积少成多Flash(7) - ActionScript 3.0 交互之鼠标事件和键盘事件

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积少成多Flash(7) - ActionScript 3.0 交互之鼠标事件和键盘事件

介绍

演示使用 Flash ActionScript 3.0 来监听用户的键盘事件和鼠标事件，并对其作相应的处理

键盘事件 - 在 flash.events.KeyboardEvent 类下。只有两个事件类型 KeyboardEvent.KEY_DOWN 和 KeyboardEvent.KEY_UP 。

鼠标事件 - 在 flash.events.MouseEvent 类下。常用的事件类型有 MouseEvent.MOUSE_DOWN, MouseEvent.DOUBLE_CLICK, MouseEvent.MOUSE_UP, MouseEvent.MOUSE_OVER, MouseEvent.MOUSE_MOVE 和 MouseEvent.MOUSE_OUT 等。

1、处理键盘事件

做 4 个只有两帧的 MovieClip 并放到 UI 上，分别用于提示上/下/左/右键的按键情况，默认情况下显示第一帧，当用户按下了对应的键时则显示第二帧。这 4 个 MovieClip 的名称分别为 btnUp, btnDown, btnLeft, btnRight

再在 UI 上画一个物体，由于显示用户的键盘事件（上/下/左/右）所产生的结果

Main.as

package 

{ 

        import flash.events.Event; 

        import flash.events.KeyboardEvent; 

        import flash.display.MovieClip; 

        import flash.ui.Keyboard; 

        import flash.events.MouseEvent; 

        public class Main extends MovieClip 

        { 

                // 保存用户是否按下了上/下/左/右键 

                public var isUp:Boolean = false; 

                public var isDown:Boolean = false; 

                public var isLeft:Boolean = false; 

                public var isRight:Boolean = false; 

                // 每次 ENTER_FRAME 物体所需移动的距离 

                public var step:Number = 5; 

                public function Main() 

                { 

                        // 设置四个用于显示方向的 MovieClip 的初始状态为停在第一帧 

                        btnUp.stop(); 

                        btnDown.stop(); 

                        btnLeft.stop(); 

                        btnRight.stop();                         

                        // 处理按键的按下、放开事件（在舞台上侦测该事件） 

                        stage.addEventListener(KeyboardEvent.KEY_DOWN, keyPressHandler); 

                        stage.addEventListener(KeyboardEvent.KEY_UP, keyReleaseHandler); 

                        // 用于响应按键事件的 ENTER_FRAME 

                        this.addEventListener(Event.ENTER_FRAME, enterFrameHandlerForKeyboard); 

                } 

                protected function keyPressHandler(event:KeyboardEvent):void 

                        // 检测用户按下的键 

                        switch (event.keyCode) 

                        { 

                                case Keyboard.UP:    

                                        isUp = true; 

                                        btnUp.gotoAndStop(2); 

                                        block.rotation = 0; 

                                        break; 

                                case Keyboard.DOWN: // 按的是“下”键 

                                        isDown = true; // 保存用户的按键信息。即用户正在按“下”键 

                                        btnDown.gotoAndStop(2); // 用于显示方向“下”的 MovieClip 停到第二帧 

                                        block.rotation = 180; // 物体旋转 180 度 

                                case Keyboard.LEFT: 

                                        isLeft = true; 

                                        btnLeft.gotoAndStop(2); 

                                        block.rotation = 270; 

                                case Keyboard.RIGHT: 

                                        isRight = true; 

                                        btnRight.gotoAndStop(2); 

                                        block.rotation = 90; 

                        } 

                protected function keyReleaseHandler(event:KeyboardEvent):void 

                        // 检测用户放开的键 

                        switch( event.keyCode ) 

                                case Keyboard.UP: // 按的是“上”键 

                                        isUp = false; // 保存用户的按键信息。即用户已经不再按“上”键了 

                                        btnUp.gotoAndStop(1); // 用于显示方向“上”的 MovieClip 停到第一帧 

                                case Keyboard.DOWN: 

                                        isDown = false; 

                                        btnDown.gotoAndStop(1); 

                                        isLeft = false; 

                                        btnLeft.gotoAndStop(1); 

                                        isRight = false; 

                                        btnRight.gotoAndStop(1); 

                protected function enterFrameHandlerForKeyboard(event:Event):void 

                        // 根据用户的按键情况。将物体向上/下/左/右移动指定的距离 

                        if (isLeft)    

                                block.x -= step; 

                        if (isRight)    

                                block.x += step; 

                        if (isUp)    

                                block.y -= step; 

                        if (isDown)    

                                block.y += step; 

        } 

}

2、处理鼠标事件

在 UI 上画一个物体，由于显示用户的鼠标事件所产生的结果，即该物体会向用户在舞台上所单击的位置移动

                // 鼠标单击位置的坐标 

                public var targetX:Number = 0; 

                public var targetY:Number = 0; 

                // 物体是否再向鼠标单击的位置移动 

                public var moving:Boolean = false; 

                        // 处理鼠标的按下事件（在舞台上侦测该事件） 

                        stage.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler); 

                        // 用于响应鼠标按下事件的 ENTER_FRAME 

                        this.addEventListener(Event.ENTER_FRAME, enterFrameHandlerForMouse); 

                protected function mouseDownHandler(event:MouseEvent):void 

                        // 当用户在舞台上按下鼠标后，获取鼠标的坐标 

                        targetX = event.stageX; 

                        targetY = event.stageY; 

                        // 物体正在向鼠标单击的位置移动 

                        moving = true; 

                }                 

                protected function enterFrameHandlerForMouse(event:Event):void 

                        if (moving) 

                                // 计算物体在 X 方向和 Y 方向上分别需要移动的距离 

                                var offsetX:Number = block.x - targetX; 

                                var offsetY:Number = block.y - targetY; 

                                // 计算物体需要旋转的角度 

                                var targetRotation:Number = -Math.atan2(offsetX, offsetY) / (Math.PI / 180); 

                                block.rotation = targetRotation; 

                                if( Math.sqrt((offsetX*offsetX) + (offsetY*offsetY)) &gt; step ) 

                                { 

                                        // 如果还没有移动到目标位，则继续移动指定的距离 

                                        block.y -= step * Math.cos(targetRotation * (Math.PI/180)); 

                                        block.x += step * Math.sin(targetRotation * (Math.PI/180)); 

                                } 

                                else 

                                        // 物体已经移动到鼠标所单击的位置 

                                        moving = false; 

OK

     本文转自webabcd 51CTO博客，原文链接：http://blog.51cto.com/webabcd/342199，如需转载请自行联系原作者