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Alawna
Guest
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 Posted: Thu Mar 24, 2005 5:21 pm Post subject: How to get GetPixel return values in a memo |
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Hi here is my code
PROCEDURE TForm1.Button2Click(Sender: TObject);
VAR
hdc1: integer;
khara:Tcolor;
BEGIN
hdc1 := GetDC(RichHwnd);
khara:=getpixel(hdc1,500,250);
memo1.Lines.Append(inttostr(khara));
END;
the handle is tested with other functions and is ok.
The value in the memo is -1 whatever the x and y are. It just does not
change.
I know inttostr(khara) is not true. But now looking for a way to get the
RGB returned by the getpixel into the memo
thanks
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Peter Below (TeamB)
Guest
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| Posted: Fri Mar 25, 2005 10:16 am Post subject: Re: How to get GetPixel return values in a memo |
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In article <4242f719 (AT) newsgroups (DOT) borland.com>, Alawna wrote:
| Quote: | PROCEDURE TForm1.Button2Click(Sender: TObject);
VAR
hdc1: integer;
khara:Tcolor;
BEGIN
hdc1 := GetDC(RichHwnd);
khara:=getpixel(hdc1,500,250);
memo1.Lines.Append(inttostr(khara));
END;
the handle is tested with other functions and is ok.
The value in the memo is -1 whatever the x and y are. It just does not
change.
|
GetPixel is documented to return -1 (CLR_INVALID) when the passed
coordinates are outside the current clipping region of the device context.
Which also means, by the way, that the part of the control you try to get
the color from has to be visible on screen. Is that the case for you? If
yes you can try to use GetDC(0) to obtain a hDC for the screen itself,
convert your coordinates to screen coordinates using the controls
ClientToScreen method, and apply GetPixel to the screen DC.
Your code contains a severe error, by the way: every DC you get via GetDC
*must* be returned to the system via ReleaseDC when you no longer need it.
--
Peter Below (TeamB)
Use the newsgroup archives :
http://www.mers.com/searchsite.html
http://www.tamaracka.com/search.htm
http://groups.google.com
http://www.prolix.be
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