repose_core/
view.rs

1use crate::{
2    BaselineShift, Brush, ClipOp, Color, DrawStyle, FontStyle, FontSynthesis, FontWeight, Modifier,
3    Rect, TextAlign, TextDecoration, TextDirection, TextSpan, Transform, Vec2,
4};
5use std::{fmt::Formatter, rc::Rc, sync::Arc};
6
7/// The constraints that will be passed to a subcomposed child. Values are in
8/// device-independent pixels (dp), matching the units used by `Modifier`.
9#[derive(Clone, Copy, Debug, PartialEq)]
10pub struct SubcomposeScope {
11    pub min_width: f32,
12    pub max_width: f32,
13    pub min_height: f32,
14    pub max_height: f32,
15}
16
17impl SubcomposeScope {
18    /// A scope with no constraints: unbounded in both dimensions. Use this as
19    /// a default when the parent constraints are not yet known.
20    pub const UNBOUNDED: Self = Self {
21        min_width: 0.0,
22        max_width: f32::INFINITY,
23        min_height: 0.0,
24        max_height: f32::INFINITY,
25    };
26
27    /// Construct a scope from raw min/max dp values.
28    pub fn new(min_width: f32, max_width: f32, min_height: f32, max_height: f32) -> Self {
29        Self {
30            min_width,
31            max_width,
32            min_height,
33            max_height,
34        }
35    }
36}
37
38/// Scope passed to [`BoxWithConstraints`](crate::prelude::BoxWithConstraints)
39/// content. All values are in dp.
40#[derive(Clone, Copy, Debug, PartialEq)]
41pub struct BoxWithConstraintsScope {
42    pub min_width: f32,
43    pub max_width: f32,
44    pub min_height: f32,
45    pub max_height: f32,
46}
47
48impl BoxWithConstraintsScope {
49    /// `true` if the width is bounded by the parent (i.e. not infinite).
50    pub fn has_bounded_width(&self) -> bool {
51        self.max_width.is_finite()
52    }
53
54    /// `true` if the height is bounded by the parent (i.e. not infinite).
55    pub fn has_bounded_height(&self) -> bool {
56        self.max_height.is_finite()
57    }
58}
59
60pub type ViewId = u64;
61
62pub type ImageHandle = u64;
63#[derive(Clone, Copy, Debug, PartialEq, Eq)]
64#[non_exhaustive]
65pub enum ImageFit {
66    /// ContentScale.Fit - default in Compose Image
67    Contain,
68    /// ContentScale.Crop
69    Cover,
70    /// ContentScale.FillWidth
71    FitWidth,
72    /// ContentScale.FillHeight
73    FitHeight,
74    /// ContentScale.FillBounds - stretch, ignore aspect
75    FillBounds,
76    /// ContentScale.Inside - like Contain but never upscales
77    Inside,
78    /// ContentScale.None - no scaling, top-left (alignment can offset later)
79    None,
80}
81
82pub type Callback = Rc<dyn Fn()>;
83
84#[derive(Clone)]
85pub struct OverlayEntry {
86    pub id: u64,
87    pub view: Box<View>,
88}
89
90#[derive(Clone)]
91#[non_exhaustive]
92pub enum ViewKind {
93    Box,
94    Row,
95    Column,
96    ZStack,
97    OverlayHost,
98    Text {
99        text: String,
100        color: Color,
101        font_size: f32,
102        soft_wrap: bool,
103        max_lines: Option<usize>,
104        overflow: TextOverflow,
105        font_family: Option<&'static str>,
106        annotations: Option<Arc<[TextSpan]>>,
107        text_align: TextAlign,
108        font_weight: FontWeight,
109        font_style: FontStyle,
110        text_decoration: TextDecoration,
111        letter_spacing: f32,
112        line_height: f32,
113        /// URL for clickable link text.
114        url: Option<Arc<str>>,
115        /// OpenType font variation settings (e.g. "wght 700, opsz 24").
