src/main.rs

@@ -26,7 +26,7 @@ use druid::widget::{
 };
 use druid::{
     AppDelegate, AppLauncher, Color, Command, Data, DelegateCtx, Env, FileDialogOptions, FileSpec,
-    Handled, Lens, Target, WindowDesc,
+    Handled, Lens, Target, WidgetId, WindowDesc,
 };
 
 use im::Vector;
@@ -107,6 +107,8 @@ impl StilettoState {
 }
 
 fn build_ui() -> impl Widget<StilettoState> {
+    let canvas_id = WidgetId::next();
+
     let history_buttons = Flex::row()
         .cross_axis_alignment(CrossAxisAlignment::Center)
         .with_child(Button::new("Undo").on_click(
@@ -125,19 +127,27 @@ fn build_ui() -> impl Widget<StilettoState> {
 
     let save_buttons = Flex::row()
         .cross_axis_alignment(CrossAxisAlignment::Center)
-        .with_child(
+        .with_child(Button::new("Up").on_click(
-            Button::new("Save").on_click(move |ctx, data: &mut StilettoState, _| {
+            move |ctx: &mut EventCtx, _data: &mut StilettoState, _env: &Env| {
-                if data.current_file_path.is_some() {
+                ctx.submit_command(Command::new(CanvasWidget::SCROLL, -30.0, canvas_id));
-                    ctx.submit_command(Command::new(commands::SAVE_FILE, (), Target::Auto));
+            },
-                } else {
+        ))
-                    ctx.submit_command(Command::new(
+        .with_child(Button::new("Down").on_click(
-                        druid::commands::SHOW_SAVE_PANEL,
+            move |ctx: &mut EventCtx, _data: &mut StilettoState, _env: &Env| {
-                        save_dialog_options_clone.clone(),
+                ctx.submit_command(Command::new(CanvasWidget::SCROLL, 30.0, canvas_id));
-                        Target::Auto,
+            },
-                    ))
+        ))
-                }
+        .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,
@@ -183,7 +193,12 @@ 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::new()
+                .lens(StilettoState::canvas)
+                .with_id(canvas_id),
+            1.0,
+        )
         .controller(ToolSwitcher::new())
 }
 

src/tool.rs

@@ -27,4 +27,3 @@ pub enum CanvasToolType {
     Pen,
     Eraser,
 }
-

src/widget/canvas.rs

@@ -21,8 +21,11 @@ use crate::canvas::Canvas;
 use crate::history::VersionedCanvas;
 use crate::DocumentSnapshot;
 
+use druid::scroll_component::ScrollComponent;
 use druid::widget::prelude::*;
-use druid::{Color, Data, Env, Event, PointerType};
+use druid::widget::Viewport;
+use druid::{Affine, Color, Data, Env, Event, PointerType, Selector};
+
 
 #[derive(Clone, Data)]
 pub struct CanvasState {
@@ -83,54 +86,102 @@ impl CanvasState {
         &mut self.tool_ctx
     }
 
-    pub fn handle_event(&mut self, mut ctx: &mut EventCtx, event: &Event, env: &Env) {
+    pub fn handle_event(&mut self, ctx: &mut EventCtx, event: &Event, transform: Affine, env: &Env) {
         self.tool_ctx
-            .handle_event(ctx, event, &mut self.versioned_canvas, env);
+            .handle_event(ctx, event, &mut self.versioned_canvas, transform, env);
     }
 }
 
-pub struct CanvasWidget;
+pub struct CanvasWidget {
+    viewport: Viewport,
+    scroll_component: ScrollComponent,
+}
+
+impl CanvasWidget {
+    pub fn new() -> Self {
+        CanvasWidget {
+            viewport: Viewport {
+                content_size: Size::new(0.0, 0.0),
+                rect: druid::Rect::new(0.0, 0.0, 0.0, 0.0),
+            },
+            scroll_component: ScrollComponent::new(),
+        }
+    }
+
+    pub const SCROLL: Selector<f64> = Selector::new("scroll_canvas");
+}
 
