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// Copyright 2019 The Druid Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//! An example of an animating widget. It is just a widget that
//! requests an animation frame when it needs to, and draws the frame in the
//! `paint` method.
//! Once the animation is over it simply stops requesting animation frames.
//! Usually we would put the state in the `Data`, but for things like animation
//! we don't. This is because the animation state is not useful to know for the
//! rest of the app. If this is something the rest of your widgets should know
//! about, you could put it in the `data`.
// On Windows platform, don't show a console when opening the app.
#![windows_subsystem = "windows"]
use std::f64::consts::PI;
use druid::kurbo::{Circle, Line};
use druid::widget::prelude::*;
use druid::{AppLauncher, Color, LocalizedString, Point, Vec2, WindowDesc};
struct AnimWidget {
t: f64,
}
impl Widget<()> for AnimWidget {
fn event(&mut self, ctx: &mut EventCtx, event: &Event, _data: &mut (), _env: &Env) {
match event {
Event::MouseDown(_) => {
self.t = 0.0;
ctx.request_anim_frame();
}
Event::AnimFrame(interval) => {
ctx.request_paint();
self.t += (*interval as f64) * 1e-9;
if self.t < 1.0 {
ctx.request_anim_frame();
} else {
// We might have t>1.0 at the end of the animation,
// we want to make sure the line points up at the
// end of the animation.
self.t = 0.0;
}
}
_ => (),
}
}
fn lifecycle(&mut self, _ctx: &mut LifeCycleCtx, _event: &LifeCycle, _data: &(), _env: &Env) {}
fn update(&mut self, _ctx: &mut UpdateCtx, _old_data: &(), _data: &(), _env: &Env) {}
fn layout(
&mut self,
_layout_ctx: &mut LayoutCtx,
bc: &BoxConstraints,
_data: &(),
_env: &Env,
) -> Size {
bc.constrain((100.0, 100.0))
}
fn paint(&mut self, ctx: &mut PaintCtx, _data: &(), _env: &Env) {
let t = self.t;
let center = Point::new(50.0, 50.0);
ctx.paint_with_z_index(1, move |ctx| {
let ambit = center + 45.0 * Vec2::from_angle((0.75 + t) * 2.0 * PI);
ctx.stroke(Line::new(center, ambit), &Color::WHITE, 1.0);
});
ctx.fill(Circle::new(center, 50.0), &Color::BLACK);
}
}
pub fn main() {
let window = WindowDesc::new(AnimWidget { t: 0.0 }).title(
LocalizedString::new("anim-demo-window-title")
.with_placeholder("You spin me right round..."),
);
AppLauncher::with_window(window)
.log_to_console()
.launch(())
.expect("launch failed");
}