work with color — HTML color to RGB

To convert an HTML color code to RGB in Go, you can parse the hexadecimal string representation of the color and extract the red, green, and blue components. HTML color codes are usually in the format #RRGGBB or #RGB.

Example: Convert HTML Color Code to RGB

Let's create an example where we define a function to convert an HTML color code to RGB components.

Step 1: Define the Function to Convert HTML Color Code to RGB

Create a function that takes an HTML color code string as input and returns the RGB components.

package main

import (
    "fmt"
    "strconv"
    "strings"
)

// Function to convert an HTML color code to RGB components
func HTMLColorToRGB(color string) (uint8, uint8, uint8, error) {
    // Remove the leading '#' if it exists
    if strings.HasPrefix(color, "#") {
        color = strings.TrimPrefix(color, "#")
    }

    // Parse the color based on its length
    var r, g, b uint64
    var err error
    if len(color) == 6 {
        // #RRGGBB format
        r, err = strconv.ParseUint(color[0:2], 16, 8)
        if err != nil {
            return 0, 0, 0, err
        }
        g, err = strconv.ParseUint(color[2:4], 16, 8)
        if err != nil {
            return 0, 0, 0, err
        }
        b, err = strconv.ParseUint(color[4:6], 16, 8)
        if err != nil {
            return 0, 0, 0, err
        }
    } else if len(color) == 3 {
        // #RGB format
        r, err = strconv.ParseUint(strings.Repeat(string(color[0]), 2), 16, 8)
        if err != nil {
            return 0, 0, 0, err
        }
        g, err = strconv.ParseUint(strings.Repeat(string(color[1]), 2), 16, 8)
        if err != nil {
            return 0, 0, 0, err
        }
        b, err = strconv.ParseUint(strings.Repeat(string(color[2]), 2), 16, 8)
        if err != nil {
            return 0, 0, 0, err
        }
    } else {
        return 0, 0, 0, fmt.Errorf("invalid color format")
    }

    return uint8(r), uint8(g), uint8(b), nil
}

Step 2: Use the Function

Finally, use the function in the main function to convert an HTML color code to RGB components and print the result.

func main() {
    // Example HTML color codes
    htmlColor1 := "#FFA500" // Orange
    htmlColor2 := "#09C"    // Shortened HTML color code for #0099CC (Light Blue)

    // Convert HTML color codes to RGB
    r1, g1, b1, err1 := HTMLColorToRGB(htmlColor1)
    if err1 != nil {
        fmt.Println("Error:", err1)
    } else {
        fmt.Printf("HTML Color %s -> RGB(%d, %d, %d)\\\\n", htmlColor1, r1, g1, b1)
    }

    r2, g2, b2, err2 := HTMLColorToRGB(htmlColor2)
    if err2 != nil {
        fmt.Println("Error:", err2)
    } else {
        fmt.Printf("HTML Color %s -> RGB(%d, %d, %d)\\\\n", htmlColor2, r2, g2, b2)
    }
}

Explanation

1. Define the HTMLColorToRGB Function:
   • The function takes an HTML color code string as input and returns the RGB components as uint8 values.
   • The strings.HasPrefix function checks if the color string starts with # and removes it using strings.TrimPrefix.
   • The function then parses the color string based on its length:
     • For the #RRGGBB format, it extracts the red, green, and blue components using strconv.ParseUint.
     • For the #RGB format, it repeats each character to form the #RRGGBB format before parsing.
   • If the color format is invalid, the function returns an error.
2. Use the Function:
   • In main, example HTML color codes are provided, including one in the shortened #RGB format.
   • The HTMLColorToRGB function is called to convert each HTML color code to RGB components, and the results are printed.

Detailed Output

The output of the above code will be:

HTML Color #FFA500 -> RGB(255, 165, 0)
HTML Color #09C -> RGB(0, 153, 204)

Summary

In Go, you can convert HTML color codes to RGB components by parsing the hexadecimal string representation of the color. By defining a function that handles both the #RRGGBB and #RGB formats, you can convert HTML color codes to their corresponding RGB values efficiently. This approach is useful for working with colors in web development and other applications where HTML color codes are used.

work with color — Color to HTML color

In Go, you can work with colors and convert them to HTML color codes. The HTML color codes are typically represented as hexadecimal strings (e.g., #RRGGBB). To achieve this, you can define a struct to represent a color with red, green, and blue (RGB) components, and then create a method to convert the color to an HTML color code.