116        font_variation_settings: Option<Arc<str>>,
117    },
118
119    Image {
120        handle: ImageHandle,
121        tint: Color, // multiplicative (WHITE = no tint)
122        fit: ImageFit,
123    },
124    /// A layout whose children are produced by calling `content` with the
125    /// current `SubcomposeScope`. The closure is invoked during reconciliation
126    /// and returns a list of `(slot_id, view)` pairs. Each slot id is a stable
127    /// identity used to reconcile the returned view across frames. This is
128    /// the building block for `BoxWithConstraints` and other
129    /// constraints-driven layouts.
130    ///
131    /// Note: any `Modifier::key` set on a returned view is overwritten by its
132    /// slot id so the slot's identity is stable across frames.
133    SubcomposeLayout {
134        content: Arc<dyn Fn(&SubcomposeScope) -> Vec<(u64, View)>>,
135    },
136    /// A collapsible section with a clickable header.
137    /// First child is the header content. Remaining children shown only when expanded.
138    Expander {
139        expanded: bool,
140        on_toggle: Option<Callback>,
141    },
142    /// A single row in a tree view with indentation and expand/select support.
143    /// First child is rendered as the row label/content.
144    TreeRow {
145        depth: usize,
146        has_children: bool,
147        is_expanded: bool,
148        is_selected: bool,
149        on_toggle: Option<Callback>,
150        on_select: Option<Callback>,
151    },
152}
153
154impl std::fmt::Debug for ViewKind {
155    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
156        match self {
157            Self::Box => f.write_str("Box"),
158            Self::Row => f.write_str("Row"),
159            Self::Column => f.write_str("Column"),
160            Self::ZStack => f.write_str("ZStack"),
161            Self::OverlayHost => f.write_str("OverlayHost"),
162
163            Self::Image { .. } => f.write_str("Image"),
164            Self::SubcomposeLayout { .. } => f.write_str("SubcomposeLayout"),
165            Self::Text { text, .. } => write!(f, "Text({:?})", text),
166
167            Self::Expander { expanded, .. } => {
168                if *expanded {
169                    write!(f, "Expander(expanded)")
170                } else {
171                    write!(f, "Expander(collapsed)")
172                }
173            }
174            Self::TreeRow {
175                depth,
176                has_children,
177                is_expanded,
178                is_selected,
179                ..
180            } => {
181                write!(
182                    f,
183                    "TreeRow(depth={}, children={}, expanded={}, selected={})",
184                    depth, has_children, is_expanded, is_selected
185                )
186            }
187        }
188    }
189}
190
191#[derive(Clone, Debug)]
192pub struct View {
193    pub id: ViewId,
194    pub kind: ViewKind,
195    pub modifier: Modifier,
196    pub children: Vec<View>,
197    pub semantics: Option<crate::semantics::Semantics>,
198    /// Set by `scope!` macro to mark this as a scope boundary node.
199    /// Carries the scope key (e.g., "title", "color_buttons") for per-scope
200    /// TaffyTree isolation.
201    pub scope_key: Option<String>,
202}
203
204impl View {
205    pub fn new(id: ViewId, kind: ViewKind) -> Self {
206        View {
207            id,
208            kind,
209            modifier: Modifier::default(),
210            children: vec![],
211            semantics: None,
212            scope_key: None,
213        }
214    }
215    pub fn modifier(mut self, m: Modifier) -> Self {
216        self.modifier = m;
217        self
218    }
219    /// Mark this view as disabled - ignores pointer events.
220    pub fn disabled(mut self) -> Self {
221        self.modifier.disabled = true;
222        self
223    }
224    pub fn with_children(mut self, kids: Vec<View>) -> Self {
225        self.children = kids;
226        self
227    }
228    pub fn children(mut self, kids: impl Into<Vec<View>>) -> Self {
229        self.children = kids.into();
230        self
231    }
232    pub fn semantics(mut self, s: crate::semantics::Semantics) -> Self {
233        self.semantics = Some(s);
234        self
235    }
236}
237
238/// Renderable scene
239#[derive(Clone, Debug, Default)]
240pub struct Scene {
241    pub clear_color: Color,
242    pub nodes: Vec<SceneNode>,
243}
244
245/// Rarely-tweaked text style properties bundled for ergonomic Default.
