feat: add canvas export to PNG via File menu, Cmd+Shift+E, and MCP tool

crates/agcanvas-mcp/src/tools.rs

@@ -203,6 +203,18 @@ pub struct RenderMermaidParam {
     pub height: Option<f32>,
 }
 
+#[derive(Debug, serde::Deserialize, schemars::JsonSchema)]
+pub struct ExportCanvasParam {
+    #[schemars(description = "Session ID to target. If omitted, uses the active session.")]
+    pub session_id: Option<String>,
+    #[schemars(description = "File path to save the PNG export to")]
+    pub path: String,
+    #[schemars(description = "Scale factor for the export (default 2.0 for high DPI)")]
+    pub scale: Option<f32>,
+    #[schemars(description = "Background color as hex e.g. '#1a1a2e' (default dark canvas color)")]
+    pub background: Option<String>,
+}
+
 #[derive(Debug, serde::Deserialize, schemars::JsonSchema)]
 pub struct BatchParam {
     #[schemars(
@@ -565,6 +577,29 @@ impl AgCanvasServer {
         self.call_agcanvas(&request).await
     }
 
+    #[tool(
+        description = "Export the canvas as a PNG image. Renders all layers (SVG, drawing elements) into a single image file."
+    )]
+    async fn export_canvas(
+        &self,
+        Parameters(params): Parameters<ExportCanvasParam>,
+    ) -> Result<CallToolResult, McpError> {
+        let mut request = serde_json::json!({
+            "type": "ExportCanvas",
+            "path": params.path,
+        });
+        if let Some(sid) = params.session_id {
+            request["session_id"] = serde_json::Value::String(sid);
+        }
+        if let Some(s) = params.scale {
+            request["scale"] = serde_json::json!(s);
+        }
+        if let Some(bg) = params.background {
+            request["background"] = serde_json::Value::String(bg);
+        }
+        self.call_agcanvas(&request).await
+    }
+
     #[tool(
         description = "Send multiple Augmented Canvas operations in one request. Accepts a JSON array of request objects and returns one response per operation in a BatchResult."
     )]

crates/agcanvas/src/command_palette.rs

@@ -10,6 +10,7 @@ pub enum CommandId {
     ClearCanvas,
     PasteSvg,
     PasteMermaid,
+    ExportPng,
     ToolSelect,
     ToolPan,
     ToolRectangle,
@@ -68,6 +69,12 @@ pub fn all_commands() -> Vec<PaletteCommand> {
             None,
             "Canvas",
         ),
+        PaletteCommand::new(
+            CommandId::ExportPng,
+            "Export as PNG",
+            Some("Cmd+Shift+E"),
+            "Canvas",
+        ),
         PaletteCommand::new(CommandId::ToolSelect, "Select Tool", Some("V"), "Tool"),
         PaletteCommand::new(CommandId::ToolPan, "Pan Tool", Some("H"), "Tool"),
         PaletteCommand::new(

