qmk-rgb/cmd/qmk-rgb-tool/brightness.go

package main

import (
	"fmt"

	"github.com/spf13/cobra"
)

func NewBrightnessCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "brightness <val>",
		Short: "Set RGB brightness",
		Long: "Set the RGB brightness value (0-255) and read it back, so a value the\n" +
			"keyboard clamps or rescales is reported instead of silently applied.",
		Args: cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			val, err := ParseUint8(args[0])
			if err != nil {
				return err
			}

			zones, err := selectedZones()
			if err != nil {
				return err
			}

			proto, err := openRGBProtocol()
			if err != nil {
				return err
			}
			defer proto.Close()

			results, err := setBrightnessVerified(proto, zones, val)
			if err != nil {
				return fmt.Errorf("set brightness: %w", err)
			}

			// Claiming "set to N" when the keyboard holds something else is
			// the contradiction this read-back exists to prevent.
			if anyMismatch(results) {
				fmt.Fprintln(cmd.OutOrStdout(), formatResults("Brightness", results))
				return nil
			}

			fmt.Fprintf(cmd.OutOrStdout(), "Brightness set to %d\n", val)
			return nil
		},
	}
}