Several improvements

- Replace usage of deprecated "io/ioutil" package with equivalent methods
  from "io" or "os" package.
- Simplify power amp code to no longer supply IDs for compiled filters.
  Filters are regenerated synchronously for some time in order to avoid
  race conditions, especially during batch processing, so these IDs are
  no longer needed in order to guarantee sequential ordering.
- Change interface of metronome value setters to support them failing to
  set a value. (This is an interface change in preparation for upcoming
  features.)
- Introduce new constants for default values in metronome.
- Update to latest version of "pure-knob", improving support for high-DPI
  displays.
- Several small bugfixes, code improvements and UI changes.
- Increment patch version number: v1.6.6 --> v1.6.7

controller/controller.go

@@ -18,7 +18,7 @@ import (
 	"github.com/andrepxx/go-dsp-guitar/tuner"
 	"github.com/andrepxx/go-dsp-guitar/wave"
 	"github.com/andrepxx/go-dsp-guitar/webserver"
-	"io/ioutil"
+	"io"
 	"math"
 	"os"
 	"runtime"
@@ -340,17 +340,18 @@ func (this *controllerStruct) getConfigurationHandler(request webserver.HttpRequ
 	fx := this.effects
 	numChannels := len(fx)
 	framesPerPeriod := uint32(0)
+	binding := this.binding
 
 	/*
 	 * If we are bound to a hardware interface, query frames per period.
 	 */
-	if this.binding != nil {
+	if binding != nil {
 		framesPerPeriod = hwio.FramesPerPeriod()
 	}
 
 	webChains := make([]webChainStruct, numChannels)
 	spatChannels := make([]webSpatializerChannelStruct, numChannels)
-	paramTypes := effects.ParameterTypes()
+	parameterTypes := effects.ParameterTypes()
 
 	/*
 	 * Iterate over the channels and the associated signal chains.
@@ -365,33 +366,54 @@ func (this *controllerStruct) getConfigurationHandler(request webserver.HttpRequ
 		for idUnit := 0; idUnit < numUnits; idUnit++ {
 			unitType, _ := chain.UnitType(idUnit)
 			bypass, _ := chain.GetBypass(idUnit)
-			params, _ := chain.Parameters(idUnit)
-			numParams := len(params)
-			webParams := make([]webParameterStruct, numParams)
+			parameters, _ := chain.Parameters(idUnit)
+			numParameters := len(parameters)
+			webParameters := make([]webParameterStruct, numParameters)
+
+			/*
+			 * Iterate over the parameters.
+			 */
+			for idParameter, parameter := range parameters {
+				name := parameter.Name
+				parameterTypeId := parameter.Type
+				parameterType := parameterTypes[parameterTypeId]
+				physicalUnit := parameter.PhysicalUnit
+				minimum := parameter.Minimum
+				maximum := parameter.Maximum
+				numericValue := parameter.NumericValue
+				discreteValueIndex := parameter.DiscreteValueIndex
+				discreteValuesSource := parameter.DiscreteValues
+				numDiscreteValues := len(discreteValuesSource)
+				discreteValues := make([]string, numDiscreteValues)
+				copy(discreteValues, discreteValuesSource)
+
+				/*
+				 * Create data structure for parameter.
+				 */
+				webParameter := webParameterStruct{
+					Name:               name,
+					Type:               parameterType,
+					PhysicalUnit:       physicalUnit,
+					Minimum:            minimum,
+					Maximum:            maximum,
+					NumericValue:       numericValue,
+					DiscreteValueIndex: discreteValueIndex,
+					DiscreteValues:     discreteValues,
+				}
+
+				webParameters[idParameter] = webParameter
+			}
 
 			/*
-			 * Iterate over the parameters and copy all values.
+			 * Create data structure for unit.
 			 */
-			for idParam, param := range params {
-				paramTypeId := param.Type
-				paramType := paramTypes[paramTypeId]
-				webParams[idParam].Name = param.Name
-				webParams[idParam].Type = paramType
-				webParams[idParam].PhysicalUnit = param.PhysicalUnit
-				webParams[idParam].Minimum = param.Minimum
-				webParams[idParam].Maximum = param.Maximum
-				webParams[idParam].NumericValue = param.NumericValue
-				webParams[idParam].DiscreteValueIndex = param.DiscreteValueIndex
-				nValues := len(param.DiscreteValues)
-				discreteValuesSource := param.DiscreteValues
-				discreteValuesTarget := make([]string, nValues)
-				copy(discreteValuesTarget, discreteValuesSource)
-				webParams[idParam].DiscreteValues = discreteValuesTarget
+			webUnit := webUnitStruct{
+				Type:       unitType,
+				Bypass:     bypass,
+				Parameters: webParameters,
 			}
 
