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Merge pull request #1867 from abarth/raw_hello_world

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Add a raw hello_world that shows "Hello, world"
This commit is contained in:
Adam Barth 2016-02-13 19:41:10 -08:00
parent 00285bf2b2 1ab3d3a71c
commit d6f28faa04
3 changed files with 159 additions and 112 deletions
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136
examples/layers/raw/hello_world.dart
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@ -1,134 +1,48 @@
// Copyright 2015 The Chromium Authors. All rights reserved.
// Copyright 2016 The Chromium 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 put some pixels on the screen using the raw
// This example shows how to show the text 'Hello, world.' using using the raw
// interface to the engine.
import 'dart:ui' as ui;
import 'dart:typed_data';
import 'package:mojo/bindings.dart' as bindings;
import 'package:mojo/core.dart' as core;
import 'package:sky_services/pointer/pointer.mojom.dart';
ui.Color color;
ui.Picture paint(ui.Rect paintBounds) {
// First we create a PictureRecorder to record the commands we're going to
// feed in the canvas. The PictureRecorder will eventually produce a Picture,
// which is an immutable record of those commands.
ui.PictureRecorder recorder = new ui.PictureRecorder();
// Next, we create a canvas from the recorder. The canvas is an interface
// which can receive drawing commands. The canvas interface is modeled after
// the SkCanvas interface from Skia. The paintBounds establishes a "cull rect"
// for the canvas, which lets the implementation discard any commands that
// are entirely outside this rectangle.
ui.Canvas canvas = new ui.Canvas(recorder, paintBounds);
// The commands draw a circle in the center of the screen.
ui.Size size = paintBounds.size;
canvas.drawCircle(
size.center(ui.Point.origin),
size.shortestSide * 0.45,
new ui.Paint()..color = color
);
// When we're done issuing painting commands, we end the recording an receive
// a Picture, which is an immutable record of the commands we've issued. You
// can draw a Picture into another canvas or include it as part of a
// composited scene.
return recorder.endRecording();
}
ui.Scene composite(ui.Picture picture, ui.Rect paintBounds) {
// The device pixel ratio gives an approximate ratio of the size of pixels on
// the device's screen to "normal" sized pixels. We commonly work in logical
// pixels, which are then scalled by the device pixel ratio before being drawn
// on the screen.
void beginFrame(Duration timeStamp) {
final double devicePixelRatio = ui.window.devicePixelRatio;
ui.Rect sceneBounds = new ui.Rect.fromLTWH(
0.0,
0.0,
ui.window.size.width * devicePixelRatio,
ui.window.size.height * devicePixelRatio
);
// TODO(abarth): ui.window.size should be in physical units.
final ui.Size logicalSize = ui.window.size;
// This transform scales the x and y coordinates by the devicePixelRatio.
Float64List deviceTransform = new Float64List(16)
..[0] = devicePixelRatio
..[5] = devicePixelRatio
..[10] = 1.0
..[15] = 1.0;
final ui.ParagraphBuilder paragraphBuilder = new ui.ParagraphBuilder()
..addText('Hello, world.');
final ui.Paragraph paragraph = paragraphBuilder.build(new ui.ParagraphStyle())
..maxWidth = logicalSize.width
..layout();
// We build a very simple scene graph with two nodes. The root node is a
// transform that scale its children by the device pixel ratio. This transform
// lets us paint in "logical" pixels which are converted to device pixels by
// this scaling operation.
ui.SceneBuilder sceneBuilder = new ui.SceneBuilder(sceneBounds)
..pushTransform(deviceTransform)
final ui.Rect physicalBounds = ui.Point.origin & (logicalSize * devicePixelRatio);
final ui.PictureRecorder recorder = new ui.PictureRecorder();
final ui.Canvas canvas = new ui.Canvas(recorder, physicalBounds);
canvas.scale(devicePixelRatio, devicePixelRatio);
paragraph.paint(canvas, new ui.Offset(
(logicalSize.width - paragraph.maxIntrinsicWidth) / 2.0,
(logicalSize.height - paragraph.height) / 2.0
));
final ui.Picture picture = recorder.endRecording();
final ui.SceneBuilder sceneBuilder = new ui.SceneBuilder(physicalBounds)
// TODO(abarth): We should be able to add a picture without pushing a
// container layer first.
