Support icon themes in snap

Telegram/SourceFiles/platform/linux/specific_linux.cpp

@@ -759,7 +759,9 @@ QImage DefaultApplicationIcon() {
 }
 
 QString ApplicationIconName() {
-	static const auto Result = QGuiApplication::desktopFileName().remove(
+	static const auto Result = (KSandbox::isSnap()
+		? u"snap.%1."_q.arg(qEnvironmentVariable("SNAP_INSTANCE_NAME"))
+		: QString()) + QGuiApplication::desktopFileName().remove(
 		u"._"_q + Core::Launcher::Instance().instanceHash());
 	return Result;
 }

snap/snapcraft.yaml

@@ -1,6 +1,5 @@
 name: telegram-desktop
 adopt-info: telegram
-icon: Telegram/Resources/art/icon512@2x.png
 
 base: core24
 grade: stable
@@ -151,7 +150,16 @@ parts:
       craftctl set version="$version"
     override-build: |
       craftctl default
-      rm -rf "$CRAFT_PART_INSTALL/usr/share/icons"
+
+      APP_ID=org.telegram.desktop
+      sed -i "s/^Icon=$APP_ID$/Icon=snap.telegram-desktop./g" "$CRAFT_PART_INSTALL/usr/share/applications/$APP_ID.desktop"
+      for i in $(find "$CRAFT_PART_INSTALL/usr/share/icons" -name "$APP_ID*.svg" -o -name "$APP_ID*.png"); do
+        PREFIXED="$(dirname "$i")/snap.$CRAFT_PROJECT_NAME.$(basename "$i" | sed "s/$APP_ID//")"
+        mv "$i" "$PREFIXED"
+        DEST="$(dirname "$i" | sed 's@usr/share@meta/gui@')"
+        mkdir -p "$DEST"
+        cp -r "$PREFIXED" "$DEST"
+      done
     after:
       - ada
       - ffmpeg