<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 14 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--></head><body lang=EN-GB link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Hello, I have a problem with PDF output. I have a system that can potentially render a huge image (e.g. a satellite photography) It does this by tiling the image and sending the tiles to Cairo which are then painted as source.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>When outputting to PDF there is an issue illustrated by the screengrabs of Adobe Reader displaying the Cairo output (see links below). The first is fine, but the second, which is the same data (approximately) rotated through 45deg. The third is a zoomed in area of the previous. The obvious problem is what looks like antialiasing on the edge of the tiles which is manifesting itself as diagonal lines on the boundaries of the tiles. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal> I set <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>cairo_set_antialias(ctxt, CAIRO_ANTIALIAS_NONE); <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>while drawing these tiles, I also tried <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>cairo_set_operator(ctxt, CAIRO_OPERATOR_SOURCE); <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>(rather than _OVER) but this had bizarre and unwanted effects on the screen drawing. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Any hints as to how I can remove these artefacts would be much appreciated, I’m using 1.10.2 <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Unrotated:<o:p></o:p></p><p class=MsoNormal><a href="http://s10.postimage.org/p0jf9u0cp/cairo_0deg.png">http://s10.postimage.org/p0jf9u0cp/cairo_0deg.png</a><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Rotated at 45 deg:<o:p></o:p></p><p class=MsoNormal><a href="http://s7.postimage.org/4zwv1z697/cairo_45deg.png">http://s7.postimage.org/4zwv1z697/cairo_45deg.png</a><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Above PDF zoomed in:<o:p></o:p></p><p class=MsoNormal><a href="http://s9.postimage.org/ra6wl28fj/cairo_45deg_zoomed.png">http://s9.postimage.org/ra6wl28fj/cairo_45deg_zoomed.png</a><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-GB'>Cheers<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-GB'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-GB'>Phil Cope<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-GB'>Senior Software Engineer (GE Energy: SSG)<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>