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// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// This example shows how to perform a simple animation using the raw interface
// to the engine.
import 'dart:math' as math;
import 'dart:typed_data';
import 'dart:ui' as ui;
void beginFrame(Duration timeStamp) {
// The timeStamp argument to beginFrame indicates the timing information we
// should use to clock our animations. It's important to use timeStamp rather
// than reading the system time because we want all the parts of the system to
// coordinate the timings of their animations. If each component read the
// system clock independently, the animations that we processed later would be
// slightly ahead of the animations we processed earlier.
// PAINT
final ui.Rect paintBounds = ui.Offset.zero & (ui.window.physicalSize / ui.window.devicePixelRatio);
final ui.PictureRecorder recorder = ui.PictureRecorder();
final ui.Canvas canvas = ui.Canvas(recorder, paintBounds);
canvas.translate(paintBounds.width / 2.0, paintBounds.height / 2.0);
// Here we determine the rotation according to the timeStamp given to us by
// the engine.
final double t = timeStamp.inMicroseconds / Duration.microsecondsPerMillisecond / 1800.0;
canvas.rotate(math.pi * (t % 1.0));
canvas.drawRect(
const ui.Rect.fromLTRB(-100.0, -100.0, 100.0, 100.0),
ui.Paint()..color = const ui.Color.fromARGB(255, 0, 255, 0),
);
final ui.Picture picture = recorder.endRecording();
// COMPOSITE
final double devicePixelRatio = ui.window.devicePixelRatio;
final Float64List deviceTransform = Float64List(16)
..[0] = devicePixelRatio
..[5] = devicePixelRatio
..[10] = 1.0
..[15] = 1.0;
final ui.SceneBuilder sceneBuilder = ui.SceneBuilder()
..pushTransform(deviceTransform)
..addPicture(ui.Offset.zero, picture)
..pop();
ui.window.render(sceneBuilder.build());
// After rendering the current frame of the animation, we ask the engine to
// schedule another frame. The engine will call beginFrame again when its time
// to produce the next frame.
ui.window.scheduleFrame();
}
void main() {
ui.window.onBeginFrame = beginFrame;
ui.window.scheduleFrame();
}