<html> <head> <base href="https://bugs.documentfoundation.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - FILESAVE: PNG: Incorrect transparency after roundtrip" href="https://bugs.documentfoundation.org/show_bug.cgi?id=141269#c12">Comment # 12</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - FILESAVE: PNG: Incorrect transparency after roundtrip" href="https://bugs.documentfoundation.org/show_bug.cgi?id=141269">bug 141269</a> from <a class="email" href="mailto:caolanm@redhat.com" title="Caolán McNamara <caolanm@redhat.com>"> Caolán McNamara</a> <pre>The icons in the sidebar in GTK3 are set by passing a block of png data to gtk which them renders the png internally, so those showing broken to me indicates that we didn't give them the correct png data, I feel there are a few separate places not working. so, currently internally in bitmap data we are supposed to be using opacity and not transparency so a fully transparent pixel has an alpha of 0 ? vcl/source/filter/png/PngImageReader.cxx:309 has: pScanAlpha[iAlpha++] = 0xFF - pRow[i + 3] is that then an out of date conversion from opacity to transparency. vcl/source/filter/png/pngwrite.cxx:566 has a matching: 255 - mpMaskAccess->GetIndexFromData(pScanlineMask, nX) to go the other direction vcl/headless/svpgdi.cxx has some "make upper layers use standard alpha" places where it does some toggling which might be wrong now (?) if BitmapEx::AdjustTransparency input cTrans is transparency then should nNewTrans = nTrans + *pAScan convert *pAScan from opacity to transparency before the addition ?</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> </ul> </body> </html>