..pushClipRect(physicalBounds)
..addPicture(ui.Offset.zero, picture)
..pop();
// When we're done recording the scene, we call build() to obtain an immutable
// record of the scene we've recorded.
return sceneBuilder.build();
}
void beginFrame(Duration timeStamp) {
ui.Rect paintBounds = ui.Point.origin & ui.window.size;
// First, record a picture with our painting commands.
ui.Picture picture = paint(paintBounds);
// Second, include that picture in a scene graph.
ui.Scene scene = composite(picture, paintBounds);
// Third, instruct the engine to render that scene graph.
ui.window.render(scene);
}
// Pointer input arrives as an array of bytes. The format for the data is
// defined by pointer.mojom, which generates serializes and parsers for a
// number of languages, including Dart, C++, Java, and Go.
void handlePointerPacket(ByteData serializedPacket) {
// We wrap the byte data up into a Mojo Message object, which we then
// deserialize according to the mojom definition.
bindings.Message message = new bindings.Message(serializedPacket, <core.MojoHandle>[], serializedPacket.lengthInBytes, 0);
PointerPacket packet = PointerPacket.deserialize(message);
// The deserialized pointer packet contains a number of pointer movements,
// which we iterate through and process.
for (Pointer pointer in packet.pointers) {
if (pointer.type == PointerType.down) {
// If the pointer went down, we change the color of the circle to blue.
color = const ui.Color(0xFF0000FF);
// Rather than calling paint() synchronously, we ask the engine to
// schedule a frame. The engine will call onBeginFrame when it is actually
// time to produce the frame.
ui.window.scheduleFrame();
} else if (pointer.type == PointerType.up) {
// Similarly, if the pointer went up, we change the color of the circle to
// green and schedule a frame. It's harmless to call scheduleFrame many
// times because the engine will ignore redundant requests up until the
// point where the engine calls onBeginFrame, which signals the boundary
// between one frame and another.
color = const ui.Color(0xFF00FF00);
ui.window.scheduleFrame();
}
}
ui.window.render(sceneBuilder.build());
}
// This function is the primary entry point to your application. The engine
// calls main() as soon as it has loaded your code.
void main() {
// Print statements go either go to stdout or to the system log, as
// appropriate for the operating system.
print('Hello, world');
color = const ui.Color(0xFF00FF00);
// The engine calls onBeginFrame whenever it wants us to produce a frame.
ui.window.onBeginFrame = beginFrame;
// The engine calls onPointerPacket whenever it had updated information about
// the pointers directed at our app.
ui.window.onPointerPacket = handlePointerPacket;
// 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.

133
examples/layers/raw/touch_input.dart Normal file
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@ -0,0 +1,133 @@
// Copyright 2015 The Chromium 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 put some pixels on the screen using the raw
// interface to the engine.
import 'dart:ui' as ui;
import 'dart:typed_data';
import 'package:mojo/bindings.dart' as bindings;
import 'package:mojo/core.dart' as core;
import 'package:sky_services/pointer/pointer.mojom.dart';
ui.Color color;
ui.Picture paint(ui.Rect paintBounds) {
// First we create a PictureRecorder to record the commands we're going to
// feed in the canvas. The PictureRecorder will eventually produce a Picture,
// which is an immutable record of those commands.
ui.PictureRecorder recorder = new ui.PictureRecorder();
// Next, we create a canvas from the recorder. The canvas is an interface
// which can receive drawing commands. The canvas interface is modeled after
// the SkCanvas interface from Skia. The paintBounds establishes a "cull rect"
// for the canvas, which lets the implementation discard any commands that
// are entirely outside this rectangle.
ui.Canvas canvas = new ui.Canvas(recorder, paintBounds);
// The commands draw a circle in the center of the screen.
ui.Size size = paintBounds.size;
canvas.drawCircle(
size.center(ui.Point.origin),
size.shortestSide * 0.45,
new ui.Paint()..color = color
);
// When we're done issuing painting commands, we end the recording an receive
// a Picture, which is an immutable record of the commands we've issued. You
// can draw a Picture into another canvas or include it as part of a
// composited scene.
