joyful/internal/mappingrules/rule_target_axis.go

package mappingrules

import (
	"errors"
	"fmt"

	"git.annabunches.net/annabunches/joyful/internal/configparser"
	"git.annabunches.net/annabunches/joyful/internal/eventcodes"
	"github.com/holoplot/go-evdev"
)

type RuleTargetAxis struct {
	DeviceName    string
	Device        Device
	Axis          evdev.EvCode
	Inverted      bool
	DeadzoneStart int32
	DeadzoneEnd   int32
	OutputMin     int32
	OutputMax     int32
	axisSize      int32
	deadzoneSize  int32
}

func NewRuleTargetAxisFromConfig(targetConfig configparser.RuleTargetConfigAxis, devs map[string]Device) (*RuleTargetAxis, error) {
	device, ok := devs[targetConfig.Device]
	if !ok {
		return nil, fmt.Errorf("non-existent device '%s'", targetConfig.Device)
	}

	if targetConfig.DeadzoneEnd < targetConfig.DeadzoneStart {
		return nil, errors.New("deadzone_end must be greater than deadzone_start")
	}

	eventCode, err := eventcodes.ParseCode(targetConfig.Axis, eventcodes.CodePrefixAxis)
	if err != nil {
		return nil, err
	}

	deadzoneStart, deadzoneEnd, err := calculateDeadzones(targetConfig, device, eventCode)
	if err != nil {
		return nil, err
	}

	return NewRuleTargetAxis(
		targetConfig.Device,
		device,
		eventCode,
		targetConfig.Inverted,
		deadzoneStart,
		deadzoneEnd,
	)
}

// calculateDeadzones produces the deadzone start and end values in absolute terms
func calculateDeadzones(targetConfig configparser.RuleTargetConfigAxis, device Device, axis evdev.EvCode) (int32, int32, error) {

	var deadzoneStart, deadzoneEnd int32
	deadzoneStart = 0
	deadzoneEnd = 0

	if targetConfig.DeadzoneStart != 0 || targetConfig.DeadzoneEnd != 0 {
		return targetConfig.DeadzoneStart, targetConfig.DeadzoneEnd, nil
	}

	var min, max int32
	absInfoMap, err := device.AbsInfos()

	if err != nil {
		min = AxisValueMin
		max = AxisValueMax
	} else {
		absInfo := absInfoMap[axis]
		min = absInfo.Minimum
		max = absInfo.Maximum
	}

	if targetConfig.DeadzoneCenter < min || targetConfig.DeadzoneCenter > max {
		return 0, 0, fmt.Errorf("deadzone_center '%d' is out of bounds", targetConfig.DeadzoneCenter)
	}

	switch {
	case targetConfig.DeadzoneSize != 0:
		deadzoneStart = targetConfig.DeadzoneCenter - targetConfig.DeadzoneSize/2
		deadzoneEnd = targetConfig.DeadzoneCenter + targetConfig.DeadzoneSize/2
	case targetConfig.DeadzoneSizePercent != 0:
		deadzoneSize := (max - min) / targetConfig.DeadzoneSizePercent
		deadzoneStart = targetConfig.DeadzoneCenter - deadzoneSize/2
		deadzoneEnd = targetConfig.DeadzoneCenter + deadzoneSize/2
	}

	deadzoneStart, deadzoneEnd = clampAndShift(deadzoneStart, deadzoneEnd, min, max)
	return deadzoneStart, deadzoneEnd, nil
}

func NewRuleTargetAxis(device_name string,
	device Device,
	axis evdev.EvCode,
	inverted bool,
	deadzoneStart int32,
	deadzoneEnd int32) (*RuleTargetAxis, error) {

	info, err := device.AbsInfos()

	if err != nil {
		// If we can't get AbsInfo (for example, we're a virtual device)
		// we set the bounds to the maximum allowable
		info = map[evdev.EvCode]evdev.AbsInfo{
			axis: {
				Minimum: AxisValueMin,
				Maximum: AxisValueMax,
			},
		}
	}

	if _, ok := info[axis]; !ok {
		return nil, fmt.Errorf("device does not support axis %v", axis)
	}

	if deadzoneStart > deadzoneEnd {
		return nil, errors.New("deadzone_end must be a higher value than deadzone_start")
	}

	deadzoneSize := Abs(deadzoneEnd - deadzoneStart)

	// Our output range is limited to 16 bits, but we represent values internally with 32 bits.
	// As a result, we shouldn't need to worry about integer overruns
	axisSize := info[axis].Maximum - info[axis].Minimum - deadzoneSize

	if axisSize == 0 {
		return nil, errors.New("axis has size 0")
	}

	return &RuleTargetAxis{
		DeviceName:    device_name,
		Device:        device,
		Axis:          axis,
		Inverted:      inverted,
		OutputMin:     AxisValueMin,
		OutputMax:     AxisValueMax,
		DeadzoneStart: deadzoneStart,
		DeadzoneEnd:   deadzoneEnd,
		deadzoneSize:  deadzoneSize,
		axisSize:      axisSize,
	}, nil
}

// NormalizeValue takes a raw input value and converts it to a value suitable for output.
//
// Axis inputs are normalized to the full signed int32 range to match the virtual device's axis
// characteristics.
//
// Typically this function is called after RuleTargetAxis.MatchEvent, which checks whether we are
// in the deadzone, among other things.
func (target *RuleTargetAxis) NormalizeValue(value int32) int32 {
	axisStrength := target.GetAxisStrength(value)
	return LerpInt(target.OutputMin, target.OutputMax, axisStrength)
}

func (target *RuleTargetAxis) CreateEvent(value int32, mode *string) *evdev.InputEvent {
	value = Clamp(value, AxisValueMin, AxisValueMax)
	return &evdev.InputEvent{
		Type:  evdev.EV_ABS,
		Code:  target.Axis,
		Value: value,
	}
}

func (target *RuleTargetAxis) MatchEvent(device Device, event *evdev.InputEvent) bool {
	return target.MatchEventDeviceAndCode(device, event) &&
		!target.InDeadZone(event.Value)
}

// TODO: Add tests
func (target *RuleTargetAxis) MatchEventDeviceAndCode(device Device, event *evdev.InputEvent) bool {
	return device == target.Device &&
		event.Type == evdev.EV_ABS &&
		event.Code == target.Axis
}

// TODO: Add tests
func (target *RuleTargetAxis) InDeadZone(value int32) bool {
	return target.deadzoneSize > 0 && value >= target.DeadzoneStart && value <= target.DeadzoneEnd
}

// GetAxisStrength returns a float between 0.0 and 1.0, representing the proportional
// position along the axis' full range. (after factoring in deadzones)
// Calling this function with `value` inside the deadzone range will produce undefined behavior
func (target *RuleTargetAxis) GetAxisStrength(value int32) float64 {
	if value > target.DeadzoneEnd {
		value -= target.deadzoneSize
	}
	strength := float64(value) / float64(target.axisSize)
	if target.Inverted {
		strength = 1.0 - strength
	}
	return strength
}