Use serde_bare and update format version

Closes #15

Cargo.toml

@@ -3,27 +3,30 @@ name = "stiletto"
 version = "0.1.0"
 authors = ["Enrico Lumetti <enrico.lumetti@gmail.com>"]
 edition = "2018"
+default-run = "stiletto"
 
 [dependencies]
 log = "0.4"
-druid = { version = "0.6.0", features = ["im"] }
+druid = { version = "0.7.0", features = ["im", "svg"] }
 im = { version = "*" }
 serde = { version = "1.0", features = ["derive"] }
-#serde_bare = "0.3.0"
+serde_bare = "0.3.0"
 serde_json = "1.0"
+clap = "3.0.0-beta.2"
 
-[patch.crates-io]
+[target.'cfg(target_os="linux")'.dependencies.gtk]
-druid = { git = "https://github.com/doppioandante/druid", branch = "v0.6.0_stiletto", features = ["im"] }
+version = "0.9.2"
-#druid = { path = "../druid/druid", features = ["im"] }
-
-[dependencies.gtk]
-version = "0.8.1"
 features = ["v3_22"]
 
-[dependencies.gio]
+[target.'cfg(target_os="linux")'.dependencies.gio]
-version = "0.8.1"
+version = "0.9.1"
 features = ["v2_56"]
 
-[dependencies.gdk]
+[target.'cfg(target_os="linux")'.dependencies.gdk]
-version = "0.12.1"
+version = "0.13.2"
 features = ["v3_22"]
+
+[patch.crates-io]
+druid = { git = "https://github.com/doppioandante/druid", branch = "v0.7.0_stiletto", features = ["im", "svg"] }
+#druid = { path = "../druid/druid/", features = ["im", "svg"] }
+

icons/eraser.svg

@@ -0,0 +1 @@
+<?xml version="1.0" encoding="utf-8"?><svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px" viewBox="0 0 122.88 103.38" style="enable-background:new 0 0 122.88 103.38" xml:space="preserve"><style type="text/css">.st0{fill-rule:evenodd;clip-rule:evenodd;fill:#f0f0f0;}</style><g><path class="st0" stroke="#f0f0f0" d="M27.66,93.53h32.49l9.1-9.08c1.4-1.4,1.41-3.7,0.01-5.1l-27.02-27.1c-1.4-1.4-3.7-1.41-5.1-0.01L14.3,75.03 c-1.41,1.4-1.41,3.7-0.01,5.1L27.66,93.53L27.66,93.53z M71.03,93.53h51.84v9.85H61.16H50.28h-12.8H25.7h-0.35L1.05,79.01 c-1.4-1.4-1.4-3.7,0.01-5.1L74.11,1.05c1.41-1.4,3.7-1.4,5.1,0.01l39.62,39.72c1.4,1.4,1.4,3.7-0.01,5.1L71.03,93.53L71.03,93.53z"/></g></svg>

icons/pen.svg

@@ -0,0 +1 @@
+<svg height="21" viewBox="0 0 21 21" width="21" xmlns="http://www.w3.org/2000/svg"><g fill="none" fill-rule="evenodd" stroke="#f0f0f0" stroke-linecap="round" stroke-linejoin="round" transform="translate(2 2)"><path d="m8.24920737-.79402796c1.17157287 0 2.12132033.94974747 2.12132033 2.12132034v13.43502882l-2.12132033 3.5355339-2.08147546-3.495689-.03442539-13.47488064c-.00298547-1.16857977.94191541-2.11832105 2.11049518-2.12130651.00180188-.00000461.00360378-.00000691.00540567-.00000691z" transform="matrix(.70710678 .70710678 -.70710678 .70710678 8.605553 -3.271644)"/><path d="m13.5 4.5 1 1"/></g></svg>

src/bin/canvas_tool_list.rs

@@ -1,122 +0,0 @@
-//  Stiletto
-//  Copyright (C) 2020 Stiletto Authors
-//
-//  This program is free software: you can redistribute it and/or modify
-//  it under the terms of the GNU Affero General Public License as published by
-//  the Free Software Foundation, either version 3 of the License, or
-//  (at your option) any later version.
-//
-//  This program is distributed in the hope that it will be useful,
-//  but WITHOUT ANY WARRANTY; without even the implied warranty of
-//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-//  GNU Affero General Public License for more details.
-//
-//  You should have received a copy of the GNU Affero General Public License
-//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-//use log::{info, warn};
-
-use druid::im::{vector, Vector};
-use druid::widget::prelude::*;
-use druid::widget::{Align, Label, Button, CrossAxisAlignment, Flex, List, ListGrowDirection, WidgetExt, SizedBox, ViewSwitcher};
-use druid::{AppLauncher, Color, Data, LocalizedString, WindowDesc, Lens, UnitPoint};
-
-#[derive(Clone, Data)]
-enum CanvasToolState {
-    Pen { thickness: f64, color: Color },
-    Eraser,
-}
-
-#[derive(Clone, PartialEq)]
-enum CanvasToolType {
-    Pen,
-    Eraser,
-}
-
-impl CanvasToolState {
-    fn tool_type(&self) -> CanvasToolType {
-        match self {
-            CanvasToolState::Pen { .. } => CanvasToolType::Pen,
-            CanvasToolState::Eraser => CanvasToolType::Eraser,
-        }
-    }
-}
-
-fn build_simple_tool_widget(tool_state: &CanvasToolState) -> Box<dyn Widget<CanvasToolState>> {
-    let (label_text, bg_color) = match tool_state {
-        CanvasToolState::Pen { thickness, color } =>
-            (format!("pen {}", thickness), color.clone()),
-        CanvasToolState::Eraser =>
-            (String::from("eraser"), Color::rgb(200, 200, 200))
-    };
-
-    Box::new(
-        SizedBox::new(
-            Label::new(label_text)
-                .align_horizontal(UnitPoint::CENTER)
-                .background(bg_color)
-                .fix_width(100.0)
-                .fix_height(100.0)
-        )
-        .padding((10.0, 0.0)))
-}
-
-
-#[derive(Clone, Data, Lens)]
-struct AppState {
-    tools: Vector<CanvasToolState>,
-}
-
-fn build_ui() -> impl Widget<AppState> {
-    let list_buttons = Flex::row()
-        .cross_axis_alignment(CrossAxisAlignment::Center)
-        .with_child(Button::new("Add"))
-        .with_child(Button::new("Remove"));
-
-    let number_list = Flex::row()
-        .cross_axis_alignment(CrossAxisAlignment::Center)
-    	.with_flex_child(
-            List::new(|| {
-                ViewSwitcher::<CanvasToolState, CanvasToolType>::new(
-                    |tool_state, _| tool_state.tool_type(),
-                    |_, tool_state, _| {
-                        build_simple_tool_widget(&tool_state)
-                    }
-                )
-            })
-            .grow(ListGrowDirection::Right)
-            .lens(AppState::tools)
-    	, 1.0);
-
-    let toolbar = Flex::row()
-        .cross_axis_alignment(CrossAxisAlignment::Center)
-        .with_spacer(30.0)
-        .with_child(Align::left(list_buttons))
-        .with_spacer(30.0)
-        .with_flex_child(Align::left(number_list), 1.0);
-
-    Flex::column()
-        .cross_axis_alignment(CrossAxisAlignment::Center)
-        .with_child(
-            SizedBox::new(toolbar)
-            .height(100.0)
-            .expand_width()
-            .align_horizontal(UnitPoint::TOP)
-        )
-}
-
-pub fn main() {
-    let window = WindowDesc::new(build_ui)
-        .window_size((1000.0, 400.00))
-        .title(
-            LocalizedString::new("custom-widget-demo-window-title").with_placeholder("Tools"),
-        );
-    let app_state = AppState {
-        tools: vector![CanvasToolState::Eraser, CanvasToolState::Pen { thickness: 3.3, color: Color::rgb(30.0, 0.4, 0.4) }]
-    };
-
-    AppLauncher::with_window(window)
-        .use_simple_logger()
-        .launch(app_state)
-        .expect("launch failed");
-}

