Torizon: Add SW renderer support for home-automation demo on GPU-less platforms

Add conditional compilation to use demo-sw-renderer.slint for home-automation
when building for platforms without GPU support (default).

- Add sw-renderer feature to home-automation Cargo.toml
- Use conditional compilation in lib.rs to select demo.slint or demo-sw-renderer.slint
- Add BUILD_HOME_AUTOMATION_SW_RENDERER ARG to Dockerfile.torizon-demos
- Configure torizon_demos.yaml to enable SW renderer for GPU-less platforms

Author: task-jp

.github/workflows/torizon_demos.yaml

@@ -26,29 +26,35 @@ jobs:
                       image_arch: linux/arm64
                       rust_toolchain_arch: aarch64-unknown-linux-gnu
                       base_image_suffix: ""
+                      build_home_automation_sw_renderer: true
                     # GPU-specific variants
                     # https://developer.toradex.com/torizon/application-development/provided-containers/debian-containers-for-torizon
                     - target: arm64
                       image_arch: linux/arm64
                       rust_toolchain_arch: aarch64-unknown-linux-gnu
                       base_image_suffix: "-imx8"
+                      build_home_automation_sw_renderer: false
                     - target: arm64
                       image_arch: linux/arm64
                       rust_toolchain_arch: aarch64-unknown-linux-gnu
                       base_image_suffix: "-am62"
+                      build_home_automation_sw_renderer: false
                     - target: arm64
                       image_arch: linux/arm64
                       rust_toolchain_arch: aarch64-unknown-linux-gnu
                       base_image_suffix: "-am62p"
+                      build_home_automation_sw_renderer: false
                     - target: arm64
                       image_arch: linux/arm64
                       rust_toolchain_arch: aarch64-unknown-linux-gnu
                       base_image_suffix: "-imx95"
+                      build_home_automation_sw_renderer: false
                     # Legacy vivante support (for backward compatibility)
                     - target: arm64
                       image_arch: linux/arm64
                       rust_toolchain_arch: aarch64-unknown-linux-gnu
                       base_image_suffix: "-vivante"
+                      build_home_automation_sw_renderer: false
 
         steps:
             - uses: actions/checkout@v5
@@ -76,3 +82,4 @@ jobs:
                       RUST_TOOLCHAIN_ARCH=${{matrix.rust_toolchain_arch}}
                       BASE_NAME=wayland-base${{matrix.base_image_suffix}}
                       WEATHER_API_KEY=${{secrets.WEATHER_API_KEY}}
+                      BUILD_HOME_AUTOMATION_SW_RENDERER=${{matrix.build_home_automation_sw_renderer}}

demos/home-automation/rust/Cargo.toml

@@ -22,6 +22,9 @@ name = "home_automation_lib"
 slint = { path = "../../../api/rs/slint" }
 chrono = "0.4"
 
+[features]
+sw-renderer = []
+
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 wasm-bindgen = { version = "0.2" }
 web-sys = { version = "0.3", features = ["console"] }

demos/home-automation/rust/lib.rs

@@ -7,6 +7,12 @@ use slint::{Timer, TimerMode};
 #[cfg(target_arch = "wasm32")]
 use wasm_bindgen::prelude::*;
 
+#[cfg(feature = "sw-renderer")]
+slint::slint! {
+    export { Api, AppWindow } from "../ui/demo-sw-renderer.slint";
+}
+
+#[cfg(not(feature = "sw-renderer"))]
 slint::slint! {
     export { Api, AppWindow } from "../ui/demo.slint";
 }

docker/Dockerfile.torizon-demos

@@ -7,9 +7,12 @@ ARG TOOLCHAIN_ARCH=arm64
 ARG IMAGE_ARCH=linux/arm64
 ARG BASE_VERSION=4
 ARG BASE_NAME=wayland-base
+ARG BUILD_HOME_AUTOMATION_SW_RENDERER=false
+
 FROM torizon/cross-toolchain-$TOOLCHAIN_ARCH:${BASE_VERSION} AS build
 ARG TOOLCHAIN_ARCH
 ARG RUST_TOOLCHAIN_ARCH=aarch64-unknown-linux-gnu
+ARG BUILD_HOME_AUTOMATION_SW_RENDERER
 
 ARG WEATHER_API_KEY
 ENV WEATHER_API=$WEATHER_API_KEY
@@ -39,10 +42,19 @@ COPY . /slint
 WORKDIR /slint
 RUN mkdir demos_compiled \
     && cargo build --release --target $RUST_TOOLCHAIN_ARCH --features slint/renderer-skia,slint/backend-linuxkms-noseat \
-        -p printerdemo -p slide_puzzle -p gallery -p opengl_underlay -p carousel -p todo -p energy-monitor -p home-automation -p weather-demo \
-    && for demo in printerdemo slide_puzzle gallery opengl_underlay carousel todo energy-monitor home-automation weather-demo; do \
+        -p printerdemo -p slide_puzzle -p gallery -p opengl_underlay -p carousel -p todo -p energy-monitor -p weather-demo \
+    && for demo in printerdemo slide_puzzle gallery opengl_underlay carousel todo energy-monitor weather-demo; do \
         cp target/$RUST_TOOLCHAIN_ARCH/release/$demo ./demos_compiled/; \
-    done
+    done \
+    && if [ "$BUILD_HOME_AUTOMATION_SW_RENDERER" = "true" ]; then \
+        cargo build --release --target $RUST_TOOLCHAIN_ARCH --features slint/renderer-skia,slint/backend-linuxkms-noseat,home-automation/sw-renderer \
+            -p home-automation \
+        && cp target/$RUST_TOOLCHAIN_ARCH/release/home-automation ./demos_compiled/home-automation; \
+    else \
+        cargo build --release --target $RUST_TOOLCHAIN_ARCH --features slint/renderer-skia,slint/backend-linuxkms-noseat \
+            -p home-automation \
+        && cp target/$RUST_TOOLCHAIN_ARCH/release/home-automation ./demos_compiled/home-automation; \
+    fi
 
 # Create container for target
 FROM --platform=${IMAGE_ARCH} torizon/${BASE_NAME}:${BASE_VERSION} AS deploy