i_slint_compiler/passes/
lower_property_to_element.rs

1// Copyright © SixtyFPS GmbH <info@slint.dev>
2// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-2.0 OR LicenseRef-Slint-Software-3.0
3
4//! Pass that lowers synthetic properties such as `opacity` and `layer` properties to their corresponding elements.
5//! For example `f := Foo { opacity: <some float>; }` is mapped to `Opacity { opacity <=> f.opacity; f := Foo { ... } }`
6
7use crate::diagnostics::BuildDiagnostics;
8use crate::expression_tree::{BindingExpression, Expression, NamedReference};
9use crate::langtype::Type;
10use crate::object_tree::{self, Component, Element, ElementRc};
11use crate::typeregister::TypeRegister;
12use smol_str::{format_smolstr, SmolStr, ToSmolStr};
13use std::rc::Rc;
14
15/// If any element in `component` declares a binding to `property_name`, then a new
16/// element of type `element_name` is created, injected as a parent to the element and bindings
17/// to property_name and all properties in  extra_properties are mapped.
18/// Default value for the property extra_properties is queried with the `default_value_for_extra_properties`
19pub(crate) fn lower_property_to_element(
20    component: &Rc<Component>,
21    property_name: &'static str,
22    extra_properties: impl Iterator<Item = &'static str> + Clone,
23    default_value_for_extra_properties: Option<&dyn Fn(&ElementRc, &str) -> Expression>,
24    element_name: &SmolStr,
25    type_register: &TypeRegister,
26    diag: &mut BuildDiagnostics,
27) {
28    if let Some(b) = component.root_element.borrow().bindings.get(property_name) {
29        diag.push_warning(
30            format!(
31                "The {property_name} property cannot be used on the root element, it will not be applied"
32            ),
33            &*b.borrow(),
34        );
35    }
36
37    object_tree::recurse_elem_including_sub_components_no_borrow(component, &(), &mut |elem, _| {
38        if elem.borrow().base_type.to_smolstr() == *element_name {
39            return;
40        }
41
42        let old_children = {
43            let mut elem = elem.borrow_mut();
44            let new_children = Vec::with_capacity(elem.children.len());
45            std::mem::replace(&mut elem.children, new_children)
46        };
47
48        let has_property_binding = |e: &ElementRc| {
49            e.borrow().base_type.lookup_property(property_name).property_type != Type::Invalid
50                && (e.borrow().bindings.contains_key(property_name)
51                    || e.borrow()
52                        .property_analysis
53                        .borrow()
54                        .get(property_name)
55                        .is_some_and(|a| a.is_set || a.is_linked))
56        };
57
58        for mut child in old_children {
59            if child.borrow().repeated.is_some() {
60                let root_elem = child.borrow().base_type.as_component().root_element.clone();
61                if has_property_binding(&root_elem) {
62                    object_tree::inject_element_as_repeated_element(
63                        &child,
64                        create_property_element(
65                            &root_elem,
66                            property_name,
67                            extra_properties.clone(),
68                            default_value_for_extra_properties,
69                            element_name,
70                            type_register,
71                        ),
72                    )
73                }
74            } else if has_property_binding(&child) {
75                let new_child = create_property_element(
76                    &child,
77                    property_name,
78                    extra_properties.clone(),
79                    default_value_for_extra_properties,
80                    element_name,
81                    type_register,
82                );
83                crate::object_tree::adjust_geometry_for_injected_parent(&new_child, &child);
84                new_child.borrow_mut().children.push(child);
85                child = new_child;
86            }
87
88            elem.borrow_mut().children.push(child);
89        }
90    });
91}
92
93fn create_property_element(
94    child: &ElementRc,
95    property_name: &'static str,
96    extra_properties: impl Iterator<Item = &'static str>,
97    default_value_for_extra_properties: Option<&dyn Fn(&ElementRc, &str) -> Expression>,
98    element_name: &SmolStr,
99    type_register: &TypeRegister,
100) -> ElementRc {
101    let bindings = core::iter::once(property_name)
102        .chain(extra_properties)
103        .map(|property_name| {
104            let mut bind =
105                BindingExpression::new_two_way(NamedReference::new(child, property_name.into()));
106            if let Some(default_value_for_extra_properties) = default_value_for_extra_properties {
107                if !child.borrow().bindings.contains_key(property_name) {
108                    bind.expression = default_value_for_extra_properties(child, property_name)
109                }
110            }
111            (property_name.into(), bind.into())
112        })
113        .collect();
114
115    let element = Element {
116        id: format_smolstr!("{}-{}", child.borrow().id, property_name),
117        base_type: type_register.lookup_element(element_name).unwrap(),
118        enclosing_component: child.borrow().enclosing_component.clone(),
119        bindings,
120        ..Default::default()
121    };
122    element.make_rc()
123}
i_slint_compiler/passes/lower_property_to_element.rs

i_slint_compiler/passes/
lower_property_to_element.rs