src/bin/stlt_migrate.rs

@@ -0,0 +1,48 @@
+//  Stiletto
+//  Copyright (C) 2020 Stiletto Authors
+//
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU Affero General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU Affero General Public License for more details.
+//
+//  You should have received a copy of the GNU Affero General Public License
+//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+use clap::{Arg, App};
+use stiletto::migration::open_stiletto_document;
+
+use std::fs::File;
+use std::path::PathBuf;
+
+fn main() {
+    let matches = App::new("Stiletto Migration CLI")
+        .version("0.1.0")
+        .author("Stiletto Authors")
+        .about("Migrate a stlt file to the latest version")
+        .arg(Arg::new("INPUT")
+            .about("Sets the input file to use")
+            .required(true)
+            .index(1))
+        .arg(Arg::new("OUTPUT")
+            .about("Sets the output file to use")
+            .required(true)
+            .index(2))
+        .get_matches();
+
+   let input_path = matches.value_of("INPUT").unwrap();
+   let output_path = matches.value_of("OUTPUT").unwrap();
+
+   let out_file = File::create(&output_path).expect("Cannot create output fle");
+
+   let result = open_stiletto_document(&PathBuf::from(&input_path));
+   if let Ok(document) = result {
+       let snapshot = document.migrate_to_latest();
+       snapshot.to_writer(out_file);
+   }
+}

src/canvas.rs

@@ -0,0 +1,241 @@
+//  Stiletto
+//  Copyright (C) 2020 Stiletto Authors
+//
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU Affero General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU Affero General Public License for more details.
+//
+//  You should have received a copy of the GNU Affero General Public License
+//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+use std::vec::Vec;
+
+use im::{vector, Vector};
+
+use serde::de::{Deserializer, SeqAccess, Visitor};
+use serde::ser::Serializer;
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, druid::Data)]
+pub struct Path {
+    pub kurbo_path: druid::kurbo::BezPath,
+}
+
+#[derive(Serialize, Deserialize)]
+#[serde(remote = "druid::Color")]
+enum ColorDef {
+    Rgba32(u32),
+}
+
+struct Interval {
+    start_pos: f64,
+    end_pos: f64,
+}
+
+impl Interval {
+    fn new(x1: f64, x2: f64) -> Interval {
+        Interval {
+            start_pos: x1.min(x2),
+            end_pos: x1.max(x2),
+        }
+    }
+
+    fn new_ordered(start: f64, end: f64) -> Interval {
+        Interval {
+            start_pos: start,
+            end_pos: end,
+        }
+    }
+
+    fn overlaps(&self, other: &Self) -> bool {
+        self.start_pos < other.end_pos && other.start_pos < self.end_pos
+    }
+}
+
+// O(1) complexity
+// TODO(francesco): Implement this in a way that is not so flamboyant
+// TODO(francesco): Implement intersection test for bezier curves
+fn segment_intersects_rect(segment: &druid::kurbo::PathSeg, rect: druid::Rect) -> bool {
+    match segment {
+        druid::kurbo::PathSeg::Line(line) => {
+            // A Segment intersects the rect
+            // if their projections on the x and y line both overlap
+            let line_x_proj = Interval::new(line.p0.x, line.p1.x);
+            let line_y_proj = Interval::new(line.p0.y, line.p1.y);
+
+            let rect_x_proj = Interval::new_ordered(rect.min_x(), rect.max_x());
+            let rect_y_proj = Interval::new_ordered(rect.min_y(), rect.max_y());
+
+            line_x_proj.overlaps(&rect_x_proj) && line_y_proj.overlaps(&rect_y_proj)
+        }
+
+        _ => {
+            unimplemented!();
+        }
+    }
+}
+
+#[derive(Debug, Clone, druid::Data, Serialize, Deserialize)]
+pub enum CanvasElement {
+    Freehand {
+        path: Path,
+        thickness: f64,
+        #[serde(with = "ColorDef")]
+        stroke_color: druid::Color,
+    },
+}
+
+impl CanvasElement {
+    pub fn bounding_box(&self) -> druid::Rect {
+        match self {
+            CanvasElement::Freehand {
+                path, thickness, ..
+            } => {
+                use druid::kurbo::Shape;
+                path.kurbo_path
+                    .bounding_box()
+                    .inflate(*thickness, *thickness)
+            }
+        }
+    }
+
+    pub fn intersects_rect(&self, rect: druid::Rect) -> bool {
+        match self {
+            CanvasElement::Freehand { path, .. } => {
+                // TODO(enrico) this doesn't handle thickness
+                path.kurbo_path
+                    .segments()
+                    .any(|segment| segment_intersects_rect(&segment, rect))
+            }
+        }
+    }
+
+    pub fn draw(&self, ctx: &mut druid::PaintCtx) {
+        match self {
+            CanvasElement::Freehand {
+                path,
+                thickness,
+                stroke_color,
+            } => {
+                use druid::RenderContext;
+                ctx.stroke(&path.kurbo_path, &*stroke_color, *thickness);
+            }
+        }
+    }
+}
+
+#[derive(Clone, druid::Data)]
+pub struct Canvas {
+    elements: Vector<CanvasElement>,
+    content_size: druid::Size,
+}
+
+impl Canvas {
+    pub fn new() -> Self {
+        Canvas {
+            elements: vector![],
+            content_size: druid::Size::new(0.0, 0.0),
+        }
+    }
+
+    pub fn new_with_elements(elements: Vector<CanvasElement>) -> Self {
+        let mut cv = Canvas::new();
+        for e in elements {
+            cv.add_element(e);
+        }
+        cv
+    }
+
+    pub fn add_element(&mut self, element: CanvasElement) {
+        self.content_size = self
+            .content_size
+            .to_rect()
+            .union(element.bounding_box())
+            .size();
+        self.elements.push_back(element);
+    }
+
+    pub fn elements(&self) -> &Vector<CanvasElement> {
+        &self.elements
+    }
+
+    /// Find all CanvasElement that intersect with rect
+    pub fn find_intersections(&self, rect: druid::Rect) -> Vec<usize> {
+        let mut found_elements = Vec::<usize>::new();
+
+        for (i, elem) in self.elements.iter().enumerate() {
+            // Check if the element intersects the eraser rect
+            if elem.bounding_box().intersect(rect).area() > 0.0 {
+                if elem.intersects_rect(rect) {
+                    found_elements.push(i);
+                }
+            }
+        }
+
+        found_elements
+    }
+
+    pub fn content_size(&self) -> druid::Size {
+        self.content_size
+    }
+}
+
+impl Serialize for Path {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        use druid::kurbo::PathEl;
+
+        serializer.collect_seq(self.kurbo_path.iter().filter_map(|path_el| match path_el {
+            PathEl::MoveTo(pt) => Some(Into::<(f64, f64)>::into(pt)),
+            PathEl::LineTo(pt) => Some(Into::<(f64, f64)>::into(pt)),
+            _ => None,
+        }).collect::<Vec<(f64, f64)>>())
+    }
+}
+
+impl<'de> Deserialize<'de> for Path {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        struct PathVisitor;
+
+        impl<'de> Visitor<'de> for PathVisitor {
+            type Value = Path;
+
+            fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+                write!(formatter, "A sequence of 2D points")
+            }
+
+            fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
+            where
+                A: SeqAccess<'de>,
+            {
+                use druid::kurbo::BezPath;
+
+                let mut kurbo_path = BezPath::new();
+                let mut first_element = true;
+                while let Some(point) = seq.next_element::<(f64, f64)>()? {
+                    if first_element {
+                        kurbo_path.move_to(point);
+                        first_element = false;
+                    } else {
+                        kurbo_path.line_to(point);
+                    }
+                }
+
+                Ok(Path { kurbo_path })
+            }
+        }
+
+        deserializer.deserialize_seq(PathVisitor)
+    }
+}

