Replace eprintln with use of the log facade

Cargo.toml

@@ -96,6 +96,8 @@ rust-version = "1.66"
 resvg = { version= "0.34.0", default-features = false, features = ["text"] }
 fontdb = { version = "0.14.1", default-features = false }
 send_wrapper = { version = "0.6.0" }
+log = { version = "0.4.19", default-features = false }
+env_logger = { version = "0.10.0" }
 
 [profile.release]
 lto = true

api/cpp/Cargo.toml

@@ -41,7 +41,7 @@ accessibility = ["i-slint-backend-selector/accessibility"]
 experimental = ["i-slint-renderer-skia", "raw-window-handle", "experimental-platform"]
 experimental-platform = []
 
-std = ["image", "i-slint-core/default", "i-slint-backend-selector"]
+std = ["image", "i-slint-core/default", "i-slint-backend-selector", "env_logger"]
 
 default = ["std", "backend-winit", "renderer-winit-femtovg", "backend-qt", "experimental"]
 
@@ -54,6 +54,7 @@ slint-interpreter = { version = "=1.1.1", path="../../internal/interpreter", def
 raw-window-handle = { version = "0.5", optional = true }
 # Enable image-rs' default features to make all image formats to C++ users
 image = { version = "0.24.0", optional = true }
+env_logger = { workspace = true, optional = true }
 
 [build-dependencies]
 anyhow = "1.0"

api/cpp/lib.rs

@@ -40,6 +40,12 @@ pub unsafe extern "C" fn slint_windowrc_init(out: *mut WindowAdapterRcOpaque) {
  core::ptr::write(out as *mut Rc<dyn WindowAdapter>, win);
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn slint_ensure_logger() {
+ #[cfg(feature = "std")]
+ env_logger::try_init().ok();
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn slint_ensure_backend() {
  with_platform(|_b| {

api/node/native/Cargo.toml

@@ -33,6 +33,7 @@ once_cell = "1.5"
 rand = "0.8"
 scoped-tls-hkt = "0.1"
 spin_on = "0.1" #FIXME: remove and delegate to async JS instead
+env_logger = { workspace = true }
 
 # Enable image-rs' default features to make all image formats available for nodejs builds
 image = { version = "0.24.0" }

api/node/native/lib.rs

@@ -677,6 +677,7 @@ fn singleshot_timer(mut cx: FunctionContext) -> JsResult<JsValue> {
 }
 
 register_module!(mut m, {
+ env_logger::try_init().ok();
  m.export_function("load", load)?;
  m.export_function("mock_elapsed_time", mock_elapsed_time)?;
  m.export_function("singleshot_timer", singleshot_timer)?;

api/rs/slint/Cargo.toml

@@ -148,7 +148,7 @@ once_cell = { version = "1.5", default-features = false, features = ["alloc"] }
 pin-weak = { version = "1.1", default-features = false }
 num-traits = { version = "0.2", default-features = false }
 
-log = { version = "0.4.17", optional = true }
+log = { workspace = true, optional = true }
 
 [dev-dependencies]
 slint-build = { path = "../build" }

internal/backends/selector/Cargo.toml

@@ -34,3 +34,4 @@ i-slint-backend-winit = { version = "=1.1.1", path = "../winit", optional = true
 i-slint-backend-qt = { version = "=1.1.1", path = "../qt", optional = true }
 
 cfg-if = "1"
+log = { workspace = true }

internal/backends/selector/lib.rs

@@ -56,7 +56,7 @@ cfg_if::cfg_if! {
  }
 
  if !backend_config.is_empty() {
- eprintln!("Could not load rendering backend {}, fallback to default", backend_config)
+ log::error!("Could not load rendering backend {}, fallback to default", backend_config)
  }
  Ok(create_default_backend())
  }

internal/backends/winit/Cargo.toml

@@ -50,6 +50,7 @@ instant = "0.1"
 raw-window-handle = { version = "0.5", features = ["alloc"] }
 scopeguard = { version = "1.1.0", default-features = false }
 send_wrapper = { workspace = true }
+log = { workspace = true }
 
 # For the FemtoVG renderer
 i-slint-renderer-femtovg = { version = "=1.1.1", path = "../../renderers/femtovg", optional = true }

internal/backends/winit/lib.rs

@@ -166,9 +166,10 @@ impl Backend {
  }
  None => window_factory_fn::<DefaultRenderer>,
  Some(renderer_name) => {
- eprintln!(
+ log::error!(
  "slint winit: unrecognized renderer {}, falling back to {}",
- renderer_name, DEFAULT_RENDERER_NAME
+ renderer_name,
+ DEFAULT_RENDERER_NAME
  );
  window_factory_fn::<DefaultRenderer>
  }

internal/common/Cargo.toml

@@ -16,12 +16,13 @@ homepage = "https://slint.dev"
 path = "lib.rs"
 
