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|
//! A retained node tree, painted immediately.
//!
//! The push/pop half of this ABI (`vidya_card_begin` … `vidya_card_end`) suits
//! a caller that writes its UI out top to bottom every frame. A *reactive*
//! caller does not: glimmer keeps a component tree, reconciles it against new
//! hiccup, and emits create/patch/append/remove against whatever the toolkit
//! calls a widget. GTK has widgets to hand it; egui has none.
//!
//! So this module is the widget layer glimmer expects, on the Rust side of the
//! FFI. The caller gets integer node handles and mutates them — set a prop,
//! append a child, drop a subtree. Nothing is drawn by those calls. Once a
//! frame, [`Tree::paint`] walks the whole tree and emits the egui calls it
//! describes, and interactions come back out as a queue of events the caller
//! drains and routes to its own handlers.
//!
//! Two things fall out of that split that the push/pop ABI could not have:
//!
//! * **Closure-shaped egui APIs work.** `ScrollArea`, `Frame` and friends take
//! an `FnOnce(&mut Ui)` and keep their `begin`/`end` private, which is why
//! `vidya_page_begin` had to reimplement scrolling by hand and why the page
//! was documented as non-scrolling. Painting from a tree we already hold
//! means the recursion *is* the closure; nothing has to stay open across a
//! call boundary.
//! * **FFI traffic tracks edits, not frames.** A static UI at 60fps costs zero
//! crossings per frame; only what the reconciler actually changed is sent.
//!
//! The tree deliberately knows nothing about egui until [`Tree::paint`], so the
//! arena and its edit operations are unit-testable with no window.
use std::collections::HashMap;
use std::collections::VecDeque;
use egui::{Align, Align2, Color32, FontId, Id, Layout, Margin, TextureOptions, Ui, Vec2};
use vidya_core::Theme;
/// A prop value. The three types the ABI can carry, and all glimmer needs:
/// keywords and colours arrive as strings, numbers as doubles, flags as ints.
#[derive(Clone, Debug, PartialEq)]
pub enum Value {
Str(String),
Num(f64),
Bool(bool),
}
/// What a node renders as. Unknown tags are kept rather than rejected: they
/// paint as a plain vertical box, so a caller using a tag this backend has not
/// grown yet still sees its children instead of nothing.
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum Tag {
Window,
Box,
Page,
Card,
Frame,
Scroll,
Label,
Link,
Title,
Title2,
DimLabel,
Button,
CheckButton,
Entry,
Separator,
Spacer,
Progress,
Spinner,
Image,
Avatar,
Reaction,
/// One emoji, drawn from the pack and nothing else: no pill, no count, no
/// pointer. `Reaction` is the same glyph wearing a tally's clothes.
Emoji,
Status,
/// A tag this backend has not grown yet, keeping the name it was created
/// with so a dump answers what the caller actually asked for.
Unknown(String),
}
impl Tag {
/// Parse a hiccup tag name. `:hbox`/`:vbox` are the same box — the tag only
/// implies an orientation, which the caller sets as a prop.
fn parse(name: &str) -> Self {
match name {
"window" => Self::Window,
"box" | "hbox" | "vbox" => Self::Box,
"page" => Self::Page,
"card" => Self::Card,
"frame" => Self::Frame,
"scroll" => Self::Scroll,
"label" => Self::Label,
"link" => Self::Link,
"title" => Self::Title,
"title-2" => Self::Title2,
"dim-label" => Self::DimLabel,
"button" => Self::Button,
"checkbutton" | "checkbox" => Self::CheckButton,
"entry" => Self::Entry,
"separator" => Self::Separator,
"spacer" | "gap" => Self::Spacer,
"progress" => Self::Progress,
"spinner" => Self::Spinner,
"image" => Self::Image,
"avatar" => Self::Avatar,
"reaction" => Self::Reaction,
"emoji" => Self::Emoji,
"status" => Self::Status,
other => Self::Unknown(other.to_owned()),
}
}
/// The canonical name of a parsed tag: `:hbox` and `:vbox` both answer
/// `box`, since the orientation lives in a prop rather than in the tag.
fn name(&self) -> &str {
match self {
Self::Window => "window",
Self::Box => "box",
Self::Page => "page",
Self::Card => "card",
Self::Frame => "frame",
Self::Scroll => "scroll",
Self::Label => "label",
Self::Link => "link",
Self::Title => "title",
Self::Title2 => "title-2",
Self::DimLabel => "dim-label",
Self::Button => "button",
Self::CheckButton => "checkbutton",
Self::Entry => "entry",
Self::Separator => "separator",
Self::Spacer => "spacer",
Self::Progress => "progress",
Self::Spinner => "spinner",
Self::Image => "image",
Self::Avatar => "avatar",
Self::Reaction => "reaction",
Self::Emoji => "emoji",
Self::Status => "status",
Self::Unknown(name) => name,
}
}
}
/// One interaction, waiting to be drained by the caller.
///
/// Names match glimmer's handler props with the `on-` dropped: `click` pairs
/// with `:on-click`, `change` with `:on-change`, and so on. `text` and `num`
/// carry the payload the handler is called with, empty when it takes none.
#[derive(Clone, Debug, PartialEq)]
pub struct Event {
pub node: u32,
pub name: &'static str,
pub text: String,
pub num: f64,
}
/// One prop value as EDN. Numbers that happen to be whole print without a
/// trailing `.0`, since every number crossed the boundary as a double and
/// `{:spacing 8.0}` reads worse than `{:spacing 8}`.
fn write_value(value: &Value, out: &mut String) {
match value {
Value::Bool(b) => out.push_str(if *b { "true" } else { "false" }),
Value::Num(n) => {
if n.is_finite() && n.fract() == 0.0 && n.abs() < 1e15 {
out.push_str(&format!("{}", *n as i64));
} else if n.is_finite() {
out.push_str(&format!("{n}"));
} else {
// EDN has no infinity or NaN literal; say so rather than emit
// something no reader will take.
out.push_str("nil");
}
}
Value::Str(text) => {
out.push('"');
for c in text.chars() {
match c {
'"' => out.push_str("\\\""),
'\\' => out.push_str("\\\\"),
'\n' => out.push_str("\\n"),
'\r' => out.push_str("\\r"),
'\t' => out.push_str("\\t"),
_ => out.push(c),
}
}
out.push('"');
}
}
}
#[derive(Clone, Debug, Default)]
struct Node {
tag: Tag,
props: HashMap<String, Value>,
children: Vec<u32>,
/// 0 when unparented. The root's parent is 0 too, which is what stops the
/// ancestor walk in [`Tree::would_cycle`].
parent: u32,
}
impl Default for Tag {
fn default() -> Self {
Self::Unknown(String::new())
}
}
/// One named source of live pixels: what has arrived, and what is on the GPU.
#[derive(Default)]
struct Feed {
/// Pixels written since the last paint, waiting to be uploaded. Taken (not
/// copied) by the paint that consumes them.
pending: Option<egui::ColorImage>,
/// The texture the last upload produced. Kept when nothing new arrives, so
/// a still source keeps painting instead of blinking out between frames.
texture: Option<egui::TextureHandle>,
}
/// The node arena.
///
/// Handles are `index + 1`, so 0 is always "no node" — the value C gets back
/// from a failed allocation and the sibling argument that means "first".
/// Freed slots are reused, so a list that churns rows does not grow the arena.
pub struct Tree {
nodes: Vec<Option<Node>>,
free: Vec<u32>,
root: u32,
/// Decoded images, by the path they came from. An `:image` node is walked
/// every frame and must not decode a file every time.
textures: HashMap<String, Option<egui::TextureHandle>>,
/// Live pixels pushed in by name, for an `:image` with a `feed` rather
/// than a `src`. A caller that has frames of its own — a camera, a video
/// decoder, a renderer — writes them here and the tag paints the latest.
