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From Robert Van Gemert <rcvangem...@gmail.com>
Subject Re: Remove page background
Date Thu, 23 Jun 2016 02:10:19 GMT
Hi Tilman,

I tried your idea but am having trouble getting the result I wanted.  My
hope was to use a stock standard pdf rendering library (mupdf or
android.graphics.pdf.PdfRenderer ) to render to a bitmap and then use
opengl to do the blend. However mupdf renders a white background BEFORE
rendering the pdf commands. So I will try to modify mupdf.

Thanks for your help,
Robert.
On 22 Jun 2016 4:25 pm, "Tilman Hausherr" <THausherr@t-online.de> wrote:

> Am 22.06.2016 um 00:05 schrieb Robert Van Gemert:
>
>> Files exported from android google slides would work for me.
>>
>> https://www.dropbox.com/s/ncnjt8tlgzasb6f/slide_test.pdf?dl=0
>>
>
> Strategy 1:
> use the command line utilities, run WriteDecodedDoc, then use an editor
> and overwrite this part with blanks:
>
> /Image3
> Do
>
>
> The file is huge now, sadly.
>
> Strategy 2:
>
> In the source code download, in the examples, there's a program
> RemoveAllText.java. That one shows how to work with the content stream:
>
>                     for (Object token : tokens)
>                     {
>                         if( token instanceof Operator)
>                         {
>                             Operator op = (Operator)token;
>                             if( op.getName().equals( "TJ") ||
> op.getName().equals( "Tj" ))
>                             {
>                                 //remove the one argument to this operator
>                                 newTokens.remove( newTokens.size() -1 );
>                                 continue;
>                             }
>                         }
>                         newTokens.add( token );
>                     }
>
> Now you don't want to remove "TJ", you want to remove "Do". I just tested
> this, it works for your file. (But it might now work with files that have a
> different structure).
>
> Tilman
>
>
>
>
>> Thanks for your help.
>>
>> Robert
>> On 22 Jun 2016 2:32 am, "Tilman Hausherr" <THausherr@t-online.de> wrote:
>>
>> Am 21.06.2016 um 13:12 schrieb Robert Van Gemert:
>>>
>>> Hi,
>>>>
>>>> I wish to use pdf as a graphics overlay over video so I need to make the
>>>> page background transparent or remove it. Can I use pdfbox to
>>>> preprocess a
>>>> pdf file?
>>>> My OS is Android. Initial tests show I cannot use pdfbox for rendering
>>>> but
>>>> preprocessing may work.
>>>>
>>>> Thanks,
>>>>
>>>> Robert
>>>>
>>>>
>>>> This is difficult to answer as there may be many methods to put a
>>> "background". There is no <BACKGROUND="image.jpg"/> command in PDF. Does
>>> your question apply to one specific PDF or to all possible PDFs in the
>>> world? If only one, please upload it somewhere.
>>>
>>> Tilman
>>>
>>>
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>>>
>
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