src/history.rs

@@ -0,0 +1,92 @@
+//  Stiletto
+//  Copyright (C) 2020 Stiletto Authors
+//
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU Affero General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU Affero General Public License for more details.
+//
+//  You should have received a copy of the GNU Affero General Public License
+//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+use super::canvas::Canvas;
+use im::Vector;
+
+#[derive(Clone, druid::Data)]
+pub struct VersionedCanvas {
+    // We internally guarantee that this vector
+    // is never empty
+    versions: Vector<Canvas>,
+    curr_version: usize,
+}
+
+impl VersionedCanvas {
+    pub fn new(canvas: Canvas) -> VersionedCanvas {
+        VersionedCanvas {
+            versions: im::vector![canvas],
+            curr_version: 0,
+        }
+    }
+
+    // Get current canvas version
+    pub fn get(&self) -> &Canvas {
+        self.versions.get(self.curr_version).unwrap()
+    }
+
+    fn has_newer_versions(&self) -> bool {
+        self.curr_version + 1 < self.versions.len()
+    }
+
+    fn has_older_versions(&self) -> bool {
+        self.curr_version > 0
+    }
+
+    pub fn undo(&mut self) {
+        if self.has_older_versions() {
+            self.curr_version -= 1;
+        }
+    }
+
+    pub fn redo(&mut self) {
+        if self.has_newer_versions() {
+            self.curr_version += 1;
+        }
+    }
+
+    pub fn update(&mut self, update_fn: impl FnOnce(&mut Canvas)) {
+        // Make a new copy of the current canvas version,
+        // so that we can safely modify it without losing
+        // the previous canvas version
+        let mut new_version = self.get().clone();
+        update_fn(&mut new_version);
+
+        // This is a linear history,
+        // so we first check if there are newer versions, if so
+        // this means we are in the past, so a change in the past destroys the future
+        // and creates a new future.
+        if self.has_newer_versions() {
+            self.versions = self.versions.take(self.curr_version + 1);
+        }
+        self.versions.push_back(new_version);
+        self.curr_version += 1;
+    }
+
+    // Do inplace update, which will be irreversible
+    pub fn irreversible_update(&mut self, update_fn: impl FnOnce(&mut Canvas)) {
+        // Do the update directly on the current canvas version
+        update_fn(self.versions.back_mut().unwrap());
+
+        // This is a linear history,
+        // so we first check if there are newer versions, if so
+        // this means we are in the past, so a change in the past destroys the future
+        // and creates a new future.
+        if self.has_newer_versions() {
+            self.versions = self.versions.take(self.curr_version + 1);
+        }
+    }
+}

src/lib.rs

@@ -12,189 +12,37 @@
 //  GNU Affero General Public License for more details.
 //
 //  You should have received a copy of the GNU Affero General Public License
-//  along with this program.  If not, see <https://www.gnu.org/licenses/>.use serde::{Serialize, Deserialize};
+//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
-use im::Vector;
+use serde::{Deserialize, Serialize};
+use std::vec::Vec;
 
-use serde::{Serialize, Deserialize};
+pub mod canvas;
-use serde::ser::{Serializer};
+pub mod history;
-use serde::de::{Deserializer, Visitor, SeqAccess};
+pub mod tool;
-use std::vec::{Vec};
+pub mod widget;
+pub mod migration;
 
-#[derive(Debug, Clone, druid::Data)]
+pub mod commands {
-pub struct Path {
+    use druid::Selector;
-    pub kurbo_path: druid::kurbo::BezPath,
+
+    pub const UPDATE_TOOL: Selector = Selector::new("stiletto_update_tool");
+    pub const PUSH_ERASER: Selector<()> = Selector::new("push_eraser_context");
+    pub const POP_ERASER: Selector<()> = Selector::new("pop_eraser_context");
 }
 
-#[derive(Debug, Clone, druid::Data, Serialize, Deserialize)]
+pub const STILETTO_FORMAT_MAJOR: u16 = 0;
-pub enum CanvasElement {
+pub const STILETTO_FORMAT_MINOR: u16 = 2;
-    Freehand { path: Path, thickness: f64 },
-}
-
-impl CanvasElement {
-    pub fn bounding_box(&self) -> druid::Rect {
-        match self {
-            CanvasElement::Freehand { path, thickness } => {
-                use druid::kurbo::Shape;
-                path.kurbo_path
-                    .bounding_box()
-                    .inflate(*thickness, *thickness)
-            }
-        }
-    }
-    pub fn draw(&self, ctx: &mut druid::PaintCtx) {
-        match self {
-            CanvasElement::Freehand { path, thickness } => {
-                use druid::RenderContext;
-                let stroke_color = druid::Color::rgb8(0, 128, 0);
-                ctx.stroke(&path.kurbo_path, &stroke_color, *thickness);
-            }
-        }
-    }
-
-    pub fn get_path_mut(&mut self) -> Option<&mut Path> {
-        match self {
-            CanvasElement::Freehand { path, .. } => Some(path),
-        }
-    }
-}
-
-// A canvas contains all elements to be drawn
-pub type Canvas = Vector<CanvasElement>;
-
-#[derive(Clone, druid::Data)]
-pub struct VersionedCanvas {
-    // We internally guarantee that this vector
-    // is never empty
-    versions: Vector<Canvas>,
-    curr_version: usize,
-}
-
-impl VersionedCanvas {
-    pub fn new(canvas: Canvas) -> VersionedCanvas {
-        VersionedCanvas {
-            versions: im::vector![canvas],
-            curr_version: 0,
-        }
-    }
-
-    // Get current canvas version
-    pub fn get(&self) -> &Canvas {
-        self.versions.get(self.curr_version).unwrap()
-    }
-
-    fn has_newer_versions(&self) -> bool {
-        self.curr_version + 1 < self.versions.len()
-    }
-
-    fn has_older_versions(&self) -> bool {
-        self.curr_version > 0
-    }
-
-    pub fn undo(&mut self) {
-        if self.has_older_versions() {
-            self.curr_version = self.curr_version - 1;
-        }
-    }
-
-    pub fn redo(&mut self) {
-        if self.has_newer_versions() {
-            self.curr_version = self.curr_version + 1;
-        }
-    }
-
-    pub fn update(&mut self, update_fn: impl FnOnce(&mut Canvas)) {
-        // Make a new copy of the current canvas version,
-        // so that we can safely modify it without losing
-        // the previous canvas version
-        let mut new_version = self.get().clone();
-        update_fn(&mut new_version);
-
-        // This is a linear history,
-        // so we first check if there are newer versions, if so
-        // this means we are in the past, so a change in the past destroys the future
-        // and creates a new future.
-        if self.has_newer_versions() {
-            self.versions = self.versions.take(self.curr_version + 1);
-        }
-        self.versions.push_back(new_version);
-        self.curr_version = self.curr_version + 1;
-    }
-
-    // Do inplace update, which will be irreversible
-    pub fn irreversible_update(&mut self, update_fn: impl FnOnce(&mut Canvas)) {
-        // Do the update directly on the current canvas version
-        update_fn(self.versions.back_mut().unwrap());
-
-        // This is a linear history,
-        // so we first check if there are newer versions, if so
-        // this means we are in the past, so a change in the past destroys the future
-        // and creates a new future.
-        if self.has_newer_versions() {
-            self.versions = self.versions.take(self.curr_version + 1);
-        }
-    }
-}
-
-struct PathDeserializer;
-
-impl<'de> Visitor<'de> for PathDeserializer {
-    type Value = Path;
-
-    fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
-        write!(formatter, "A sequence of 2D points")
-    }
-
-    fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
-    where
-        A: SeqAccess<'de>
-    {
-        use druid::kurbo::BezPath;
-
-        let mut kurbo_path = BezPath::new();
-        let mut first_element = true;
-        while let Some(point) = seq.next_element::<(f64, f64)>()? {
-            if first_element {
-                kurbo_path.move_to(point);
-                first_element = false;
-            } else {
-                kurbo_path.line_to(point);
-            }
-        }
-
-        Ok(Path{ kurbo_path })
-    }
-}
-
-impl<'de> Deserialize<'de> for Path {
-    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-    where
-        D: Deserializer<'de>
-    {
-        deserializer.deserialize_seq(PathDeserializer)
-    }
-}
-
-impl Serialize for Path {
-    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    where
-        S: Serializer,
-    {
-        use druid::kurbo::{PathEl};
-
-        serializer.collect_seq(
-            self.kurbo_path.iter()
-                .filter_map(|path_el| {
-                    match path_el {
-                        PathEl::MoveTo(pt) => Some(Into::<(f64, f64)>::into(pt)),
-                        PathEl::LineTo(pt) => Some(Into::<(f64, f64)>::into(pt)),
-                        _ => None
-                    }
-                }))
-    }
-}
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct DocumentSnapshot {
-    pub canvas_elements: Vec<CanvasElement>,
+    pub format_version_major: u16,
+    pub format_version_minor: u16,
+    pub canvas_elements: Vec<canvas::CanvasElement>,
+}
+
+impl DocumentSnapshot {
+    pub fn to_writer<W: std::io::Write>(&self, writer: W) -> Result<(), serde_bare::Error> {
+        serde_bare::to_writer(writer, &self)
+    }
 }

