blob: 20a53b0c7c9ee52b0982ebe4aaa445503ef5faaf [file] [log] [blame]
// 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 show the text 'Hello, world.' using the raw
// interface to the engine.
import 'dart:ui' as ui;
void beginFrame(Duration timeStamp) {
final double devicePixelRatio = ui.window.devicePixelRatio;
final ui.Size logicalSize = ui.window.physicalSize / devicePixelRatio;
final ui.ParagraphBuilder paragraphBuilder = ui.ParagraphBuilder(
ui.ParagraphStyle(textDirection: ui.TextDirection.ltr),
..addText('Hello, world.');
final ui.Paragraph paragraph =
..layout(ui.ParagraphConstraints(width: logicalSize.width));
final ui.Rect physicalBounds = & (logicalSize * devicePixelRatio);
final ui.PictureRecorder recorder = ui.PictureRecorder();
final ui.Canvas canvas = ui.Canvas(recorder, physicalBounds);
canvas.scale(devicePixelRatio, devicePixelRatio);
canvas.drawParagraph(paragraph, ui.Offset(
(logicalSize.width - paragraph.maxIntrinsicWidth) / 2.0,
(logicalSize.height - paragraph.height) / 2.0,
final ui.Picture picture = recorder.endRecording();
final ui.SceneBuilder sceneBuilder = ui.SceneBuilder()
// TODO(abarth): We should be able to add a picture without pushing a
// container layer first.
..addPicture(, picture)
// This function is the primary entry point to your application. The engine
// calls main() as soon as it has loaded your code.
void main() {
// The engine calls onBeginFrame whenever it wants us to produce a frame.
ui.PlatformDispatcher.instance.onBeginFrame = beginFrame;
// Here we kick off the whole process by asking the engine to schedule a new
// frame. The engine will eventually call onBeginFrame when it is time for us
// to actually produce the frame.