246#[derive(Clone, Debug, PartialEq)]
247pub struct TextExtraStyle {
248    pub text_direction: TextDirection,
249    pub font_synthesis: FontSynthesis,
250    pub baseline_shift: BaselineShift,
251    pub draw_style: DrawStyle,
252}
253
254impl Default for TextExtraStyle {
255    fn default() -> Self {
256        Self {
257            text_direction: TextDirection::Ltr,
258            font_synthesis: FontSynthesis::Unspecified,
259            baseline_shift: BaselineShift::Unspecified,
260            draw_style: DrawStyle::Fill,
261        }
262    }
263}
264
265#[derive(Clone, Debug)]
266#[non_exhaustive]
267pub enum SceneNode {
268    Rect {
269        rect: Rect,
270        brush: Brush,
271        radius: [f32; 4],
272    },
273    Border {
274        rect: Rect,
275        color: Color,
276        width: f32,
277        radius: [f32; 4],
278    },
279    Text {
280        rect: Rect,
281        text: Arc<str>,
282        color: Color,
283        size: f32,
284        font_family: Option<&'static str>,
285        text_align: TextAlign,
286        font_weight: FontWeight,
287        font_style: FontStyle,
288        text_decoration: TextDecoration,
289        letter_spacing: f32,
290        line_height: f32,
291        /// Rarely-tweaked style properties, bundled for ergonomic Default.
292        extra_style: TextExtraStyle,
293        /// URL for clickable link text.
294        url: Option<Arc<str>>,
295        /// OpenType font variation settings (e.g. "wght 700, opsz 24").
296        font_variation_settings: Option<Arc<str>>,
297    },
298    Ellipse {
299        rect: Rect,
300        brush: Brush,
301    },
302    EllipseBorder {
303        rect: Rect,
304        color: Color,
305        width: f32, // screen-space width (px)
306    },
307    PushClip {
308        rect: Rect,
309        radius: [f32; 4],
310        op: ClipOp,
311    },
312    PopClip,
313    PushTransform {
314        transform: Transform,
315    },
316    PopTransform,
317    Image {
318        rect: Rect,
319        handle: ImageHandle,
320        tint: Color,
321        fit: ImageFit,
322    },
323    /// Shadow behind a rounded rect, typically driven by `StateElevation`.
324    /// The `elevation` field controls offset and alpha.
325    Shadow {
326        rect: Rect,
327        radius: [f32; 4],
328        elevation: f32,
329        color: Color,
330    },
331    /// Mark the start of a graphics layer: the contained subtree is rendered
332    /// into an offscreen texture and then composited back into the parent.
333    /// `alpha` is the group-compositing alpha applied at composite time.
334    /// `blur_radius_x` / `blur_radius_y` are the gaussian blur radii in pixels
335    /// applied to the layer before compositing (0.0 = no blur on that axis).
336    /// `rectangle_edge` true = clamp edge pixels (Rectangle). False = transparent out-of-bounds (Unbounded).
337    BeginLayer {
338        rect: Rect,
339        layer_id: u32,
340        alpha: f32,
341        blur_radius_x: f32,
342        blur_radius_y: f32,
343        rectangle_edge: bool,
344    },
345    /// Closes the graphics layer opened by the matching `BeginLayer`.
346    EndLayer {
347        layer_id: u32,
348    },
349    /// Draws a blurred drop shadow underneath a previously-rendered layer.
350    /// Emitted between `EndLayer` and the layer's `CompositeLayer`. The
351    /// quad samples the layer's texture with a 3x3 Gaussian blur and an
352    /// optional vertical offset.
