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::{PropertyLookupMode, Type};
10use crate::object_tree::{self, Component, Element, ElementRc};
11use crate::typeregister::TypeRegister;
12use smol_str::{SmolStr, ToSmolStr, format_smolstr};
13use std::rc::Rc;
14
15/// If any element in `component` declares a binding to any of `property_names`, then a new
16/// element of type `element_name` is created, injected as a parent to the element and bindings
17/// to all properties in property_names and 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_names: impl Iterator<Item = &'static str> + Clone,
22    extra_properties: impl Iterator<Item = &'static str> + Clone,
23    default_value_for_extra_properties: Option<&dyn Fn(&ElementRc, &str) -> Option<Expression>>,
24    element_name: &SmolStr,
25    type_register: &TypeRegister,
26    diag: &mut BuildDiagnostics,
27) {
28    for property_name in property_names.clone() {
29        if let Some(b) = component.root_element.borrow().binding(property_name) {
30            diag.push_warning(
31                format!(
32                    "The {property_name} property cannot be used on the root element, it will not be applied"
33                ),
34                &*b,
35            );
36        }
37    }
38
39    object_tree::recurse_elem_including_sub_components_no_borrow(component, &(), &mut |elem, _| {
40        if elem.borrow().base_type.to_smolstr() == *element_name {
41            return;
42        }
43
44        let old_children = {
45            let mut elem = elem.borrow_mut();
46            let new_children = Vec::with_capacity(elem.children.len());
47            std::mem::replace(&mut elem.children, new_children)
48        };
49
50        let has_property_binding = |e: &ElementRc| {
51            property_names.clone().any(|property_name| {
52                e.borrow()
53                    .base_type
54                    .lookup_property(property_name, PropertyLookupMode::ComponentLocal)
55                    .property_type
56                    != Type::Invalid
57                    && (e.borrow().binding(property_name).is_some()
58                        || e.borrow()
59                            .property_analysis
60                            .borrow()
61                            .get(property_name)
62                            .is_some_and(|a| a.is_set || a.is_linked))
63            })
64        };
65
66        for mut child in old_children {
67            if child.borrow().repeated.is_some() {
68                let root_elem = child.borrow().base_type.as_component().root_element.clone();
69                if has_property_binding(&root_elem) {
70                    object_tree::inject_element_as_repeated_element(
71                        &child,
72                        create_property_element(
73                            &root_elem,
74                            property_names.clone().chain(extra_properties.clone()),
75                            default_value_for_extra_properties,
76                            element_name,
77                            type_register,
78                        ),
79                    )
80                }
81            } else if has_property_binding(&child) {
82                let new_child = create_property_element(
83                    &child,
84                    property_names.clone().chain(extra_properties.clone()),
85                    default_value_for_extra_properties,
86                    element_name,
87                    type_register,
88                );
89                crate::object_tree::adjust_geometry_for_injected_parent(&new_child, &child);
90                new_child.borrow_mut().children.push(child);
91                child = new_child;
92            }
93
94            elem.borrow_mut().children.push(child);
95        }
96    });
97}
98
99fn create_property_element(
100    child: &ElementRc,
101    properties: impl Iterator<Item = &'static str>,
102    default_value_for_extra_properties: Option<&dyn Fn(&ElementRc, &str) -> Option<Expression>>,
103    element_name: &SmolStr,
104    type_register: &TypeRegister,
105) -> ElementRc {
106    let bindings = properties
107        .map(|property_name| {
108            let property_name = SmolStr::new_static(property_name);
109            let mut bind = BindingExpression::new_two_way(
110                NamedReference::new(child, property_name.clone()).into(),
111            );
112            if let Some(default_value_for_extra_properties) = default_value_for_extra_properties
113                && child.borrow().binding(&property_name).is_none()
114                && let Some(e) = default_value_for_extra_properties(child, &property_name)
115            {
116                bind.expression = e;
117            }
118            (property_name, bind.into())
119        })
120        .collect();
121
122    let element = Element {
123        id: format_smolstr!("{}-{}", child.borrow().id, element_name),
124        base_type: type_register.lookup_element(element_name).unwrap(),
125        enclosing_component: child.borrow().enclosing_component.clone(),
126        bindings,
127        is_injected_wrapper_element: true,
128        ..Default::default()
129    };
130    element.make_rc()
131}
132
133pub fn transform_property_default_value(
134    element: &ElementRc,
135    property_name: &str,
136) -> Option<Expression> {
137    let transform_origin = crate::typeregister::transform_origin_property();
138
139    let prop_div_2 = |prop: &str| Expression::BinaryExpression {
140        lhs: Expression::PropertyReference(NamedReference::new(element, prop.into())).into(),
141        op: '/',
142        rhs: Expression::NumberLiteral(2., Default::default()).into(),
143        source_location: None,
144    };
145
146    match property_name {
147        "transform-origin" => Some(Expression::Struct {
148            ty: transform_origin.1.clone(),
149            values: [
150                (SmolStr::new_static("x"), prop_div_2("width")),
151                (SmolStr::new_static("y"), prop_div_2("height")),
152            ]
153            .into_iter()
154            .collect(),
155        }),
156        "transform-scale-x" | "transform-scale-y" => {
157            if element.borrow().is_binding_set("transform-scale", true) {
158                Some(Expression::PropertyReference(NamedReference::new(
159                    element,
160                    SmolStr::new_static("transform-scale"),
161                )))
162            } else {
163                Some(Expression::NumberLiteral(1., Default::default()))
164            }
165        }
166        "transform-scale" => None,
167        "transform-rotation" => Some(Expression::NumberLiteral(0., Default::default())),
168        _ => unreachable!(),
169    }
170}
171
172/// Wrapper around lower_property_to_element for the Transform element
173pub fn lower_transform_properties(
174    component: &Rc<Component>,
175    tr: &TypeRegister,
176    diag: &mut BuildDiagnostics,
177) {
178    let transform_origin = crate::typeregister::transform_origin_property();
179
180    lower_property_to_element(
181        component,
182        crate::typeregister::RESERVED_TRANSFORM_PROPERTIES.iter().map(|(prop_name, _)| *prop_name),
183        std::iter::once(transform_origin.0),
184        Some(&|e, prop| transform_property_default_value(e, prop)),
185        &SmolStr::new_static("Transform"),
186        tr,
187        diag,
188    );
189}
i_slint_compiler/passes/lower_property_to_element.rs

i_slint_compiler/passes/
lower_property_to_element.rs
