Animated PNG only display the first frame.

[Renari]

Environment:

• OS: CachyOS
• qView version: 7.1

Information:
Opening an animated PNG in qView will only display the first frame of the animation.

Sample Image:

[jurplel]

Did you download the qt Apng plug-in?

[Renari]

I have:

qt6-base
qt6-tools
kimageformats
qt6-imageformats
qt6-svg

I'm not seeing any such qt6 plugin for apng, I do see one for qt5.

[Renari]

I looked into this a bit today, it looks like the qt5 package adding apng support has not been updated to qt6, my first assumption was because it was likely implemented upstream in qt6. That is not that case however, so as far as I can tell there's currently no drop in support for apng in qt6.

[jurplel]

Try this one: https://github.com/jurplel/qtapng

[Renari]

Hmm, that did not appear to work. I made a PKGBUILD for that repo:

pkgname=qt6-apng-plugin-git
_pkgname=QtApng
pkgver=1.3.0.r0.gbd15516
pkgrel=1
pkgdesc='An apng image plugin for Qt to support animated PNGs'
arch=('x86_64')
url='https://github.com/jurplel/QtApng'
license=('BSD-3-Clause')
depends=('qt6-base')
makedepends=('cmake' 'git' 'ninja')
provides=('qt6-apng-plugin')
conflicts=('qt6-apng-plugin')
source=("${_pkgname}::git+https://github.com/jurplel/QtApng.git#branch=master")
sha256sums=('SKIP')

pkgver() {
  cd "${srcdir}/${_pkgname}"
  git describe --long --tags --abbrev=7 | sed 's/^v//;s/\([^-]*-g\)/r\1/;s/-/./g'
}

build() {
  cmake -S "${srcdir}/${_pkgname}" -B build -G Ninja \
    -DCMAKE_BUILD_TYPE=None \
    -DCMAKE_INSTALL_PREFIX=/usr \
    -DAPNG_QT6=ON \
    -DAPNG_TESTS=OFF \
    -DAPNG_EXAMPLES=OFF

  cmake --build build
}

package() {
  local qt_plugin_dir
  qt_plugin_dir="$(qmake6 -query QT_INSTALL_PLUGINS)"

  install -Dm755 build/plugins/imageformats/libqapng.so \
    "${pkgdir}/${qt_plugin_dir#/}/imageformats/libqapng.so"
  install -Dm644 "${srcdir}/${_pkgname}/LICENSE" \
    "${pkgdir}/usr/share/licenses/${pkgname}/LICENSE"
  install -Dm644 "${srcdir}/${_pkgname}/README.md" \
    "${pkgdir}/usr/share/doc/${pkgname}/README.md"
}

Then wiped my AUR cache and reinstalled qView to no avail.

[jurplel]

Hmmm, I'm not sure then. That's what I deploy it with on other platforms. Did you try the app image? I expect it to work there.

[Renari]

The above apng does not work in the appimage for me either.

[jurplel]

Okay, fair enough. I just tested on macOS (apologies I did not do this at first) and it isn't working here either. Maybe the plugin has broken at some point? Seems like a real bug.

[jdpurcell]

The sample APNG played fine for me on both macOS and Linux (AppImage) with the 7.1 release and also the latest nightly build.

However, I did have problems in the past with APNGs playing on Linux in my qView fork (maybe because I updated the AppImage to build with Qt6?). When troubleshooting I found that QtApng was calling into a different version of libpng than it was build with, which seemed to indicate a symbol collision problem. After this change it was working fine.