353    CompositeShadow {
354        layer_id: u32,
355        blur_px: f32,
356        offset_px: (f32, f32),
357        color: Color,
358    },
359    /// Arc stroke
360    Arc {
361        rect: Rect,
362        start_angle: f32,
363        sweep_angle: f32,
364        stroke_width: f32,
365        color: Color,
366        cap: StrokeCap,
367    },
368    /// Pre-tessellated vector mesh (fill or stroke geometry produced by the
369    /// host, e.g. lyon tessellation). Vertices live in the mesh's own local
370    /// space; `transform` is a 2x3 affine that maps local -> world pixels and
371    /// is applied in the vertex shader. The current scene `PushTransform`
372    /// stack is folded in on top of `transform`.
373    VectorMesh {
374        mesh: Arc<VectorMeshData>,
375        transform: [f32; 6],
376        paint: PaintDesc,
377        /// Reserved for explicit clip assignment. Clipping is otherwise
378        /// structural via `PushVectorClip`/`PopVectorClip`.
379        clip: Option<u32>,
380        blend: BlendMode,
381    },
382    /// Screen-space overlays (handles, rubber bands, playhead). Each mesh
383    /// is positioned in final device pixels and ignores the world
384    /// PushTransform stack. Emit outside the viewport's world transform.
385    VectorOverlay {
386        meshes: Arc<[VectorMeshData]>,
387    },
388    /// Start a vector clip: the mesh is rendered into the stencil buffer
389    /// (increment) and subsequent content is masked to it. Mirrors the
390    /// rect-based `PushClip` but for arbitrary tessellated masks.
391    PushVectorClip {
392        mesh: Arc<VectorMeshData>,
393    },
394    /// End a vector clip opened by `PushVectorClip`.
395    PopVectorClip,
396}
397
398/// Shared vertex/index buffers for a tessellated vector mesh.
399#[derive(Clone, Debug, Default)]
400pub struct VectorMeshData {
401    pub vertices: Arc<[VectorVertex]>,
402    pub indices: Arc<[u32]>,
403}
404
405/// Pre-tessellated vertex: local position, premultiplied-linear color, and a
406/// free-form uv channel (unused for solid fills, reserved for texture/gradient
407/// sampling).
408#[derive(Clone, Copy, Debug, PartialEq)]
409#[repr(C)]
410pub struct VectorVertex {
411    pub pos: [f32; 2],
412    pub color: [f32; 4],
413    pub uv: [f32; 2],
414}
415
416/// How a `VectorMesh` is painted.
417#[derive(Clone, Copy, Debug, PartialEq)]
418#[non_exhaustive]
419pub enum PaintDesc {
420    /// Use per-vertex color.
421    Solid,
422    /// Two-stop linear gradient in the mesh's local space.
423    Linear {
424        start: Vec2,
425        end: Vec2,
426        start_color: Color,
427        end_color: Color,
428    },
429}
430
431/// Blend mode for a `VectorMesh`. Only `Alpha` (premultiplied alpha) is wired
432/// into the renderer today. The remaining variants are reserved.
433#[derive(Clone, Copy, Debug, PartialEq, Eq)]
434#[non_exhaustive]
435#[derive(Default)]
436pub enum BlendMode {
437    /// Standard premultiplied alpha blending.
438    #[default]
439    Alpha,
440    /// Additive (screen-space light). Not yet implemented.
441    Add,
442    /// Multiply. Not yet implemented.
443    Multiply,
444    /// Overlay. Not yet implemented.
445    Overlay,
446}
447
448#[derive(Clone, Copy, Debug, PartialEq, Eq)]
449#[non_exhaustive]
450pub enum TextOverflow {
451    Visible,
452    Clip,
453    Ellipsis,
454}
455
456/// Controls how line segments are joined in a stroked path.
457#[derive(Clone, Copy, Debug, PartialEq, Default)]
458pub enum StrokeJoin {
459    #[default]
460    /// Sharp corner joins.