-			webUnits[idUnit].Type = unitType
-			webUnits[idUnit].Bypass = bypass
-			webUnits[idUnit].Parameters = webParams
+			webUnits[idUnit] = webUnit
 		}
 
 		webChains[idChannel].Units = webUnits
@@ -403,11 +425,19 @@ func (this *controllerStruct) getConfigurationHandler(request webserver.HttpRequ
 		if spat != nil {
 			idChannel32 := uint32(idChannel)
 			azimuth, _ := spat.GetAzimuth(idChannel32)
-			spatChannels[idChannel].Azimuth = azimuth
 			distance, _ := spat.GetDistance(idChannel32)
-			spatChannels[idChannel].Distance = distance
 			level, _ := spat.GetLevel(idChannel32)
-			spatChannels[idChannel].Level = level
+
+			/*
+			 * Create data structure for spatializer channel.
+			 */
+			spatChannel := webSpatializerChannelStruct{
+				Azimuth:  azimuth,
+				Distance: distance,
+				Level:    level,
+			}
+
+			spatChannels[idChannel] = spatChannel
 		}
 
 	}
@@ -474,7 +504,7 @@ func (this *controllerStruct) getConfigurationHandler(request webserver.HttpRequ
 		Enabled: levelMeterEnabled,
 	}
 
-	batchProcessing := (this.binding == nil)
+	batchProcessing := (binding == nil)
 
 	/*
 	 * Create configuration structure.
@@ -895,7 +925,7 @@ func (this *controllerStruct) persistenceRestoreHandler(request webserver.HttpRe
 
 		} else {
 			patchFile := patchFiles[0]
-			patchBytes, err := ioutil.ReadAll(patchFile)
+			patchBytes, err := io.ReadAll(patchFile)
 
 			/*
 			 * Check if patch file could be successfully read.
@@ -2061,12 +2091,12 @@ func (this *controllerStruct) setMetronomeValueHandler(request webserver.HttpReq
 		 */
 		switch param {
 		case "beats-per-period":
-			rawValue, err := strconv.ParseUint(value, 10, 32)
+			rawValue, errParse := strconv.ParseUint(value, 10, 32)
 
 			/*
 			 * Check if value failed to parse.
 			 */
-			if err != nil {
+			if errParse != nil {
 
 				/*
 				 * Indicate failure.
@@ -2078,14 +2108,33 @@ func (this *controllerStruct) setMetronomeValueHandler(request webserver.HttpReq
 
 			} else {
 				value := uint32(rawValue)
-				metr.SetBeatsPerPeriod(value)
+				errSet := metr.SetBeatsPerPeriod(value)
 
 				/*
-				 * Indicate success.
+				 * Check if value could be set.
 				 */
-				webResponse = webResponseStruct{
-					Success: true,
-					Reason:  "",
+				if errSet != nil {
+					msg := errSet.Error()
+					reason := fmt.Sprintf("Failed to set metronome beats per period: %s", msg)
+
+					/*
+					 * Indicate failure.
+					 */
+					webResponse = webResponseStruct{
+						Success: false,
+						Reason:  reason,
+					}
+
+				} else {
+
+					/*
+					 * Indicate success.
+					 */
+					webResponse = webResponseStruct{
+						Success: true,
+						Reason:  "",
+					}
+
 				}
 
 			}
@@ -2120,12 +2169,12 @@ func (this *controllerStruct) setMetronomeValueHandler(request webserver.HttpReq
 			}
 
 		case "speed":
-			rawValue, err := strconv.ParseUint(value, 10, 32)
+			rawValue, errParse := strconv.ParseUint(value, 10, 32)
 
 			/*
 			 * Check if value failed to parse.
 			 */
-			if err != nil {
+			if errParse != nil {
 
 				/*
 				 * Indicate failure.
@@ -2137,7 +2186,34 @@ func (this *controllerStruct) setMetronomeValueHandler(request webserver.HttpReq
 
 			} else {
 				value := uint32(rawValue)
-				metr.SetSpeed(value)
+				errSet := metr.SetSpeed(value)
+
+				/*
+				 * Check if value could be set.
+				 */
+				if errSet != nil {
+					msg := errSet.Error()
+					reason := fmt.Sprintf("Failed to set metronome speed: %s", msg)
+
+					/*
+					 * Indicate failure.
+					 */
+					webResponse = webResponseStruct{
+						Success: false,
+						Reason:  reason,
+					}
+
+				} else {
+
+					/*
+					 * Indicate success.
+					 */
+					webResponse = webResponseStruct{
+						Success: true,
+						Reason:  "",
+					}
+
+				}
 