src/main.rs

@@ -14,221 +14,67 @@
 //  You should have received a copy of the GNU Affero General Public License
 //  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+use std::path::PathBuf;
+
 use log::{info, warn};
 
-use druid::im::{vector, Vector};
-use druid::kurbo::BezPath;
-use druid::widget::prelude::*;
-use druid::{AppLauncher, Color, Data, Event, LocalizedString, WindowDesc, AppDelegate, Target, Env, DelegateCtx, FileDialogOptions, FileSpec, Command};
 use druid::commands;
+use druid::im::vector;
+use druid::widget::prelude::*;
+use druid::widget::{
+    Align, Button, Controller, CrossAxisAlignment, Flex, List, SizedBox, WidgetExt,
+};
+use druid::{
+    AppDelegate, AppLauncher, Color, Command, Data, DelegateCtx, Env, FileDialogOptions, FileSpec,
+    Handled, Lens, Target, WindowDesc,
+};
 
-use stiletto::{CanvasElement, VersionedCanvas, Canvas, DocumentSnapshot};
+use im::Vector;
 
-struct Delegate;
+use stiletto::tool::CanvasToolParams;
-
+use stiletto::widget::tool_ctx::{CanvasToolCtx};
-#[derive(Clone, Data)]
+use stiletto::widget::{build_simple_tool_widget, CanvasState, CanvasToolIconState, CanvasWidget};
-struct CanvasData {
+use stiletto::DocumentSnapshot;
-    current_element: Option<CanvasElement>,
-    elements: VersionedCanvas,
-}
-
-impl CanvasData {
-    fn is_drawing(&self) -> bool {
-        self.current_element.is_some()
-    }
-
-    fn perform_undo(&mut self) {
-        if !self.is_drawing() {
-            self.elements.undo();
-        }
-    }
-
-    fn perform_redo(&mut self) {
-        if !self.is_drawing() {
-            self.elements.redo();
-        }
-    }
-
-    fn get_document_snapshot(&self) -> DocumentSnapshot {
-        DocumentSnapshot {
-            canvas_elements: self.elements.get().iter().cloned().collect()
-        }
-    }
-
-    fn set_from_snapshot(&mut self, snapshot: DocumentSnapshot) {
-        self.current_element = None;
-        self.elements = VersionedCanvas::new(Vector::from(snapshot.canvas_elements));
-    }
-}
-
-struct CanvasWidget;
-
-impl Widget<CanvasData> for CanvasWidget {
-    fn event(&mut self, _ctx: &mut EventCtx, event: &Event, data: &mut CanvasData, _env: &Env) {
-        match event {
-            Event::MouseDown(mouse_event) => {
-                let mut kurbo_path = BezPath::new();
-                kurbo_path.move_to((mouse_event.pos.x, mouse_event.pos.y));
-                data.current_element = Some(CanvasElement::Freehand {
-                    path: stiletto::Path { kurbo_path },
-                    thickness: 2.0,
-                });
-            }
-            Event::MouseMove(mouse_event) => {
-                if data.is_drawing() {
-                    if let Some(current_element) = data.current_element.as_mut() {
-                        current_element
-                            .get_path_mut()
-                            .unwrap()
-                            .kurbo_path
-                            .line_to((mouse_event.pos.x, mouse_event.pos.y));
-                    }
-                }
-            }
-            Event::MouseUp(_) => {
-                if data.is_drawing() {
-                    if let Some(current_element) = data.current_element.take() {
-
-                        data.elements.update(move |canvas: &mut Canvas| {
-                            canvas.push_back(current_element);
-                        });
-
-                    }
-                }
-            }
-            _ => {}
-        }
-    }
-
-    fn lifecycle(
-        &mut self,
-        _ctx: &mut LifeCycleCtx,
-        _event: &LifeCycle,
-        _data: &CanvasData,
-        _env: &Env,
-    ) {
-    }
-
-    fn update(
-        &mut self,
-        ctx: &mut UpdateCtx,
-        old_data: &CanvasData,
-        data: &CanvasData,
-        _env: &Env,
-    ) {
-        // the current_element is moved to the elements array, no need to repaint
-        if old_data.is_drawing() && !data.is_drawing() {
-            return;
-        }
-        if data.is_drawing() {
-            if let Some(e) = data.current_element.as_ref() {
-                ctx.request_paint_rect(e.bounding_box());
-            }
-        } else {
-            ctx.request_paint();
-        }
-    }
-
-    fn layout(
-        &mut self,
-        _layout_ctx: &mut LayoutCtx,
-        bc: &BoxConstraints,
-        _data: &CanvasData,
-        _env: &Env,
-    ) -> Size {
-        // BoxConstraints are passed by the parent widget.
-        // This method can return any Size within those constraints:
-        // bc.constrain(my_size)
-        //
-        // To check if a dimension is infinite or not (e.g. scrolling):
-        // bc.is_width_bounded() / bc.is_height_bounded()
-        bc.max()
-    }
-
-    // The paint method gets called last, after an event flow.
-    // It goes event -> update -> layout -> paint, and each method can influence the next.
-    // Basically, anything that changes the appearance of a widget causes a paint.
-    fn paint(&mut self, ctx: &mut PaintCtx, data: &CanvasData, _env: &Env) {
-        // (ctx.size() returns the size of the layout rect we're painting in)
-        let size = ctx.size();
-        let rect = size.to_rect();
-        // Note: ctx also has a `clear` method, but that clears the whole context,
-        // and we only want to clear this widget's area.
-        ctx.fill(rect, &Color::WHITE);
-
-        for element in data.elements.get().iter() {
-            element.draw(ctx);
-        }
-        if let Some(element) = &data.current_element {
-            element.draw(ctx);
-        }
-    }
-}
-
-fn build_ui() -> impl Widget<CanvasData> {
-    use druid::widget::{Align, Button, CrossAxisAlignment, Flex, SizedBox};
-    let history_buttons = Flex::row()
-        .cross_axis_alignment(CrossAxisAlignment::Center)
-        .with_child(
-            Button::new("Undo").on_click(|_ctx: &mut EventCtx, data: &mut CanvasData, _env: &Env| data.perform_undo())
-        )
-        .with_child(Button::new("Redo").on_click(|_ctx: &mut EventCtx, data: &mut CanvasData, _env: &Env| data.perform_redo()));
-
-    let stlt = FileSpec::new("Stiletto notebook", &["stlt"]);
-    let save_dialog_options = FileDialogOptions::new()
-        .allowed_types(vec![stlt])
-        .default_type(stlt);
-    let open_dialog_options = save_dialog_options.clone();
-
-    let save_buttons = Flex::row()
-        .cross_axis_alignment(CrossAxisAlignment::Center)
-        .with_child(
-            Button::new("Open")
-                .on_click(move |ctx, _, _| {
-                    ctx.submit_command(
-                        Command::new(
-                            druid::commands::SHOW_OPEN_PANEL,
-                            open_dialog_options.clone(),
-                        ),
-                        None,
-                    )
-                }))
-        .with_child(
-            Button::new("Save")
-                .on_click(move |ctx, _, _| {
-                    ctx.submit_command(
-                        Command::new(
-                            druid::commands::SHOW_SAVE_PANEL,
-                            save_dialog_options.clone(),
-                        ),
-                        None,
-                    )
-                }));
-
-
-    let toolbar = Flex::row()
-        .cross_axis_alignment(CrossAxisAlignment::Center)
-        .with_spacer(30.0)
-        .with_flex_child(Align::left(history_buttons), 1.0)
-        .with_flex_child(Align::right(save_buttons), 1.0)
-        .with_spacer(30.0);
-
-    Flex::column()
-        .cross_axis_alignment(CrossAxisAlignment::Center)
-        .must_fill_main_axis(true)
-        .with_child(SizedBox::new(Align::left(toolbar)).height(50.0))
-        .with_flex_child(CanvasWidget {}, 1.0)
-}
 
