Displays & Meters

Overview

Display controls visualize real-time data from the audio thread. They use the ISender system to safely transmit data from the DSP thread to the UI thread.

Thread Safety: Never access UI controls directly from ProcessBlock. Always use ISender objects to transmit data.

Vector Meter Control

IVMeterControl displays audio levels with linear or logarithmic response.

Constructor

template <int MAXNC = 1>
class IVMeterControl;

IVMeterControl(
  const IRECT& bounds,
  const char* label,
  const IVStyle& style = DEFAULT_STYLE,
  EDirection dir = EDirection::Vertical,
  std::initializer_list<const char*> trackNames = {},
  int totalNSegs = 0,
  EResponse response = EResponse::Linear,
  float lowRangeDB = -72.f,
  float highRangeDB = 12.f,
  std::initializer_list<int> markers = {0, -6, -12, -24, -48}
);

MAXNC

int

default:"1"

Template parameter: maximum number of channels

bounds

IRECT

required

Position and size

label

const char*

required

Label text

style

IVStyle

default:"DEFAULT_STYLE"

Visual styling

dir

EDirection

default:"EDirection::Vertical"

Meter orientation: Vertical or Horizontal

trackNames

std::initializer_list<const char*>

Names for each channel track

totalNSegs

int

default:"0"

Number of LED segments (0 = continuous meter)

response

EResponse

default:"EResponse::Linear"

Linear or Log response curve

lowRangeDB

float

default:"-72.f"

Minimum dB level displayed

highRangeDB

float

default:"12.f"

Maximum dB level displayed

markers

std::initializer_list<int>

dB values to mark with lines (log response only)

Example

// In plugin header
class MyPlugin : public Plugin {
public:
  ISender<2> mMeterSender;  // 2 channels
};

// In plugin constructor
mMeterSender.SetControl(kCtrlTagMeter);

// In ProcessBlock
void ProcessBlock(sample** inputs, sample** outputs, int nFrames) {
  // Process audio...
  
  // Send meter data
  mMeterSender.ProcessBlock(outputs, nFrames, kCtrlTagMeter);
}

// In UI setup
pGraphics->AttachControl(
  new IVMeterControl<2>(
    IRECT(10, 10, 50, 200),
    "Output",
    DEFAULT_STYLE,
    EDirection::Vertical,
    {"L", "R"},           // Channel names
    0,                     // Continuous (not segmented)
    IVMeterControl<2>::EResponse::Log,
    -60.f,                 // Min -60 dB
    6.f,                   // Max +6 dB
    {0, -6, -12, -24, -48} // Markers
  ),
  kCtrlTagMeter
);

Methods

void SetResponse(EResponse response); // Switch between Linear/Log

Peak/Average Meter Control

IVPeakAvgMeterControl displays both peak and average (RMS) levels with held peaks.

Constructor

template <int MAXNC = 1>
class IVPeakAvgMeterControl;

IVPeakAvgMeterControl(
  const IRECT& bounds,
  const char* label,
  const IVStyle& style = DEFAULT_STYLE,
  EDirection dir = EDirection::Vertical,
  std::initializer_list<const char*> trackNames = {},
  int totalNSegs = 0,
  float lowRangeDB = -60.f,
  float highRangeDB = 12.f,
  std::initializer_list<int> markers = {0, -6, -12, -24, -48}
);

Requires IPeakAvgSender instead of regular ISender.

Example

// In plugin header
IPeakAvgSender<2> mMeterSender;

// In plugin constructor
mMeterSender.SetControl(kCtrlTagMeter);

// In ProcessBlock
mMeterSender.ProcessBlock(outputs, nFrames, kCtrlTagMeter);

// In UI setup
pGraphics->AttachControl(
  new IVPeakAvgMeterControl<2>(
    IRECT(10, 10, 60, 200),
    "Master",
    DEFAULT_STYLE,
    EDirection::Vertical,
    {"L", "R"},
    0,      // Continuous
    -60.f,  // Low range
    6.f     // High range
  ),
  kCtrlTagMeter
);

LED Meter Control

IVLEDMeterControl displays segmented LED-style meters with customizable color ranges.