 [features]
-shared-fontdb = ["dep:fontdb", "dep:libloading", "derive_more", "cfg-if"]
+shared-fontdb = ["dep:fontdb", "dep:libloading", "derive_more", "cfg-if", "log"]
 
 [dependencies]
 fontdb = { workspace = true, optional = true }
 derive_more = { version = "0.99.5", optional = true }
 cfg-if = { version = "1", optional = true }
+log = { workspace = true, optional = true }
 
 [target.'cfg(not(any(target_family = "windows", target_os = "macos", target_os = "ios", target_arch = "wasm32")))'.dependencies]
 libloading = { version = "0.8.0", optional = true }

internal/common/sharedfontdb.rs

@@ -91,7 +91,7 @@ fn init_fontdb() -> FontDatabase {
  Some((family_ids, family_names))
  }
  Err(err) => {
- eprintln!(
+ log::error!(
  "Could not load the font set via `SLINT_DEFAULT_FONT`: {}: {}",
  path.display(),
  err,
@@ -139,7 +139,7 @@ fn init_fontdb() -> FontDatabase {
  fontconfig_fallback_families = fallback_families;
  }
  Err(e) => {
- eprintln!("Error opening libfontconfig.so.1: {}", e);
+ log::error!("Error opening libfontconfig.so.1: {}", e);
  }
  }
  }

internal/compiler/generator/cpp.rs

@@ -1212,14 +1212,20 @@ fn generate_item_tree(
  init_parent_parameters = ", parent";
  }
 
- let mut create_code = vec![
+ let mut create_code = Vec::new();
+
+ if parent_ctx.is_none() {
+ create_code.push("slint::cbindgen_private::slint_ensure_logger();".into());
+ }
+
+ create_code.extend([
  format!(
  "auto self_rc = vtable::VRc<slint::private_api::ComponentVTable, {0}>::make();",
  target_struct.name
  ),
  format!("auto self = const_cast<{0} *>(&*self_rc);", target_struct.name),
  "self->self_weak = vtable::VWeak(self_rc).into_dyn();".into(),
- ];
+ ]);
 
  if parent_ctx.is_none() {
  create_code.push("slint::cbindgen_private::slint_ensure_backend();".into());

internal/core/Cargo.toml

@@ -74,6 +74,7 @@ unicode-segmentation = "1.8.0"
 unicode-linebreak = { version = "0.1.2", optional = true }
 unicode-script = { version = "0.5.3", optional = true }
 integer-sqrt = { version = "0.1.5" }
+log = { workspace = true }
 
 image = { version = "0.24.0", optional = true, default-features = false, features = [ "png", "jpeg" ] }
 clru = { version = "0.6.0", optional = true }

internal/core/graphics/image.rs

@@ -362,7 +362,7 @@ impl ImageInner {
  match svg.render(_target_size_for_scalable_source.unwrap_or_default()) {
  Ok(b) => Some(b),
  Err(err) => {
- eprintln!("Error rendering SVG: {}", err);
+ log::error!("Error rendering SVG: {}", err);
  None
  }
  }

internal/core/graphics/image/cache.rs

@@ -86,7 +86,7 @@ impl ImageCache {
  return Some(ImageInner::Svg(vtable::VRc::new(
  super::svg::load_from_path(path, cache_key).map_or_else(
  |err| {
- eprintln!("Error loading SVG from {}: {}", &path, err);
+ log::error!("Error loading SVG from {}: {}", &path, err);
  None
  },
  Some,
@@ -96,7 +96,7 @@ impl ImageCache {
 
  image::open(std::path::Path::new(&path.as_str())).map_or_else(
  |decode_err| {
- eprintln!("Error loading image from {}: {}", &path, decode_err);
+ log::error!("Error loading image from {}: {}", &path, decode_err);
  None
  },
  |image| {
@@ -121,7 +121,7 @@ impl ImageCache {
  return Some(ImageInner::Svg(vtable::VRc::new(
  super::svg::load_from_data(data.as_slice(), cache_key).map_or_else(
  |svg_err| {
- eprintln!("Error loading SVG: {}", svg_err);
+ log::error!("Error loading SVG: {}", svg_err);
  None
  },
  Some,
@@ -144,7 +144,7 @@ impl ImageCache {
  buffer: dynamic_image_to_shared_image_buffer(image),
  }),
  Err(decode_err) => {
- eprintln!("Error decoding embedded image: {}", decode_err);
+ log::error!("Error decoding embedded image: {}", decode_err);
  None
  }
  }

