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<div class="moz-cite-prefix">This problem is not solvable, at least
not completely:<br>
<br>
1. You draw a stave with graphical operators<br>
2. You draw stave notes as glyphs of a font.<br>
3. You render it to an image with in this case much too low
resolution (141.146 dpi)<br>
<br>
So we have here either splash or cairo (for drawing the stave) and
freetype (for drawing the glyphs) which draw it to an image
without having pixel boundaries.<br>
<br>
This problem was discussed a lot of times also in the bug reports,
s. i.e. <a class="moz-txt-link-freetext" href="https://bugs.freedesktop.org/show_bug.cgi?id=37347">https://bugs.freedesktop.org/show_bug.cgi?id=37347</a><br>
<br>
If anyone is able to develop a pixel scissors I would take a
deeper look into it (and would nominate him to get a Nobel Prize J
), in the meantime I would advice to take a much higher resolution
when render it to an image (at least 300 dpi)<br>
<br>
Cheers,<br>
Thomas<br>
<br>
Am 26.03.2017 um 22:11 schrieb William Bader:<br>
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<p>When I open the test PDF in atril (the Mate desktop version
of evince) and change the window size (with 'fit page width'),
once I get below about 80%, small changes make the bars of the
staff go up and down, and not all of the bars of the
staff shift equally, so the space between the bars is not
equal, and that might contribute to the effect that the notes
are misplaced. I am not sure, but it seems as if it is not
antialiasing the bars. When you reduce the image to the point
where pixels are significant and the total number of pixels is
not the exact amount to leave the same number of pixels
between each bar, rounding can't create more pixels. You need
to simulate fractional pixels through antialiasing. The 'w'
command in PDF sets the line width. It looks like it is
drawing lines of 0.4, 0.65, 0.8, and 1 point. The tests for <span>thinLineMode
are in splash/Splash.cc.</span></p>
<p><span><br>
</span></p>
<p><span>William</span></p>
<p><span><br>
</span></p>
<div style="color: rgb(0, 0, 0);">
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<div id="x_divRplyFwdMsg" dir="ltr"><font
style="font-size:11pt" color="#000000" face="Calibri,
sans-serif"><b>From:</b> poppler
<a class="moz-txt-link-rfc2396E" href="mailto:poppler-bounces@lists.freedesktop.org"><poppler-bounces@lists.freedesktop.org></a> on behalf
of <a class="moz-txt-link-abbreviated" href="mailto:pqt@LEFerguson.com">pqt@LEFerguson.com</a> <a class="moz-txt-link-rfc2396E" href="mailto:pqt@LEFerguson.com"><pqt@LEFerguson.com></a><br>
<b>Sent:</b> Sunday, March 26, 2017 12:34 PM<br>
<b>To:</b> Albert Astals Cid;
<a class="moz-txt-link-abbreviated" href="mailto:poppler@lists.freedesktop.org">poppler@lists.freedesktop.org</a><br>
<b>Subject:</b> Re: [poppler] Scaling factor and
placement accuracy</font>
<div> </div>
</div>
</div>
<font size="2"><span style="font-size:10pt;">
<div class="PlainText">>>
ourParent->document->setRenderHint(Poppler::Document::Antialiasing);<br>
>>
ourParent->document->setRenderHint(Poppler::Document::TextAntialiasing<br>
>>ourParent->document->setRenderHint(Poppler::Document::ThinLineSolid);<br>
<br>
>Tried thin line shape instead of thing line solid?<br>
<br>
Thanks, Albert, I just tried it, same result.<br>
<br>
I spent a couple hours last night trying to find the
area of code that does the actual placement without any
real luck, to see if there is any kind of rounding
issue. I saw a lot of other possible areas like
anti-aliasing, but basically got lost in the code
because I don't know enough to know what is actually
inside the PDF (I tried PDFStreamDumper and can see
what's inside, and even seeing it I do not understand
it).
<br>
<br>
So far making the x/y scale factor integral appears to
avoid the problem; it's hard to prove a negative, but I
have not seen it occur in that case. This just very
slightly throws off the desired size I want, and I just
needed to put a proper color border into the overall
page to avoid showing an outline, so it's very workable
for what I want, if it keeps working.<br>
<br>
Thanks again,<br>
<br>
Linwood<br>
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