 				/*
 				 * Indicate success.
@@ -2819,7 +2895,7 @@ func (this *controllerStruct) processFiles(scanner *bufio.Scanner, targetRate ui
 			inputs[fileId] = make([]float64, 0)
 			sampleRates[fileId] = DEFAULT_SAMPLE_RATE
 		} else {
-			buf, err := ioutil.ReadFile(fileName)
+			buf, err := os.ReadFile(fileName)
 
 			/*
 			 * Check if file could be read.
@@ -3156,7 +3232,7 @@ func (this *controllerStruct) processFiles(scanner *bufio.Scanner, targetRate ui
  * Initialize the controller.
  */
 func (this *controllerStruct) initialize(nInputs uint32, useHardware bool) error {
-	content, err := ioutil.ReadFile(CONFIG_PATH)
+	content, err := os.ReadFile(CONFIG_PATH)
 
 	/*
 	 * Check if file could be read.
@@ -3442,7 +3518,7 @@ func CreateController() Controller {
  * Returns version information.
  */
 func Version() (string, error) {
-	content, err := ioutil.ReadFile(CONFIG_PATH)
+	content, err := os.ReadFile(CONFIG_PATH)
 
 	/*
 	 * Check if file could be read.

effects/poweramp.go

@@ -22,7 +22,7 @@ type poweramp struct {
 /*
  * Compile a new filter for this power amplifier.
  */
-func (this *poweramp) compile(sampleRate uint32, id uint64) (filter.Filter, error) {
+func (this *poweramp) compile(sampleRate uint32) (filter.Filter, error) {
 	irs := this.impulseResponses
 
 	/*
@@ -115,7 +115,8 @@ func (this *poweramp) compile(sampleRate uint32, id uint64) (filter.Filter, erro
 			 * Check for errors.
 			 */
 			if err != nil {
-				return nil, fmt.Errorf("Failed to add filter: %s", err.Error())
+				msg := err.Error()
+				return nil, fmt.Errorf("Failed to add filter: %s", msg)
 			}
 
 		}
@@ -137,9 +138,7 @@ func (this *poweramp) SetDiscreteValue(name string, value string) error {
 	 */
 	if err == nil {
 		sr := this.sampleRate
-		id := this.idCompiled + 1
-		this.idCompiled = id
-		flt, err := this.compile(sr, id)
+		flt, err := this.compile(sr)
 
 		/*
 		 * Check if filter was compiled.
@@ -166,9 +165,7 @@ func (this *poweramp) SetNumericValue(name string, value int32) error {
 	 */
 	if err == nil {
 		sr := this.sampleRate
-		id := this.idCompiled + 1
-		this.idCompiled = id
-		flt, err := this.compile(sr, id)
+		flt, err := this.compile(sr)
 
 		/*
 		 * Check if filter was compiled.
@@ -194,9 +191,7 @@ func (this *poweramp) Process(in []float64, out []float64, sampleRate uint32) {
 	if sampleRate != this.sampleRate {
 		this.sampleRate = sampleRate
 		sr := this.sampleRate
-		id := this.idCompiled + 1
-		this.idCompiled = id
-		flt, err := this.compile(sr, id)
+		flt, err := this.compile(sr)
 
 		/*
 		 * Check if filter was compiled.

filter/filter.go

@@ -6,9 +6,9 @@ import (
 	"github.com/andrepxx/go-dsp-guitar/fft"
 	"github.com/andrepxx/go-dsp-guitar/resample"
 	"github.com/andrepxx/go-dsp-guitar/wave"
-	"io/ioutil"
 	"math"
 	"math/cmplx"
+	"os"
 	"strconv"
 )
 
@@ -702,7 +702,7 @@ func (this *impulseResponsesStruct) Names() []string {
  * Imports a set of impulse responses using a descriptor file.
  */
 func Import(descriptorFilePath string) (ImpulseResponses, error) {
-	content, err := ioutil.ReadFile(descriptorFilePath)
+	content, err := os.ReadFile(descriptorFilePath)
 
 	/*
 	 * Check if file could be read.
@@ -732,7 +732,7 @@ func Import(descriptorFilePath string) (ImpulseResponses, error) {
 				dcFloat := float64(dc)
 				compensation := 0.05 * dcFloat
 				fac := math.Pow(10.0, compensation)
-				waveBuffer, err := ioutil.ReadFile(wavePath)
+				waveBuffer, err := os.ReadFile(wavePath)
 
 				/*
 				 * Check if file was read successfully.