stiletto/src/widget/canvas.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 im::Vector;

use super::tool_ctx::{CanvasToolCtx};
use crate::canvas::Canvas;
use crate::{DocumentSnapshot, VersionedCanvas};

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);
        }
    }
}