 pub fn main() {
     let window = WindowDesc::new(build_ui)
         .window_size((1024.0, 1400.0))
-        .title(
+        .title(|data: &StilettoState, _env: &Env| {
-            LocalizedString::new("custom-widget-demo-window-title").with_placeholder("Stiletto"),
+            let doc_name = if let Some(path) = &data.current_file_path {
-        );
+                String::from(path.to_string_lossy())
-    let canvas_data = CanvasData {
+            } else {
-        current_element: None,
+                String::from("New Document")
-        elements: VersionedCanvas::new(vector![]),
+            };
+            format!("Stiletto - {}", doc_name)
+        });
+
+    let default_pen_params = CanvasToolParams::Pen {
+        thickness: 2.0,
+        color: Color::rgb(0.0, 0.0, 0.0),
+    };
+    let default_pen_params_2 = CanvasToolParams::Pen {
+        thickness: 2.0,
+        color: Color::rgb(255.0, 0.0, 0.0),
+    };
+    let canvas_data = StilettoState {
+        canvas: CanvasState::new(CanvasToolCtx::new(default_pen_params.clone())),
+        tool_icons: vector![
+            CanvasToolIconState {
+                tool_params: default_pen_params,
+                selected: true,
+            },
+            CanvasToolIconState {
+                tool_params: default_pen_params_2,
+                selected: false,
+            },
+            CanvasToolIconState {
+                tool_params: CanvasToolParams::Eraser,
+                selected: false,
+            },
+        ],
+        current_tool: 0,
+        eraser_tool_id: 2,
+        current_file_path: None,
     };
     AppLauncher::with_window(window)
         .use_simple_logger()
@@ -237,43 +83,213 @@ pub fn main() {
         .expect("launch failed");
 }
 
-impl AppDelegate<CanvasData> for Delegate {
+#[derive(Clone, Data, Lens)]
+struct StilettoState {
+    canvas: CanvasState,
+    tool_icons: Vector<CanvasToolIconState>,
+    current_tool: usize,
+    eraser_tool_id: usize,
+    #[data(same_fn = "PartialEq::eq")]
+    current_file_path: Option<PathBuf>,
+}
+
+impl StilettoState {
+    pub fn set_tool(&mut self, new_tool: usize) {
+        let old_tool = self.current_tool;
+        info!("Changing active tool to: tool #{}", new_tool);
+        self.tool_icons.get_mut(old_tool).unwrap().selected = false;
+        self.tool_icons.get_mut(new_tool).unwrap().selected = true;
+        self.current_tool = new_tool;
+        self.canvas.set_tool_ctx(CanvasToolCtx::new(
+            self.tool_icons.get(new_tool).unwrap().tool_params.clone(),
+        ));
+    }
+}
+
+fn build_ui() -> impl Widget<StilettoState> {
+    let history_buttons = Flex::row()
+        .cross_axis_alignment(CrossAxisAlignment::Center)
+        .with_child(Button::new("Undo").on_click(
+            |_ctx: &mut EventCtx, data: &mut StilettoState, _env: &Env| data.canvas.perform_undo(),
+        ))
+        .with_child(Button::new("Redo").on_click(
+            |_ctx: &mut EventCtx, data: &mut StilettoState, _env: &Env| data.canvas.perform_redo(),
+        ));
+
+    let stlt = FileSpec::new("Stiletto notebook", &["stlt"]);
+    let save_dialog_options = FileDialogOptions::new()
+        .allowed_types(vec![stlt])
+        .default_type(stlt);
+    let save_dialog_options_clone = save_dialog_options.clone();
+    let open_dialog_options = save_dialog_options.clone();
+
+    let save_buttons = Flex::row()
+        .cross_axis_alignment(CrossAxisAlignment::Center)
+        .with_child(
+            Button::new("Save").on_click(move |ctx, data: &mut StilettoState, _| {
+                if data.current_file_path.is_some() {
+                    ctx.submit_command(Command::new(commands::SAVE_FILE, (), Target::Auto));
+                } else {
+                    ctx.submit_command(Command::new(
+                        druid::commands::SHOW_SAVE_PANEL,
+                        save_dialog_options_clone.clone(),
+                        Target::Auto,
+                    ))
+                }
+            }),
+        )
+        .with_child(Button::new("Save As").on_click(move |ctx, _, _| {
+            ctx.submit_command(Command::new(
+                druid::commands::SHOW_SAVE_PANEL,
+                save_dialog_options.clone(),
+                Target::Auto,
+            ))
+        }))
+        .with_child(Button::new("Open").on_click(move |ctx, _, _| {
+            ctx.submit_command(Command::new(
+                druid::commands::SHOW_OPEN_PANEL,
+                open_dialog_options.clone(),
+                Target::Auto,
+            ))
+        }));
+
+    let tool_buttons = Flex::row()
+        .cross_axis_alignment(CrossAxisAlignment::Center)
+        .with_flex_child(
+            List::new(|| {
+                build_simple_tool_widget(30.0, 30.0, 5.0)
+                    .padding((8.0, 0.0))
+                    .on_click(|ctx, tool_state, _| {
+                        tool_state.selected = true;
+                        ctx.submit_notification(stiletto::commands::UPDATE_TOOL);
+                    })
+            })
+            .horizontal()
+            .lens(StilettoState::tool_icons),
+            1.0,
+        );
+
+    let toolbar = Flex::row()
+        .cross_axis_alignment(CrossAxisAlignment::Center)
+        .with_spacer(30.0)
+        .with_flex_child(Align::left(history_buttons), 1.0)
+        .with_spacer(10.0)
+        .with_flex_child(Align::left(tool_buttons), 2.0)
+        .with_spacer(20.0)
+        .with_flex_child(Align::right(save_buttons), 1.0)
+        .with_spacer(30.0);
+
+    Flex::column()
+        .cross_axis_alignment(CrossAxisAlignment::Center)
+        .must_fill_main_axis(true)
+        .with_child(SizedBox::new(Align::left(toolbar)).height(50.0))
+        .with_flex_child((CanvasWidget).lens(StilettoState::canvas), 1.0)
+        .controller(ToolSwitcher::new())
+}
+
+struct ToolSwitcher {
+    saved_tool: usize,
+}
+
+impl ToolSwitcher {
+    pub fn new() -> Self {
+        ToolSwitcher { saved_tool: 0 }
+    }
+}
+
+impl<W: Widget<StilettoState>> Controller<StilettoState, W> for ToolSwitcher {
+    fn event(
+        &mut self,
+        child: &mut W,
+        ctx: &mut EventCtx,
+        event: &Event,
+        data: &mut StilettoState,
+        env: &Env,
+    ) {
+        match event {
+            Event::Notification(cmd) => {
+                let new_tool = if cmd.get(stiletto::commands::PUSH_ERASER).is_some() {
+                    ctx.set_handled();
+                    self.saved_tool = data.current_tool;
+                    Some(data.eraser_tool_id)
+                } else if cmd.get(stiletto::commands::POP_ERASER).is_some() {
+                    ctx.set_handled();
+                    Some(self.saved_tool)
+                } else if cmd.get(stiletto::commands::UPDATE_TOOL).is_some() {
+                    ctx.set_handled();
+                    let old_tool = data.current_tool;
+                    data.tool_icons
+                        .iter()
+                        .enumerate()
+                        .position(|(pos, x)| pos != old_tool && x.selected)
+                } else {
+                    None
+                };
+
+                if let Some(new_tool) = new_tool {
+                    data.set_tool(new_tool);
+                }
+            }
+            _ => {}
+        }
+        child.event(ctx, event, data, env);
+    }
+}
+
+struct Delegate;
+
+impl AppDelegate<StilettoState> for Delegate {
     fn command(
         &mut self,
         _ctx: &mut DelegateCtx,
         _target: Target,
         cmd: &Command,
-        data: &mut CanvasData,
+        data: &mut StilettoState,
         _env: &Env,
-    ) -> bool {
+    ) -> Handled {
         use std::fs::File;
 
