cranpose_ui/widgets/
icon.rs

1//! Generic vector icons and clickable icon buttons.
2
3use cranpose_core::{NodeId, rememberKeyed};
4use cranpose_ui_graphics::{Brush, Color, VectorPath};
5use cranpose_ui_layout::Alignment;
6
7use crate::{
8    Modifier, SemanticsWidgetRole, Size, composable,
9    interaction::{MutableInteractionSource, rememberMutableInteractionSource},
10    widgets::{Box, BoxSpec},
11};
12
13/// The coordinate system every icon path is authored in.
14const ICON_VIEW_BOX: f32 = 24.0;
15
16/// The size an icon is drawn at when the caller states none.
17pub const DEFAULT_ICON_SIZE: f32 = 24.0;
18
19/// The smallest square a pointer target may be.
20///
21/// Every platform's accessibility guidance lands on the same number, and it is
22/// why an icon button is bigger than its icon: the glyph is 24dp and the target
23/// around it is 48dp, so a 24dp icon is still comfortable to hit.
24pub const MINIMUM_TOUCH_TARGET: f32 = 48.0;
25
26/// How an icon is drawn.
27#[derive(Clone, Copy, Debug, PartialEq)]
28pub struct IconSpec {
29    /// The square the icon is drawn in.
30    pub size: f32,
31    /// The tint. `None` leaves the path's own colouring, which is what a
32    /// multi-colour illustration wants.
33    pub tint: Option<Color>,
34}
35
36impl Default for IconSpec {
37    fn default() -> Self {
38        Self {
39            size: DEFAULT_ICON_SIZE,
40            tint: None,
41        }
42    }
43}
44
45impl IconSpec {
46    /// An icon of `size`, untinted.
47    pub const fn sized(size: f32) -> Self {
48        Self { size, tint: None }
49    }
50
51    /// Sets the drawn size.
52    pub const fn with_size(mut self, size: f32) -> Self {
53        self.size = size;
54        self
55    }
56
57    /// Sets the tint.
58    pub const fn with_tint(mut self, tint: Color) -> Self {
59        self.tint = Some(tint);
60        self
61    }
62}
63
64/// Draws an SVG path in the standard 24dp icon coordinate system.
65///
66/// An icon is decorative by default: it carries no content description, because
67/// the control around it names the action. Use [`IconWith`] to give a
68/// standalone icon a description a screen reader reads out.
69#[composable]
70pub fn Icon(
71    path: &'static str,
72    content_description: Option<String>,
73    size: f32,
74    color: Color,
75) -> NodeId {
76    IconWith(
77        Modifier::empty(),
78        path,
79        IconSpec::sized(size).with_tint(color),
80        content_description,
81    )
82}
83
84/// An icon with a modifier, a spec, and an optional content description.
85#[composable]
86pub fn IconWith(
87    modifier: Modifier,
88    path: &'static str,
89    spec: IconSpec,
90    content_description: Option<String>,
91) -> NodeId {
92    let parsed = rememberKeyed(path, |value| VectorPath::parse(value).ok());
93    let size = spec.size;
94    let tint = spec.tint;
95    let modifier = modifier
96        .size(Size::new(size, size))
97        .draw_behind(move |scope| {
98            if let Some(path) = &parsed {
99                let scaled = path.scaled(size / ICON_VIEW_BOX);
100                match tint {
101                    Some(tint) => scope.draw_vector_path(&scaled, Brush::solid(tint)),
102                    None => {
103                        scope.draw_vector_path(&scaled, Brush::solid(Color(0.0, 0.0, 0.0, 1.0)));
104                    }
105                }
106            }
107        });
108    let modifier = match content_description {
109        Some(description) => modifier.semantics_spec(
110            cranpose_foundation::SemanticsSpec::new()
111                .content_description(description)
112                .role(SemanticsWidgetRole::Image),
113        ),
114        None => modifier,
115    };
116    Box(modifier, BoxSpec::default(), || {})
117}
118
119/// The colours an icon button paints itself with.
120#[derive(Clone, Copy, Debug, Default, PartialEq)]
121pub struct IconButtonColors {
122    /// The surface behind the icon at rest.
123    pub background: Option<Color>,
124    /// The surface while the button is held.
125    pub pressed_background: Option<Color>,
126    /// The surface while the button is disabled.
127    pub disabled_background: Option<Color>,
128}
129
130impl IconButtonColors {
131    /// Sets the resting surface.
132    pub const fn with_background(mut self, color: Color) -> Self {
133        self.background = Some(color);
134        self
135    }
136
137    /// Sets the held surface.
