Convert hex string to color

Question

I am passing a hex value in my QueryString. I'd like to convert that to a color to use the ForeColor in a cell in a grid view. Tried both System.Drawing.ColorTranslator.FromHtml() and System.Drawing.Color.FromArgb() with no luck.

My QueryString is urlencoded so the part that matters looks like:

QueryString...&color=%23AA4643

Below is how I have tried .FromArg:

string sColor = Request.QueryString["color"]; // sColor is now #AA4643
Int32 iColorInt = Convert.ToInt32(sColor,16); //Get error message - Could not find any recognizable digits
Color curveColor = System.Drawing.Color.FromArgb(iColorInt); //Never makes it here

And here is how I have tried .FromHtml:

string sColor = Request.QueryString["color"]; 
System.Drawing.Color myColor = new System.Drawing.Color();
myColor = System.Drawing.ColorTranslator.FromHtml(sColor);

In this case myColor gets set to - myColor = "{Name=ffaa4643, ARGB=(255, 170, 70, 67)}"

But when I go to use it I get an error:

Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index

Any and all help greatly appreciated

SergeyS · Accepted Answer · 2013-02-20 20:08:06Z

8

Try this:

string sColor = Request.QueryString["color"]; // sColor is now #AA4643
Int32 iColorInt = Convert.ToInt32(sColor.Substring(1),16); 
Color curveColor = System.Drawing.Color.FromArgb(iColorInt);

edited Feb 20, 2013 at 20:08

answered Dec 6, 2012 at 16:31

SergeyS

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3 Comments

RichP Over a year ago

Thaks, that gets past the line it was erroring on and sets curveColor to: curveColor = "{Name=aa4643, ARGB=(0, 170, 70, 67)}" But when I go to use it in the grid I get same error as other attempt "Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index"

SergeyS Over a year ago

It means that sometimes you have Request.QueryString["color"] as empty. Please check it under debugger

RichP Over a year ago

SergeyS your solution does in fact work as does my other one. I was so focused on the color I was not looking at where I was setting it. I needed my line to set the color AFTER I called grid.DataBind. There was no Rows in my grid yet...Was so focused on the conversion of the color I overlooked the obvious Thanks! BTW this also works:System.Drawing.ColorConverter oConverter = new System.Drawing.ColorConverter(); Color myColor = (Color)oConverter.ConvertFromString(sColor);

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