-        if let Some(Some(file_info)) = cmd.get(commands::SAVE_FILE) {
+        if cmd.get(commands::SAVE_FILE_AS).is_some() || cmd.get(commands::SAVE_FILE).is_some() {
-            let res_file = File::create(file_info.path());
+            let mut path_buf = cmd
+                .get(commands::SAVE_FILE_AS)
+                .map(|file_info| file_info.path().to_path_buf())
+                .or_else(|| data.current_file_path.as_ref().cloned())
+                .unwrap();
+            path_buf.set_extension("stlt");
+
+            let res_file = File::create(&path_buf);
             if let Ok(f) = res_file {
-                let write_res = serde_json::to_writer_pretty(f, &data.get_document_snapshot());
+                let write_res =
+                    data.canvas.get_document_snapshot().to_writer(f);
                 if write_res.is_err() {
                     warn!("Error while saving: {:?}", write_res.err());
                 } else {
-                    info!("Written to file: {}", file_info.path().display());
+                    info!("Written to file: {}", &path_buf.display());
+                    data.current_file_path = Some(path_buf);
                 }
             } else {
                 warn!("Cannot create file: {:?}", res_file.err());
             }
-            return true;
+            return Handled::Yes;
         }
         if let Some(file_info) = cmd.get(commands::OPEN_FILE) {
             if let Ok(f) = File::open(file_info.path()) {
-                let res_snapshot: Result<DocumentSnapshot, serde_json::Error> = serde_json::from_reader(f);
+                let res_snapshot: Result<DocumentSnapshot, serde_bare::Error> =
+                    serde_bare::from_reader(f);
                 if let Ok(document_snapshot) = res_snapshot {
-                    data.set_from_snapshot(document_snapshot);
+                    data.canvas.set_from_snapshot(document_snapshot);
+                    data.current_file_path = Some(file_info.path().to_path_buf());
                     info!("Loaded file {}", file_info.path().display());
                 } else {
-                    warn!("didn't work: {:?}", res_snapshot.err());
+                    warn!(
+                        "Error while loading {}: {:?}",
+                        file_info.path().display(),
+                        res_snapshot.err()
+                    );
                 }
             }
-            return true;
+            return Handled::Yes;
         }
-        false
+        Handled::No
     }
 }

src/migration.rs

@@ -0,0 +1,142 @@
+//  Stiletto
+//  Copyright (C) 2020 Stiletto Authors
+//
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU Affero General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU Affero General Public License for more details.
+//
+//  You should have received a copy of the GNU Affero General Public License
+//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+use crate::{DocumentSnapshot, STILETTO_FORMAT_MAJOR, STILETTO_FORMAT_MINOR};
+
+use std::error::Error;
+use std::fmt;
+use std::fs::File;
+use std::io;
+use std::path::PathBuf;
+
+#[derive(Debug)]
+pub enum MigrationError {
+    SerdeJsonError(serde_json::Error),
+    SerdeBareError(serde_bare::Error),
+    IoError(io::Error),
+
+    UnexpectedVersion(u16, u16, u16, u16),
+}
+
+#[derive(Debug)]
+pub enum StilettoDocument {
+    DocumentSnapshot0_1(DocumentSnapshot),
+    DocumentSnapshot0_2(DocumentSnapshot),
+}
+
+impl StilettoDocument {
+    pub fn version(&self) -> (u16, u16) {
+        match &self {
+            StilettoDocument::DocumentSnapshot0_1(_) => (0, 1),
+            StilettoDocument::DocumentSnapshot0_2(_) => (0, 2),
+        }
+    }
+
+    pub fn migrate_to_next(self) -> StilettoDocument {
+        match self {
+            StilettoDocument::DocumentSnapshot0_1(snapshot) =>  StilettoDocument::DocumentSnapshot0_2(snapshot) ,
+            StilettoDocument::DocumentSnapshot0_2(_) => self,
+        }
+    }
+
+    pub fn migrate_to_latest(mut self) -> DocumentSnapshot {
+        while self.version() != (STILETTO_FORMAT_MAJOR, STILETTO_FORMAT_MINOR) {
+            self = self.migrate_to_next()
+        }
+
+        assert!(matches!(self, StilettoDocument::DocumentSnapshot0_2(_)));
+        match self {
+            StilettoDocument::DocumentSnapshot0_2(snapshot) => snapshot,
+            _ => panic!("Wrong Document Snapshot Version")
+        }
+    }
+}
+
+
+impl fmt::Display for MigrationError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match &self {
+            MigrationError::SerdeJsonError(e) => e.fmt(f),
+            MigrationError::SerdeBareError(e) => e.fmt(f),
+            MigrationError::IoError(e) => e.fmt(f),
+            MigrationError::UnexpectedVersion(major, minor, e_major, e_minor) => {
+                write!(
+                    f, "Unexpected version ({}, {}): was expecting ({}, {})",
+                    major, minor, e_major, e_minor
+                )
+            },
+        }
+    }
+}
+
+impl Error for MigrationError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match self {
+            MigrationError::SerdeJsonError(e) => e.source(),
+            MigrationError::SerdeBareError(e) => e.source(),
+            MigrationError::IoError(e) => e.source(),
+            MigrationError::UnexpectedVersion(..) => None,
+        }
+    }
+}
+
+impl From<io::Error> for MigrationError {
+    fn from(error: io::Error) -> Self {
+        MigrationError::IoError(error)
+    }
+}
+
+impl From<serde_json::Error> for MigrationError {
+    fn from(error: serde_json::Error) -> Self {
+        MigrationError::SerdeJsonError(error)
+    }
+}
+
+impl From<serde_bare::Error> for MigrationError {
+    fn from(error: serde_bare::Error) -> Self {
+        MigrationError::SerdeBareError(error)
+    }
+}
+
+fn open_0_1(path: &PathBuf) -> Result<StilettoDocument, MigrationError> {
+    let f = File::open(path)?;
+    let document_snapshot: DocumentSnapshot = serde_json::from_reader(f)?;
+    if document_snapshot.format_version_major != 0 ||
+        document_snapshot.format_version_minor != 1 {
+        Err(MigrationError::UnexpectedVersion(
+            document_snapshot.format_version_major,
+            document_snapshot.format_version_minor,
+            0, 1
+        ))
+    } else {
+        Ok(StilettoDocument::DocumentSnapshot0_1(document_snapshot))
+    }
+}
+
+fn open_0_2(path: &PathBuf) -> Result<StilettoDocument, MigrationError> {
+    let f = File::open(path)?;
+    let document_snapshot: DocumentSnapshot = serde_bare::from_reader(f)?;
+    Ok(StilettoDocument::DocumentSnapshot0_2(document_snapshot))
+}
+
+pub fn open_stiletto_document(path: &PathBuf) -> Result<StilettoDocument, MigrationError> {
+    if let Ok(res) = open_0_1(path) {
+        return Ok(res);
+    }
+
+    open_0_2(path)
+}
+