138    pub const fn with_pressed_background(mut self, color: Color) -> Self {
139        self.pressed_background = Some(color);
140        self
141    }
142
143    /// Sets the disabled surface.
144    pub const fn with_disabled_background(mut self, color: Color) -> Self {
145        self.disabled_background = Some(color);
146        self
147    }
148
149    fn surface(&self, enabled: bool, pressed: bool) -> Option<Color> {
150        if !enabled {
151            return self.disabled_background.or(self.background);
152        }
153        if pressed {
154            return self.pressed_background.or(self.background);
155        }
156        self.background
157    }
158}
159
160/// How an icon button behaves and looks.
161#[derive(Clone, Copy, Debug, PartialEq)]
162pub struct IconButtonSpec {
163    /// Whether the button accepts input. A disabled button still publishes
164    /// itself to a screen reader, which is how the user learns it exists.
165    pub enabled: bool,
166    /// The square the pointer target occupies, never smaller than
167    /// [`MINIMUM_TOUCH_TARGET`].
168    pub touch_target: f32,
169    /// The surfaces the button paints.
170    pub colors: IconButtonColors,
171}
172
173impl Default for IconButtonSpec {
174    fn default() -> Self {
175        Self {
176            enabled: true,
177            touch_target: MINIMUM_TOUCH_TARGET,
178            colors: IconButtonColors::default(),
179        }
180    }
181}
182
183impl IconButtonSpec {
184    /// Sets whether the button accepts input.
185    pub const fn with_enabled(mut self, enabled: bool) -> Self {
186        self.enabled = enabled;
187        self
188    }
189
190    /// Sets the pointer target size. Values below [`MINIMUM_TOUCH_TARGET`] are
191    /// raised to it: a control smaller than that is a control people miss.
192    pub fn with_touch_target(mut self, size: f32) -> Self {
193        self.touch_target = size.max(MINIMUM_TOUCH_TARGET);
194        self
195    }
196
197    /// Sets the surfaces.
198    pub const fn with_colors(mut self, colors: IconButtonColors) -> Self {
199        self.colors = colors;
200        self
201    }
202
203    /// The target size this spec actually uses.
204    pub fn resolved_touch_target(&self) -> f32 {
205        self.touch_target.max(MINIMUM_TOUCH_TARGET)
206    }
207}
208
209/// A semantic icon button with caller-provided content.
210#[composable]
211pub fn IconButton<F>(
212    modifier: Modifier,
213    content_description: impl Into<String>,
214    on_click: impl Fn() + 'static,
215    content: F,
216) -> NodeId
217where
218    F: FnMut() + 'static,
219{
220    IconButtonWith(
221        modifier,
222        content_description,
223        IconButtonSpec::default(),
224        None,
225        on_click,
226        content,
227    )
228}
229
230/// An icon button with an enabled state, colours, a touch target, and an
231/// interaction source the caller can observe.
232///
233/// Passing an interaction source is how a button's visual reacts to being held
234/// without the caller writing pointer handling: read
235/// [`MutableInteractionSource::collectIsPressedAsState`] in the content.
236#[composable]
237pub fn IconButtonWith<F>(
238    modifier: Modifier,
239    content_description: impl Into<String>,
240    spec: IconButtonSpec,
241    interaction_source: Option<MutableInteractionSource>,
242    on_click: impl Fn() + 'static,
243    content: F,
244) -> NodeId
245where
246    F: FnMut() + 'static,
247{
248    let description = content_description.into();
249    let enabled = spec.enabled;
250    let target = spec.resolved_touch_target();
251    let source = interaction_source.unwrap_or_else(rememberMutableInteractionSource);
252    let pressed = source.collectIsPressedAsState().get();
253
254    let mut modifier = modifier
255        .size(Size::new(target, target))
256        .press_interaction_source(source)
257        .semantics(move |config| {
258            config.content_description = Some(description.clone());
259            config.role = Some(SemanticsWidgetRole::Button);
260            config.enabled = enabled;
261            config.is_clickable = enabled;
262        });
263    if let Some(surface) = spec.colors.surface(enabled, pressed) {
264        modifier = modifier.background(surface);
265    }
266    if enabled {
267        modifier = modifier.clickable(move |_| on_click());
268    }
269
270    Box(
271        modifier,
272        BoxSpec::default().content_alignment(Alignment::CENTER),
273        content,
274    )
275}
276
277#[cfg(test)]
278#[path = "tests/icon_tests.rs"]
279mod tests;
cranpose_ui/widgets/icon.rs

cranpose_ui/widgets/
icon.rs
