Lighten or darken a hex color

I'm attempting to convert this piece of Javascript to VB.net code, and I'm having some trouble getting it to work. All the JS does is some math/byte operations, so I don't think I'm going beyond the scope of either language. Here the original code, sourced from:

Pimp Trizkit's Colour Shading Code

function shadeColor2(color, percent) {   
var f=parseInt(color.slice(1),16),t=percent<0?0:255,p=percent<0?percent*-1:percent,R=f>>16,G=f>>8&0x00FF,B=f&0x0000FF;
return "#"+(0x1000000+(Math.round((t-R)*p)+R)*0x10000+(Math.round((t-G)*p)+G)*0x100+(Math.round((t-B)*p)+B)).toString(16).slice(1);}

And here's what I've attempted to convert it to:

Public Function LightColor(color As String, percent As Integer) As Color
    Dim f As Integer = Convert.ToInt32(color.Substring(1), 16)
    Dim t As Integer
    If percent < 0 Then
        t = 0
    Else
        t = 255
    End If
    Dim p As Integer
    If percent < 0 Then
        p = percent * -1
    Else
        p = percent
    End If
    Dim R As Integer = f >> 16
    Dim G As Integer = f >> 8 And &HFF
    Dim B As Integer = f And &HFF
    Dim finalColor As String = "#" + (Convert.ToString( _
                                      (&H1000000 + (Math.Round((t - R) * p) + R) * &H10000 + _
                                          (Math.Round((t - G) * p) + G) * &H100 + _
                                          (Math.Round((t - B) * p) + B))) _
                                  ).Substring(1)
    Me.txtID.Text = finalColor
    Return ColorTranslator.FromHtml(finalColor)

End Function

I would greatly appreciate some help regarding my amateur conversion and whether it could work, I've researched the relevant JS syntax but I'm not sure whether I changed it properly. After running my code with these parameters:

LightColor("#2980b9", 20)

I obtain a 8-digit hex color (#00642865) which is not even a color-I think I have some problems with the formatting of the hex output.

---

I'm not exactly sure why your code fails, but I do see some potential pitfalls. The most obvious is the percent parameter. This should be a double or a single as the accepted range is >= -1.0 and <= +1.0 .

I've created a simple .net fiddle, available here: https://dotnetfiddle.net/QhowPP

Public Shared Function LightColor(htmlColor As String, percent As Double) As Color

    If (String.IsNullOrEmpty(htmlColor)) Then
        Throw New ArgumentNullException("htmlColor")
    ElseIf ((percent < -1D) Or (percent > +1D)) Then
        Throw New ArgumentOutOfRangeException("percent")
    End If

    Dim c = ColorTranslator.FromHtml(htmlColor)
    Dim f = Int32.Parse(htmlColor.Substring(1), Globalization.NumberStyles.AllowHexSpecifier)
    Dim t = If((percent < 0), 0, 255)
    Dim p = If((percent < 0), (percent * -1), percent)

    Dim result = ("#" & CInt(
        &H1000000 + (Math.Round((t - c.R) * p) + c.R) *
        &H10000 + (Math.Round((t - c.G) * p) + c.G) *
        &H100 + (Math.Round((t - c.B) * p) + c.B)
    ).ToString("X").Substring(1))

    Return ColorTranslator.FromHtml(result)

End Function

C#:

public static Color LightColor(String htmlColor, Double percent)
{

    if (String.IsNullOrEmpty(htmlColor))
    {
        throw new ArgumentNullException("htmlColor");
    }
    else if ((percent < -1D) | (percent > +1D))
    {
        throw new ArgumentOutOfRangeException("percent");
    }

    var c = ColorTranslator.FromHtml(htmlColor);
    var f = Int32.Parse(htmlColor.Substring(1), System.Globalization.NumberStyles.AllowHexSpecifier);
    var t = ((percent < 0) ? 0 : 255); 
    var p = ((percent < 0) ? (percent * -1) : percent);

    var result = ("#" + ((Int32)(
        0x1000000 + (Math.Round((t - c.R) * p) + c.R) *
        0x10000 + (Math.Round((t - c.G) * p) + c.G) *
        0x100 + (Math.Round((t - c.B) * p) + c.B)
    )).ToString("X").Substring(1));

    return ColorTranslator.FromHtml(result);

}

链接地址: http://www.djcxy.com/p/87414.html

上一篇: 任何检测浏览器控制台是否能够呈现颜色的方法？

下一篇: 使六角形颜色变暗或变暗