I think this is an example of the kind of thing you want...
code:
//Show color picker common dialog
//Create our CHOOSECOLOR data block
var CHOOSECOLOR = Interop.Allocate(36);
CHOOSECOLOR.WriteDWORD(0, 36); //DWORD lStructSize
CHOOSECOLOR.WriteDWORD(4, 0); //HWND hwndOwner
CHOOSECOLOR.WriteDWORD(8, 0); //HWND hInstance
CHOOSECOLOR.WriteDWORD(12, 0x000000FF); //COLORREF rgbResult (COLORREF = 0x00bbggrr)
var CustColors = Interop.Allocate(64); //Create an array of 16 COLORREFs for CustColors
CHOOSECOLOR.WriteDWORD(16, CustColors.DataPtr); //COLORREF *lpCustColors (pointer to our array)
CHOOSECOLOR.WriteDWORD(20, 3); //DWORD Flags (3 = 2 (CC_FULLOPEN) + 1 (CC_RGBINIT) )
CHOOSECOLOR.WriteDWORD(24, 0); //LPARAM lCustData
CHOOSECOLOR.WriteDWORD(28, 0); //LPCCHOOKPROC lpfnHook
CHOOSECOLOR.WriteDWORD(32, 0); //LPCTSTR lpTemplateName
//Open the dialog box
var result = Interop.Call('comdlg32.dll', 'ChooseColorA', CHOOSECOLOR);
//If the user pressed ok convert it to hex
if(result == 1){
//Get decimal values
var r = CHOOSECOLOR.ReadDWORD(12) & 0xFF;
var g = (CHOOSECOLOR.ReadDWORD(12) / 0x100) & 0xFF;
var b = (CHOOSECOLOR.ReadDWORD(12) / 0x10000) & 0xFF;
Debug.Trace('RGB: ' + r + ',' + g + ',' + b)
//Get hex values
var hexchars="0123456789ABCDEF";
var r = hexchars.charAt((r >> 4) & 0xf) + hexchars.charAt(r & 0xF);
var g = hexchars.charAt((g >> 4) & 0xf) + hexchars.charAt(g & 0xF);
var b = hexchars.charAt((b >> 4) & 0xf) + hexchars.charAt(b & 0xF);
Debug.Trace('HEX: ' + r + g + b);
}
You need to use Interop.Allocate and ReadDWORD and so on
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