///
/// Two halves, because the writer is not in a frame and the uploader is:
/// `pending` is what arrived since the last paint, `texture` is what was
/// uploaded from it. A frame that arrives twice between paints overwrites
/// the first, so a 30fps source cannot outrun a 60fps window into a queue.
feeds: HashMap<String, Feed>,
/// The width a centred row measured last frame, by node id. A row is
/// indented to the middle of the space it is given, and nothing here
/// knows how wide it is until it has been painted once — so the previous
/// frame's width is what the indent is computed from. Kept here rather
/// than written back onto the node: props are cleared and rewritten on
/// every re-render, and a row would jump to the left edge for a frame on
/// every keystroke typed into it.
row_widths: HashMap<u32, f32>,
/// The node the pointer is over, so that starting and ending a hover can
/// be told apart from being in the middle of one. Only one node is
/// hovered at a time — the innermost one that senses it.
hovered: Option<u32>,
/// Set while the children of a hovered node are being painted into the
/// panel beside the pointer. What is painted there does not report hovers
/// of its own: the panel sits under the pointer, so a face on the card
/// would take the hover away from the face the card is about, and the
/// card would close itself the moment it opened.
in_hover_panel: bool,
pending: VecDeque<Event>,
/// The event most recently dequeued by `poll`, whose fields the accessors
/// read. Held here so the ABI can return a payload without out-parameters.
current: Option<Event>,
}
/// A stable colour for a name: the same person is the same colour every time,
/// and two people are unlikely to share one. Kept dark enough for the light
/// text drawn on top and dull enough not to compete with the accent.
fn name_colour(name: &str, theme: &Theme) -> Color32 {
let mut hash: u32 = 2166136261;
for b in name.as_bytes() {
hash ^= *b as u32;
hash = hash.wrapping_mul(16777619);
}
// Six hues around the wheel, at a fixed saturation and value, rather than
// free RGB: random channels give muddy colours as often as good ones.
let sector = (hash % 6) as f32;
let (r, g, b) = match sector as u32 {
0 => (0.80, 0.35, 0.35),
1 => (0.80, 0.55, 0.25),
2 => (0.45, 0.65, 0.35),
3 => (0.30, 0.60, 0.65),
4 => (0.40, 0.50, 0.80),
_ => (0.65, 0.40, 0.70),
};
let _ = theme;
Color32::from_rgb((r * 255.0) as u8, (g * 255.0) as u8, (b * 255.0) as u8)
}
impl Tree {
/// Whether anything under `id` has `:scroll-here` set this frame.
///
/// Walked rather than remembered: the prop is set for the moment of a jump
/// and taken off again, so there is nothing to keep, and this runs once
/// per scroll area rather than once per node.
fn wants_scroll_to(&self, id: u32) -> bool {
let Some(node) = self.slot(id) else {
return false;
};
matches!(node.props.get("scroll-here"), Some(Value::Bool(true)))
|| node
.children
.iter()
.any(|child| self.wants_scroll_to(*child))
}
/// The texture for a file, decoding it the first time it is asked for.
/// A file that will not decode is remembered as such, so a bad path costs
/// one failed read rather than one per frame.
/// Hand the tree a frame of live pixels under `key`, to be painted by any
/// `:image` whose `feed` names it. `rgba` is `width * height * 4` bytes,
/// row-major, and is copied — the caller keeps ownership and may reuse the
/// buffer the moment this returns.
///
/// Rejects a frame whose length disagrees with its dimensions rather than
/// painting torn pixels: a capture path that changes resolution mid-stream
/// otherwise reads the tail of the old buffer as the head of the new one.
pub fn set_frame(&mut self, key: &str, width: u32, height: u32, rgba: &[u8]) -> bool {
if key.is_empty() || width == 0 || height == 0 {
return false;
}
let expected = (width as usize)
.saturating_mul(height as usize)
.saturating_mul(4);
if rgba.len() != expected {
return false;
}
let image =
egui::ColorImage::from_rgba_unmultiplied([width as usize, height as usize], rgba);
// Overwrites whatever had not been painted yet: the newest frame is
// the only one worth showing, and a backlog of stale ones is latency.
self.feeds.entry(key.to_owned()).or_default().pending = Some(image);
true
}
/// Forget a feed and release its texture. A call that ends leaves a tile
/// behind otherwise — the last frame of a participant who has gone.
pub fn drop_frame(&mut self, key: &str) -> bool {
self.feeds.remove(key).is_some()
}
/// The texture for a feed, uploading this paint's pending frame first.
fn feed_texture(&mut self, ui: &Ui, key: &str) -> Option<egui::TextureHandle> {
let feed = self.feeds.get_mut(key)?;
if let Some(image) = feed.pending.take() {
match feed.texture.as_mut() {
// `set` reuses the allocation when the size is unchanged,
// which is the whole point at video rates.
Some(texture) => texture.set(image, TextureOptions::LINEAR),
None => {
feed.texture = Some(ui.ctx().load_texture(
format!("vidya/tree/feed/{key}"),
image,
TextureOptions::LINEAR,
))
}
}
}
feed.texture.clone()
}
fn texture(&mut self, ui: &Ui, path: &str) -> Option<egui::TextureHandle> {
if let Some(cached) = self.textures.get(path) {
return cached.clone();
}
let handle = std::fs::read(path)
.ok()
.and_then(|bytes| decode_png_rgba(&bytes))
.map(|image| {
ui.ctx()
.load_texture(format!("vidya/tree/{path}"), image, TextureOptions::LINEAR)
});
self.textures.insert(path.to_owned(), handle.clone());
handle
}
}
/// PNG bytes as an egui image. PNG alone: it is what the vendored decoder
/// reads, and what the media this paints is served as.
fn decode_png_rgba(bytes: &[u8]) -> Option<egui::ColorImage> {
let mut decoder = png::Decoder::new(std::io::Cursor::new(bytes));
decoder.set_transformations(png::Transformations::EXPAND | png::Transformations::ALPHA);
let mut reader = decoder.read_info().ok()?;
let mut buf = vec![0; reader.output_buffer_size()];
let info = reader.next_frame(&mut buf).ok()?;
let (w, h) = (info.width as usize, info.height as usize);
let raw = &buf[..info.buffer_size()];
let rgba: Vec<u8> = match info.color_type {
png::ColorType::Rgba => raw.to_vec(),
png::ColorType::Rgb => raw
.as_chunks::<3>()
.0
.iter()
.flat_map(|c| [c[0], c[1], c[2], 255])
.collect(),
_ => return None,
};
(rgba.len() == w * h * 4).then(|| egui::ColorImage::from_rgba_unmultiplied([w, h], &rgba))
}
impl Default for Tree {
fn default() -> Self {
let mut tree = Self {
nodes: Vec::new(),
free: Vec::new(),
root: 0,
textures: HashMap::new(),
feeds: HashMap::new(),
row_widths: HashMap::new(),
hovered: None,
in_hover_panel: false,
pending: VecDeque::new(),
current: None,
};
tree.root = tree.new_node("window");
tree
}
}
impl Tree {
pub fn root(&self) -> u32 {
self.root
}
fn slot(&self, id: u32) -> Option<&Node> {
if id == 0 {
return None;
}
self.nodes.get(id as usize - 1).and_then(Option::as_ref)
}
fn slot_mut(&mut self, id: u32) -> Option<&mut Node> {
if id == 0 {
return None;
}
self.nodes.get_mut(id as usize - 1).and_then(Option::as_mut)
}
pub fn exists(&self, id: u32) -> bool {
self.slot(id).is_some()
}
// ── editing ─────────────────────────────────────────────────────────────
pub fn new_node(&mut self, tag: &str) -> u32 {
let node = Node {
tag: Tag::parse(tag),
..Node::default()
};
match self.free.pop() {
Some(id) => {
self.nodes[id as usize - 1] = Some(node);
id
}
None => {
self.nodes.push(Some(node));
self.nodes.len() as u32
}
}
}
/// Drop `id` and everything under it, unparenting it first.
