GDI : Get LOGPEN from HGDIOBJ or HPEN

Question

I would like to get LOGPEN structure for currently using HGDIOBJ(which is actually HPEN). Lets assume we have something like this:

CPen ColoredPen;
ColoredPen.Create(...);
...
HGDIOBJ PriorPen = SelectObject(PaintingDC, ColoredPen);

Now I need to get LOGPEN structure from PriorPen. I tried in 2 ways:

1. LOGPEN LogPen;
CPen* pPen = CPen::FromHandle((HPEN)PriorPen);
pPen->GetLogPen(&LogPen);

2. LOGPEN LogPen;
GetObject(PriorPen, sizeof(LogPen), &LogPen);

None of these give me a correct LOGPEN structure object because all fields are 0. I also tried to get LOGPEN for actual CPen and it works perfectly:

ColoredPen.GetLogPen(&LogPen);

but I need to work only with HPEN. So my question is how can I get LOGPEN from HPEN?

Andrew Komiagin · Accepted Answer · 2015-04-08T19:38:42.083

2

You can do the following:

LOGPEN LogPen;     
CPen* pTempPen = CPen::FromHandle(hPen);
pTempPen->GetLogPen(&LogPen);

Please note that this temporary CPen object is valid only until the next time the application has idle time in its event loop, at which time all temporary graphic objects are deleted. In other words, the temporary object is only valid during the processing of one window message.

edited Apr 08 '15 at 19:38

answered Apr 08 '15 at 19:36

Andrew Komiagin

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In my question I said that I tried to do this and it gives me an empty LOGPEN with all fields equal 0. – IKM2007 Apr 08 '15 at 19:38
It means that this GDI object is no longer valid. There is no other way around. See my comments on that in the answer. – Andrew Komiagin Apr 08 '15 at 19:39
It is strange because I tried this immediately after HGDIOBJ PriorPen = SelectObject(PaintingDC, ColoredPen); and PriorPen is not NULL, why it should be invalid? – IKM2007 Apr 08 '15 at 19:41
This GDI object is only valid during the processing of one WM_PAINT message by design. – Andrew Komiagin Apr 08 '15 at 19:43
So there is no way to get LOGPEN? Thanks for your help anyway. – IKM2007 Apr 08 '15 at 19:46
Do you need to get the default pen settings or what? – Andrew Komiagin Apr 08 '15 at 19:50
No, in some drawing function there is a switch where for different cases I do priorPen = SetObject(PaintingDC, PenColor1) e.t.c. and I want to avoid doing PenColor1.GetLogPen(&LogPen) and then for the next case PenColor2.GetLogPen(&LogPen); but seems the only way is it. – IKM2007 Apr 08 '15 at 19:58
That's the only way of doing things in GDI – Andrew Komiagin Apr 08 '15 at 19:59

GDI : Get LOGPEN from HGDIOBJ or HPEN

1 Answers1