CairoOutputDev: Colored emojis are rendered incorrectly
I reported this issue in the issue-tracker of evince but I got told that it seems to be an issue in poppler which is used by evince internally, so I am reproducing that issue here.
As a testcase I created a simple presentation with emojis as shown in the following picture:
I generated the Presentation.pdf from it (using Decktape) which looks fine in different mobile (Android) PDF viewer apps as well as in different browsers (Chrome, Chromium, Firefox, Edge) and in Adobe Reader, but looks really weird in evince:
It seems as if the shapes of the emojis are printed, but the colors are omitted.
The fonts seem to be all embedded, although evince seems to have problems with displaying the names (and does not know its encoding):
By the way, these problems also occur with PDFs generated with other tools than Decktape. Printing into a PDF from Chrome and displaying that yields the same results.
The Emoji font used here is the default font used in Chrome: Noto Color Emoji
Printing it from Firefox yields a slightly different PDF, because Firefox seems to use another default-font for emojis. This PDF is displayed by evince as it is displayed in Firefox and also the embedded fonts could be read just fine:
I am on Ubuntu 18.04 and calling evince --version
yields:
GNOME Document Viewer 3.28.4