///
/// glimmer has no separate destroy operation — `remove-child!` is the last
/// the reconciler ever says about a widget — so removal frees, and a node
/// handle the caller still holds after that is simply dead.
pub fn free_node(&mut self, id: u32) {
let parent = match self.slot(id) {
Some(n) => n.parent,
None => return,
};
self.detach(parent, id);
self.free_subtree(id);
}
fn free_subtree(&mut self, id: u32) {
let Some(node) = self.slot_mut(id).map(std::mem::take) else {
return;
};
self.nodes[id as usize - 1] = None;
self.free.push(id);
for child in node.children {
self.free_subtree(child);
}
// An event queued against a node that has since been removed would be
// routed to a handler the caller has already forgotten.
self.pending.retain(|e| e.node != id);
}
/// Unparent `child` without freeing it. `parent` may be 0 (already loose).
fn detach(&mut self, parent: u32, child: u32) {
if let Some(p) = self.slot_mut(parent) {
p.children.retain(|&c| c != child);
}
if let Some(c) = self.slot_mut(child) {
c.parent = 0;
}
}
/// True when parenting `child` under `parent` would make a loop — `child`
/// is `parent`, or an ancestor of it. A cycle here is an infinite paint,
/// so it is checked rather than trusted.
fn would_cycle(&self, parent: u32, child: u32) -> bool {
let mut at = parent;
while at != 0 {
if at == child {
return true;
}
at = match self.slot(at) {
Some(n) => n.parent,
None => 0,
};
}
false
}
pub fn append(&mut self, parent: u32, child: u32) -> bool {
self.insert_at(parent, child, usize::MAX)
}
fn insert_at(&mut self, parent: u32, child: u32, index: usize) -> bool {
if parent == 0 || child == 0 || !self.exists(parent) || !self.exists(child) {
return false;
}
if self.would_cycle(parent, child) {
return false;
}
// Moving a child that already has a parent (including this one) is a
// reparent, not a duplicate: take it out first so it appears once.
let old_parent = self.slot(child).map_or(0, |n| n.parent);
self.detach(old_parent, child);
let p = self.slot_mut(parent).expect("checked above");
let at = index.min(p.children.len());
p.children.insert(at, child);
self.slot_mut(child).expect("checked above").parent = parent;
true
}
pub fn remove(&mut self, parent: u32, child: u32) {
if self.slot(child).is_none_or(|n| n.parent != parent) {
return;
}
self.free_node(child);
}
/// Move `child` to sit immediately after `sibling`; `sibling` 0 means first.
/// glimmer's keyed reconciliation calls this to reorder a list without
/// rebuilding the widgets in it.
pub fn insert_after(&mut self, parent: u32, child: u32, sibling: u32) -> bool {
if !self.exists(parent) || !self.exists(child) {
return false;
}
let index = if sibling == 0 {
0
} else {
match self
.slot(parent)
.and_then(|p| p.children.iter().position(|&c| c == sibling))
{
// The sibling's own slot, once `child` is out of the way, is
// the position after it.
Some(i) => i + 1,
None => return false,
}
};
// Re-derive the index after detaching: removing `child` from earlier in
// the list shifts everything after it down one.
let before = self
.slot(parent)
.and_then(|p| p.children.iter().position(|&c| c == child))
.is_some_and(|i| i < index);
self.insert_at(parent, child, if before { index - 1 } else { index })
}
pub fn replace(&mut self, parent: u32, old: u32, new: u32) -> bool {
let Some(index) = self
.slot(parent)
.and_then(|p| p.children.iter().position(|&c| c == old))
else {
return false;
};
if !self.insert_at(parent, new, index) {
return false;
}
self.remove(parent, old);
true
}
/// The canonical tag name, or the empty string for a node that is not
/// there. With [`Tree::child_count`] and [`Tree::child_at`] this is enough
/// for a caller to read back the tree it built — which is how the jolt
/// backend's tests assert against a real reconcile with no window open.
pub fn tag_name(&self, id: u32) -> &str {
self.slot(id).map_or("", |n| n.tag.name())
}
pub fn child_count(&self, id: u32) -> usize {
self.slot(id).map_or(0, |n| n.children.len())
}
pub fn child_at(&self, id: u32, index: usize) -> u32 {
self.slot(id)
.and_then(|n| n.children.get(index))
.copied()
.unwrap_or(0)
}
// ── props ───────────────────────────────────────────────────────────────
pub fn set(&mut self, id: u32, key: &str, value: Value) {
if let Some(node) = self.slot_mut(id) {
node.props.insert(key.to_owned(), value);
}
}
pub fn clear_props(&mut self, id: u32) {
if let Some(node) = self.slot_mut(id) {
node.props.clear();
}
}
pub fn get(&self, id: u32, key: &str) -> Option<&Value> {
self.slot(id).and_then(|n| n.props.get(key))
}
// ── reading it back as hiccup ───────────────────────────────────────────
/// The subtree at `id` as pretty-printed hiccup, in the same shape the
/// caller wrote: `[:tag {props} children…]`, one node to a line.
///
/// This is what the tree *is*, not what a component said — it is read from
/// the arena after the reconciler has had its way with it, so a patch that
/// went to the wrong node shows up here as a difference from the source.
///
/// A node that does not exist dumps as `nil`. `:hbox` and `:vbox` both
/// dump as `:box`, as they are both stored as one; their orientation is in
/// the props. Handlers are not here — they never crossed the boundary.
pub fn dump(&self, id: u32) -> String {
let mut out = String::new();
self.dump_into(id, 0, &mut out);
out
}
fn dump_into(&self, id: u32, depth: usize, out: &mut String) {
let Some(node) = self.slot(id) else {
out.push_str("nil");
return;
};
let indent = " ".repeat(depth);
out.push_str("[:");
out.push_str(node.tag.name());
// Sorted, so two dumps of the same tree compare as text.
let mut keys: Vec<&String> = node.props.keys().collect();
keys.sort();
out.push_str(" {");
for (i, key) in keys.iter().enumerate() {
if i > 0 {
out.push(' ');
}
out.push(':');
out.push_str(key);
out.push(' ');
write_value(&node.props[*key], out);
}
out.push('}');
for child in &node.children {
out.push('\n');
out.push_str(&indent);
out.push_str(" ");
self.dump_into(*child, depth + 1, out);
}
out.push(']');
}
// ── events ──────────────────────────────────────────────────────────────
/// Report the edges of a pointer hover on `node`: "hover" when it starts,
/// "unhover" when it ends. One node is hovered at a time, so the previous
/// one is closed out here rather than needing a pass of its own — a
/// pointer that leaves an avatar for another emits both in one frame.