 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;
+        self.scroll_component
-        match event {
+            .event(&mut self.viewport, ctx, event, env);
-            Event::MouseDown(mouse_event) => {
+        if !ctx.is_handled() {
-                toggle_eraser_event = true;
+            let mut scroll_amount = 0.0;
-                enable_temporary_erasing = mouse_event.pointer_type == PointerType::Eraser;
+            let mut toggle_eraser_event = false;
+            let mut enable_temporary_erasing = false;
+            match event {
+                Event::Command(cmd) => {
+                    if let Some(value) = cmd.get(CanvasWidget::SCROLL) {
+                        scroll_amount = *value;
+                    }
+                }
+                Event::KeyDown(key_event) => {
+                    if key_event.code == druid::Code::ArrowDown {
+                        scroll_amount = 30.0;
+                    } else if key_event.code == druid::Code::ArrowUp {
+                        scroll_amount = -30.0;
+                    }
+                }
+                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;
+                }
+                _ => {}
             }
-            Event::MouseMove(mouse_event) => {
+            // TODO: the first eraser toggle is not handled
-                toggle_eraser_event = true;
+            if toggle_eraser_event && data.temporary_erasing != enable_temporary_erasing {
-                enable_temporary_erasing = mouse_event.pointer_type == PointerType::Eraser;
+                if enable_temporary_erasing {
-            }
+                    ctx.submit_notification(crate::commands::PUSH_ERASER);
-            Event::MouseUp(mouse_event) => {
+                } else {
-                toggle_eraser_event = true;
+                    ctx.submit_notification(crate::commands::POP_ERASER);
-                enable_temporary_erasing = mouse_event.pointer_type == PointerType::Eraser;
+                }
-            }
+                data.temporary_erasing = enable_temporary_erasing;
-            _ => {}
-        }
-        // 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);
+                let transform =
+                    Affine::translate((self.viewport.rect.x0, self.viewport.rect.y0));
+                data.handle_event(ctx, event, transform, env);
+            }
+            if scroll_amount != 0.0 {
+                self.viewport.rect.y0 = 0.0_f64.max(self.viewport.rect.y0 + scroll_amount);
+                self.scroll_component
+                    .reset_scrollbar_fade(|d| ctx.request_timer(d), env);
+                ctx.request_paint();
+                ctx.set_handled();
             }
-            data.temporary_erasing = enable_temporary_erasing;
-        } else {
-            data.handle_event(ctx, event, env);
         }
+        // TODO: replace this by own handling of Wheel event (must be able to extend content size)
+        self.scroll_component
+            .handle_scroll(&mut self.viewport, ctx, event, env);
     }
 
     fn lifecycle(
         &mut self,
-        _ctx: &mut LifeCycleCtx,
+        ctx: &mut LifeCycleCtx,
-        _event: &LifeCycle,
+        event: &LifeCycle,
         _data: &CanvasState,
-        _env: &Env,
+        env: &Env,
     ) {
+        self.scroll_component.lifecycle(ctx, event, env);
     }
 
     fn update(
@@ -149,6 +200,7 @@ impl Widget<CanvasState> for CanvasWidget {
         //        ctx.request_paint_rect(e.bounding_box());
         //    }
         //} else {
+
         ctx.request_paint();
         //}
     }
@@ -177,12 +229,28 @@ impl Widget<CanvasState> for CanvasWidget {
         let size = ctx.size();
         let rect = size.to_rect();
 
+        ctx.clip(rect);
         ctx.fill(rect, &Color::WHITE);
+
+        let page_content_size = data.versioned_canvas.get().content_size();
+        self.viewport.rect = self.viewport.rect.with_size(size);
+        self.viewport.content_size = druid::Size::new(
+            self.viewport.rect.x1.max(page_content_size.width),
+            self.viewport.rect.y1.max(page_content_size.height),
+        );
+
+        ctx.save().unwrap();
+        ctx.transform(Affine::translate((
+            -self.viewport.rect.x0,
+            -self.viewport.rect.y0,
+        )));
         for element in data.versioned_canvas.get().elements().iter() {
             element.draw(ctx);
         }
+        ctx.restore().unwrap();
         if data.tool_ctx.needs_repaint() {
             data.tool_ctx.paint(ctx, env);
         }
+        self.scroll_component.draw_bars(ctx, &self.viewport, env);
     }
 }

src/widget/tool_ctx.rs

@@ -19,7 +19,7 @@ use crate::canvas::{Canvas, CanvasElement};
 use crate::history::VersionedCanvas;
 
 use druid::kurbo::BezPath;
-use druid::{Data, Env, Event, EventCtx, MouseButton, MouseEvent, PaintCtx};
+use druid::{Affine, Data, Env, Event, EventCtx, MouseButton, MouseEvent, PaintCtx};
 
