this report has been filed here: https://bugs.edge.launchpad.net/poppler/+bug/318130 "We have a pdf file exported from Open Office Impress. The background is blue and there are horizontal lines through the image. The lines vary somewhat in colour, going from white to the blue. If the slide show is made in OO Impress, all is well (showing that this isn't a hardware problem). Likewise if the same exported pdf file is shown on Windows XP, all is well." PDF: http://launchpadlibrarian.net/21362015/seminar1.pdf
Not a cairo only problem.
Thanks Albert, Do you have any information on where the problem lies? Or any information on how we can determine where the problem lies?
My guess is that the algorithm that draws the gradient "overlaps" two sections of the gradient and that results in the wrong coloring, the problem most probably lies in Gfx.cc
Created attachment 57654 [details] [review] align fills Here's an experimental patch for the cairo backend. It doesn't completely solve the problem but it does eliminate the seams in some cases. Some test cases I tried it with: https://bugs.launchpad.net/ubuntu/+source/poppler/+bug/348679/+attachment/510918/+files/test.pdf Eliminates the seams sometimes depending on the resolution rendered at. https://bugs.launchpad.net/ubuntu/+source/poppler/+bug/318130/+attachment/441616/+files/seminar1.pdf Seems to eliminate the seams at all resolutions I tested. https://bugs.launchpad.net/ubuntu/+source/poppler/+bug/387016/+attachment/606341/+files/Evince%20incorrect%20rendering.zip Eliminates the seams for all resolutions I tested except 150ppi where the one seam is worse. This is because the the coordinates of the adjacent fill where the line is worse are not identical (0.1 difference vertically).
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