fn track_hover(&mut self, node: u32, response: &egui::Response) {
if self.in_hover_panel {
return;
}
if response.hovered() {
if self.hovered != Some(node) {
if let Some(was) = self.hovered {
self.emit(was, "unhover", String::new(), 0.0);
}
self.hovered = Some(node);
self.emit(node, "hover", String::new(), 0.0);
}
} else if self.hovered == Some(node) {
self.hovered = None;
self.emit(node, "unhover", String::new(), 0.0);
}
}
fn has_children(&self, id: u32) -> bool {
self.slot(id).is_some_and(|n| !n.children.is_empty())
}
fn emit(&mut self, node: u32, name: &'static str, text: String, num: f64) {
self.pending.push_back(Event {
node,
name,
text,
num,
});
}
/// Dequeue one event into the accessor slot. False when the queue is empty.
pub fn poll(&mut self) -> bool {
self.current = self.pending.pop_front();
self.current.is_some()
}
pub fn current(&self) -> Option<&Event> {
self.current.as_ref()
}
// ── painting ────────────────────────────────────────────────────────────
/// Emit the whole tree into `ui`. Called once per frame.
pub fn paint(&mut self, ui: &mut Ui, theme: &Theme) {
let root = self.root;
self.paint_node(root, ui, theme);
}
fn paint_children(&mut self, id: u32, ui: &mut Ui, theme: &Theme) {
// The child list is copied rather than borrowed: painting a child can
// write a prop back (an entry's text) or queue an event, both of which
// need `&mut self` while the walk is in flight. A UI's worth of `u32`s
// is a cheap price for not threading a cell through every widget.
let children = self
.slot(id)
.map(|n| n.children.clone())
.unwrap_or_default();
for child in children {
self.paint_node(child, ui, theme);
}
}
fn paint_node(&mut self, id: u32, ui: &mut Ui, theme: &Theme) {
let Some((tag, props)) = self
.slot(id)
.map(|n| (n.tag.clone(), Props(n.props.clone())))
else {
return;
};
let enabled = props.bool("sensitive", true);
// `:scroll-here` brings this node into view in whatever scroll area it
// sits in. It fires on every frame the prop is set, so a caller sets it
// for the moment of a jump and takes it off again — leaving it on would
// pin the area there and take scrolling away from the reader.
let scroll_here = props.bool("scroll-here", false);
let before = ui.cursor().top();
self.with_width(&props, ui, |tree, ui| {
if enabled {
tree.paint_tag(id, &tag, &props, ui, theme);
} else {
// Scoped rather than per-widget: a dimmed container dims its
// whole subtree, which is what `:sensitive false` means
// everywhere else in glimmer.
ui.add_enabled_ui(false, |ui| tree.paint_tag(id, &tag, &props, ui, theme));
}
});
if scroll_here {
// Horizontally the rect is the visible width, not the node's own:
// a rect wider than the viewport is off-screen sideways as far as
// egui is concerned, so it scrolls across to centre it and the
// reader lands on a message with its left edge cut off. Already
// visible on that axis means only the vertical scroll happens.
let clip = ui.clip_rect();
let rect = egui::Rect::from_min_max(
egui::pos2(clip.left(), before),
egui::pos2(clip.right(), ui.cursor().top()),
);
ui.scroll_to_rect(rect, Some(Align::Center));
}
}
/// Constrain `add` to the node's `:width-request`, when it has one.
///
/// Immediate mode has no natural width for a field: an entry asks for
/// whatever is left, so an entry beside a button in an `:hbox` takes the
/// row and wraps the button onto the next line. This is how a caller says
/// otherwise.
fn with_width(&mut self, props: &Props, ui: &mut Ui, add: impl FnOnce(&mut Self, &mut Ui)) {
let requested = props.num("width-request", 0.0) as f32;
let fill_height = props.bool("fill-height", false);
if requested <= 0.0 && !fill_height {
add(self, ui);
return;
}
let avail = ui.available_width().max(1.0);
let width = if requested > 0.0 {
requested.min(avail)
} else {
avail
};
// The height is the row's, not zero: a region allocated with no height
// leaves the row measuring nothing at the moment the next widget is
// placed, so a button beside a text field lands at the row's top edge
// instead of beside it.
//
// A column of a split is the other case. Inside a row, "what is left"
// is the row's own height — one button tall at the moment the column
// is placed — so a pane asking for it is allocated a strip, and the
// scrolling list inside it gets no room. `:fill-height` measures
// against what is visible below the cursor instead, the way `:scroll`
// does: everything from here to the bottom of the window.
//
// And `:reserve` bounds it the way it bounds a `:scroll`, for the same
// reason: everything to the bottom of the window is too much when
// something has to come after it. A column that takes the whole
// remainder pushes the row below it — a compose bar under a message
// list — against the bottom edge, whatever margin that row asked for.
// The number is what the caller knows: the height of what follows.
let height = if fill_height {
let reserve = props.num("reserve", 0.0) as f32;
((ui.clip_rect().bottom() - ui.cursor().top()) - reserve).max(0.0)
} else {
ui.available_height().max(0.0)
};
ui.allocate_ui_with_layout(
Vec2::new(width, height),
Layout::top_down(Align::Min),
|ui| {
ui.set_min_width(width);
ui.set_max_width(width);
add(self, ui);
},
);
}
fn paint_tag(&mut self, id: u32, tag: &Tag, props: &Props, ui: &mut Ui, theme: &Theme) {
match tag {
// The root is the window itself: its children stack down the page.
//
// Its width is written back onto it, the way an entry writes back
// its text: a caller laying out against the window — one pane on a
// phone, two side by side on a desktop — has no other way to ask
// how much room it has, since nothing else here measures.
Tag::Window => {
let width = ui.available_width().max(0.0) as f64;
self.set(id, "window-width", Value::Num(width));
self.paint_children(id, ui, theme)
}
Tag::Box | Tag::Unknown(_) => {
let horizontal = props.str("orientation") == "horizontal";
let spacing = props.num("spacing", theme.spacing.sm as f64) as f32;
self.with_margin(props, ui, |tree, ui| {
let axis = if horizontal {
Vec2::new(spacing, ui.spacing().item_spacing.y)
} else {
Vec2::new(ui.spacing().item_spacing.x, spacing)
};
if horizontal {
// `:align :end` lays the row out from the right edge of
// the space it is given, which is how a trailing group
// — an action beside a message, a count beside a name —
// sits against the right of a row rather than trailing
// whatever came before it.
if props.str("align") == "end" {
// Nested in a row of its own: a right-to-left
// layout takes the height available to it, which
// in a column is everything below — every such row
// would be as tall as the rest of the screen, and
// the gaps would land between the rows above it.
ui.horizontal(|ui| {
ui.with_layout(Layout::right_to_left(Align::Center), |ui| {
ui.spacing_mut().item_spacing = axis;
tree.paint_children(id, ui, theme);
});
});
} else if props.str("align") == "center" {
// `:align :center` puts a row on the middle of the
// width rather than against its left edge — what a
// compose bar wants on a window wider than the
// line being typed into it.
