Add support to stylus eraser

src/lib.rs

@@ -26,6 +26,8 @@ pub mod commands {
     use druid::Selector;
 
     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(Serialize, Deserialize, Debug)]

src/main.rs

@@ -21,7 +21,9 @@ use log::{info, warn};
 use druid::commands;
 use druid::im::vector;
 use druid::widget::prelude::*;
-use druid::widget::{Align, Button, CrossAxisAlignment, Flex, List, SizedBox, WidgetExt};
+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,
@@ -70,6 +72,7 @@ pub fn main() {
             },
         ],
         current_tool: 0,
+        eraser_tool_id: 2,
         current_file_path: None,
     };
     AppLauncher::with_window(window)
@@ -84,10 +87,24 @@ 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)
@@ -107,17 +124,19 @@ fn build_ui() -> impl Widget<StilettoState> {
 
     let save_buttons = Flex::row()
         .cross_axis_alignment(CrossAxisAlignment::Center)
-        .with_child(Button::new("Save").on_click(move |ctx, data: &mut StilettoState, _| {
+        .with_child(
-            if data.current_file_path.is_some() {
+            Button::new("Save").on_click(move |ctx, data: &mut StilettoState, _| {
-                ctx.submit_command(Command::new(commands::SAVE_FILE, (), Target::Auto));
+                if data.current_file_path.is_some() {
-            } else {
+                    ctx.submit_command(Command::new(commands::SAVE_FILE, (), Target::Auto));
-                ctx.submit_command(Command::new(
+                } else {
-                    druid::commands::SHOW_SAVE_PANEL,
+                    ctx.submit_command(Command::new(
-                    save_dialog_options_clone.clone(),
+                        druid::commands::SHOW_SAVE_PANEL,
-                    Target::Auto,
+                        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,
@@ -141,7 +160,7 @@ fn build_ui() -> impl Widget<StilettoState> {
                     .padding((8.0, 0.0))
                     .on_click(|ctx, tool_state, _| {
                         tool_state.selected = true;
-                        ctx.submit_command(stiletto::commands::UPDATE_TOOL);
+                        ctx.submit_notification(stiletto::commands::UPDATE_TOOL);
                     })
             })
             .horizontal()
@@ -163,13 +182,60 @@ fn build_ui() -> impl Widget<StilettoState> {
         .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)
+        .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() {
+                    self.saved_tool = data.current_tool;
+                    Some(data.eraser_tool_id)
+                } else if cmd.get(stiletto::commands::POP_ERASER).is_some() {
+                    Some(self.saved_tool)
+                } else if cmd.get(stiletto::commands::UPDATE_TOOL).is_some() {
+                    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);
+                    ctx.set_handled();
+                }
+            }
+            _ => {}
+        }
+        child.event(ctx, event, data, env);
+    }
 }
 
 struct Delegate;
 
 impl AppDelegate<StilettoState> for Delegate {
-
     fn command(
         &mut self,
         _ctx: &mut DelegateCtx,
@@ -181,7 +247,8 @@ impl AppDelegate<StilettoState> for Delegate {
         use std::fs::File;
 
         if cmd.get(commands::SAVE_FILE_AS).is_some() || cmd.get(commands::SAVE_FILE).is_some() {
-            let mut path_buf = cmd.get(commands::SAVE_FILE_AS)
+            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();
@@ -220,22 +287,6 @@ impl AppDelegate<StilettoState> for Delegate {
             }
             return Handled::Yes;
         }
-        if cmd.get(stiletto::commands::UPDATE_TOOL).is_some() {
-            let old_tool = data.current_tool;
-            if let Some(new_tool) = data
-                .tool_icons
-                .iter()
-                .enumerate()
-                .position(|(pos, x)| pos != old_tool && x.selected)
-            {
-                info!("Changing active tool to: tool #{}", new_tool);
-                data.tool_icons.get_mut(old_tool).unwrap().selected = false;
-                data.current_tool = new_tool;
-                data.canvas.set_tool_ctx(CanvasToolCtx::new(
-                    data.tool_icons.get(new_tool).unwrap().tool_params.clone(),
-                ));
-            }
-        }
         Handled::No
     }
 }

src/tool.rs

@@ -91,8 +91,7 @@ impl CanvasToolCtx {
                 self.state = CanvasToolState::Erasing;
             }
             (CanvasToolState::Erasing, Event::MouseMove(mouse_event)) => {
-                let eraser_rect =
+                let eraser_rect = druid::Rect::from_center_size(mouse_event.pos, (5.0, 5.0));
-                    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| {

src/widget/canvas.rs

@@ -22,19 +22,21 @@ use crate::tool::CanvasToolCtx;
 use crate::DocumentSnapshot;
 
 use druid::widget::prelude::*;
-use druid::{Color, Data, Env, Event};
+use druid::{Color, Data, Env, Event, PointerType};
 
 #[derive(Clone, Data)]
 pub struct CanvasState {
-    pub versioned_canvas: VersionedCanvas,
+    versioned_canvas: VersionedCanvas,
-    pub tool_ctx: CanvasToolCtx,
+    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: tool_ctx,
+            temporary_erasing: true,
         }
     }
     pub fn perform_undo(&mut self) {
@@ -72,14 +74,54 @@ impl CanvasState {
     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) {
-        data.tool_ctx
+        ctx.request_focus();
-            .handle_event(ctx, event, &mut data.versioned_canvas, env);
+        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(