Simple KDE Splash screen that displays a background image (ideally the desktop wallpaper)

install.sh

#!/bin/bash

set -euo pipefail

BREEZE='/usr/share/plasma/look-and-feel/org.kde.breeze.desktop'

print_usage() {
  cat << EOF
Usage: $0 [options] image
Creates a KDE Splash Screen that displays the given image in
the background.
Options:
  -t [src]  The directory containing the Breeze theme for the Plasma
            desktop (default: $BREEZE).
EOF
  exit 1
}

while getopts 't:' flag; do
  case "$flag" in
    t) BREEZE="$OPTARG" ;;
    *) print_usage ;;
  esac
done
shift $((OPTIND -1))
if [ "$#" -ne 1 ]; then print_usage; fi

IMAGE="$1"
DEST="$(dirname "$BREEZE")/me.hugmanrique.image-splash.desktop"

if [[ "$IMAGE" != *.jpg ]]; then
	echo "Only .jpg background files are supported"
	exit 1
fi

# Move files to theme directory.
mkdir -p "$DEST/contents/splash/images"
cp "$IMAGE" "$DEST/contents/splash/images/background.jpg"
mv Splash.qml "$DEST/contents/splash"

# Copy busy widget icon from the Breeze theme
cp "$BREEZE/contents/splash/images/busywidget.svgz" "$DEST/contents/splash/images"

echo "Success! Enable the theme in System Settings → Appearance → Splash Screen"

metadata.json

{
    "KPlugin": {
        "Authors": [
            {
                "Email": "plasma-devel@kde.org",
                "Name": "KDE Visual Design Group",
                "Name[ar]": "مجموعة التصميم المرئي لكدي",
                "Name[az]": "KDE Vizual Dizayn Qrupu",
                "Name[bg]": "KDE Visual Design Group",
                "Name[ca@valencia]": "Grup de disseny visual de KDE",
                "Name[ca]": "Grup de disseny visual de KDE",
                "Name[cs]": "Skupina vizuálního návrhu KDE",
                "Name[da]": "KDE Visual Design Group",
                "Name[de]": "KDE Visual Design Group",
                "Name[en_GB]": "KDE Visual Design Group",
                "Name[es]": "El grupo de diseño visual de KDE",
                "Name[eu]": "KDE Diseinu bisualeko taldea",
                "Name[fi]": "KDE:n visuaalinen suunnitteluryhmä",
                "Name[fr]": "Groupe de conception visuelle de KDE",
                "Name[hu]": "KDE Visual Design Group",
                "Name[ia]": "KDE Visual Design Group (Gruppo de Designo Visual de KDE)",
                "Name[id]": "Grup Desain Visual KDE",
                "Name[is]": "Myndrænn hönnunarhópur KDE",
                "Name[it]": "KDE Visual Design Group",
                "Name[ja]": "KDE Visual Design Group",
                "Name[ka]": "KDE-ის ვიზუალური დიზაინის ჯგუფი",
                "Name[ko]": "KDE 시각 디자인 그룹",
                "Name[lt]": "KDE vaizdinio dizaino grupė",
                "Name[nl]": "KDE Visuele ontwerpgroep",
                "Name[nn]": "KDE Visual Design Group",
                "Name[pl]": "Grupa oprawy graficznej KDE",
                "Name[pt]": "Grupo de Desenho Visual do KDE",
                "Name[pt_BR]": "Grupo de Design Visual do KDE",
                "Name[ro]": "KDE Visual Design Group",
                "Name[ru]": "Группа KDE Visual Design",
                "Name[sk]": "KDE Visual Design Group",
                "Name[sl]": "Skupina vizualnega designa KDE",
                "Name[sv]": "KDE:s visuella designgrupp",
                "Name[ta]": "கே.டீ.யீ. வரைகலை வடிவமைப்புக் குழு",
                "Name[tr]": "KDE Görsel Tasarım Grubu",
                "Name[uk]": "Група з візуального дизайну KDE",
                "Name[vi]": "Đội Thiết kế Trực quan KDE",
                "Name[x-test]": "xxKDE Visual Design Groupxx",
                "Name[zh_CN]": "KDE 视觉设计团队"
            },
            {
                "Email": "contact@hugmanrique.me",
                "Name": "Hugo Manrique"
            }
        ],
        "Category": "",
        "Description": "Image splash screen",
        "Id": "me.hugmanrique.image-splash.desktop",
        "License": "GPLv2+",
        "Name": "Image splash screen",
        "ServiceTypes": [
            "Plasma/LookAndFeel"
        ],
        "Version": "1.0",
        "Website": "https://hugmanrique.me"
    },
    "Keywords": "Desktop;Workspace;Appearance;Look and Feel;",
    "X-Plasma-APIVersion": "2",
    "X-Plasma-MainScript": "defaults"
}

Splash.qml

/*
    SPDX-FileCopyrightText: 2014 Marco Martin <mart@kde.org>
    SPDX-FileCopyrightText: 2023 Hugo Manrique <contact@hugmanrique.me>

    SPDX-License-Identifier: GPL-2.0-or-later
*/

import QtQuick 2.5
import QtQuick.Window 2.2
import org.kde.plasma.core 2.0 as PlasmaCore

Image {
    id: root
    source: "images/background.jpg"
    fillMode: Image.PreserveAspectCrop

    property int stage

    onStageChanged: {
        if (stage == 2) {
            introAnimation.running = true;
        } else if (stage == 5) {
            introAnimation.target = busyIndicator;
            introAnimation.from = 1;
            introAnimation.to = 0;
            introAnimation.running = true;
        }
    }

    Item {
        id: content
        anchors.fill: parent
        opacity: 0

        // TODO: port to PlasmaComponents3.BusyIndicator
        Image {
            id: busyIndicator
            y: parent.height * 3 / 4
            anchors.horizontalCenter: parent.horizontalCenter
            source: "images/busywidget.svgz"
            sourceSize.height: PlasmaCore.Units.gridUnit * 2
            sourceSize.width: PlasmaCore.Units.gridUnit * 2
            RotationAnimator on rotation {
                id: rotationAnimator
                from: 0
                to: 360
                // Not using a standard duration value because we don't want the
                // animation to spin faster or slower based on the user's animation
                // scaling preferences; it doesn't make sense in this context
                duration: 2000
                loops: Animation.Infinite
                // Don't want it to animate at all if the user has disabled animations
                running: PlasmaCore.Units.longDuration > 1
            }
        }
    }

    OpacityAnimator {
        id: introAnimation
        running: false
        target: content
        from: 0
        to: 1
        duration: PlasmaCore.Units.veryLongDuration
        easing.type: Easing.InOutQuad
    }
}