//
// Indented rather than laid out centred: egui
// places a row as it goes, and knows how wide it
// came out only once it is painted. The width it
// measured last frame is what the indent is
// computed from, which is exact for a row whose
// contents keep their size and one frame late for
// one that changes.
let last = tree.row_widths.get(&id).copied().unwrap_or(0.0);
ui.horizontal(|ui| {
let avail = ui.available_width();
ui.add_space(((avail - last) * 0.5).max(0.0));
let left = ui.cursor().min.x;
ui.spacing_mut().item_spacing = axis;
tree.paint_children(id, ui, theme);
let width = (ui.min_rect().max.x - left).max(0.0);
tree.row_widths.insert(id, width);
});
} else if props.bool("wrap", true) {
ui.horizontal_wrapped(|ui| {
ui.spacing_mut().item_spacing = axis;
tree.paint_children(id, ui, theme);
});
} else {
// `:wrap false` for a row whose children are
// columns rather than controls. A wrapped row moves
// a child that does not fit onto a line below,
// which is right for buttons beside a message and
// ruinous for the second half of a split: a pane
// asking for a few points more than are left is
// painted under the first one, off the bottom of
// the window, and reads as a pane that renders
// nothing at all.
ui.horizontal(|ui| {
ui.spacing_mut().item_spacing = axis;
tree.paint_children(id, ui, theme);
});
}
} else {
// `:align :center` puts a column's children on the
// middle of the width rather than against its left
// edge — what a picture on a screen of its own wants,
// and nothing a column of text ever does.
let cross = if props.str("align") == "center" {
Align::Center
} else {
Align::Min
};
ui.with_layout(Layout::top_down(cross), |ui| {
ui.spacing_mut().item_spacing = axis;
tree.paint_children(id, ui, theme);
});
}
});
}
// A scrolling column with page padding, optionally centred at a
// maximum width — the shell most Vidya apps put everything inside.
Tag::Page => {
let max_width = props.num("max-width", 0.0) as f32;
let pad = theme.spacing.page;
egui::ScrollArea::vertical()
.auto_shrink([false, false])
.show(ui, |ui| {
egui::Frame::new()
.inner_margin(Margin::same(pad.clamp(0.0, 127.0) as i8))
.show(ui, |ui| {
let avail = ui.available_width();
let width = if max_width > 0.0 {
max_width.min(avail)
} else {
avail
};
let indent = ((avail - width) * 0.5).max(0.0);
ui.horizontal(|ui| {
ui.add_space(indent);
ui.allocate_ui_with_layout(
Vec2::new(width, 0.0),
Layout::top_down(Align::Min),
|ui| {
ui.set_min_width(width);
ui.set_max_width(width);
vidya_core::vstack(ui, theme, |ui| {
self.paint_children(id, ui, theme);
});
},
);
});
});
});
}
Tag::Scroll => {
let area = match props.str("orientation") {
"horizontal" => egui::ScrollArea::horizontal(),
"both" => egui::ScrollArea::both(),
_ => egui::ScrollArea::vertical(),
};
// Without a bound a scroll area takes every point left in its
// parent, so anything after it — a compose bar under a message
// list — is pushed off the bottom. `:max-height` bounds it
// outright; `:reserve` bounds it by what it must leave behind,
// which is what a caller actually knows: the compose bar's
// height, not the window's.
let area = {
let reserve = props.num("reserve", 0.0) as f32;
let max_height = if reserve > 0.0 {
// Clamped against the clip rect as well as the layout's
// own idea of what is left: on Android the two differ
// once the soft keyboard takes the bottom of the
// screen, and it is the visible one that has to win or
// the row below the list is pushed off under the
// keyboard.
let visible = (ui.clip_rect().bottom() - ui.cursor().top()).max(0.0);
(ui.available_height().min(visible) - reserve).max(0.0)
} else {
props.num("max-height", 0.0) as f32
};
if max_height > 0.0 {
area.max_height(max_height)
} else {
area
}
};
// Keyed by the node rather than by where it sits: egui derives
// a scroll area's id from its parent ui, so two areas that
// occupy the same place in the tree at different times — the
// message list and the picture that replaces the screen it is
// on — would otherwise share one offset, and the list would
// come back showing whatever the picture left behind.
//
// `:scroll-key` names an area that outlives its node instead.
// A node id is only as durable as the node: a list unmounted
// while another screen is up comes back as a new node, and a
// position keyed by that is a position thrown away. A caller
// that means "this same list again" says so with a name, and
// the reader returns to the line they left.
let key = {
let name = props.str("scroll-key");
if name.is_empty() {
Id::new(("vidya_scroll", id))
} else {
Id::new(("vidya_scroll_key", name))
}
};
let area = area.id_salt(key);
// A chat wants the newest line, not the oldest — except on a
// frame where something inside asked to be scrolled to. The
// two are the same control pulling opposite ways, and sticking
// wins every time it is asked, so a jump to an old message
// would land nowhere.
let sticks = props.bool("stick-to-bottom", false) && !self.wants_scroll_to(id);
let area = area.stick_to_bottom(sticks);
// `:scroll-to-bottom` is a number the caller bumps rather than
// a flag it sets: a flag would have to be cleared afterwards,
// and there is no frame in which the caller could do it. A
// value it has not seen before means "now".
let jump_key = key.with("jump");
let jump = props.num("scroll-to-bottom", 0.0);
let jumped = ui.ctx().data(|d| d.get_temp::<f64>(jump_key));
let jump_now = jump > 0.0 && jumped != Some(jump);
// The end is last frame's own maximum offset, kept for exactly
// this. Not f32::MAX — egui subtracts the viewport from what it
// is given, and MAX minus anything is still MAX, an offset the
// content can never reach: the area painted nothing and stayed
// that way. Not `scroll_to_rect` either, which a scroll area
// that has been scrolled away from ignores here.
let end_offset_key = key.with("end_offset");
let area = if jump_now {
ui.ctx().data_mut(|d| d.insert_temp(jump_key, jump));
let end = ui
.ctx()
.data(|d| d.get_temp::<f32>(end_offset_key))
.unwrap_or(0.0);
area.vertical_scroll_offset(end)
} else {
area
};
// Hold the content to the viewport's width, as `:page` does,
// so a wrapping child wraps at the visible edge.
let viewport_width = ui.available_width();
let output = area.auto_shrink([false, false]).show(ui, |ui| {
ui.set_max_width(viewport_width);
self.paint_children(id, ui, theme);
// The end asked for by scrolling to it, not by setting an
// offset of f32::MAX: egui subtracts the viewport from
// whatever it is given, and MAX minus anything is still
// MAX — an offset the content can never reach, which left
// the area painting nothing at all.
});
// Say when the view leaves the end and when it comes back, so
// a caller can offer the way back. Reported on change only: the
// position itself changes every frame of a scroll, and an event
// a frame is not news.
// Within a line of the end counts as the end, and content
// shorter than the viewport is always at it.
let max_offset = (output.content_size.y - output.inner_rect.height()).max(0.0);
// What `:scroll-to-bottom` will aim at next time it is asked.
ui.ctx()
.data_mut(|d| d.insert_temp(end_offset_key, max_offset));
let at_end = output.state.offset.y >= max_offset - 24.0;
// Reaching the end is reported at once; leaving it has to hold
// for a few frames first. A burst of arriving messages grows
// the content faster than the offset follows it, and reporting
// that honestly would blink "scrolled away" whenever a channel
// is busy.
let end_key = key.with("at_end");
let away_key = key.with("away_frames");
let away_frames = ui.ctx().data(|d| d.get_temp::<u32>(away_key)).unwrap_or(0);
let away_frames = if at_end {
0
} else {
away_frames.saturating_add(1)
};
ui.ctx().data_mut(|d| d.insert_temp(away_key, away_frames));
let settled = if at_end {
Some(true)
} else if away_frames >= 3 {
Some(false)
} else {
None
};
if let Some(at_end) = settled {
let was_at_end = ui.ctx().data(|d| d.get_temp::<bool>(end_key));
if was_at_end != Some(at_end) {
ui.ctx().data_mut(|d| d.insert_temp(end_key, at_end));
// Only after the first report: the opening one would
// arrive before the content has a height.
if was_at_end.is_some() {
self.emit(
id,
"change",
if at_end { "end" } else { "away" }.to_owned(),
if at_end { 1.0 } else { 0.0 },
);
}
}
}
}
Tag::Card => {
vidya_core::card(ui, theme, |ui| self.paint_children(id, ui, theme));
}
// A card with a heading — glimmer-tui's `:frame` label, in the
// idiom this theme actually has for one.
