Flex坐标系统及转换

    

    这些天简单重新玩了一下Flex，感受觉坐标这块挺有意思，下面译一下关于坐标的文档

        flash和flex针对不同的目的，提供了3种不同的坐标系

          全局的就是(stage级别的)

          本地坐标系（组件级别的）

          内容坐标系（相对于本地坐标系说的）

    这些坐标系的点是可以转换的，并且有相应的方法，看来adobe想得挺周到。我们一个一个的说一下

   

    全局

           这个坐标系的原点在整个flash舞台的左上角，MouseEvent实例的stageX,stageY就是这个坐标系中的值，

    本地

        坐标原点是相对的组件的左上角，MouseEvent中的localX,localY就是相对这个坐标系说的，

    内容

        这个东西比较抽象了UIComponent类实例的contentMouseX 和 contentMouseY 就是了，这个主要针对有滚动条的组件说的，有滚动条了，内容肯定不少，内容所占的区域的坐标就是这个坐标系了。

下面有个官方的图说明了三个坐标系的关系及位置：

坐标转换还有现成的方法

contentMouseX	返回mouse的内容坐标x值
contentMouseY	返回mouse的内容坐标Y值
contentToGlobal	将内容坐标转换成全局坐标
contentToLocal	将内容坐标转换成内容坐标
globalToContent	将全局的转成内容坐标
globalToLocal	全局的转成本地的
localToContent	本地到内容坐标
localToGlobal	本地到全局坐标

 

 

下面是一个小例子

 

<?xml version="1.0"?>
<!-- containers/intro/MousePosition.mxml -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
    backgroundColor="white">
   
    <mx:Script>
        <![CDATA[
          import mx.controls.Alert;

          // Handle the mouseDown event generated
          // by clicking in the application.
          private function handleMouseDown(event:MouseEvent):void {
               
            // Convert the mouse position to global coordinates.
            // The localX and localY properties of the mouse event contain
            // the coordinates at which the event occurred relative to the
            // event target, typically one of the
            // colored internal Canvas controls.
            // A production version of this example could use the stageX
            // and stageY properties, which use the global coordinates,
            // and avoid this step.
            // This example uses the localX and localY properties only to
            // illustrate conversion between different frames of reference.
            var pt:Point = new Point(event.localX, event.localY);
            pt = event.target.localToGlobal(pt);
               
            // Convert the global coordinates to the content coordinates
            // inside the outer c1 Canvas control.
            pt = c1.globalToContent(pt);
              
            // Figure out which quadrant was clicked.
            var whichColor:String = "border area";
             
            if (pt.x < 150) {
                if (pt.y < 150)
                    whichColor = "red";
                else
                    whichColor = "blue";
            }
            else {
                if (pt.y < 150)
                    whichColor = "green";
                else
                    whichColor = "magenta";
            }
               
            Alert.show("You clicked on the " + whichColor);
          }
        ]]>
    </mx:Script>

    <!-- Canvas container with four child Canvas containers -->
    <mx:Canvas id="c1"
        borderStyle="none"
        width="300" height="300"
        mouseDown="handleMouseDown(event);">
       
        <mx:Canvas
            width="150" height="150"
            x="0" y="0"
            backgroundColor="red">
            <mx:Button label="I'm in Red"/>
        </mx:Canvas>
        <mx:Canvas
            width="150" height="150"
            x="150" y="0"
            backgroundColor="green">
            <mx:Button label="I'm in Green"/>
        </mx:Canvas>
        <mx:Canvas
            width="150" height="150"
            x="0" y="150"
            backgroundColor="blue">
            <mx:Button label="I'm in Blue"/>
        </mx:Canvas>
        <mx:Canvas
            width="150" height="150"
            x="150" y="150"
            backgroundColor="magenta">
            <mx:Button label="I'm in Magenta"/>
        </mx:Canvas>
    </mx:Canvas>
</mx:Application>

我想大概就这些了，有兴趣的大家再研究研究，一起学哦