 #[derive(Clone, Data)]
 pub enum CanvasToolState {
@@ -61,30 +61,34 @@ impl CanvasToolCtx {
 
     pub fn handle_event(
         &mut self,
-        ctx: &EventCtx,
+        ctx: &mut EventCtx,
         event: &Event,
-        mut vcanvas: &mut VersionedCanvas,
+        vcanvas: &mut VersionedCanvas,
+        transform: Affine,
         env: &Env,
     ) {
         match self.initial_params.tool_type() {
-            CanvasToolType::Pen => self.handle_pen_event(&ctx, &event, &mut vcanvas, &env),
+            CanvasToolType::Pen => self.handle_pen_event(ctx, event, vcanvas, transform, env),
-            CanvasToolType::Eraser => self.handle_erase_event(&ctx, &event, &mut vcanvas, &env),
+            CanvasToolType::Eraser => self.handle_erase_event(ctx, event, vcanvas, transform, env),
         }
     }
 
     pub fn handle_erase_event(
         &mut self,
-        _ctx: &EventCtx,
+        ctx: &mut EventCtx,
         event: &Event,
         vcanvas: &mut VersionedCanvas,
+        transform: Affine,
         _env: &Env,
     ) {
         match (&mut self.state, event) {
             (CanvasToolState::Idle, Event::MouseDown(mouse_event)) if pressed(mouse_event) => {
                 self.state = CanvasToolState::Erasing;
+                ctx.set_handled();
             }
             (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 eraser_rect =
+                    druid::Rect::from_center_size(transform * mouse_event.pos, (5.0, 5.0));
                 let old_elements = vcanvas.get().elements();
                 let mut new_elements = old_elements.clone();
                 new_elements.retain(|elem| {
@@ -101,9 +105,11 @@ impl CanvasToolCtx {
                         *canvas = Canvas::new_with_elements(new_elements);
                     });
                 }
+                ctx.set_handled();
             }
             (CanvasToolState::Erasing, Event::MouseUp(mouse_event)) if pressed(mouse_event) => {
                 self.state = CanvasToolState::Idle;
+                ctx.set_handled();
             }
             _ => {}
         }
@@ -111,9 +117,10 @@ impl CanvasToolCtx {
 
     pub fn handle_pen_event(
         &mut self,
-        _ctx: &EventCtx,
+        ctx: &mut EventCtx,
         event: &Event,
         vcanvas: &mut VersionedCanvas,
+        transform: Affine,
         _env: &Env,
     ) {
         match (&mut self.state, event) {
@@ -130,6 +137,7 @@ impl CanvasToolCtx {
                         },
                     };
                 }
+                ctx.set_handled();
             }
             (
                 CanvasToolState::DrawingFreehand {
@@ -142,6 +150,7 @@ impl CanvasToolCtx {
                     path.kurbo_path
                         .line_to((mouse_event.pos.x, mouse_event.pos.y));
                 }
+                ctx.set_handled();
             }
             (CanvasToolState::DrawingFreehand { .. }, Event::MouseUp(mouse_event)) if pressed(mouse_event) => {
                 vcanvas.update(move |canvas: &mut Canvas| {
@@ -149,10 +158,11 @@ impl CanvasToolCtx {
                     if let CanvasToolState::DrawingFreehand { current_path, .. } = current_state {
                         if let CanvasElement::Freehand {
                             mut path,
-                            mut thickness,
+                            thickness,
                             stroke_color,
                         } = current_path
                         {
+                            path.kurbo_path.apply_affine(transform);
                             canvas.add_element(CanvasElement::Freehand {
                                 path,
                                 thickness,
@@ -161,6 +171,7 @@ impl CanvasToolCtx {
                         }
                     }
                 });
+                ctx.set_handled();
             }
             _ => {}
         }