src/tool.rs

@@ -0,0 +1,30 @@
+//  Stiletto
+//  Copyright (C) 2020 Stiletto Authors
+//
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU Affero General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU Affero General Public License for more details.
+//
+//  You should have received a copy of the GNU Affero General Public License
+//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+use druid::{Color, Data};
+
+#[derive(Clone, Data)]
+pub enum CanvasToolParams {
+    Pen { thickness: f64, color: Color },
+    Eraser,
+}
+
+#[derive(Clone, PartialEq)]
+pub enum CanvasToolType {
+    Pen,
+    Eraser,
+}
+

src/widget/canvas.rs

@@ -0,0 +1,188 @@
+//  Stiletto
+//  Copyright (C) 2020 Stiletto Authors
+//
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU Affero General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU Affero General Public License for more details.
+//
+//  You should have received a copy of the GNU Affero General Public License
+//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+use im::Vector;
+
+use super::tool_ctx::{CanvasToolCtx};
+use crate::canvas::Canvas;
+use crate::history::VersionedCanvas;
+use crate::DocumentSnapshot;
+
+use druid::widget::prelude::*;
+use druid::{Color, Data, Env, Event, PointerType};
+
+#[derive(Clone, Data)]
+pub struct CanvasState {
+    versioned_canvas: VersionedCanvas,
+    tool_ctx: CanvasToolCtx,
+    temporary_erasing: bool,
+}
+
+impl CanvasState {
+    pub fn new(tool_ctx: CanvasToolCtx) -> Self {
+        CanvasState {
+            versioned_canvas: VersionedCanvas::new(Canvas::new()),
+            tool_ctx: tool_ctx,
+            temporary_erasing: true,
+        }
+    }
+    pub fn perform_undo(&mut self) {
+        //if !self.is_drawing() {
+        self.versioned_canvas.undo();
+        //}
+    }
+
+    pub fn perform_redo(&mut self) {
+        //if !self.is_drawing() {
+        self.versioned_canvas.redo();
+        //}
+    }
+
+    pub fn get_document_snapshot(&self) -> DocumentSnapshot {
+        DocumentSnapshot {
+            format_version_major: 0,
+            format_version_minor: 1,
+            canvas_elements: self
+                .versioned_canvas
+                .get()
+                .elements()
+                .iter()
+                .cloned()
+                .collect(),
+        }
+    }
+
+    pub fn set_from_snapshot(&mut self, snapshot: DocumentSnapshot) {
+        self.versioned_canvas = VersionedCanvas::new(Canvas::new_with_elements(Vector::from(
+            snapshot.canvas_elements,
+        )));
+    }
+
+    pub fn set_tool_ctx(&mut self, ctx: CanvasToolCtx) {
+        self.tool_ctx = ctx;
+    }
+
+    pub fn get_tool_ctx(&self) -> &CanvasToolCtx {
+        &self.tool_ctx
+    }
+
+    pub fn get_tool_ctx_mut(&mut self) -> &mut CanvasToolCtx {
+        &mut self.tool_ctx
+    }
+
+    pub fn handle_event(&mut self, mut ctx: &mut EventCtx, event: &Event, env: &Env) {
+        self.tool_ctx
+            .handle_event(ctx, event, &mut self.versioned_canvas, env);
+    }
+}
+
+pub struct CanvasWidget;
+
+impl Widget<CanvasState> for CanvasWidget {
+    fn event(&mut self, ctx: &mut EventCtx, event: &Event, data: &mut CanvasState, env: &Env) {
+        ctx.request_focus();
+        let mut toggle_eraser_event = false;
+        let mut enable_temporary_erasing = false;
+        match event {
+            Event::MouseDown(mouse_event) => {
+                toggle_eraser_event = true;
+                enable_temporary_erasing = mouse_event.pointer_type == PointerType::Eraser;
+            }
+            Event::MouseMove(mouse_event) => {
+                toggle_eraser_event = true;
+                enable_temporary_erasing = mouse_event.pointer_type == PointerType::Eraser;
+            }
+            Event::MouseUp(mouse_event) => {
+                toggle_eraser_event = true;
+                enable_temporary_erasing = mouse_event.pointer_type == PointerType::Eraser;
+            }
+            _ => {}
+        }
+        // TODO: the first eraser toggle is not handled
+        if toggle_eraser_event && data.temporary_erasing != enable_temporary_erasing {
+            if enable_temporary_erasing {
+                ctx.submit_notification(crate::commands::PUSH_ERASER);
+            } else {
+                ctx.submit_notification(crate::commands::POP_ERASER);
+            }
+            data.temporary_erasing = enable_temporary_erasing;
+        } else {
+            data.handle_event(ctx, event, env);
+        }
+    }
+
+    fn lifecycle(
+        &mut self,
+        _ctx: &mut LifeCycleCtx,
+        _event: &LifeCycle,
+        _data: &CanvasState,
+        _env: &Env,
+    ) {
+    }
+
+    fn update(
+        &mut self,
+        ctx: &mut UpdateCtx,
+        _old_data: &CanvasState,
+        _data: &CanvasState,
+        _env: &Env,
+    ) {
+        // the current_element is moved to the versioned_canvas array, no need to repaint
+        //if old_data.is_drawing() && !data.is_drawing() {
+        //    return;
+        //}
+        //if data.is_drawing() {
+        //    if let Some(e) = data.current_element.as_ref() {
+        //        ctx.request_paint_rect(e.bounding_box());
+        //    }
+        //} else {
+        ctx.request_paint();
+        //}
+    }
+
+    fn layout(
+        &mut self,
+        _layout_ctx: &mut LayoutCtx,
+        bc: &BoxConstraints,
+        _data: &CanvasState,
+        _env: &Env,
+    ) -> Size {
+        // BoxConstraints are passed by the parent widget.
+        // This method can return any Size within those constraints:
+        // bc.constrain(my_size)
+        //
+        // To check if a dimension is infinite or not (e.g. scrolling):
+        // bc.is_width_bounded() / bc.is_height_bounded()
+        bc.max()
+    }
+
+    // The paint method gets called last, after an event flow.
+    // It goes event -> update -> layout -> paint, and each method can influence the next.
+    // Basically, anything that changes the appearance of a widget causes a paint.
+    fn paint(&mut self, ctx: &mut PaintCtx, data: &CanvasState, env: &Env) {
+        // (ctx.size() returns the size of the layout rect we're painting in)
+        let size = ctx.size();
+        let rect = size.to_rect();
+
+        ctx.fill(rect, &Color::WHITE);
+        for element in data.versioned_canvas.get().elements().iter() {
+            element.draw(ctx);
+        }
+        if data.tool_ctx.needs_repaint() {
+            data.tool_ctx.paint(ctx, env);
+        }
+    }
+}

src/widget/mod.rs

@@ -0,0 +1,6 @@
+pub mod canvas;
+pub mod tool_icon;
+pub mod tool_ctx;
+
+pub use canvas::*;
+pub use tool_icon::*;

