How to get the correct hDC to fill in the DRAWITEMSTRUCT?

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dotNeter - 12 Dec 2006 11:16 GMT

For some reason, I have to manually raise the WM_DRAMITEM when drew a
ListBox, but I got a problem that I couldn't get the correct hdc.
See definition of DRAWITEMSTRUCT. It has a field hDC, the description
is,

HDC hDC;
Handle to a device context; this device context must be used when
performing drawing operations on the control.

I assigned the ListBox control hdc to it, but I got the OutOfMemory
error.
Btw, I sent this msg when I caught WM_WINDOWPOSCHANGING, so I believe
it wouldn't generate the infinite loop.

The thing I didn't understand is which DC I should assign to the msg.
And it looks like there is no way to just get the DC of certain item.
But a WM_DRAWITEM corresponds to an item.

Who can tell me how to do it?
Thx in advance.

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Jeff Gaines - 12 Dec 2006 11:52 GMT

On 12/12/2006 in message

>For some reason, I have to manually raise the WM_DRAMITEM when drew a
>ListBox, but I got a problem that I couldn't get the correct hdc.
[quoted text clipped - 16 lines]
>Who can tell me how to do it?
>Thx in advance.

Is this an Owner Draw ListBox?

You can get the HDC:

Graphics gfx = lstBox.CreateGraphics();
IntPtr hdc = gfx.GetHdc();

You *must* dispose the hdc and the Graphics when you have finished:

gfx.ReleaseHdc(hdc);
gfx.Dispose();

If you give us a little more information about what you are drawing, with
the code, there may be a better way of doing it.

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Jeff Gaines
Damerham Hampshire UK

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How to get the correct hDC to fill in the DRAWITEMSTRUCT?

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