I need help - I can help - Memory leak drawing RichTextBox to Canvas

Memory leak drawing RichTextBox to Canvas - SOLVED

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Category: For Users of the Library
Forum Name: I need help - I can help
Forum Description: Problems and solutions while programming with the Debenu Quick PDF Library and Debenu PDF Viewer SDK
URL: http://www.quickpdf.org/forum/forum_posts.asp?TID=3918
Printed Date: 30 Apr 24 at 12:52AM
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Topic: Memory leak drawing RichTextBox to Canvas - SOLVED

Posted By: Sopracenery
Subject: Memory leak drawing RichTextBox to Canvas - SOLVED
Date Posted: 21 May 21 at 9:44PM

Hi all,

I have a memory leak using 18.11 when drawing content of a RichTextBox via Canvas to a new PDF doc.

No problem with the first 15 pages. But reaching 20 or more pages the library on windows needs more and more time for each page and above 25-30 pages the system fails with Out Of Memory.

Here are the commands I am using:

fr.hdc = GetCanvasDC // get a canvas device context from the library and set it into the format range structure fr

SendMessage(RTF.hWnd, EM_FORMATRANGE, True, fr) // Send text from a RichTextBox RTF to DC in fr

LoadFromCanvasDC 1.422 1

fr.hdc = GetCanvasDC

SendMessage(RTF.hWnd, EM_FORMATRANGE, True, fr)

NewPageFromCanvasDC 0.203 2

fr.hdc = GetCanvasDC

SendMessage(RTF.hWnd, EM_FORMATRANGE, True, fr)

...

Repeat every page: (GetCanvasDC + SendMessage between every line not listed here)

Method Time in seconds Page

============================================

NewPageFromCanvasDC 0.031 3

NewPageFromCanvasDC 0.031 4

NewPageFromCanvasDC 0.023 5

NewPageFromCanvasDC 0.031 6

NewPageFromCanvasDC 0.031 7

NewPageFromCanvasDC 0.039 8

NewPageFromCanvasDC 0.070 9

NewPageFromCanvasDC 0.094 10

NewPageFromCanvasDC 0.172 11

NewPageFromCanvasDC 0.305 12

NewPageFromCanvasDC 0.633 13

NewPageFromCanvasDC 1.102 14

NewPageFromCanvasDC 2.391 15

NewPageFromCanvasDC 4.344 16

NewPageFromCanvasDC 9.547 17

NewPageFromCanvasDC 17.383 18

NewPageFromCanvasDC 38.266 19

NewPageFromCanvasDC 69.586 20

Can anybody help?

Martin

Some more hints:

I guess that each GetCanvasDC allocates memory and does not release it after NewPageFromCanvasDC.

Calling CoTaskMemFree in ole32 with the pointer of fr.hdc has no effect.

Only RemoveDocument or MergeDocument has effect in releasing memory.

Replies:

Posted By: mLipok
Date Posted: 26 May 21 at 7:45AM

Question.
Do this works well when you try it with single page ?
I mean do you have properly created PDF ?

-------------
Here you can find description how to test my examples:
http://www.quickpdf.org/forum/forum_posts.asp?TID=2932&PID=12600&title=drawcapturedpagematrix-matrix-howto#12600

Posted By: Sopracenery
Date Posted: 26 May 21 at 11:16PM

Hi Michał,

Sorry, I do not understand what you mean with „single page“. If I produce only one page then everything is fine. I can close the PDF and it is OK. My program is doing this now for months on thousands of documents. Normally producing 1-5 pages. But now that some documents need more than 20 pages I get this new error.

Martin

Posted By: mLipok
Date Posted: 27 May 21 at 8:01AM

you said: "No problem with the first 15 pages"

What if your source document have only 1 page ?

-------------
Here you can find description how to test my examples:
http://www.quickpdf.org/forum/forum_posts.asp?TID=2932&PID=12600&title=drawcapturedpagematrix-matrix-howto#12600

Posted By: Sopracenery
Date Posted: 27 May 21 at 9:13AM

If the source document in the RichTextBox has only one page then the output in PDF is only one page and anything is ok.

If I repeat sending this one page 20 times to to same PDF to generate more payload I get the same memory leak.

Posted By: Sopracenery
Date Posted: 28 May 21 at 7:34PM

After seaching in the completely wrong direction I finally found the reason why the library goes into trouble.

It is the option for font embeding in NewPageFromCanvasDC(dpi, Options)

It can have the following values:

Options

-1 = Convert the drawing commands to a single image using GDI+
0 = Process the drawing commands as vector graphics, fonts are not embedded
1 = Process the drawing commands as vector graphics, fonts are embedded but not compressed
2 = Process the drawing commands as vector graphics, fonts are embedded and compressed
3 = Process the drawing commands as vector graphics, fonts not in the no embed font list are embedded and compressed
4 = Same as 3 but fonts already added during previous calls to this function or the https://www.debenu.com/docs/pdf_library_reference/LoadFromCanvasDC.php" rel="nofollow - LoadFromCanvasDC function are reused

and I have chosen FontOption=4 which is the only one which leads into trouble. All others are working.

So the library probably has a bug with option 4.

Even when I do nothing else than repeated

GetCanvasDC

NewPageFromCanvasDC(dpi, 4)

without printing anything to the canvas the memory runs out.

Now I will use option 3 instead.