AS3 CookBook学习整理(三)
1. 在可视化对象列表中添加项目
Flash Player 现在把ActionScript 虚拟机(AVM)和渲染引擎两块功能集成在一起了。AVM 完成执行ActionScript 代码，而渲染引擎负责在屏幕上绘制对象，绘制对象需要两步骤：通过ActionScript引擎创建可视化对象。渲染引擎把可视化对象绘制在屏幕上
AVM中创建了一个可视化对象后，并没有绘制在屏幕上，因为它还不存在于渲染引擎里，要把它放到渲染引擎里需要添加该对象到可视化对象列表，通过调用DisplayObjectContainer实例的addChild()或addChildAt()方法添加
package {
import flash.display.Shape;
import flash.display.Sprite;
public class Sample1120 extends Sprite
{
public function Sample1120()
{
var red:Shape = new Shape();
var green:Shape = new Shape();
var blue:Shape = new Shape();
red.graphics.beginFill(0xFF0000);
red.graphics.drawCircle(10,20,10);
red.graphics.endFill();
green.graphics.beginFill(0x00FF00);
green.graphics.drawCircle(15,25,10);
green.graphics.endFill();
blue.graphics.beginFill(0x0000FF);
blue.graphics.drawCircle(20,20,10);
blue.graphics.endFill();
stage.addChild(red);
stage.addChild(green);
stage.addChildAt(blue,2);
//下面演示重复添加同一对象
//var container1:Sprite = new Sprite();
//container1.addChild(red);
//container1.addChild(green);
//container1.addChild(blue);
//this.addChild(container1);
//var container2:Sprite = new Sprite();
//container2.addChild(red);
//this.addChild(container2);
}
}
}
2. 在可视化对象列表中删除项目
使用DisplayObectContainer类的removeChild()和removeChildAt()方法
package {
import flash.display.DisplayObjectContainer;
import flash.display.Sprite;
import flash.text.TextField;
public class Sample1120 extends Sprite
{
public function Sample1120()
{
this.addChild(new TextField());
this.addChild(new TextField());
this.addChild(new TextField());
trace("删除前："+this.numChildren);
RemoveAllElement(this);
trace("删除后："+this.numChildren);
}
private function RemoveAllElement(container:DisplayObjectContainer):void
{
var length:int = container.numChildren;
for(var i:int=0;i<length;i++)
{
this.removeChildAt(0);
}
}
}
}
3. 在可视化对象列表中移动对象位置
使用DisplayObectContainer类的setChildIndex()方法改变项目的位置，getChildIndex()和getChildAt()方法得到项目在显示列表中的位置。getChildIndex()返回当前对象的索引，getChildAt()返回当前对象的引用
package {
import flash.display.Shape;
import flash.display.Sprite;
import flash.events.MouseEvent;
public class Sample1120 extends Sprite
{
public function Sample1120()
{
var arrColor:Array = [0xFF0000,0x00FF00,0x0000FF,0xFFFF00,0x00FFFF];
stage.addEventListener(MouseEvent.CLICK,OnClick);
for(var i:int=0; i<arrColor.length;i++)
{
var shape:Shape = AddElement(arrColor[i]);
shape.x = i*3+20;
shape.y = 20;
}
}
private function AddElement(color:int):Shape
{
var shape:Shape = new Shape();
shape.graphics.beginFill(color);
shape.graphics.drawCircle(10,10,30);
shape.graphics.endFill();
this.addChild(shape);
return shape;
}
private function OnClick(event:MouseEvent):void
{
this.setChildIndex(this.getChildAt(0),this.numChildren-1);
}
}
}
4. 创建自定义可视化类
继承DisplayObject 或它的子类来创建新类
package {
import flash.display.Shape;
import flash.display.Sprite;
public class Sample1121 extends Sprite
{
public function Sample1121()
{
var _circle:Circle = new Circle(0xFF0000,80);
_circle.x = 100;
_circle.y = 100;
addChild(_circle);
}
}
}
import flash.display.Shape;
internal class Circle extends Shape
{
private var _color:uint;
private var _radius:uint;
public function Circle(color:uint=0x000000,radius:uint=10)
{
_color = color;
