viewer: use the new Compiler API and add a --component command line arg

internal/compiler/object_tree.rs

@@ -248,9 +248,9 @@ impl Document {
         self.exports
             .iter()
             .filter_map(|e| Some((&e.0.name_ident, e.1.as_ref().left()?)))
+            .filter(|(_, c)| !c.is_global())
             .max_by_key(|(n, _)| n.text_range().end())
             .map(|(_, c)| c.clone())
-            .or_else(|| self.exported_roots().last())
     }
 
     /// visit all root and used component (including globals)

internal/compiler/passes/check_public_api.rs

@@ -60,13 +60,26 @@ pub fn check_public_api(
             }
         }),
         // Only keep the component with the given name
-        ComponentsToGenerate::ComponentWithName(name) => doc.exports.retain(|export| {
-            if let Either::Left(c) = &export.1 {
-                c.is_global() || &c.id == name
-            } else {
-                true
+        ComponentsToGenerate::ComponentWithName(name) => {
+            doc.exports.retain(|export| {
+                if let Either::Left(c) = &export.1 {
+                    c.is_global() || &c.id == name
+                } else {
+                    true
+                }
+            });
+            if doc.last_exported_component().is_none() {
+                // We maybe requested to preview a non-exported component.
+                if let Ok(ElementType::Component(c)) = doc.local_registry.lookup_element(&name) {
+                    if let Some(name_ident) = c.node.clone() {
+                        doc.exports.add_reexports(
+                            [(ExportedName{ name: name.clone(), name_ident }, Either::Left(c))],
+                            diag,
+                        );
+                    }
+                }
             }
-        }),
+        },
     }
 
     for c in doc.exported_roots() {

internal/interpreter/api.rs

@@ -493,8 +493,8 @@ impl FromIterator<(String, Value)> for Struct {
     }
 }
 
-/// ComponentCompiler is deprecated, use `Compiler` instead
-//#[deprecated(note = "Use Complier instead")]
+/// ComponentCompiler is deprecated, use [`Compiler`] instead
+// #[deprecated(note = "Use slint_interpreter::Complier instead")]
 pub struct ComponentCompiler {
     config: i_slint_compiler::CompilerConfiguration,
     diagnostics: Vec<Diagnostic>,
@@ -705,6 +705,11 @@ impl Default for Compiler {
 }
 
 impl Compiler {
+    /// Returns a new Compiler.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
     /// Allow access to the underlying `CompilerConfiguration`
     ///
     /// This is an internal function without and ABI or API stability guarantees.

tools/viewer/README.md

@@ -40,6 +40,7 @@ slint-viewer path/to/myfile.slint
  - `--style <style>`: Set the style. Defaults to `native` if the Qt backend is compiled, otherwise `fluent`
  - `--backend <backend>`: Override the Slint rendering backend
  - `--on <callback> <handler>`: Set a callback handler, see [callback handler](#callback-handlers)
+ - `--component <name>`: Load the component with the given name. If not specified, load the last exported component
 
 Instead of a path to a file, one can use `-` for the standard input or the standard output.
 

tools/viewer/main.rs

@@ -3,8 +3,11 @@
 
 #![doc = include_str!("README.md")]
 
+use clap::Parser;
+use i_slint_compiler::ComponentsToGenerate;
 use i_slint_core::model::{Model, ModelRc};
 use i_slint_core::SharedVector;
+use itertools::Itertools;
 use slint_interpreter::{
     ComponentDefinition, ComponentHandle, ComponentInstance, SharedString, Value,
 };
@@ -14,9 +17,6 @@ use std::path::PathBuf;
 use std::sync::atomic::{AtomicU32, Ordering};
 use std::sync::{Arc, Mutex};
 
-use clap::Parser;
-use itertools::Itertools;
-
 type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
 
 #[derive(Clone, clap::Parser)]
@@ -38,6 +38,11 @@ struct Cli {
     #[arg(long, value_name = "style name", action)]
     style: Option<String>,
 