461    Miter,
462    /// Semi-circular joins.
463    Round,
464    /// Beveled (flat) joins.
465    Bevel,
466}
467
468/// Controls how the endpoints of a stroked arc are drawn.
469#[derive(Clone, Copy, Debug, PartialEq, Default)]
470pub enum StrokeCap {
471    #[default]
472    /// Flat ends at the exact arc endpoint. No extension.
473    Butt,
474    /// Semicircle with diameter equal to the stroke width, centered at the
475    /// arc endpoint.
476    Round,
477    /// Flat-ended rectangle extending half the stroke width beyond the arc
478    /// endpoint.
479    Square,
480}
481
482#[cfg(test)]
483mod tests {
484    use super::*;
485
486    #[test]
487    fn subcompose_scope_unbounded_has_infinite_max() {
488        let s = SubcomposeScope::UNBOUNDED;
489        assert!(!s.max_width.is_finite());
490        assert!(!s.max_height.is_finite());
491        assert_eq!(s.min_width, 0.0);
492        assert_eq!(s.min_height, 0.0);
493    }
494
495    #[test]
496    fn subcompose_scope_new_round_trips() {
497        let s = SubcomposeScope::new(10.0, 200.0, 20.0, 300.0);
498        assert_eq!(s.min_width, 10.0);
499        assert_eq!(s.max_width, 200.0);
500        assert_eq!(s.min_height, 20.0);
501        assert_eq!(s.max_height, 300.0);
502    }
503
504    #[test]
505    fn box_with_constraints_scope_bounded_predicates() {
506        let bounded = BoxWithConstraintsScope {
507            min_width: 0.0,
508            max_width: 360.0,
509            min_height: 0.0,
510            max_height: 640.0,
511        };
512        assert!(bounded.has_bounded_width());
513        assert!(bounded.has_bounded_height());
514
515        let unbounded = BoxWithConstraintsScope {
516            min_width: 0.0,
517            max_width: f32::INFINITY,
518            min_height: 0.0,
519            max_height: f32::INFINITY,
520        };
521        assert!(!unbounded.has_bounded_width());
522        assert!(!unbounded.has_bounded_height());
523    }
524
525    #[test]
526    fn view_kind_subcompose_layout_holds_closure() {
527        let v: View = View {
528            id: 0,
529            kind: ViewKind::SubcomposeLayout {
530                content: std::sync::Arc::new(|scope| {
531                    let _ = scope.max_width;
532                    vec![(0, View::new(0, ViewKind::Box))]
533                }),
534            },
535            modifier: Modifier::default(),
536            children: vec![],
537            scope_key: None,
538            semantics: None,
539        };
540        match &v.kind {
541            ViewKind::SubcomposeLayout { .. } => {}
542            _ => panic!("expected SubcomposeLayout"),
543        }
544    }
545
546    #[test]
547    fn view_kind_subcompose_layout_supports_multiple_slots() {
548        let v: View = View {
549            id: 0,
550            kind: ViewKind::SubcomposeLayout {
551                content: std::sync::Arc::new(|_scope| {
552                    vec![
553                        (1, View::new(0, ViewKind::Box)),
554                        (2, View::new(0, ViewKind::Box)),
555                        (3, View::new(0, ViewKind::Box)),
556                    ]
557                }),
558            },
559            modifier: Modifier::default(),
560            children: vec![],
561            scope_key: None,
562            semantics: None,
563        };
564        if let ViewKind::SubcomposeLayout { content } = &v.kind {
565            let slots = content(&SubcomposeScope::UNBOUNDED);
566            assert_eq!(slots.len(), 3);
567            assert_eq!(slots[0].0, 1);
568            assert_eq!(slots[1].0, 2);
569            assert_eq!(slots[2].0, 3);
570        } else {
571            panic!("expected SubcomposeLayout");
572        }
573    }
574}
repose_core/view.rs

repose_core/
view.rs