_radius = radius;
Draw();
}
private function Draw():void
{
graphics.beginFill(_color);
graphics.drawCircle(0,0,_radius);
graphics.endFill();
}
}
5. 创建简单的按钮
创建SimpleButton 类实例和创建upState,downState,overState和hitTestState等对象。当用户点击按钮时用click事件激活方法
package {
import flash.display.Sprite;
public class Sample1124 extends Sprite
{
public function Sample1124()
{
var button1:MyButton = new MyButton( "Button 1", 100, 20 );
button1.x = 20;
button1.y = 20;
var button2:MyButton = new MyButton( "Button 2", 100, 30 );
button2.x = 180;
button2.y = 20;
var button3:MyButton = new MyButton( "Button 3", 100, 40 );
button3.x = 340;
button3.y = 20;
addChild( button1 );
addChild( button2 );
addChild( button3 );
}
}
}
import flash.display.SimpleButton;
import flash.display.Sprite;
import flash.display.Shape;
import flash.filters.DropShadowFilter;
import flash.text.TextField;
import flash.text.TextFormat;
import flash.text.TextFormatAlign;
internal class MyButton extends SimpleButton
{
private var _text:String;
private var _width:Number;
private var _height:Number;
public function MyButton(text:String,width:Number,height:Number)
{
this._text = text;
this._width = width;
this._height = height;
this.upState = CreateUpState();
this.downState = CreateDownState();
this.overState = CreateOverState();
this.hitTestState = upState;
}
private function CreateUpState():Sprite
{
var sprite:Sprite = new Sprite();
var background:Shape = CreateColoredRectangle(0x33FF66);
var text:TextField = CreateTextField(false);
sprite.addChild(background);
sprite.addChild(text);
return sprite;
}
private function CreateDownState():Sprite
{
var sprite:Sprite = new Sprite();
var background:Shape = CreateColoredRectangle(0xCCCCCC);
var text:TextField = CreateTextField(,true);
sprite.addChild(background);
sprite.addChild(text);
return sprite;
}
private function CreateOverState():Sprite
{
var sprite:Sprite = new Sprite();
var background:Shape = CreateColoredRectangle(0x70FF94);
var text:TextField = CreateTextField(false);
sprite.addChild(background);
sprite.addChild(text);
return sprite;
}
private function CreateColoredRectangle(color:uint):Shape
{
var rect:Shape = new Shape();
rect.graphics.lineStyle(1,0x000000);
rect.graphics.beginFill(color);
rect.graphics.drawRoundRect(0,0,_width,_height,10)//最后那个参数，值越大，越接近椭圆
rect.graphics.endFill();
rect.filters = [new DropShadowFilter(2)]//滤镜
return rect;
}
private function CreateTextField(downState:Boolean):TextField
{
var textField:TextField = new TextField();
textField.text = _text;
textField.width = _width;
var format:TextFormat = new TextFormat();
format.align = TextFormatAlign.CENTER;
textField.setTextFormat(format);
//垂直居中
textField.y = (_height - textField.textHeight)/2;
textField.y -= 2;//Subtract 2 pixels to adjust for offset
if(downState)
{
textField.x += 1;
textField.y += 1;
}
return textField;
}
}
6. 动态载入外部图片
使用新的Loader类载入图片(jpg，png，gif)，load()方法下载图片或.swf文件，它需要一个URLRequest 对象作为参数，该对象指定一个需要下载资源的URL。
flash.display.Loader 类非常类似于flash.net.URLLoader 类。不同的是Loader实例能载入外部图片和flash，在传输数据方面URLLoader更有用些。
载入外部内容需要三个步骤：
创建Loader 类实例
把Loader 实例加到显示列表里
调用load( )方法载入外部内容
