Filter gst-audio-thumbnailer from ThumbnailProvider options

Sanitize "make install" machinery

Audiobooks.pro

@@ -55,21 +55,33 @@ resources.files = \
 
 RESOURCES += resources
 
-# ---- install prefix ----
 isEmpty(PREFIX) {
     PREFIX = /usr/local
 }
 
+isEmpty(BINDIR) {
+    BINDIR = $$PREFIX/bin
+}
+isEmpty(DATADIR) {
+    DATADIR = $$PREFIX/share
+}
+isEmpty(APPDIR) {
+    APPDIR = $$DATADIR/applications
+}
+isEmpty(ICONDIR) {
+    ICONDIR = $$DATADIR/icons/hicolor/512x512/apps
+}
+
 # ---- binary ----
-target.path = $$PREFIX/bin
+target.path = $$BINDIR
 INSTALLS += target
 
 # ---- desktop file ----
 desktop.files = Audiobooks.desktop
-desktop.path = $$PREFIX/share/applications
+desktop.path = $$APPDIR
 INSTALLS += desktop
 
 # ---- icon ----
 icon.files = Audiobooks.png
-icon.path = $$PREFIX/share/icons/hicolor/512x512/apps
+icon.path = $$ICONDIR
 INSTALLS += icon

src/thumbnailprovider.cpp

@@ -28,6 +28,7 @@ void AsyncThumbnailResponse::fetch() {
 
     KFileItem item(url, KFileItem::NormalMimeTypeDetermination);
     QStringList plugins = KIO::PreviewJob::availablePlugins();
+    plugins.removeAll("gst-audio-thumbnailer"); // This doesn't work for our purposes, but claims to support M4B
     auto job = KIO::filePreview({ item }, thumbSize, &plugins);
 
     QObject::connect(job, &KIO::PreviewJob::gotPreview, this,