Tag::Frame => {
let label = props.label();
vidya_core::card(ui, theme, |ui| {
if !label.is_empty() {
vidya_core::title_2(ui, theme, label);
}
self.paint_children(id, ui, theme);
});
}
Tag::Label => vidya_core::body(ui, theme, props.label()),
// Body text that answers the pointer: the accent colour and the
// hand cursor are the whole affordance, and the click is reported
// like a button's so the caller decides what opening it means.
Tag::Link => {
let response = ui
.add(
egui::Label::new(
egui::RichText::new(props.label())
.size(theme.type_scale.body)
.color(theme.palette.accent),
)
.wrap()
.sense(egui::Sense::click()),
)
.on_hover_cursor(egui::CursorIcon::PointingHand);
if response.clicked() {
self.emit(id, "click", props.label().to_owned(), 0.0);
}
}
Tag::Title => vidya_core::title(ui, theme, props.label()),
Tag::Title2 => vidya_core::title_2(ui, theme, props.label()),
Tag::DimLabel => vidya_core::dim_label(ui, theme, props.label()),
Tag::Button => {
let kind = match props.str("kind") {
"primary" => 1,
"destructive" => 2,
_ => 0,
};
if crate::ui::button(ui, theme, props.label(), kind) {
self.emit(id, "click", String::new(), 0.0);
}
}
Tag::CheckButton => {
let was = props.bool("active", false);
let (now, changed) = crate::ui::checkbox(ui, theme, was, props.label());
if changed {
// The widget does not own the value: the new state is
// written back so a component that ignores `:on-toggled`
// still tracks the click, and the handler decides whether
// it survives the next render of `:active`.
self.set(id, "active", Value::Bool(now));
self.emit(id, "toggled", String::new(), if now { 1.0 } else { 0.0 });
}
}
Tag::Entry => {
let mut text = props.str("text").to_owned();
let placeholder = props.str("placeholder").to_owned();
let rows = props.num("rows", 4.0) as usize;
let response = if props.bool("multiline", false) {
vidya_core::text_field_multiline(ui, theme, &mut text, rows.max(1))
} else {
crate::ui::text_field(ui, theme, &mut text, &placeholder)
};
if text != props.str("text") {
self.set(id, "text", Value::Str(text.clone()));
self.emit(id, "change", text, 0.0);
}
if response.lost_focus() && ui.input(|i| i.key_pressed(egui::Key::Enter)) {
self.emit(id, "activate", String::new(), 0.0);
}
// A paste of something that is not text. egui turns Ctrl+V
// into a `Paste` event carrying the clipboard's text, and a
// clipboard holding a picture has none — so the keystroke
// arrives as a key press with no paste behind it, and the
// field would otherwise swallow it. Reported instead, for a
// caller that has somewhere to put a picture; one that has not
// ignores it and the keystroke stays as inert as it was.
//
// The clipboard is not read here: whether there is a picture
// on it is answered by `vidya_clipboard_image_png`, and asking
// twice would copy every pasted image for nothing.
if response.has_focus() {
let paste_without_text = ui.input(|i| {
i.events.iter().any(|e| {
matches!(
e,
egui::Event::Key {
key: egui::Key::V,
pressed: true,
modifiers,
..
} if modifiers.command
)
}) && !i.events.iter().any(|e| matches!(e, egui::Event::Paste(_)))
});
if paste_without_text {
self.emit(id, "paste-empty", String::new(), 0.0);
}
}
}
Tag::Separator => crate::ui::separator(ui),
Tag::Spacer => crate::ui::gap(ui, props.num("size", theme.spacing.md as f64) as f32),
Tag::Status => crate::ui::status(ui, theme, props.label(), props.bool("live", false)),
Tag::Progress => {
let value = props.num("value", 0.0) as f32;
let mut bar = egui::ProgressBar::new(value.clamp(0.0, 1.0));
if !props.label().is_empty() {
bar = bar.text(props.label());
}
ui.add(bar);
}
// A picture from a file the caller has already fetched. Decoded
// once and kept as a texture: the tree is walked every frame, and
// decoding a PNG sixty times a second is not a thing to do.
// Someone's face, or the next best thing. A chat wants one column
// of them down the left, so this is a fixed square whatever the
// picture's own proportions are, and there is always something to
// draw: a name with no picture behind it becomes its initial on a
// colour of its own, which keeps the column straight and still
// tells one person from another at a glance.
Tag::Avatar => {
let size = props.num("size", 24.0) as f32;
let label = props.label().to_owned();
let path = props.str("src").to_owned();
let (rect, response) =
ui.allocate_exact_size(Vec2::splat(size), egui::Sense::click());
let texture = if path.is_empty() {
None
} else {
self.texture(ui, &path)
};
match texture {
// A corner radius of half the side is a circle.
Some(texture) => egui::Image::new(egui::load::SizedTexture::new(
texture.id(),
Vec2::splat(size),
))
.corner_radius(size * 0.5)
.paint_at(ui, rect),
None => {
let initial = label
.trim_start_matches(['#', '&', '@', '+', '%', '~'])
.chars()
.next()
.map(|c| c.to_uppercase().to_string())
.unwrap_or_else(|| "?".to_owned());
ui.painter().circle_filled(
rect.center(),
size * 0.5,
name_colour(&label, theme),
);
ui.painter().text(
rect.center(),
Align2::CENTER_CENTER,
initial,
FontId::proportional((size * 0.45).max(9.0)),
theme.palette.accent_fg,
);
}
}
if response.clicked() {
self.emit(id, "click", label, 0.0);
}
// The face answers the pointer as well as the tap. A hover
// says so once, when it starts, and once when it ends —
// per-frame events would be a flood, and the caller only
// wants the two edges. What it does with them is its own
// business; the usual answer is to render children here,
// which are painted as the hover's own panel below.
self.track_hover(id, &response);
// A hovered avatar with children shows them beside the
// pointer: a profile card is a thing the tree can already
// describe, and this is the only layer above the page that
// exists to put one in.
if response.hovered() && !self.in_hover_panel && self.has_children(id) {
self.in_hover_panel = true;
response.show_tooltip_ui(|ui| {
ui.set_max_width(320.0);
self.paint_children(id, ui, theme);
});
self.in_hover_panel = false;
}
}
// A reaction chip: the emoji drawn from the Twemoji pack rather
// than set as text, so it is the colour picture people expect and
// not a monochrome glyph — or, where the font has no glyph at all,
// tofu. `:count` rides beside it once more than one person is on
// it, and `:mine` is what marks the ones you put there yourself.
Tag::Reaction => {
let emoji = props.str("emoji").to_owned();
let emoji = if emoji.is_empty() {
props.label().to_owned()
} else {
emoji
};
let count = props.num("count", 0.0).max(0.0) as usize;
let mine = props.bool("mine", false);
// `:size` is the glyph's, and the pill is sized from it.
let size = props.num("size", 0.0) as f32;
let response = if size > 0.0 {
vidya_core::reaction_chip_sized(ui, theme, &emoji, count, mine, size)
} else {
vidya_core::reaction_chip(ui, theme, &emoji, count, mine)
};
if response.clicked() {
self.emit(id, "click", emoji, count as f64);
}
// A pill answers the pointer the way a face does: the two
// edges of a hover, and children painted beside the pointer
// while it rests. A reaction is a tally, and who is in it is
// the thing the tally leaves out.
self.track_hover(id, &response);
if response.hovered() && !self.in_hover_panel && self.has_children(id) {
self.in_hover_panel = true;
response.show_tooltip_ui(|ui| {
ui.set_max_width(320.0);
self.paint_children(id, ui, theme);
});
self.in_hover_panel = false;
}
}
Tag::Emoji => {
// A glyph the text font cannot set, drawn from the pack and
// put in the line as if it were a word. `Reaction` draws the
// same picture, but a reaction is a tally: it wears a pill, it
// answers the pointer, and it names the people in it on hover.