internal/core/graphics/path.rs

@@ -304,7 +304,7 @@ impl PathData {
  ) {
  Ok(()) => LyonPathIteratorVariant::FromPath(builder.build()),
  Err(e) => {
- eprintln!("Error while parsing path commands '{commands}': {e:?}");
+ log::error!("Error while parsing path commands '{commands}': {e:?}");
  LyonPathIteratorVariant::FromPath(Default::default())
  }
  }

internal/core/graphics/rendering_metrics_collector.rs

@@ -81,7 +81,7 @@ impl RenderingMetricsCollector {
  let refresh_mode = match RefreshMode::try_from(&options) {
  Ok(mode) => mode,
  Err(_) => {
- eprintln!("Missing refresh mode in SLINT_DEBUG_PERFORMANCE. Please specify either refresh_full_speed or refresh_lazy");
+ log::info!("Missing refresh mode in SLINT_DEBUG_PERFORMANCE. Please specify either refresh_full_speed or refresh_lazy");
  return None;
  }
  };
@@ -90,7 +90,7 @@ impl RenderingMetricsCollector {
  let output_overlay = options.contains(&"overlay");
 
  if !output_console && !output_overlay {
- eprintln!("Missing output mode in SLINT_DEBUG_PERFORMANCE. Please specify either console or overlay (or both)");
+ log::info!("Missing output mode in SLINT_DEBUG_PERFORMANCE. Please specify either console or overlay (or both)");
  return None;
  }
 
@@ -107,7 +107,7 @@ impl RenderingMetricsCollector {
  #[cfg(not(debug_assertions))]
  let build_config = "release";
 
- eprintln!("Slint: Build config: {}; Backend: {}", build_config, winsys_info);
+ log::info!("Slint: Build config: {}; Backend: {}", build_config, winsys_info);
 
  let self_weak = Rc::downgrade(&collector);
  collector.update_timer.stop();
@@ -134,7 +134,7 @@ impl RenderingMetricsCollector {
  }
 
  if this.output_console {
- eprintln!(
+ log::info!(
  "average frames per second: {} {}",
  this.collected_frame_data_since_second_ago.borrow().len(),
  last_frame_details

internal/core/model.rs

@@ -138,8 +138,7 @@ pub trait Model {
  /// If the model can update the data, it should also call [`ModelNotify::row_changed`] on its
  /// internal [`ModelNotify`].
  fn set_row_data(&self, _row: usize, _data: Self::Data) {
- #[cfg(feature = "std")]
- eprintln!(
+ log::error!(
  "Model::set_row_data called on a model of type {} which does not re-implement this method. \
  This happens when trying to modify a read-only model",
  core::any::type_name::<Self>(),

internal/interpreter/Cargo.toml

@@ -101,6 +101,7 @@ lyon_path = { version = "1.0" }
 once_cell = "1.5"
 thiserror = "1"
 document-features = { version = "0.2.0", optional = true }
+log = { workspace = true }
 
 [dependencies.spin_on]
 version = "0.1"

internal/interpreter/eval.rs

@@ -305,7 +305,7 @@ pub fn eval_expression(expression: &Expression, local_context: &mut EvalLocalCon
  todo!()
  }
  }.unwrap_or_else(|_| {
- eprintln!("Could not load image {:?}",resource_ref );
+ log::error!("Could not load image {:?}",resource_ref );
  Default::default()
  }))
  }
@@ -1056,7 +1056,7 @@ fn eval_assignment(lhs: &Expression, op: char, rhs: Value, local_context: &mut E
  }
  }
  _ => {
- eprintln!("Attempting to write into an array that cannot be written");
+ log::error!("Attempting to write into an array that cannot be written");
  }
  }
  }

internal/interpreter/value_model.rs

@@ -74,7 +74,7 @@ impl Model for ValueModel {
  fn set_row_data(&self, row: usize, data: Self::Data) {
  match &mut *self.value.borrow_mut() {
  Value::Model(model_ptr) => model_ptr.set_row_data(row, data),
- _ => eprintln!("Trying to change the value of a read-only integer model."),
+ _ => log::error!("Trying to change the value of a read-only integer model."),
  }
  }
 

tools/viewer/Cargo.toml

@@ -57,7 +57,7 @@ notify = { version = "6.0.0", default-features = false, features = ["macos_kqueu
 serde_json = "1"
 shlex = "1"
 spin_on = "0.1"
-env_logger = "0.10.0"
+env_logger = { workspace = true }
 
 # Enable image-rs' default features to make all image formats available for preview
 image = { version = "0.24.0" }