crates/agcanvas/src/export.rs

@@ -0,0 +1,442 @@
+use std::path::Path;
+
+use crate::drawing::{DrawingElement, Shape, ShapeStyle};
+use anyhow::{anyhow, Result};
+use tiny_skia::{FillRule, LineCap, LineJoin, Paint, PathBuilder, Pixmap, Stroke, Transform};
+
+const EXPORT_PADDING: f32 = 20.0;
+
+/// Data needed to export a canvas snapshot (no egui dependency).
+pub struct ExportData {
+    pub svg_source: Option<String>,
+    pub drawing_elements: Vec<DrawingElement>,
+    pub background_color: tiny_skia::Color,
+}
+
+#[derive(Debug, Clone, Copy)]
+struct Bounds {
+    min_x: f32,
+    min_y: f32,
+    max_x: f32,
+    max_y: f32,
+}
+
+impl Bounds {
+    fn from_rect(min_x: f32, min_y: f32, max_x: f32, max_y: f32) -> Self {
+        Self {
+            min_x,
+            min_y,
+            max_x,
+            max_y,
+        }
+    }
+
+    fn union(self, other: Self) -> Self {
+        Self {
+            min_x: self.min_x.min(other.min_x),
+            min_y: self.min_y.min(other.min_y),
+            max_x: self.max_x.max(other.max_x),
+            max_y: self.max_y.max(other.max_y),
+        }
+    }
+}
+
+pub fn export_canvas_to_png(data: &ExportData, path: &str, scale: f32) -> Result<(u32, u32)> {
+    if !(scale.is_finite() && scale > 0.0) {
+        return Err(anyhow!("Scale must be a positive finite value"));
+    }
+
+    if let Some(parent) = Path::new(path).parent() {
+        if !parent.as_os_str().is_empty() && !parent.exists() {
+            return Err(anyhow!(
+                "Export directory does not exist: {}",
+                parent.display()
+            ));
+        }
+    }
+
+    let mut total_bounds = compute_total_bounds(data)?;
+    total_bounds.min_x -= EXPORT_PADDING;
+    total_bounds.min_y -= EXPORT_PADDING;
+    total_bounds.max_x += EXPORT_PADDING;
+    total_bounds.max_y += EXPORT_PADDING;
+
+    let width_f = (total_bounds.max_x - total_bounds.min_x).max(1.0) * scale;
+    let height_f = (total_bounds.max_y - total_bounds.min_y).max(1.0) * scale;
+    let width = width_f.ceil().max(1.0) as u32;
+    let height = height_f.ceil().max(1.0) as u32;
+
+    let mut pixmap =
+        Pixmap::new(width, height).ok_or_else(|| anyhow!("Failed to create export pixmap"))?;
+    pixmap.fill(data.background_color);
+
+    if let Some(svg_source) = &data.svg_source {
+        let tree = parse_svg(svg_source)?;
+        let tx = -total_bounds.min_x * scale;
+        let ty = -total_bounds.min_y * scale;
+        let transform = Transform::from_row(scale, 0.0, 0.0, scale, tx, ty);
+        resvg::render(&tree, transform, &mut pixmap.as_mut());
+    }
+
+    render_drawing_elements(
+        &mut pixmap,
+        &data.drawing_elements,
+        total_bounds.min_x,
+        total_bounds.min_y,
+        scale,
+    )?;
+
+    pixmap.save_png(path)?;
+    Ok((width, height))
+}
+
+fn compute_total_bounds(data: &ExportData) -> Result<Bounds> {
+    let mut bounds: Option<Bounds> = None;
+
+    if let Some(svg_source) = &data.svg_source {
+        let tree = parse_svg(svg_source)?;
+        let size = tree.size();
+        bounds = Some(Bounds::from_rect(0.0, 0.0, size.width(), size.height()));
+    }
+
+    if let Some(drawing_bounds) = compute_drawing_bounds(&data.drawing_elements) {
+        bounds = Some(match bounds {
+            Some(existing) => existing.union(drawing_bounds),
+            None => drawing_bounds,
+        });
+    }
+
+    bounds.ok_or_else(|| anyhow!("Cannot export empty canvas"))
+}
+
+fn compute_drawing_bounds(elements: &[DrawingElement]) -> Option<Bounds> {
+    let mut min_x = f32::INFINITY;
+    let mut min_y = f32::INFINITY;
+    let mut max_x = f32::NEG_INFINITY;
+    let mut max_y = f32::NEG_INFINITY;
+
+    for element in elements {
+        let rect = element.bounding_rect();
+        let half_stroke = (element.style.stroke_width * 0.5).max(0.0);
+        min_x = min_x.min(rect.min.x - half_stroke);
+        min_y = min_y.min(rect.min.y - half_stroke);
+        max_x = max_x.max(rect.max.x + half_stroke);
+        max_y = max_y.max(rect.max.y + half_stroke);
+    }
+
+    if min_x.is_finite() && min_y.is_finite() && max_x.is_finite() && max_y.is_finite() {
+        Some(Bounds::from_rect(min_x, min_y, max_x, max_y))
+    } else {
+        None
+    }
+}
+
+fn render_drawing_elements(
+    pixmap: &mut Pixmap,
+    elements: &[DrawingElement],
+    min_x: f32,
+    min_y: f32,
+    scale: f32,
+) -> Result<()> {
+    for element in elements {
+        match &element.shape {
+            Shape::Rectangle { pos, size } => {
+                if size.x <= 0.0 || size.y <= 0.0 {
+                    continue;
+                }
+                let x = (pos.x - min_x) * scale;
