GDI + problem

This is a discussion on GDI + problem within the Windows Programming forums, part of the Platform Specific Boards category; I m now using .NET And I have a little problem in understanding Graphics class... Question raised in my mind ...

  1. #1
    Registered User cfrost's Avatar
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    Post GDI + problem

    I m now using .NET
    And I have a little problem in understanding Graphics class...
    Question raised in my mind is that:

    Is it a helper class for drawing or is it like CDC having objects assosiated with it...

    What is effect of writing:

    Graphics grph(dc);

    Are we getting object from dc or just using it...
    If we are using dc then how can i save some thing drawn on CBitmap that is used by that dc ...
    I am well Fimiliar with Image and Bitmap class and I also know how to save images using them
    Last edited by cfrost; 08-24-2004 at 04:45 AM.

  2. #2
    Registered User cfrost's Avatar
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    Looks like know one expert here

  3. #3
    the hat of redundancy hat nvoigt's Avatar
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    The Graphics class encapsulates a device context. It is an object like any other reference type in .NET.

    Are we getting object from dc or just using it...
    I have never seen a Graphics object created by a contructor. You can call the static FromHdc and FromHwnd methods to get a new Graphics object though. You then get a System.Drawing.Graphics instance that encapsulates this device context.

    You can manipulate Images by calling Gaphics::FromImage first to get a Graphics object for this Image. After manipulating the Image by using methods of this Graphics object, you can save the image by calling the Save method on your Image.

    Questions concerning .NET might be answered faster if you put them into the C# Board
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  4. #4
    Registered User cfrost's Avatar
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    Bit bliting CBitmap on to Image Object

    How can i BitBlit a CBitmap Object into a Image Object .....
    I want to save CBitmap via Image

  5. #5
    Yes, my avatar is stolen anonytmouse's Avatar
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    The MFC CBitmap class has a cast operator to retrieve an HBITMAP.

    The GDI+ Bitmap class, which inherits from the Image class, has a constructor that accepts an HBITMAP.

    Put these two bits of information together and you have a conversion from an MFC CBitmap to a GDI+ Image.

  6. #6
    Registered User cfrost's Avatar
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    it also requires HPLATTE how can i get platte??

  7. #7
    Yes, my avatar is stolen anonytmouse's Avatar
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    Try using NULL.

  8. #8
    Registered User cfrost's Avatar
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    Thanx anonytmouse but what is logic of passing NULL (sorry for question again)
    Software is like sex it is good when it is free

  9. #9
    Yes, my avatar is stolen anonytmouse's Avatar
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    NULL passed to a function call typically signifies an empty argument or tells the function to use the default. In this case, you don't have an HPALETTE so you can try passing NULL. I suspect it will work but you could confirm if it works or not after trying it.

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