Constructor

template <int MAXNC = 1>
class IVLEDMeterControl;

struct LEDRange {
  float lowRangeDB;
  float highRangeDB;
  int nSegs;
  IColor color;
};

IVLEDMeterControl(
  const IRECT& bounds,
  const char* label = "",
  const IVStyle& style = DEFAULT_STYLE,
  EDirection dir = EDirection::Vertical,
  std::initializer_list<const char*> trackNames = {},
  int totalNSegs = 13,
  const std::vector<LEDRange>& ranges = {
    {0., 6., 1, LED5},         // Red: 0 to +6 dB
    {-18., 0., 3, LED4},       // Orange: -18 to 0 dB
    {-36., -18., 3, LED3},     // Yellow: -36 to -18 dB
    {-54., -36., 3, LED2},     // Light green: -54 to -36 dB
    {-72., -54., 3, LED1}      // Dark green: -72 to -54 dB
  }
);

totalNSegs

int

default:"13"

Total number of LED segments (must match sum of segments in ranges)

ranges

std::vector<LEDRange>

LED color ranges from top (highest dB) to bottom (lowest dB)

Example

// Custom LED ranges
std::vector<IVLEDMeterControl<2>::LEDRange> customRanges = {
  {0.f, 3.f, 1, COLOR_RED},           // 1 red LED at top
  {-12.f, 0.f, 4, COLOR_YELLOW},      // 4 yellow LEDs
  {-48.f, -12.f, 8, COLOR_GREEN}      // 8 green LEDs
};

pGraphics->AttachControl(
  new IVLEDMeterControl<2>(
    IRECT(10, 10, 70, 200),
    "Output",
    DEFAULT_STYLE,
    EDirection::Vertical,
    {"L", "R"},
    13,  // Total segments
    customRanges
  ),
  kCtrlTagMeter
);

Bitmap Meter Control

IBMeterControl uses a bitmap filmstrip for meter visualization.

Constructor

IBMeterControl(
  const IRECT& bounds,
  const IBitmap& bitmap,
  EResponse response = EResponse::Log,
  float lowRangeDB = -72.f,
  float highRangeDB = 12.f
);

Example

const IBitmap meterBitmap = pGraphics->LoadBitmap("meter.png", 100); // 100 frames

pGraphics->AttachControl(
  new IBMeterControl(
    IRECT(10, 10, 30, 200),
    meterBitmap,
    IBMeterControl::EResponse::Log,
    -60.f,
    6.f
  ),
  kCtrlTagMeter
);

Scope Control

IVScopeControl displays a real-time oscilloscope of audio waveforms.

Constructor

template <int MAXNC = 1, int MAXBUF = 128>
class IVScopeControl;

IVScopeControl(
  const IRECT& bounds,
  const char* label = "",
  const IVStyle& style = DEFAULT_STYLE
);

MAXNC

int

default:"1"

Template parameter: maximum number of channels

MAXBUF

int

default:"128"

Template parameter: buffer size (number of samples to display)

Example

// In plugin header
IScopeBufSender<2, 128> mScopeSender;

// In plugin constructor
mScopeSender.SetControl(kCtrlTagScope);

// In ProcessBlock
mScopeSender.ProcessBlock(outputs, nFrames, kCtrlTagScope);

// In UI setup
pGraphics->AttachControl(
  new IVScopeControl<2, 128>(
    IRECT(10, 10, 400, 200),
    "Oscilloscope"
  ),
  kCtrlTagScope
);

Methods

void SetBufferSize(int bufferSize); // Change displayed buffer size

Display Control

IVDisplayControl shows a rolling display of historical values (like a chart recorder).

Constructor

IVDisplayControl(
  const IRECT& bounds,
  const char* label = "",
  const IVStyle& style = DEFAULT_STYLE,
  EDirection dir = EDirection::Horizontal,
  float lo = 0.,
  float hi = 1.f,
  float defaultVal = 0.,
  uint32_t bufferSize = 100,
  float strokeThickness = 2.f
);

dir

EDirection

default:"EDirection::Horizontal"

Scroll direction: Horizontal (left to right) or Vertical (top to bottom)

float

default:"0.f"

Minimum value (bottom of display)

float

default:"1.f"

Maximum value (top of display)

defaultVal

float

default:"0.f"

Initial value to fill buffer

bufferSize

uint32_t

default:"100"

Number of historical values to display

strokeThickness

float

default:"2.f"

