based on
the range property of the attached parameter. It is also possible now to create
the Combobox item list by connecting it to a parameter through the Attachment.

The Demo Projects

PresetVsUserSettings

This example illustrates some modifications I have made to the
AudioProcessorValueTreeState class. There are now two groups of Parameters that
are handled differently:

• Preset Parameters - The state of these is saved with the preset.
• User Settings - Their state is loaded from a settings file when the
  processor is created. The file is saved whenever a user setting is changed
  and also when the processor is destroyed. It is advised to disable host
  automation for this parameter group.

Both preset parameters and user settings are made available to the host and can
be modified through the host interface if present.

RadioGroup

The RadioGroup example features a component that is populated with a group of
radio buttons. The Buttons are created by a SbRadioGroupAttachment upon
connection to the component.

AttachmentsDemo

The AttachmentsDemo example project illustrates the use of the enhanced
ComboBoxAttachment and the new LabelAttachment.

SliderMonitor

This example features a status bar at the bottom of the UI panel. The status bar
displays the value of the most recently moved slider. It can also serve to
change the value via text input. The text representation of the status bar is
determined by the valueToText function of the parameter that is attached to the
selected slider. The example shows how a complete custom attachment can be
implemented outside the framework code.

ConverterWithState

This example shows how a stateful text converter can be used with the
AudioProcessorValueTreeState. The radio button allows changing the text display
of the parameter value from numbers to letters (each letter of the alphabet
representing a number.) In a real world application the mechanism might be used
to offer:

• Different pitch display options (note number, note name, frequency,
  localized note names (indian, persian, italian, ...))
• Different amplitude display options (percent, decibel)

Please note

The original AudioProcessorValueTreeState class design does not permit the
addition of user defined Attachments from outside the class definition. Because
of that, I had to modify some files from the juce framework to make things
possible. Before compiling the demo projects you will have to replace these
files with the versions that are supplied with this release:

• juce_AudioProcessorParameters.cpp
• juce_AudioProcessorParameterWithID.h
• juce_AudioProcessorValueTreeState.cpp
• juce_AudioProcessorValueTreeState.h

Changes

• RadioGroup: templated the component. It can now be populated with any button
  type.
• Added a canAutomate property to AudioProcessorParameterWithID
• Modified AudioProcessorValueTreeState to allow for separate handling of user
  settings
• Added a radio button group example
• Added a stateful converter example.
• Bugfix: Combobox is now initialized correctly.
• Added a SliderMonitor example
• Bugfix: AttachmentsDemo: Combobox now always shows the correct item text