/
color.go
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/
color.go
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// Copyright 2016 Google Inc. All rights reserved.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to writing, software distributed
// under the License is distributed on a "AS IS" BASIS, WITHOUT WARRANTIES OR
// CONDITIONS OF ANY KIND, either express or implied.
//
// See the License for the specific language governing permissions and
// limitations under the License.
package flags
import (
"flag"
"fmt"
"image/color"
"strconv"
)
type hexColor struct {
color.Color
}
func (c *hexColor) String() string {
r, g, b, a := c.Color.RGBA()
return fmt.Sprintf("rgba(%d, %d, %d, %d)", r, g, b, a)
}
func (c *hexColor) Set(s string) error {
if len(s) != 6 {
return fmt.Errorf("color should be 6 digits")
}
n, err := strconv.ParseInt(s, 16, 64)
if err != nil {
return fmt.Errorf("not hexadecimal: %v", err)
}
rgba := &color.RGBA{}
rgba.B, n = uint8(n%256), n/256
rgba.G, n = uint8(n%256), n/256
rgba.R = uint8(n % 256)
rgba.A = 255
c.Color = rgba
return nil
}
// HexColor defines a hex color flag with specified name, default value, and usage string.
// The return value is the address of an RGBA color variable that stores the value of the flag.
func HexColor(name string, value color.Color, usage string) color.Color {
c := &hexColor{value}
flag.Var(c, name, usage)
return c
}
// HexColorVar defines a hex color flag with specified name, default value, and usage string.
// The argument c points to an RGBA color variable in which to store the value of the flag.
func HexColorVar(c *color.Color, name string, value color.Color, usage string) {
p := &hexColor{value}
*c = p
flag.Var(p, name, usage)
}