+                let y = (pos.y - min_y) * scale;
+                let w = size.x * scale;
+                let h = size.y * scale;
+
+                let Some(rect) = tiny_skia::Rect::from_xywh(x, y, w, h) else {
+                    continue;
+                };
+                let mut pb = PathBuilder::new();
+                pb.push_rect(rect);
+                if let Some(path) = pb.finish() {
+                    fill_and_stroke_path(pixmap, &path, &element.style, scale);
+                }
+            }
+            Shape::Ellipse { center, radii } => {
+                if radii.x <= 0.0 || radii.y <= 0.0 {
+                    continue;
+                }
+                let x = (center.x - radii.x - min_x) * scale;
+                let y = (center.y - radii.y - min_y) * scale;
+                let w = radii.x * 2.0 * scale;
+                let h = radii.y * 2.0 * scale;
+
+                let Some(rect) = tiny_skia::Rect::from_xywh(x, y, w, h) else {
+                    continue;
+                };
+                let mut pb = PathBuilder::new();
+                pb.push_oval(rect);
+                if let Some(path) = pb.finish() {
+                    fill_and_stroke_path(pixmap, &path, &element.style, scale);
+                }
+            }
+            Shape::Line { start, end } => {
+                if let Some(path) = build_line_path(*start, *end, min_x, min_y, scale) {
+                    stroke_path(pixmap, &path, &element.style, scale);
+                }
+            }
+            Shape::Arrow { start, end } => {
+                if let Some(path) = build_line_path(*start, *end, min_x, min_y, scale) {
+                    stroke_path(pixmap, &path, &element.style, scale);
+                }
+                if let Some(arrowhead) = build_arrowhead_path(*start, *end, min_x, min_y, scale) {
+                    stroke_path(pixmap, &arrowhead, &element.style, scale);
+                }
+            }
+            Shape::Text {
+                pos,
+                content,
+                font_size,
+            } => {
+                render_text_element(
+                    pixmap,
+                    content,
+                    (pos.x - min_x) * scale,
+                    (pos.y - min_y) * scale,
+                    *font_size * scale,
+                    element.style.stroke_color,
+                )?;
+            }
+            Shape::Path { polygons } => {
+                for polygon in polygons {
+                    let mut pb = PathBuilder::new();
+                    add_ring_to_path(&mut pb, &polygon.exterior, min_x, min_y, scale, true);
+                    for hole in &polygon.holes {
+                        add_ring_to_path(&mut pb, hole, min_x, min_y, scale, true);
+                    }
+                    let Some(path) = pb.finish() else {
+                        continue;
+                    };
+                    fill_and_stroke_path_even_odd(pixmap, &path, &element.style, scale);
+                }
+            }
+        }
+    }
+
+    Ok(())
+}
+
+fn fill_and_stroke_path(
+    pixmap: &mut Pixmap,
+    path: &tiny_skia::Path,
+    style: &ShapeStyle,
+    scale: f32,
+) {
+    if let Some(fill) = style.fill {
+        let mut fill_paint = Paint::default();
+        fill_paint.set_color(egui_to_skia_color(fill));
+        pixmap.fill_path(
+            path,
+            &fill_paint,
+            FillRule::Winding,
+            Transform::identity(),
+            None,
+        );
+    }
+
+    stroke_path(pixmap, path, style, scale);
+}
+
+fn fill_and_stroke_path_even_odd(
+    pixmap: &mut Pixmap,
+    path: &tiny_skia::Path,
+    style: &ShapeStyle,
+    scale: f32,
+) {
+    if let Some(fill) = style.fill {
+        let mut fill_paint = Paint::default();
+        fill_paint.set_color(egui_to_skia_color(fill));
+        pixmap.fill_path(
+            path,
+            &fill_paint,
+            FillRule::EvenOdd,
+            Transform::identity(),
+            None,
+        );
+    }
+
+    stroke_path(pixmap, path, style, scale);
+}
+
+fn stroke_path(pixmap: &mut Pixmap, path: &tiny_skia::Path, style: &ShapeStyle, scale: f32) {
+    let stroke_width = style.stroke_width * scale;
+    if stroke_width <= 0.0 {
+        return;
+    }
+
+    let mut paint = Paint::default();
+    paint.set_color(egui_to_skia_color(style.stroke_color));
+
+    let stroke = Stroke {
+        width: stroke_width,
+        line_cap: LineCap::Round,
+        line_join: LineJoin::Round,
+        ..Stroke::default()
+    };
+
+    pixmap.stroke_path(path, &paint, &stroke, Transform::identity(), None);
+}
+
+fn build_line_path(
+    start: egui::Pos2,
+    end: egui::Pos2,
+    min_x: f32,
+    min_y: f32,