Loader实例的contentLoaderInfo属性会对不同的情况作出不同的反应事件。contentLoaderInfo 属性是flash.display.LoaderInfo 类实例，用来提供目标被载入时的信息，下面是LoaderInfo 类的一些有用的事件：
open
当资源开始下载时触发
progress
资源在下载中时触发
complete
当资源下载完成时触发
init
当载入外部的.swf初始化时触发
httpStatus
当载入外部资源的HTTP请求产生状态代码错误时触发
ioError
当一个错误导致下载被终止时触发，比如找不到相应资源
securityError
当试图读取安全沙漏以外的数据时触发
unload
当unload( )方法被调用或移除载入的内容时或再次调用load( )方法时都会触发该事件
package {
import flash.display.Loader;
import flash.display.Sprite;
import flash.events.Event;
import flash.events.ProgressEvent;
import flash.net.URLRequest;
import flash.text.TextField;
public class Sample1127 extends Sprite
{
private var label:TextField;
public function Sample1127()
{
var loader:Loader = new Loader();
this.addChild(loader);
loader.contentLoaderInfo.addEventListener(Event.OPEN,OnOpened);
loader.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS,OnProgressing);
loader.contentLoaderInfo.addEventListener(Event.COMPLETE,OnCompleted);
loader.load(new URLRequest("http://www.baidu.com/img/baidu_logo.gif"));
}
private function OnOpened(event:Event):void
{
label = new TextField();
this.addChild(label);
}
private function OnProgressing(event:ProgressEvent):void
{
label.text = parseInt((event.bytesLoaded/event.bytesTotal*100).toString())+"%";
}
private function OnCompleted(event:Event):void
{
this.removeChild(label);
}
}
}
7. 载入外部swf文件并与之交互
使用Loader类载入.swf 文件，然后通过Loader实例的content属性访问被引入对象的实例
主swf文件：
package {
import flash.display.Loader;
import flash.display.Sprite;
import flash.events.Event;
import flash.net.URLRequest;
public class Sample1128 extends Sprite
{
public function Sample1128()
{
var loader:Loader = new Loader();
loader.contentLoaderInfo.addEventListener(Event.INIT,OnInit);
this.addChild(loader);
loader.load(new URLRequest("Sub1rr128.swf"));
}
private function OnInit(event:Event):void
{
trace(event.target.content);//打印出：object Sub1128 (被导入的对象)
var movie:Object = event.target.content;
trace(movie.GetColor());
movie.SetColor(0xFFFF00);
}
}
}
被引用swf文件：
package
{
import flash.display.Shape;
import flash.display.Sprite;
public class Sub1128 extends Sprite
{
private var _color:uint = 0x000000;
private var _circle:Shape;
public function Sub1128()
{
DisplayCircle();
}
private function DisplayCircle():void
{
if(_circle==null)
{
_circle = new Shape();
this.addChild(_circle);
}
_circle.graphics.clear();
_circle.graphics.beginFill(_color);
_circle.graphics.drawCircle(100,100,40);
_circle.graphics.endFill();
}
public function GetColor():uint
{
return _color;
}
public function SetColor(color:uint):void
{
_color = color;
DisplayCircle();
}
}
}
8. 理解this,root,parent
如下图所示，处在最顶层的是stage对象，而我们一般在文档里声明的this，其实在层级关系里处于第二层。而在文档里声明的root，则指向文档类(第二层)，可以通过root.parent得到stage对象
package {
import flash.display.Sprite;
import flash.events.MouseEvent;
import flash.text.TextField;
public class Sample1209 extends Sprite
{
private var lblMain:TextField = new TextField();
private var lblSub:TextField = new TextField();
public function Sample1209()
{
trace(this); //object Sample1209
trace(root); //object Sample1209
trace(this.parent);//object Stage
trace(root.parent);//object Stage
}
}
}
9. 得到当前坐标值
使用DisplayObject实例的只读属性mouseX和mouseY检查鼠标相对位置，或者MouseEvent事件的localX和localY属性
package {
import flash.display.Sprite;