// An emoji in a sentence is none of those things — it is a
// character — so this allocates the square and paints, and
// stops there.
let emoji = props.str("emoji").to_owned();
let emoji = if emoji.is_empty() {
props.label().to_owned()
} else {
emoji
};
// Body size by default, because the words either side are what
// it has to sit level with.
let size = props.num("size", theme.type_scale.body as f64) as f32;
vidya_core::emoji_icon(ui, theme, &emoji, size);
}
Tag::Image => {
// Two sources, one tag: a `src` is a file decoded once and
// cached by its path, a `feed` is live pixels pushed in under
// a name (`vidya_frame_rgba`) and re-uploaded as they arrive.
// Everything downstream — fit, bounds, the click — is the same
// for both, which is why this is a prop and not a second tag.
let feed = props.str("feed").to_owned();
let path = props.str("src").to_owned();
let max_width = props.num("max-width", 0.0) as f32;
let texture = if !feed.is_empty() {
self.feed_texture(ui, &feed)
} else if !path.is_empty() {
self.texture(ui, &path)
} else {
return;
};
let Some(texture) = texture else {
// A file that will not decode is not worth a broken-image
// glyph; the message text beside it already says what it
// was meant to be. A feed that has had no frame yet is the
// same: the tile appears when the first one lands.
return;
};
let size = texture.size_vec2();
// `:fit` gives the picture every point of the space it has
// been handed and centres it in it — a picture on a screen of
// its own, rather than one in a line of chat. It is the one
// case that scales *up*: a picture opened to be looked at is
// meant to fill the window, and how big the window is this
// frame is something only this side knows. Everywhere else the
// caller's `:max-height` bounds it and nothing is enlarged
// past its own pixels.
if props.bool("fit", false) {
let space = ui.available_size();
if space.x <= 0.0 || space.y <= 0.0 || size.x <= 0.0 || size.y <= 0.0 {
return;
}
let scale = (space.x / size.x).min(space.y / size.y);
let (rect, response) = ui.allocate_exact_size(space, egui::Sense::click());
let painted = egui::Rect::from_center_size(rect.center(), size * scale);
egui::Image::new(egui::load::SizedTexture::new(texture.id(), size * scale))
.paint_at(ui, painted);
if response.clicked() {
self.emit(id, "click", String::new(), 0.0);
}
return;
}
let max_height = props.num("max-height", 240.0) as f32;
let avail = if max_width > 0.0 {
max_width.min(ui.available_width())
} else {
ui.available_width()
};
// A picture in a message is never enlarged past its own
// pixels: blowing up a screenshot to fill a column makes it
// worse, and the reader can open it if they want it bigger.
//
// `:upscale` says this one is different. A video tile is a
// *slot* whose size the layout decided — how many people are
// in the call, how big the window is — and a camera sending
// 480 wide into a 900-point slot should fill it, the way every
// other video surface does. Left off, the picture would sit at
// its own size in the middle of a space reserved for it and
// the layout would look broken.
let scale = (avail / size.x).min(max_height / size.y);
let scale = if props.bool("upscale", false) {
scale
} else {
scale.min(1.0)
};
// Clickable whether or not the caller listens: the tree does
// not know which nodes have handlers, and an unheard event
// costs a queue slot.
let response = ui
.add(
egui::Image::new(egui::load::SizedTexture::new(texture.id(), size * scale))
.corner_radius(theme.spacing.radius_sm)
.sense(egui::Sense::click()),
)
.on_hover_cursor(egui::CursorIcon::PointingHand);
if response.clicked() {
self.emit(id, "click", String::new(), 0.0);
}
}
Tag::Spinner => {
ui.horizontal(|ui| {
ui.add(egui::Spinner::new());
if !props.label().is_empty() {
vidya_core::body(ui, theme, props.label());
}
});
}
}
}
/// Wrap `add` in the node's `:margin`, when it has one.
fn with_margin(&mut self, props: &Props, ui: &mut Ui, add: impl FnOnce(&mut Self, &mut Ui)) {
// `:margin` sets all four sides; `:margin-top` and its siblings say
// otherwise for one of them. A row that sits at the bottom of a screen
// wants its space above it, not under it, and that is not a thing a
// single number can express.
let side = |key: &str| props.num(key, props.num("margin", 0.0)).clamp(0.0, 127.0) as i8;
let margin = Margin {
left: side("margin-left"),
right: side("margin-right"),
top: side("margin-top"),
bottom: side("margin-bottom"),
};
if margin == Margin::ZERO {
add(self, ui);
return;
}
egui::Frame::new()
.inner_margin(margin)
.show(ui, |ui| add(self, ui));
}
}
/// Typed reads over a node's prop map, with the defaults each widget wants.
struct Props(HashMap<String, Value>);
impl Props {
fn str(&self, key: &str) -> &str {
match self.0.get(key) {
Some(Value::Str(s)) => s,
_ => "",
}
}
fn num(&self, key: &str, default: f64) -> f64 {
match self.0.get(key) {
Some(Value::Num(n)) => *n,
Some(Value::Bool(b)) => {
if *b {
1.0
} else {
0.0
}
}
_ => default,
}
}
fn bool(&self, key: &str, default: bool) -> bool {
match self.0.get(key) {
Some(Value::Bool(b)) => *b,
Some(Value::Num(n)) => *n != 0.0,
_ => default,
}
}
/// `:label` is the family's name for a widget's text; `:text` is what a
/// label is also allowed to use (and what an entry always uses).
fn label(&self) -> &str {
let label = self.str("label");
if label.is_empty() {
self.str("text")
} else {
label
}
}
}
#[cfg(test)]
mod tests {
use super::*;
fn kids(tree: &Tree, id: u32) -> Vec<u32> {
tree.slot(id)
.map(|n| n.children.clone())
.unwrap_or_default()
}
/// The pointer resting on a reaction pill says so, the way it does on a
/// face: a chip is where a tally is, and who is in the tally is what a
/// hover is for.
#[test]
fn hovering_a_reaction_emits_hover() {
let mut tree = Tree::default();
let pill = tree.new_node("reaction");
tree.set(pill, "emoji", Value::Str("\u{1f44d}".to_owned()));
tree.set(pill, "count", Value::Num(2.0));
tree.append(tree.root(), pill);
let theme = Theme::dark();
let ctx = egui::Context::default();
let mut input = egui::RawInput::default();
input
.events
.push(egui::Event::PointerMoved(egui::pos2(20.0, 20.0)));
let _ = ctx.run(input.clone(), |ctx| {
egui::CentralPanel::default().show(ctx, |ui| tree.paint(ui, &theme));
});
let _ = ctx.run(input, |ctx| {
egui::CentralPanel::default().show(ctx, |ui| tree.paint(ui, &theme));
});
let mut names = Vec::new();
while tree.poll() {
names.push(tree.current().unwrap().name);
}
assert!(names.contains(&"hover"), "no hover from a pill: {names:?}");
// And a pill with children paints them beside the pointer. A window
// node is the probe: painting one writes its width back, so the prop
// appearing is the card having been drawn.