Line thickness in pixels

Example

// In plugin header
ISender<1> mEnvelopeSender;

// In plugin constructor
mEnvelopeSender.SetControl(kCtrlTagEnvDisplay);

// In ProcessBlock (send envelope follower value)
float envelope = CalculateEnvelope();
mEnvelopeSender.PushData({kCtrlTagEnvDisplay}, {envelope});

// In UI setup
pGraphics->AttachControl(
  new IVDisplayControl(
    IRECT(10, 10, 410, 110),
    "Envelope",
    DEFAULT_STYLE,
    EDirection::Horizontal,
    0.f,     // Min value
    1.f,     // Max value
    0.f,     // Default
    200,     // 200 points
    2.f      // 2px line
  ),
  kCtrlTagEnvDisplay
);

Spectrum Analyzer Control

IVBarGraphSpectrumAnalyzerControl displays frequency spectrum as bar graph.

See IGraphics/Controls/IVBarGraphSpectrumAnalyzerControl.h for full API.

Label Control

IVLabelControl displays static or dynamic text.

Constructor

IVLabelControl(
  const IRECT& bounds,
  const char* label,
  const IVStyle& style = DEFAULT_STYLE
    .WithDrawFrame(false)
    .WithColor(kSH, COLOR_BLACK)
    .WithShadowOffset(1)
    .WithValueText(
      DEFAULT_VALUE_TEXT
        .WithSize(20.f)
        .WithFGColor(COLOR_WHITE)
    )
);

Example

// Static label
pGraphics->AttachControl(
  new IVLabelControl(
    IRECT(10, 10, 110, 40),
    "Master Volume"
  )
);

// Dynamic label
auto* label = new IVLabelControl(
  IRECT(10, 10, 200, 40),
  "Ready"
);
pGraphics->AttachControl(label, kCtrlTagStatus);

// Update label text later
label->SetStr("Processing...");

ISender System

The ISender system safely transmits data from audio thread to UI thread.

Basic ISender

// In plugin header
ISender<MAXNC> mSender;  // MAXNC = max channels

// In constructor
mSender.SetControl(kCtrlTag);

// In ProcessBlock
mSender.ProcessBlock(outputs, nFrames, kCtrlTag);

// Or send custom data
float values[2] = {0.5f, 0.75f};
mSender.PushData({kCtrlTag}, values);

IPeakAvgSender

// For peak/average meters
IPeakAvgSender<MAXNC> mPeakAvgSender;

mPeakAvgSender.SetControl(kCtrlTag);
mPeakAvgSender.ProcessBlock(outputs, nFrames, kCtrlTag);

IScopeBufSender

// For oscilloscopes
IScopeBufSender<MAXNC, MAXBUF> mScopeSender;

mScopeSender.SetControl(kCtrlTag);
mScopeSender.ProcessBlock(outputs, nFrames, kCtrlTag);

Thread Safety Rules:

Create ISender in plugin constructor
Call SetControl() after UI is created
Only call ProcessBlock() or PushData() from audio thread
Never access controls directly from ProcessBlock

Source Reference

Files:

IGraphics/Controls/IVMeterControl.h - Meters
IGraphics/Controls/IVScopeControl.h - Scope
IGraphics/Controls/IVDisplayControl.h - Display
IGraphics/Controls/IControls.h - Label
IPlug/ISender.h - Data transmission system

​Overview

​Vector Meter Control

​Constructor

​Example

​Methods

​Peak/Average Meter Control

​Constructor

​Example

​LED Meter Control

​Constructor

​Example

​Bitmap Meter Control

​Constructor

​Example

​Scope Control

​Constructor

​Example

​Methods

​Display Control

​Constructor

​Example

​Spectrum Analyzer Control

​Label Control

​Constructor

​Example

​ISender System

​Basic ISender

​IPeakAvgSender

​IScopeBufSender

​Source Reference

Overview

Vector Meter Control

Constructor

Example

Methods

Peak/Average Meter Control

Constructor

Example

LED Meter Control

Constructor

Example

Bitmap Meter Control

Constructor

Example

Scope Control

Constructor

Example

Methods

Display Control

Constructor

Example

Spectrum Analyzer Control

Label Control

Constructor

Example

ISender System

Basic ISender

IPeakAvgSender

IScopeBufSender

Source Reference