import flash.events.MouseEvent;
import flash.text.TextField;
import flash.text.TextFieldAutoSize;
[SWF(backgroundColor="#004D84")]
public class Sample1209 extends Sprite
{
private var lblMain:TextField;
private var lblSub:TextField;
private var rect:Sprite;
public function Sample1209()
{
this.lblMain = new TextField();
lblMain.autoSize = TextFieldAutoSize.CENTER;
this.addChild(lblMain);
this.lblSub = new TextField();
lblSub.autoSize = TextFieldAutoSize.CENTER;
lblSub.y = 40;
this.addChild(lblSub);
this.rect = new Sprite();
rect.graphics.beginFill(0xFFFF00);
rect.graphics.drawRect(0,0,200,100);
rect.graphics.endFill();
rect.addEventListener(MouseEvent.MOUSE_MOVE,rect_OnMouseMove);
rect.x = 30;
rect.y = 60;
this.addChild(rect);
}
private function rect_OnMouseMove(event:MouseEvent):void
{
this.lblMain.text = "stage里的X是："+Math.round(this.mouseX)+",Y是："+Math.round(this.mouseY);
this.lblSub.text = "sprite里的X是："+Math.round(this.rect.mouseX)+",Y是："+Math.round(this.rect.mouseY);
//this.lblSub.text = "sprite里的X是："+Math.round(event.localX)+",Y是："+Math.round(event.localY);
}
}
}
10. 用鼠标拖拽对象
使用Sprite的startDrag()和stopDrag()来实现拖拽效果，同时使用dropTarget属性判断是否是目标位置
startDrag()有两个参数：
lockCenter
当为true时Sprite的中心被鼠标位置锁定，不管鼠标是否按下。当为false时只有鼠标点击它时Sprite才会跟着移动，默认为false
bounds
一个矩形范围来约束拖动，被拖动Sprite是不能超出这个范围，默认为null，意味着没有约束
一般会指定一个flash.geom.Rectangle作为被拖动元素的限制框。如果这个限制框和被拖动元素没有重合点(即不在一起)，则点击被拖动元素开始拖动时，会马上进入到限制框。
Sprite还有一个重要的方法：hitTestPoint(x,y,ShapeFlag)，它返回一个Boolean值，用来检测Sprite是否与指定的坐标点重合;
它接受三个参数：X坐标，Y坐标，ShapeFlag。其中X，Y为定义的坐标点。ShapeFlag用来指定是检测对象实际像素，还是边框实际像素。对于一个circle形状的Sprite，则这个参数就显得尤为重要，如果指定为true，则检测对象实际像素，只有当circle与点有重合，方法才会返回true。而指定为flase，则检测边框实际像素，此时只需要该circle的边框与点重合，则返回true(此时该circle可能并未到达该坐标点)。
直接使用Sprite的startDrag()和stopDrag()方法的确可以实现拖拽效果，但是有很多局限性。首先，Sprite的Drag受到FrameRate(画面更新率)的影响。如果FrameRate很低，则拖动效果会很不流畅。其次，一次只能拖动一个Sprite，无法实现同时拖动多个Sprite。
ascb里有一个DraggableSprite类(ascb.display.DraggableSprite)，扩展了Sprite的拖拽效果，使其不受到FrameRate的影响，且可同时拖动多个对象。但是在DraggableSprite里dropTarget属性不能用了，代替它的是getObjectsUnderPoint()方法，它返回鼠标位置下面的对象数组。索引为0为最底层元素(如果在stage上则为自身)，索引为length-1则为自身(因为它在最顶层)，索引为length-2则为最上层的容纳元素。
演示DraggableSprite类的getObjectsUnderPoint()方法：
package {
import ascb.display.DraggableSprite;
import flash.display.Sprite;
import flash.events.MouseEvent;
import flash.geom.Point;
import flash.text.TextField;
import flash.text.TextFieldAutoSize;
public class Sample1230 extends Sprite
{
private var label:TextField;
public function Sample1230()
{
var red:Sprite = new Sprite();
red.name = "red";
red.graphics.beginFill(0xFF0000);
red.graphics.drawRect(40,40,300,300);
red.graphics.endFill();
this.addChild(red);
var blue:Sprite = new Sprite();
blue.name = "blue";
blue.graphics.beginFill(0x0000FF);
blue.graphics.drawRect(80,80,200,200);
blue.graphics.endFill();
this.addChild(blue);
var yellow:Sprite = new Sprite();
yellow.name = "yellow";
yellow.graphics.beginFill(0xFFFF00);
yellow.graphics.drawRect(120,120,100,100);
yellow.graphics.endFill();
this.addChild(yellow);
var circle:DraggableSprite = new DraggableSprite();
circle.name = "circle";
circle.graphics.beginFill(0x00FF00);
circle.graphics.drawCircle(400,200,25);
circle.graphics.endFill();