let card = tree.new_node("window");
tree.append(pill, card);
let mut input = egui::RawInput::default();
input
.events
.push(egui::Event::PointerMoved(egui::pos2(20.0, 20.0)));
let _ = ctx.run(input, |ctx| {
egui::CentralPanel::default().show(ctx, |ui| tree.paint(ui, &theme));
});
assert!(
tree.get(card, "window-width").is_some(),
"a hovered pill did not paint its card"
);
}
#[test]
fn root_exists_and_is_a_window() {
let tree = Tree::default();
assert!(tree.exists(tree.root()));
assert_eq!(tree.slot(tree.root()).unwrap().tag, Tag::Window);
}
#[test]
fn append_parents_once_even_when_reparenting() {
let mut tree = Tree::default();
let a = tree.new_node("vbox");
let b = tree.new_node("hbox");
let leaf = tree.new_node("label");
tree.append(tree.root(), a);
tree.append(tree.root(), b);
tree.append(a, leaf);
tree.append(b, leaf);
assert_eq!(kids(&tree, a), vec![]);
assert_eq!(kids(&tree, b), vec![leaf]);
}
#[test]
fn a_cycle_is_refused() {
let mut tree = Tree::default();
let outer = tree.new_node("vbox");
let inner = tree.new_node("vbox");
tree.append(tree.root(), outer);
tree.append(outer, inner);
assert!(!tree.append(inner, outer));
assert_eq!(kids(&tree, inner), vec![]);
}
#[test]
fn remove_frees_the_whole_subtree_and_reuses_slots() {
let mut tree = Tree::default();
let parent = tree.new_node("vbox");
let child = tree.new_node("label");
tree.append(tree.root(), parent);
tree.append(parent, child);
tree.remove(tree.root(), parent);
assert!(!tree.exists(parent));
assert!(!tree.exists(child));
assert_eq!(tree.new_node("label"), child);
}
#[test]
fn remove_ignores_a_child_of_someone_else() {
let mut tree = Tree::default();
let a = tree.new_node("vbox");
let b = tree.new_node("vbox");
let leaf = tree.new_node("label");
tree.append(tree.root(), a);
tree.append(tree.root(), b);
tree.append(a, leaf);
tree.remove(b, leaf);
assert!(tree.exists(leaf));
assert_eq!(kids(&tree, a), vec![leaf]);
}
#[test]
fn insert_after_reorders_in_both_directions() {
let mut tree = Tree::default();
let parent = tree.new_node("vbox");
tree.append(tree.root(), parent);
let a = tree.new_node("label");
let b = tree.new_node("label");
let c = tree.new_node("label");
for id in [a, b, c] {
tree.append(parent, id);
}
// Move a forward, past two siblings.
assert!(tree.insert_after(parent, a, c));
assert_eq!(kids(&tree, parent), vec![b, c, a]);
// And back to the front.
assert!(tree.insert_after(parent, a, 0));
assert_eq!(kids(&tree, parent), vec![a, b, c]);
// A no-op move keeps the order it already had.
assert!(tree.insert_after(parent, b, a));
assert_eq!(kids(&tree, parent), vec![a, b, c]);
}
#[test]
fn replace_swaps_in_place_and_drops_the_old_node() {
let mut tree = Tree::default();
let parent = tree.new_node("vbox");
tree.append(tree.root(), parent);
let a = tree.new_node("label");
let b = tree.new_node("label");
let c = tree.new_node("button");
tree.append(parent, a);
tree.append(parent, b);
assert!(tree.replace(parent, a, c));
assert_eq!(kids(&tree, parent), vec![c, b]);
assert!(!tree.exists(a));
}
#[test]
fn props_round_trip_and_clear() {
let mut tree = Tree::default();
let id = tree.new_node("button");
tree.set(id, "label", Value::Str("Save".into()));
tree.set(id, "value", Value::Num(0.5));
tree.set(id, "active", Value::Bool(true));
assert_eq!(tree.get(id, "label"), Some(&Value::Str("Save".into())));
assert_eq!(tree.get(id, "value"), Some(&Value::Num(0.5)));
assert_eq!(tree.get(id, "active"), Some(&Value::Bool(true)));
tree.clear_props(id);
assert_eq!(tree.get(id, "label"), None);
}
#[test]
fn events_drain_in_order_and_skip_removed_nodes() {
let mut tree = Tree::default();
let a = tree.new_node("button");
let b = tree.new_node("button");
tree.append(tree.root(), a);
tree.append(tree.root(), b);
tree.emit(a, "click", String::new(), 0.0);
tree.emit(b, "click", String::new(), 0.0);
// Dropping `a` must drop the event still queued against it, or it would
// be routed to a handler the caller has already forgotten.
tree.remove(tree.root(), a);
assert!(tree.poll());
assert_eq!(tree.current().unwrap().node, b);
assert!(!tree.poll());
assert!(tree.current().is_none());
}
#[test]
fn unknown_tags_are_kept_as_boxes() {
let mut tree = Tree::default();
let id = tree.new_node("carousel");
assert!(tree.exists(id));
assert_eq!(
tree.slot(id).unwrap().tag,
Tag::Unknown("carousel".to_owned())
);
}
#[test]
fn dump_is_hiccup_of_what_the_tree_holds() {
let mut tree = Tree::default();
let root = tree.new_node("vbox");
tree.set(root, "spacing", Value::Num(8.0));
tree.set(root, "orientation", Value::Str("vertical".to_owned()));
let button = tree.new_node("button");
tree.set(button, "label", Value::Str("go".to_owned()));
tree.set(button, "sensitive", Value::Bool(false));
tree.append(root, button);
assert_eq!(
tree.dump(root),
"[:box {:orientation \"vertical\" :spacing 8}\n \
[:button {:label \"go\" :sensitive false}]]"
);
}
#[test]
fn dump_keeps_an_unknown_tag_and_escapes_a_string() {
let mut tree = Tree::default();
let id = tree.new_node("carousel");
tree.set(
id,
"label",
Value::Str("a \"quote\"\nand a line".to_owned()),
);
assert_eq!(
tree.dump(id),
"[:carousel {:label \"a \\\"quote\\\"\\nand a line\"}]"
);
assert_eq!(tree.dump(9999), "nil");
}
#[test]
fn a_frame_is_kept_for_the_paint_that_will_upload_it() {
let mut tree = Tree::default();
assert!(tree.set_frame("nandi", 2, 2, &[0u8; 16]));
assert!(tree.feeds["nandi"].pending.is_some());
// The newest frame is the only one worth painting: a second one
// arriving before the first was drawn replaces it rather than queuing.
assert!(tree.set_frame("nandi", 2, 2, &[7u8; 16]));
let pending = tree.feeds["nandi"].pending.as_ref().unwrap();
assert_eq!(pending.size, [2, 2]);
assert_eq!(tree.feeds.len(), 1);
}
#[test]
fn a_frame_that_does_not_match_its_dimensions_is_refused() {
let mut tree = Tree::default();
// Short of 2x2x4 — a capture path that changed resolution mid-stream
// would otherwise paint the tail of the old buffer as the new one.
assert!(!tree.set_frame("nandi", 2, 2, &[0u8; 15]));
assert!(!tree.set_frame("nandi", 0, 2, &[]));
assert!(!tree.set_frame("", 2, 2, &[0u8; 16]));
assert!(tree.feeds.is_empty());
}
#[test]
fn dropping_a_feed_forgets_it() {
let mut tree = Tree::default();
tree.set_frame("nandi", 1, 1, &[0u8; 4]);
assert!(tree.drop_frame("nandi"));
assert!(!tree.drop_frame("nandi"));
assert!(tree.feeds.is_empty());
}
}
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