+    scale: f32,
+) -> Option<tiny_skia::Path> {
+    let mut pb = PathBuilder::new();
+    pb.move_to((start.x - min_x) * scale, (start.y - min_y) * scale);
+    pb.line_to((end.x - min_x) * scale, (end.y - min_y) * scale);
+    pb.finish()
+}
+
+fn build_arrowhead_path(
+    start: egui::Pos2,
+    end: egui::Pos2,
+    min_x: f32,
+    min_y: f32,
+    scale: f32,
+) -> Option<tiny_skia::Path> {
+    let dx = end.x - start.x;
+    let dy = end.y - start.y;
+    let len = (dx * dx + dy * dy).sqrt();
+
+    if len < 1e-6 {
+        return None;
+    }
+
+    let dir_x = dx / len;
+    let dir_y = dy / len;
+    let perp_x = -dir_y;
+    let perp_y = dir_x;
+    let arrow_size = 12.0;
+
+    let left = egui::pos2(
+        end.x - dir_x * arrow_size + perp_x * (arrow_size * 0.4),
+        end.y - dir_y * arrow_size + perp_y * (arrow_size * 0.4),
+    );
+    let right = egui::pos2(
+        end.x - dir_x * arrow_size - perp_x * (arrow_size * 0.4),
+        end.y - dir_y * arrow_size - perp_y * (arrow_size * 0.4),
+    );
+
+    let mut pb = PathBuilder::new();
+    pb.move_to((left.x - min_x) * scale, (left.y - min_y) * scale);
+    pb.line_to((end.x - min_x) * scale, (end.y - min_y) * scale);
+    pb.move_to((right.x - min_x) * scale, (right.y - min_y) * scale);
+    pb.line_to((end.x - min_x) * scale, (end.y - min_y) * scale);
+    pb.finish()
+}
+
+fn add_ring_to_path(
+    pb: &mut PathBuilder,
+    ring: &[egui::Pos2],
+    min_x: f32,
+    min_y: f32,
+    scale: f32,
+    close: bool,
+) {
+    if ring.is_empty() {
+        return;
+    }
+
+    pb.move_to((ring[0].x - min_x) * scale, (ring[0].y - min_y) * scale);
+    for point in ring.iter().skip(1) {
+        pb.line_to((point.x - min_x) * scale, (point.y - min_y) * scale);
+    }
+    if close {
+        pb.close();
+    }
+}
+
+fn render_text_element(
+    pixmap: &mut Pixmap,
+    text: &str,
+    x: f32,
+    y: f32,
+    font_size: f32,
+    color: egui::Color32,
+) -> Result<()> {
+    if text.is_empty() || font_size <= 0.0 {
+        return Ok(());
+    }
+
+    let escaped = escape_xml(text);
+    let approx_width = (font_size * text.chars().count() as f32 * 0.7).max(font_size);
+    let approx_height = (font_size * 1.6).max(font_size);
+    let opacity = color.a() as f32 / 255.0;
+    let svg_text = format!(
+        r#"<svg xmlns="http://www.w3.org/2000/svg" width="{w}" height="{h}"><text x="0" y="{baseline}" font-family="Inter, system-ui, -apple-system, sans-serif" font-size="{size}" fill="rgb({r},{g},{b})" fill-opacity="{opacity}">{text}</text></svg>"#,
+        w = approx_width,
+        h = approx_height,
+        baseline = font_size,
+        size = font_size,
+        r = color.r(),
+        g = color.g(),
+        b = color.b(),
+        opacity = opacity,
+        text = escaped,
+    );
+
+    let tree = parse_svg(&svg_text)?;
+    let transform = Transform::from_translate(x, y);
+    resvg::render(&tree, transform, &mut pixmap.as_mut());
+    Ok(())
+}
+
+fn parse_svg(svg_source: &str) -> Result<usvg::Tree> {
+    let mut options = usvg::Options::default();
+    options.fontdb_mut().load_system_fonts();
+    Ok(usvg::Tree::from_str(svg_source, &options)?)
+}
+
+fn escape_xml(text: &str) -> String {
+    let mut escaped = String::with_capacity(text.len());
+    for ch in text.chars() {
+        match ch {
+            '&' => escaped.push_str("&amp;"),
+            '<' => escaped.push_str("&lt;"),
+            '>' => escaped.push_str("&gt;"),
+            '"' => escaped.push_str("&quot;"),
+            '\'' => escaped.push_str("&apos;"),
+            _ => escaped.push(ch),
+        }
+    }
+    escaped
+}
+
+fn egui_to_skia_color(c: egui::Color32) -> tiny_skia::Color {
+    tiny_skia::Color::from_rgba8(c.r(), c.g(), c.b(), c.a())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn export_simple_rectangle() {
+        let data = ExportData {
+            svg_source: None,
+            drawing_elements: vec![DrawingElement::new(
+                Shape::Rectangle {
+                    pos: egui::Pos2::new(10.0, 10.0),
+                    size: egui::Vec2::new(100.0, 50.0),
+                },
+                ShapeStyle::default(),
+            )],
+            background_color: tiny_skia::Color::from_rgba8(26, 26, 46, 255),
+        };
+
+        let path = "/tmp/agcanvas_test_export.png";
+        let result = export_canvas_to_png(&data, path, 1.0);
+        assert!(result.is_ok());
+        assert!(std::path::Path::new(path).exists());
+        std::fs::remove_file(path).ok();
+    }
+}

crates/agcanvas/src/main.rs

@@ -5,6 +5,7 @@ mod clipboard;
 mod command_palette;
 mod drawing;
 mod element_tree;
+mod export;
 mod history;
 mod mermaid;
 mod persistence;