circle.addEventListener(MouseEvent.MOUSE_DOWN,OnMouseDown);
circle.addEventListener(MouseEvent.MOUSE_UP,OnMouseUp);
this.addChild(circle);
label = new TextField();
label.autoSize = TextFieldAutoSize.CENTER;
label.text = "label";
this.addChild(label);
}
private function OnMouseDown(event:MouseEvent):void
{
var tmpSprite:DraggableSprite = event.target as DraggableSprite;
tmpSprite.drag();
}
private function OnMouseUp(event:MouseEvent):void
{
var tmpSprite:DraggableSprite = event.target as DraggableSprite;
tmpSprite.drop();
var arr:Array = getObjectsUnderPoint(new Point(mouseX,mouseY));
//this.label.text = arr[0].name; //当在stage上移动时，值是"circle"，否则为最底层元素
//this.label.text = arr[arr.length-1].name; //值为它自己，也为"circle"
this.label.text = arr[arr.length-2].name; //值为其最上层元素
}
}
}
综合示例：
package {
import ascb.display.DraggableSprite;
import flash.display.Sprite;
import flash.events.MouseEvent;
import flash.filters.DropShadowFilter;
import flash.geom.Point;
public class Sample1231 extends Sprite
{
private var curPoint:Point;
private var white:Sprite;
public function Sample1231()
{
var red:DraggableSprite = new DraggableSprite();
red.name = "red";
red.graphics.beginFill(0xFF0000);
red.graphics.drawCircle(40,40,20);
red.graphics.endFill();
red.addEventListener(MouseEvent.MOUSE_DOWN,OnMouseDown);
red.addEventListener(MouseEvent.MOUSE_UP,OnMouseUp);
this.addChild(red);
var yellow:DraggableSprite = new DraggableSprite();
yellow.name = "yellow";
yellow.graphics.beginFill(0xFFFF00);
yellow.graphics.drawCircle(40,100,20);
yellow.graphics.endFill();
yellow.addEventListener(MouseEvent.MOUSE_DOWN,OnMouseDown);
yellow.addEventListener(MouseEvent.MOUSE_UP,OnMouseUp);
this.addChild(yellow);
var blue:DraggableSprite = new DraggableSprite();
blue.name = "blue";
blue.graphics.beginFill(0x0000FF);
blue.graphics.drawCircle(40,160,20);
blue.graphics.endFill();
blue.addEventListener(MouseEvent.MOUSE_DOWN,OnMouseDown);
blue.addEventListener(MouseEvent.MOUSE_UP,OnMouseUp);
this.addChild(blue);
white = new Sprite();
white.graphics.beginFill(0xFFFFFF);
white.graphics.drawCircle(0,0,40);
white.x = 140;
white.y = 100;
white.graphics.endFill();
this.addChild(white);
}
private function OnMouseDown(event:MouseEvent):void
{
var tmpSprite:DraggableSprite = event.target as DraggableSprite;
this.setChildIndex(tmpSprite,this.numChildren-1);
tmpSprite.filters = [new DropShadowFilter()];
tmpSprite.drag();
curPoint = new Point(tmpSprite.x,tmpSprite.y);
}
private function OnMouseUp(event:MouseEvent):void
{
var tmpSprite:DraggableSprite = event.target as DraggableSprite;
tmpSprite.filters = null;
tmpSprite.drop();
var arr:Array = getObjectsUnderPoint(new Point(mouseX,mouseY));
var color:uint = 0xFFFFFF;
if(tmpSprite.name == "red")
{
color = 0xFF0000;
}
else if(tmpSprite.name == "yellow")
{
color = 0xFFFF00;
}
else if(tmpSprite.name == "blue")
{
color = 0x0000FF;
}
if(arr[arr.length-2]==white&&tmpSprite.hitTestPoint(white.x,white.y,,true))
{
white.graphics.clear();
white.graphics.beginFill(color);
white.graphics.drawCircle(0,0,40);
white.x = 140;
white.y = 100;
white.graphics.endFill();
this.addChild(white);
}
tmpSprite.x = curPoint.x;
tmpSprite.y = curPoint.y;
}
}
}