src/widget/tool_ctx.rs

@@ -0,0 +1,179 @@
+//  Stiletto
+//  Copyright (C) 2020 Stiletto Authors
+//
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU Affero General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU Affero General Public License for more details.
+//
+//  You should have received a copy of the GNU Affero General Public License
+//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+use crate::tool::{CanvasToolParams, CanvasToolType};
+use crate::canvas::{Canvas, CanvasElement};
+use crate::history::VersionedCanvas;
+
+use druid::kurbo::BezPath;
+use druid::{Data, Env, Event, EventCtx, MouseButton, MouseEvent, PaintCtx};
+
+#[derive(Clone, Data)]
+pub enum CanvasToolState {
+    Idle,
+    DrawingFreehand {
+        pen_params: CanvasToolParams,
+        current_path: CanvasElement,
+    },
+    Erasing,
+}
+
+#[derive(Clone, Data)]
+pub struct CanvasToolCtx {
+    initial_params: CanvasToolParams,
+    state: CanvasToolState,
+}
+
+impl CanvasToolParams {
+    pub fn tool_type(&self) -> CanvasToolType {
+        match self {
+            CanvasToolParams::Pen { .. } => CanvasToolType::Pen,
+            CanvasToolParams::Eraser => CanvasToolType::Eraser,
+        }
+    }
+}
+
+fn pressed(mouse_event: &MouseEvent) -> bool {
+    mouse_event.buttons.contains(MouseButton::Left)
+        || mouse_event.button == MouseButton::Left
+}
+
+impl CanvasToolCtx {
+    pub fn new(params: CanvasToolParams) -> Self {
+        CanvasToolCtx {
+            initial_params: params,
+            state: CanvasToolState::Idle,
+        }
+    }
+
+    pub fn handle_event(
+        &mut self,
+        ctx: &EventCtx,
+        event: &Event,
+        mut vcanvas: &mut VersionedCanvas,
+        env: &Env,
+    ) {
+        match self.initial_params.tool_type() {
+            CanvasToolType::Pen => self.handle_pen_event(&ctx, &event, &mut vcanvas, &env),
+            CanvasToolType::Eraser => self.handle_erase_event(&ctx, &event, &mut vcanvas, &env),
+        }
+    }
+
+    pub fn handle_erase_event(
+        &mut self,
+        _ctx: &EventCtx,
+        event: &Event,
+        vcanvas: &mut VersionedCanvas,
+        _env: &Env,
+    ) {
+        match (&mut self.state, event) {
+            (CanvasToolState::Idle, Event::MouseDown(mouse_event)) if pressed(mouse_event) => {
+                self.state = CanvasToolState::Erasing;
+            }
+            (CanvasToolState::Erasing, Event::MouseMove(mouse_event)) if pressed(mouse_event) => {
+                let eraser_rect = druid::Rect::from_center_size(mouse_event.pos, (5.0, 5.0));
+                let old_elements = vcanvas.get().elements();
+                let mut new_elements = old_elements.clone();
+                new_elements.retain(|elem| {
+                    // Check if the element intersects the eraser rect
+                    if elem.bounding_box().intersect(eraser_rect).area() > 0.0 {
+                        if elem.intersects_rect(eraser_rect) {
+                            return false;
+                        }
+                    }
+                    return true;
+                });
+                if new_elements.len() != old_elements.len() {
+                    vcanvas.update(|canvas: &mut Canvas| {
+                        *canvas = Canvas::new_with_elements(new_elements);
+                    });
+                }
+            }
+            (CanvasToolState::Erasing, Event::MouseUp(mouse_event)) if pressed(mouse_event) => {
+                self.state = CanvasToolState::Idle;
+            }
+            _ => {}
+        }
+    }
+
+    pub fn handle_pen_event(
+        &mut self,
+        _ctx: &EventCtx,
+        event: &Event,
+        vcanvas: &mut VersionedCanvas,
+        _env: &Env,
+    ) {
+        match (&mut self.state, event) {
+            (CanvasToolState::Idle, Event::MouseDown(mouse_event)) if pressed(mouse_event) => {
+                let mut kurbo_path = BezPath::new();
+                kurbo_path.move_to((mouse_event.pos.x, mouse_event.pos.y));
+                if let CanvasToolParams::Pen { thickness, color } = &self.initial_params {
+                    self.state = CanvasToolState::DrawingFreehand {
+                        pen_params: self.initial_params.clone(),
+                        current_path: CanvasElement::Freehand {
+                            path: crate::canvas::Path { kurbo_path },
+                            thickness: *thickness,
+                            stroke_color: color.clone(),
+                        },
+                    };
+                }
+            }
+            (
+                CanvasToolState::DrawingFreehand {
+                    ref mut current_path,
+                    ..
+                },
+                Event::MouseMove(mouse_event),
+            ) => if pressed(mouse_event) {
+                if let CanvasElement::Freehand { ref mut path, .. } = current_path {
+                    path.kurbo_path
+                        .line_to((mouse_event.pos.x, mouse_event.pos.y));
+                }
+            }
+            (CanvasToolState::DrawingFreehand { .. }, Event::MouseUp(mouse_event)) if pressed(mouse_event) => {
+                vcanvas.update(move |canvas: &mut Canvas| {
+                    let current_state = std::mem::replace(&mut self.state, CanvasToolState::Idle);
+                    if let CanvasToolState::DrawingFreehand { current_path, .. } = current_state {
+                        if let CanvasElement::Freehand {
+                            mut path,
+                            mut thickness,
+                            stroke_color,
+                        } = current_path
+                        {
+                            canvas.add_element(CanvasElement::Freehand {
+                                path,
+                                thickness,
+                                stroke_color,
+                            });
+                        }
+                    }
+                });
+            }
+            _ => {}
+        }
+    }
+
+    pub fn needs_repaint(&self) -> bool {
+        true
+    }
+
+    pub fn paint(&self, ctx: &mut PaintCtx, _env: &Env) {
+        match &self.state {
+            CanvasToolState::DrawingFreehand { current_path, .. } => current_path.draw(ctx),
+            _ => {}
+        }
+    }
+}

src/widget/tool_icon.rs

@@ -0,0 +1,70 @@
+//  Stiletto
+//  Copyright (C) 2020 Stiletto Authors
+//
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU Affero General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU Affero General Public License for more details.
+//
+//  You should have received a copy of the GNU Affero General Public License
+//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+use druid::widget::{Container, SizedBox, Svg, SvgData, ViewSwitcher, WidgetExt};
+use druid::{Color, Data, UnitPoint};
+
+use crate::tool::CanvasToolParams;
+
+#[derive(Clone, Data)]
+pub struct CanvasToolIconState {
+    pub tool_params: CanvasToolParams,
+    pub selected: bool,
+}
+
+impl CanvasToolIconState {
+    fn svg_data(&self) -> SvgData {
+        match self.tool_params {
+            CanvasToolParams::Pen { .. } => include_str!("../../icons/pen.svg")
+                .parse::<SvgData>()
+                .unwrap(),
+            CanvasToolParams::Eraser => include_str!("../../icons/eraser.svg")
+                .parse::<SvgData>()
+                .unwrap(),
+        }
+    }
+}
+
+pub fn build_simple_tool_widget(
+    width: f64,
+    height: f64,
+    padding: f64,
+) -> ViewSwitcher<CanvasToolIconState, CanvasToolIconState> {
+    ViewSwitcher::<CanvasToolIconState, CanvasToolIconState>::new(
+        |tool_state, _| tool_state.clone(),
+        move |_, tool_state, _| {
+            Box::new(
+                Container::new(
+                    SizedBox::new(
+                        Svg::new(tool_state.svg_data())
+                            .align_horizontal(UnitPoint::CENTER)
+                            .fix_width(width)
+                            .fix_height(height),
+                    )
+                    .padding(padding),
+                )
+                .border(
+                    if tool_state.selected {
+                        Color::rgb(10.0, 10.0, 10.0)
+                    } else {
+                        Color::BLACK
+                    },
+                    1.0,
+                ),
+            )
+        },
+    )
+}