Clas Member problem

Hi,

Im Using Visual C++ Windows Forms in Visual studio 2008

I am trying to use ToCOLORREF (ToCOLORREF Method (ColorColor))

However, I keep getting error...
'ToCOLORREF' : is not a member of 'System:rawing::Color'

Code:

#include<gdiplus.h>
#include<Gdipluscolor.h>
#include<windows.h>

Code:

			 for(int i = 0; i < iImageW; i++)
				 {
					 for(int j = 0; j < iImageH; j++)
					 {
						 // Get the Pixel colour at i, j
						 Color c1 = Bmp1->GetPixel(i, j);

						 COLORREF crRGB = c1.ToCOLORREF();
...

Anyone know why this won't work or can help me overcome this problem?


thanks in adavnce

Any Ideas?

Is more info required of my problem?

It doesn't work because you're mixing functions from two different frameworks. ToCOLORREF is a GDI+ function, while this particular Color object is from .Net's System.Drawing. The two are roughly analogous, but nevertheless not interoperable. This is what you're working with so the ToArgb method would seem to be the equivalent.

wrong way

Originally Posted by adeyblue

It doesn't work because you're mixing functions from two different frameworks. ToCOLORREF is a GDI+ function, while this particular Color object is from .Net's System.Drawing. The two are roughly analogous, but nevertheless not interoperable. This is what you're working with so the ToArgb method would seem to be the equivalent.

Thanks for your reply!

The reason I want to convert to COLORREF is to be able to convert from RGB to HLS using:
ColorRGBToHLS() ColorRGBToHLS Function ()

How else can I go about this?

Thanks again

One possible solution...

Code:

#include<windows.h>
#include<gdiplus.h>
#include <Shlwapi.h>
#include <stdio.h>

#pragma comment (lib, "Gdiplus.lib")  
#pragma comment (lib, "Shlwapi.lib")  

using namespace Gdiplus;

void Demo(void)
{
    GdiplusStartupInput gdiplusStartupInput;
    ULONG_PTR gdiplusToken;
    Color c1;
    WORD Hue = 0;
    WORD Luminance = 0;
    WORD Saturation = 100;  

    GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);
    Bitmap Bmp1(L"Test.bmp");
    int iImageW = Bmp1.GetWidth();
    int iImageH = Bmp1.GetHeight();
    printf("width %d height %d\n", iImageW, iImageW);

    for(int i = 0; i < iImageW; i++)
    {
        for(int j = 0; j < iImageH; j++)
        {
            Bmp1.GetPixel(i, j, &c1);
            COLORREF crRGB = c1.ToCOLORREF();
            ColorRGBToHLS(crRGB, &Hue, &Luminance, &Saturation);
        }
    }
}

int main(void)
{
    Demo();
    return 0;
}

Hey, thanks for the suggestion!!!

Is it necessary for me to go to this lengths just to convert the RGB to HLS?

All I want to do is set the saturation to zero for a smooth gryscale gradient

Any Ideas????

Is it necessary for me to go to this lengths just to convert the RGB to HLS?
All I want to do is set the saturation to zero for a smooth gryscale gradient

Yep, this is necessary if you want to convert to HLS, change to grayscale and then possible convert back to RGB.

The steps necessary to convert to grayscale are as follows:

1. Get each pixel in the RGB image
2. Convert RGB to HLS and get the saturation
3. Set the saturation to 1 and convert back to RGB
4. Set the new image pixel.

The above entails adding four more statements to the demo code posted. IMHO, that isn't going to great lengths to accomplish your goal.

Originally Posted by BobS0327

GdiplusStartupInput gdiplusStartupInput;
ULONG_PTR gdiplusToken;





GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);
}[/CODE]

What are these statements doing?

Originally Posted by paulogrady

What are these statements doing?

The MSDN docs best describe what these statements are doing. Essentially, it initializes Microsoft Windows GDI+ and is required.

Originally Posted by paulogrady

Is it necessary for me to go to this lengths

It's necessary at some point because that's just how the API works, however you don't have to chuck your existing code and drop to native Gdi+. As the Argb value returned from ToArgb() is essentially just a backwards COLORREF, some bit twiddling is all that's required to be able to use the functions taking one.

Code:

// inside the for loops
Color c1 = Bmp1->GetPixel(i, j);
DWORD colorAsArgb = c1.ToArgb();
// colorAsArgb stored as 0xAARRGGBB
// instead of 0x00BBGGRR as a normal COLORREF
// so we shift and mask the appropriate bits to convert
COLORREF colorAsColorRef = RGB(LOBYTE(HIWORD(colorAsArgb)), HIBYTE(LOWORD(colorAsArgb)), LOBYTE(LOWORD(colorAsArgb)));
WORD hue, luminence, saturation;
ColorRGBToHLS(colorAsColorRef, &hue, &luminence, &saturation);
// manipulate the hls values
// however you want to
colorAsColorRef = ColorHLSToRGB(hue, luminence, saturation);
c1 = c1.FromArgb(GetRValue(colorAsColorRef), GetGValue(colorAsColorRef), GetBValue(colorAsColorRef));
Bmp1->SetPixel(i, j, c1);

Code:

#using <mscorlib.dll>
#using <System.dll>
#using <System.Drawing.dll>

using namespace System;

int main(void)
{
    System::Drawing::Bitmap Bmp("Test.bmp");
    for(int iIndexY = 0; iIndexY <Bmp.Height; iIndexY++)
    {
        for(int iIndexX = 0; iIndexX < Bmp.Width; iIndexX++)
        {
            System::Drawing::Color c = Bmp.GetPixel(iIndexX,iIndexY);
            int iGreyScale = (int)(c.R*0.3 + c.G*0.59+ c.B*0.11);
            Bmp.SetPixel(iIndexX,iIndexY,System::Drawing::Color::FromArgb(iGreyScale,iGreyScale,iGreyScale));
        }
    }
    Bmp.Save("NewTest.bmp");
return 0;
}