gantz_egui 0.2.0

UI traits and widgets that make up the GUI for gantz, an environment for creative systems.
Documentation 
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use crate::{NodeCtx, NodeUi};

/// A widget used to allow for editing and parsing a steel expression.
pub struct ExprEdit<'a> {
    expr: &'a mut gantz_core::node::Expr,
    pub id: egui::Id,
}

#[derive(Clone, Default)]
struct ExprEditState {
    expr_hash: u64,
    code: String,
}

impl<'a> egui::Widget for ExprEdit<'a> {
    fn ui(self, ui: &mut egui::Ui) -> egui::Response {
        let Self { expr, id } = self;
        let code_id = id.with("code");

        // Retrieve the working state.
        let mut state: ExprEditState = ui
            .memory_mut(|m| m.data.remove_temp(code_id))
            .unwrap_or_default();

        // If the input hash has changed, reset the working code string.
        let expr_hash = expr_hash(expr);
        if expr_hash != state.expr_hash {
            state.expr_hash = expr_hash;
            state.code = expr.src().to_string();
        }

        let language = "scm";
        let theme = egui_extras::syntax_highlighting::CodeTheme::from_memory(ui.ctx(), ui.style());

        let mut layouter = |ui: &egui::Ui, buf: &dyn egui::TextBuffer, wrap_width: f32| {
            let mut layout_job = egui_extras::syntax_highlighting::highlight(
                ui.ctx(),
                ui.style(),
                &theme,
                buf.as_str(),
                language,
            );
            layout_job.wrap.max_width = wrap_width;
            ui.fonts_mut(|fonts| fonts.layout_job(layout_job))
        };

        // Find the longest line width.
        let mut max_line_width: f32 = 0.0;
        let font_sel = egui::FontSelection::from(egui::TextStyle::Monospace);
        let font_id = font_sel.resolve(ui.style());
        ui.fonts_mut(|fonts| {
            for line in state.code.split('\n').clone() {
                // Use the layout_no_wrap function to get width without wrapping
                let galley = fonts.layout_no_wrap(
                    line.to_string(),
                    font_id.clone(),
                    egui::Color32::PLACEHOLDER,
                );
                max_line_width = max_line_width.max(galley.rect.width());
            }
        });
        max_line_width += 7.0;

        let response = ui.add(
            egui::TextEdit::multiline(&mut state.code)
                .id(id)
                .code_editor()
                .font(font_id)
                .desired_rows(1)
                .desired_width(max_line_width)
                .hint_text("(+ $l $r)")
                .layouter(&mut layouter),
        );
        if response.changed() {
            if let Ok(new_expr) = gantz_core::node::expr(&state.code) {
                *expr = new_expr;
            }
        }

        // Persist the WIP editing code.
        ui.memory_mut(|m| m.data.insert_temp(code_id, state));

        response
    }
}

impl NodeUi for gantz_core::node::Expr {
    fn name(&self, _: &dyn crate::Registry) -> &str {
        "expr"
    }

    fn ui(
        &mut self,
        ctx: NodeCtx,
        uictx: egui_graph::NodeCtx,
    ) -> egui::InnerResponse<egui::Response> {
        uictx.framed(|ui| {
            let id = egui::Id::new("ExprEdit").with(ctx.path());
            ui.add(ExprEdit::new(self, id))
        })
    }
}

impl<'a> ExprEdit<'a> {
    /// Create a new Steel code editing widget.
    pub fn new(expr: &'a mut gantz_core::node::Expr, id: egui::Id) -> Self {
        Self { expr, id }
    }
}

fn expr_hash(expr: &gantz_core::node::Expr) -> u64 {
    use std::hash::{Hash, Hasher};
    let mut hasher = std::collections::hash_map::DefaultHasher::default();
    expr.hash(&mut hasher);
    hasher.finish()
}