Read Pixel

This is a discussion on Read Pixel within the C Programming forums, part of the General Programming Boards category; I'm an admittedly green programmer - but I am just playing with a program and I want to add the ...

  1. #1
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    Read Pixel

    I'm an admittedly green programmer - but I am just playing with a program and I want to add the capability for the program to be able to read the RGB color value of a pixel at a certain location of the screen, and put it in a variable I can work with.

    I know that will require some work with a Windows API/SDK - but any help or ideas you can provide would be great. I really have no idea how to go about this.

    Oh, and I only have experience in C, and minimal experience at that.

    Thanks.

  2. #2
    Guest Sebastiani's Avatar
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    not sure, but something like this should work:

    Code:
    COLORREF color = GetPixel( GetDC( HWND_DESKTOP ), x, y );
    Code:
    #include <cmath>
    #include <complex>
    bool flip(bool value)
    {
           return std::pow
        (
            std::complex<float>(std::exp(1.0)), 
            std::complex<float>(0, 1) * std::complex<float>(std::atan(1.0)*(1 << (value + 2)))
        ).real() < 0;
    }

  3. #3
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    Thanks - Another Error

    I tried that - and got this error:
    "undefinted reference to '_GetPixel@12'
    collect2: ld returned 1 exit status"

    Any thoughts? Thanks.

  4. #4
    and the Hat of Guessing tabstop's Avatar
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    And did you link with gdi32.lib?

  5. #5
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    gdi32

    I thought I did, but then again I'm not really sure I did it right. Like I said I have very minimal experience, and to be honest this is well over my head - but I know that if I can just get this to work I can handle the rest of the program.

  6. #6
    and the Hat of Guessing tabstop's Avatar
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    On the basis that "ld" makes me think of gcc, I'm guessing you're either using Code::Blocks or Dev-C++. Depending which you have determines how you add the flag, but you'll need to go somewhere in options and add it in.

  7. #7
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    Yup - Dev-C++

  8. #8
    and the Hat of Guessing tabstop's Avatar
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    Then under the assumption you're using a project, you should do Alt-P for project options, and then go to parameters, and where it says linker add "-lgdi32".

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