Implement axis targets, axis -> button and axis -> relative axis mappings. (#1)

Co-authored-by: Anna Rose Wiggins <annabunches@gmail.com>
Co-committed-by: Anna Rose Wiggins <annabunches@gmail.com>

internal/mappingrules/mapping_rule_axis_to_relaxis.go

@@ -0,0 +1,99 @@
+package mappingrules
+
+import (
+	"time"
+
+	"git.annabunches.net/annabunches/joyful/internal/logger"
+	"github.com/holoplot/go-evdev"
+	"github.com/jonboulle/clockwork"
+)
+
+// TODO: add tests
+
+// MappingRuleAxisToRelaxis represents a rule that converts an axis input into a (potentially repeating)
+// relative axis output. This is most commonly used to generate mouse output events
+type MappingRuleAxisToRelaxis struct {
+	MappingRuleBase
+	Input         *RuleTargetAxis
+	Output        *RuleTargetRelaxis
+	RepeatRateMin int
+	RepeatRateMax int
+	Increment     int32
+	nextEvent     time.Duration
+	lastEvent     time.Time
+	clock         clockwork.Clock
+}
+
+func NewMappingRuleAxisToRelaxis(
+	base MappingRuleBase,
+	input *RuleTargetAxis,
+	output *RuleTargetRelaxis,
+	repeatRateMin, repeatRateMax, increment int) *MappingRuleAxisToRelaxis {
+
+	return &MappingRuleAxisToRelaxis{
+		MappingRuleBase: base,
+		Input:           input,
+		Output:          output,
+		RepeatRateMin:   repeatRateMin,
+		RepeatRateMax:   repeatRateMax,
+		Increment:       int32(increment),
+		lastEvent:       time.Now(),
+		nextEvent:       NoNextEvent,
+		clock:           clockwork.NewRealClock(),
+	}
+}
+
+func (rule *MappingRuleAxisToRelaxis) MatchEvent(
+	device RuleTargetDevice,
+	event *evdev.InputEvent,
+	mode *string) (*evdev.InputDevice, *evdev.InputEvent) {
+
+	if !rule.MappingRuleBase.modeCheck(mode) ||
+		!rule.Input.MatchEventDeviceAndCode(device, event) {
+		return nil, nil
+	}
+
+	defer func() {
+		logger.Logf("DEBUG: Rule '%s' nextEvent == '%v' with device value '%d'", rule.Name, rule.nextEvent, event.Value)
+	}()
+
+	// If we're inside the deadzone, unset the next event
+	if rule.Input.InDeadZone(event.Value) {
+		rule.nextEvent = NoNextEvent
+		return nil, nil
+	}
+
+	// If we aren't repeating, we trigger the event immediately
+	// TODO: this still needs the pressed parameter...
+	if rule.RepeatRateMin == 0 || rule.RepeatRateMax == 0 {
+		rule.nextEvent = time.Millisecond
+		return nil, nil
+	}
+
+	// use the axis value and the repeat rate to set a target time until the next event
+	strength := 1.0 - rule.Input.GetAxisStrength(event.Value)
+	rate := int64(LerpInt(rule.RepeatRateMax, rule.RepeatRateMin, strength))
+	rule.nextEvent = time.Duration(rate * int64(time.Millisecond))
+	return nil, nil
+}
+
+// TimerEvent returns an event when enough time has passed (compared to the last recorded axis value)
+// to emit an event.
+func (rule *MappingRuleAxisToRelaxis) TimerEvent() *evdev.InputEvent {
+	// This indicates that we should not emit another event
+	if rule.nextEvent == NoNextEvent {
+		rule.lastEvent = rule.clock.Now()
+		return nil
+	}
+
+	if rule.clock.Now().Compare(rule.lastEvent.Add(rule.nextEvent)) > -1 {
+		rule.lastEvent = rule.clock.Now()
+		return rule.Output.CreateEvent(rule.Increment, nil)
+	}
+
+	return nil
+}
+
+func (rule *MappingRuleAxisToRelaxis) GetOutputDevice() *evdev.InputDevice {
+	return rule.Output.Device.(*evdev.InputDevice)
+}