stiletto/src/main.rs

//  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::prelude::*;
use druid::{
    AppLauncher, Color, Data, Event, Lens, LensExt, LocalizedString, WidgetExt, WindowDesc,
};

use stiletto::canvas::Canvas;
use stiletto::canvas_tools::CanvasTool;
use stiletto::versioned_canvas::VersionedCanvas;

#[derive(Clone, Data, Lens)]
struct CanvasData {
    #[lens(name = "current_tool_lens")]
    current_tool: CanvasTool,
    elements: VersionedCanvas,
}

impl CanvasData {
    fn perform_undo(&mut self) {
        self.elements.undo();
    }

    fn perform_redo(&mut self) {
        self.elements.redo();
    }

    fn handle_tool_event(&mut self, event: &Event) {
        self.current_tool.handle_event(event, &mut self.elements);
    }
}

struct CanvasWidget;

impl Widget<CanvasData> for CanvasWidget {
    fn event(&mut self, _ctx: &mut EventCtx, event: &Event, data: &mut CanvasData, _env: &Env) {
        data.handle_tool_event(event);
    }

    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,
    ) {
        // TODO: Polish a bit this logic
        match (&old_data.current_tool, &data.current_tool) {
            (
                CanvasTool::Pen {
                    current_element: old_element,
                },
                CanvasTool::Pen {
                    current_element: new_element,
                },
            ) => {
                // the current_element is moved to the elements array, no need to repaint
                if old_element.is_some() && !new_element.is_some() {
                    return;
                }

                if new_element.is_some() {
                    if let Some(e) = new_element.as_ref() {
                        ctx.request_paint_rect(e.bounding_box());
                    }
                } else {
                    ctx.request_paint();
                }
            }
            (CanvasTool::Eraser { eraser_rect: _ }, CanvasTool::Eraser { eraser_rect }) => {
                // We just stopped erasing, no need to repaint
                if let Some(rect) = eraser_rect {
                    ctx.request_paint_rect(*rect);
                } else {
                    ctx.request_paint();
                }
            }
            _ => {
                // we just changed the canvas tool, there is no need to repaint
                return;
            }
        }
    }

    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().elements.iter() {
            element.draw(ctx);
        }

        match &data.current_tool {
            CanvasTool::Pen { current_element } => {
                if let Some(element) = &current_element {
                    element.draw(ctx);
                }
            }
            _ => {}
        }
    }
}

// Enum containing an entry for each canvas tool
// it is used to implement the radio group for selecting the tool
#[derive(Clone, Data, PartialEq)]
enum ToolType {
    Pen,
    Eraser,
}

// Make a CanvasTool of a given type
fn update_canvas_tool_from_type(tool: &mut CanvasTool, new_type: ToolType) {
    match new_type {
        ToolType::Pen => *tool = CanvasTool::new_pen(),
        ToolType::Eraser => *tool = CanvasTool::new_eraser(),
    }
}

// Get a ToolType from a CanvasTool
fn canvas_tool_type(tool: &CanvasTool) -> ToolType {
    match tool {
        CanvasTool::Pen { .. } => ToolType::Pen,
        CanvasTool::Eraser { .. } => ToolType::Eraser,
    }
}

fn build_ui() -> impl Widget<CanvasData> {
    use druid::widget::{Align, Button, CrossAxisAlignment, Flex, RadioGroup, SizedBox};

    let radio_group = RadioGroup::new(vec![("Pen", ToolType::Pen), ("Eraser", ToolType::Eraser)])
        .lens(CanvasData::current_tool_lens.map(canvas_tool_type, update_canvas_tool_from_type));
    // ^ We use a lens to make the radiogroup act only on the tool portion of data.
    // Actually we must also perform a conversion, between ToolType and CanvasTool,
    // that's why we perform a map on the lens.

    let toolbar = Flex::row()
        .cross_axis_alignment(CrossAxisAlignment::Center)
        .with_spacer(30.0)
        .with_child(
            Button::new("Undo").on_click(|_ctx, data: &mut CanvasData, _env| data.perform_undo()),
        )
        .with_child(
            Button::new("Redo").on_click(|_ctx, data: &mut CanvasData, _env| data.perform_redo()),
        )
        .with_child(radio_group);

    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(
            LocalizedString::new("custom-widget-demo-window-title").with_placeholder("Stiletto"),
        );
    let canvas_data = CanvasData {
        current_tool: CanvasTool::new_pen(),
        elements: VersionedCanvas::new(Canvas::new()),
    };
    AppLauncher::with_window(window)
        .use_simple_logger()
        .launch(canvas_data)
        .expect("launch failed");
}