return recorder.endRecording();
}
ui.Scene composite(ui.Picture picture, ui.Rect paintBounds) {
// The device pixel ratio gives an approximate ratio of the size of pixels on
// the device's screen to "normal" sized pixels. We commonly work in logical
// pixels, which are then scalled by the device pixel ratio before being drawn
// on the screen.
final double devicePixelRatio = ui.window.devicePixelRatio;
ui.Rect sceneBounds = new ui.Rect.fromLTWH(
0.0,
0.0,
ui.window.size.width * devicePixelRatio,
ui.window.size.height * devicePixelRatio
);
// This transform scales the x and y coordinates by the devicePixelRatio.
Float64List deviceTransform = new Float64List(16)
..[0] = devicePixelRatio
..[5] = devicePixelRatio
..[10] = 1.0
..[15] = 1.0;
// We build a very simple scene graph with two nodes. The root node is a
// transform that scale its children by the device pixel ratio. This transform
// lets us paint in "logical" pixels which are converted to device pixels by
// this scaling operation.
ui.SceneBuilder sceneBuilder = new ui.SceneBuilder(sceneBounds)
..pushTransform(deviceTransform)
..addPicture(ui.Offset.zero, picture)
..pop();
// When we're done recording the scene, we call build() to obtain an immutable
// record of the scene we've recorded.
return sceneBuilder.build();
}
void beginFrame(Duration timeStamp) {
ui.Rect paintBounds = ui.Point.origin & ui.window.size;
// First, record a picture with our painting commands.
ui.Picture picture = paint(paintBounds);
// Second, include that picture in a scene graph.
ui.Scene scene = composite(picture, paintBounds);
// Third, instruct the engine to render that scene graph.
ui.window.render(scene);
}
// Pointer input arrives as an array of bytes. The format for the data is
// defined by pointer.mojom, which generates serializes and parsers for a
// number of languages, including Dart, C++, Java, and Go.
void handlePointerPacket(ByteData serializedPacket) {
// We wrap the byte data up into a Mojo Message object, which we then
// deserialize according to the mojom definition.
bindings.Message message = new bindings.Message(serializedPacket, <core.MojoHandle>[], serializedPacket.lengthInBytes, 0);
PointerPacket packet = PointerPacket.deserialize(message);
// The deserialized pointer packet contains a number of pointer movements,
// which we iterate through and process.
for (Pointer pointer in packet.pointers) {
if (pointer.type == PointerType.down) {
// If the pointer went down, we change the color of the circle to blue.
color = const ui.Color(0xFF0000FF);
// Rather than calling paint() synchronously, we ask the engine to
// schedule a frame. The engine will call onBeginFrame when it is actually
// time to produce the frame.
ui.window.scheduleFrame();
} else if (pointer.type == PointerType.up) {
// Similarly, if the pointer went up, we change the color of the circle to
// green and schedule a frame. It's harmless to call scheduleFrame many
// times because the engine will ignore redundant requests up until the
// point where the engine calls onBeginFrame, which signals the boundary
// between one frame and another.
color = const ui.Color(0xFF00FF00);
ui.window.scheduleFrame();
}
}
}
// This function is the primary entry point to your application. The engine
// calls main() as soon as it has loaded your code.
void main() {
color = const ui.Color(0xFF00FF00);
// The engine calls onBeginFrame whenever it wants us to produce a frame.
ui.window.onBeginFrame = beginFrame;
// The engine calls onPointerPacket whenever it had updated information about
// the pointers directed at our app.
ui.window.onPointerPacket = handlePointerPacket;
// 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.
ui.window.scheduleFrame();
}

2
examples/layers/rendering/hello_world.dart
View file

@ -14,7 +14,7 @@ void main() {
// child both vertically and horizontally.
root: new RenderPositionedBox(
alignment: const FractionalOffset(0.5, 0.5),
// We use a RenderParagraph to display the text "Hello, world." without
// We use a RenderParagraph to display the text 'Hello, world.' without
// any explicit styling.
child: new RenderParagraph(new PlainTextSpan('Hello, world.'))
)