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Eric Carlson
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 Posted: Sun Aug 21, 2005 7:39 am Post subject: TCanvas.StretchDraw GDI leak |
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Image1, Image2: TBitmap;
Image2.LoadFromFile('C:windowsgreenstone.bmp');
Image2 is valid, the file load is for example, Image1 has only had this done
to it
Image1.Width := 100;
Image1.Height := 100;
Image1.Canvas.StretchDraw(Image1.Canvas.ClipRect, Image2);
Image1 and Image2 are in a custom class and are created in its contstructor.
Its destructor is
Image1.FreeImage;
freeAndNil(Image1);
Image2.FreeImage;
freeAndNil(Image2);
The custom class is created each time. In a timer loop of 200ms I'm getting
2 GDI leaks every 30 secs or so. When I slow the loop to 1 sec its every few
minutes. What have I missed please?
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Mat Ballard
Guest
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| Posted: Sun Aug 21, 2005 11:20 pm Post subject: Re: TCanvas.StretchDraw GDI leak |
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Eric Carlson wrote:
| Quote: | Image1, Image2: TBitmap;
Image2.LoadFromFile('C:windowsgreenstone.bmp');
Image2 is valid, the file load is for example, Image1 has only had this done
to it
Image1.Width := 100;
Image1.Height := 100;
Image1.Canvas.StretchDraw(Image1.Canvas.ClipRect, Image2);
Image1 and Image2 are in a custom class and are created in its contstructor.
Its destructor is
Image1.FreeImage;
freeAndNil(Image1);
Image2.FreeImage;
freeAndNil(Image2);
The custom class is created each time. In a timer loop of 200ms I'm getting
2 GDI leaks every 30 secs or so. When I slow the loop to 1 sec its every few
minutes. What have I missed please?
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i've run into a few oddities myself with graphics operations not being carried
out. after going mildly nuts i found out about the Windows.GdiFlush function -
check it out in the Win32 SDK. the bad news was that adding calls to GdiFlush
did not help.
what did help in the end was code like:
j := Image1.Picture.Bitmap.Handle; // look at what GetHandle does
inc(j); // so the compiler does not remove the above line
not sure if it will help, but the GDI does some weird things.
cheers,
Mat
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Eric Carlson
Guest
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| Posted: Tue Aug 23, 2005 10:25 am Post subject: Re: TCanvas.StretchDraw GDI leak |
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| Quote: | what did help in the end was code like:
j := Image1.Picture.Bitmap.Handle; // look at what GetHandle does
inc(j); // so the compiler does not remove the above
line
not sure if it will help, but the GDI does some weird things.
Hey thanks! Was that before or after the stretchDraw? |
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Mat Ballard
Guest
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| Posted: Tue Aug 23, 2005 11:26 pm Post subject: Re: TCanvas.StretchDraw GDI leak |
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g'day Eric,
re:
| Quote: | what did help in the end was code like:
j := Image1.Picture.Bitmap.Handle; // look at what GetHandle does
inc(j); // so the compiler does not remove the above
line
not sure if it will help, but the GDI does some weird things.
Hey thanks! Was that before or after the stretchDraw?
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it occurred randomly after intensive graphics operations - sometimes Draw or
StretchDraw, sometimes pixel manipulation through ScanLine, sometimes simple
Assigning.
it was as though the GDI engine ran out of of puff and just skipped a few
operations.
cheers,
Mat
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