+    /// The name of the component to view. If unset, the last exported component of the file is used.
+    /// If the component name is not in the .slint file , nothing will be shown
+    #[arg(long, value_name = "component name", action)]
+    component: Option<String>,
+
     /// The rendering backend
     #[arg(long, value_name = "backend", action)]
     backend: Option<String>,
@@ -97,14 +102,22 @@ fn main() -> Result<()> {
     };
 
     let fswatcher = if args.auto_reload { Some(start_fswatch_thread(args.clone())?) } else { None };
-    let mut compiler = init_compiler(&args, fswatcher);
-
-    let c = spin_on::spin_on(compiler.build_from_path(args.path));
-    slint_interpreter::print_diagnostics(compiler.diagnostics());
-
-    let c = match c {
-        Some(c) => c,
-        None => std::process::exit(-1),
+    let compiler = init_compiler(&args, fswatcher);
+    let r = spin_on::spin_on(compiler.build_from_path(&args.path));
+    slint_interpreter::print_diagnostics(&r.diagnostics().collect::<Vec<_>>());
+    if r.has_error() {
+        std::process::exit(-1);
+    }
+    let Some(c) = r.component_names().next().and_then(|n| r.component(n)) else {
+        match args.component {
+            Some(name) => {
+                eprintln!("Component '{name}' not found in file '{}'", args.path.display());
+            }
+            None => {
+                eprintln!("No component found in file '{}'", args.path.display());
+            }
+        }
+        std::process::exit(-1);
     };
 
     let component = c.create().unwrap();
@@ -166,8 +179,8 @@ fn main() -> Result<()> {
 fn init_compiler(
     args: &Cli,
     fswatcher: Option<Arc<Mutex<notify::RecommendedWatcher>>>,
-) -> slint_interpreter::ComponentCompiler {
-    let mut compiler = slint_interpreter::ComponentCompiler::default();
+) -> slint_interpreter::Compiler {
+    let mut compiler = slint_interpreter::Compiler::new();
     #[cfg(feature = "gettext")]
     if let Some(domain) = args.translation_domain.clone() {
         compiler.set_translation_domain(domain);
@@ -192,6 +205,13 @@ fn init_compiler(
             Box::pin(async { None })
         })
     }
+
+    compiler.compiler_configuration(i_slint_core::InternalToken).components_to_generate =
+        match &args.component {
+            Some(component) => ComponentsToGenerate::ComponentWithName(component.clone()),
+            None => ComponentsToGenerate::LastComponent,
+        };
+
     compiler
 }
 
@@ -275,11 +295,10 @@ fn start_fswatch_thread(args: Cli) -> Result<Arc<Mutex<notify::RecommendedWatche
 }
 
 async fn reload(args: Cli, fswatcher: Arc<Mutex<notify::RecommendedWatcher>>) {
-    let mut compiler = init_compiler(&args, Some(fswatcher));
-    let c = compiler.build_from_path(&args.path).await;
-    slint_interpreter::print_diagnostics(compiler.diagnostics());
-
-    if let Some(c) = c {
+    let compiler = init_compiler(&args, Some(fswatcher));
+    let r = compiler.build_from_path(&args.path).await;
+    slint_interpreter::print_diagnostics(&r.diagnostics().collect::<Vec<_>>());
+    if let Some(c) = r.component_names().next().and_then(|n| r.component(n)) {
         CURRENT_INSTANCE.with(|current| {
             let mut current = current.borrow_mut();
             if let Some(handle) = current.take() {
@@ -298,6 +317,11 @@ async fn reload(args: Cli, fswatcher: Arc<Mutex<notify::RecommendedWatcher>>) {
             }
             eprintln!("Successful reload of {}", args.path.display());
         });
+    } else if !r.has_error() {
+        match &args.component {
+            Some(name) => println!("Component {name} not found"),
+            None => println!("No component found"),
+        }
     }
 
     PENDING_EVENTS.fetch_sub(1, Ordering::SeqCst);