線條不畫到pixi.dart的畫布

Question

我以爲我有這段代碼需要繪製一條線，但似乎不是。我能指出我做錯了什麼/沒有做什麼嗎？

import 'dart:html'; 
import 'package:pixi/pixi.dart'; 

class BunnyExample 
{ 
    CanvasRenderer renderer = new CanvasRenderer(width: 400, height: 300); 
    Stage stage  = new Stage(new Colour.fromHtml('#ffffff')); 
    Graphics graph = new Graphics(); 

    BunnyExample() 
    { 
     document.body.append(this.renderer.view); 
     window.requestAnimationFrame(_lineAnim); 
    } 

    void _lineAnim(var num) 
    { 
     window.requestAnimationFrame(this._lineAnim); 
     graph 
     ..position = new Point(0, 0) 
     ..pivot = new Point(50, 50) 
     ..lineStyle(1,new Colour(255, 0, 0)) 
     ..beginFill(new Colour(255,0,0)) 
     ..lineTo(50, 70) 
     ..endFill(); 
     stage.children.add(graph); 
     renderer.render(stage); 
    } 
} 

void main() 
{ 
    new BunnyExample(); 
} 

Answer 1

看來你要調用moveTo()前lineTo()：

void _lineAnim(var num) 
{ 
    window.requestAnimationFrame(this._lineAnim); 
    graph 
    ..position = new Point(0, 0) 
    ..pivot = new Point(50, 50) 
    ..lineStyle(1,new Colour(255, 0, 0)) 
    ..beginFill(new Colour(255,0,0)) 
    ..moveTo(50, 50) 
    ..lineTo(50, 70) 
    ..endFill(); 
    renderer.render(stage); 
} 

而且，最好是設置舞臺的構造，也可以有內存泄漏：

BunnyExample() 
{ 
    stage.children.add(graph); //doing this in the animation loop leads to a memory leak 
    document.body.append(this.renderer.view); 
    window.requestAnimationFrame(_lineAnim); 
}