Re: Graphics.GetHdc causes InvalidOperationException

From: Nicole Calinoiu (calinoiu)
Date: 06/29/05

  • Next message: Rob R. Ainscough: "SSL certificates -- how are they validated?" 
    Date: Wed, 29 Jun 2005 13:45:27 -0400

    "Richard Morris" <khiron@community.nospam> wrote in message
    news:esWHh18eFHA.688@TK2MSFTNGP14.phx.gbl...
    > Hi Nicole,
    >
    > Thanks for answering. The problem is that assigning Full Trust to
    > assemblies with MS strongkey is not enough. Is it possible that some
    > assemblies which come from MS aren't signed with their key?

    The strong names of Microsoft assemblies are irrelevent here. The problem
    is that your control assembly does not have SecurityPermission\UnmanagedCode
    on the client machine.

    > protected override void OnPaint(PaintEventArgs e) {
    > // serurity exception
    > IntPtr hdc = e.Graphics.GetHdc();
    > e.Graphics.ReleaseHdc(hdc);

    Since you're not actually using the GDI device context, I'm wondering why
    you're bothering with this. If it's just an incomplete sample, and you
    actually need to use unmanaged GDI functions, then you'll need to set up the
    client to grant SecurityPermission\UnmanagedCode to your assembly (which it
    will also need for the actual GDI calls). Otherwise, you should be able to
    get the method to work by dropping the above two lines.

    > Would you like to take a closer look at this scenario? I could send you a
    > sample project and screenshots showing the problem.

    Not necessary. I was able to repro based on your sample code.

  • Next message: Rob R. Ainscough: "SSL certificates -- how are they validated?"

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